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The basement membrane (BM) is a layer of specialized extracellular matrix that surrounds normal prostate glands and preserves tissue integrity. Lack or discontinuity of the BM is a prerequisite for tumor cell invasion into interstitial spaces, thus favoring metastasis. Therefore, BM maintenance represents a barrier against cancer development and progression. In the study, we show that miR-205 participates in a network involving ΔNp63α, which is essential for maintenance of the BM in prostate epithelium. At the molecular level, ΔNp63α is able to enhance miR-205 transcription by binding to its promoter, whereas the microRNA can post-transcriptionally limit the amount of ΔNp63α protein, mostly by affecting ΔNp63α proteasomal degradation rather than through a canonical miRNA/target interaction. Functionally, miR-205 is able to control the deposition of laminin-332 and its receptor integrin-β4. Hence, pathological loss of miR-205, as widely observed in prostate cancer, may favor tumorigenesis by creating discontinuities in the BM. Here we demonstrate that therapeutic replacement of miR-205 in prostate cancer (PCa) cells can restore BM deposition and 3D organization into normal-like acinar structures, thus hampering cancer progression. [ABSTRACT FROM AUTHOR]

Epigenetic alterations my play a role in the aggressive behavior of Non-Small Cell Lung Cancer (NSCLC). Treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) has been reported to interfere with the proliferative and invasive potential of NSCLC cells. In addition, the DNA methyltransferase inhibitor azacytidine (AZA, vidaza) can modulate the levels of the metastasis suppressor KiSS-1. Thus, since cisplatin is still clinically available for NSCLC therapy, the aim of this study was to evaluate drug combinations between cisplatin and SAHA as well as AZA using cisplatin-sensitive H460 and -resistant H460/Pt NSCLC cells in relation to KiSS-1 modulation. An analysis of drug interaction according to the Combination-Index values indicated a more marked synergistic effect when the exposure to SAHA or AZA preceded cisplatin treatment with respect to a simultaneous schedule. A modulation of proteins involved in apoptosis (p53, Bax) was found in both sensitive and resistant cells, and compared to the treatment with epigenetic agents alone, the combination of cisplatin and SAHA or AZA increased apoptosis induction. The epigenetic treatments, both as single agents and in combination, increased the release of KiSS-1. Finally, the exposure of cisplatin-sensitive and -resistant cells to the kisspeptin KP10 enhanced cisplatin induced cell death. The efficacy of the combination of SAHA and cisplatin was tested in vivo after subcutaneous inoculum of parental and resistant cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies. These results, together with the available literature, support that epigenetic drugs are amenable for the combination treatment of NSCLC, including patients bearing cisplatin-resistant tumors. [ABSTRACT FROM AUTHOR]

A growing number of studies have suggested the involvement of long non-coding RNAs as the key players in not just the initiation and progression of the tumor microenvironment, but also in chemotherapy tolerance. In the present study, generated 5-FU-resistant SW480/DR cells were analyzed via cDNA microarray for its aberrant lncRNAs and mRNAs expression in comparison with the 5-FU-susceptible SW480/DS cells. Among the 126 lncRNAs described, lncRNAs GNAS-AS1, MIR205HG, and LOC102723721 have been identified to be significantly upregulated, while lncRNs lnc-RP11-597K23.2.1-2, LOC100507639, and CCDC144NL-AS1 have been found to be significantly downregulated. In the meantime, bioinformatic analysis through gene ontology studies of aberrantly expressed mRNAs revealed "regulated exocytosis", among others, as the biological process most impacted in SW480/DR cells. To investigate, exosome purification was then carried out and its characterization were validated via transmission electron microscopy and nanoparticle tracking analysis. Interestingly, it was determined that the 5-FU-resistant SW480/DR cells secretes significantly higher concentration of extracellular vesicles, particularly, exosomes when compared to the 5-FU-susceptible SW480/DS cells. Based on the lncRNA-mRNA interaction network analysis generated, lncRNA GNAS-AS1 and MIR205HG have been identified to be potentially involved in the incidence of 5-FU resistance in SW480 colon cancer cells through promoting increased release of exosomes into the intercellular matrix. Our study hopes not only to provide insights on the list of involved candidate lncRNAs, but also to elucidate the role exosomes play in the initiation and development of 5-FU chemotherapy resistance in colon cancer cells. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) represents one of the most prevalent malignant threats to women globally. Tumor relapse or metastasis is facilitated by BC stemness progression, contributing to tumorigenicity. Therefore, comprehending the characteristics of stemness progression and the underlying molecular mechanisms is pivotal for BC advancement. Hinokitiol (β-thujaplicin), a tropolone-related compound abundant in the heartwood of cupressaceous plants, exhibits antimicrobial activity. In our study, we employed three BC cell lines (MDA-MB-231, MCF-7, and T47D) to assess the expression of stemness-, apoptosis-, and autophagy-related proteins. Hinokitiol significantly reduced the viability of cancer cells in a dose-dependent manner. Furthermore, we observed that hinokitiol enhances apoptosis by increasing the levels of cleaved poly-ADP-ribose polymerase (PARP) and phospho-p53. It also induces dysfunction in autophagy through the upregulation of LC3B and p62 protein expression. Additionally, hinokitiol significantly suppressed the number and diameter of cancer cell line spheres by reducing the expression of cluster of differentiation44 (CD44) and key transcription factors. These findings underscore hinokitiol's potential as a therapeutic agent for breast cancer, particularly as a stemness-progression inhibitor. Further research and clinical studies are warranted to explore the full therapeutic potential of hinokitiol in the treatment of breast cancer. [ABSTRACT FROM AUTHOR]

Background: Cervical cancer (CC) causes more than 311,000 deaths annually worldwide. The integration of human papillomavirus (HPV) is a crucial genetic event that contributes to cervical carcinogenesis. Despite HPV DNA integration is known to disrupt the genomic architecture of both the host and viral genomes in CC, the complexity of this process remains largely unexplored. Results: In this study, we conducted whole-genome sequencing (WGS) at 55-65X coverage utilizing the PacBio long-read sequencing platform in SiHa and HeLa cells, followed by comprehensive analyses of the sequence data to elucidate the complexity of HPV integration. Firstly, our results demonstrated that PacBio long-read sequencing effectively identifies HPV integration breakpoints with comparable accuracy to targeted-capture Next-generation sequencing (NGS) methods. Secondly, we constructed detailed models of complex integrated genome structures that included both the HPV genome and nearby regions of the human genome by utilizing PacBio long-read WGS. Thirdly, our sequencing results revealed the occurrence of a wide variety of genome-wide structural variations (SVs) in SiHa and HeLa cells. Additionally, our analysis further revealed a potential correlation between changes in gene expression levels and SVs on chromosome 13 in the genome of SiHa cells. Conclusions: Using PacBio long-read sequencing, we have successfully constructed complex models illustrating HPV integrated genome structures in SiHa and HeLa cells. This accomplishment serves as a compelling demonstration of the valuable capabilities of long-read sequencing in detecting and characterizing HPV genomic integration structures within human cells. Furthermore, these findings offer critical insights into the complex process of HPV16 and HPV18 integration and their potential contribution to the development of cervical cancer. [ABSTRACT FROM AUTHOR]

Long-term administration of tyrosine kinase inhibitors (TKIs) used for the treatment of non-small cell lung cancer (NSCLC) induces TKI resistance in cells. The appearance of resistant cells requires the combined administration of another therapeutic agent and may cause side effects in the gastrointestinal and central nervous system. In previous studies, we found that derivatives of cilengitide, a cyclic Arg-Gly-Asp (RGD) peptide, exert NSCLC apoptotic and anti-epithelial-mesenchymal transition (EMT) effects. In particular, cRGDwV and cRGDyV, which are cyclic peptides containing aromatic amino acids, were found to inhibit NSCLC cell growth, TGF-ß1-induced EMT, and invasion. In this study, we confirmed the effects of cRGDwV and cRGDyV on proliferation, TGF-ß1-induced EMT marker expression, migration, and invasion in gefitinib-resistant NSCLC A549 (A549GR) cells. In A549GR cells, cRGDwV and cRGDyV showed inhibitory effects on the expression of mesenchymal marker expression, migration, and invasion. These results indicate that cyclic RGD peptides containing aromatic amino acids can be used to inhibit mesenchymal marker expression as well as migration and invasion in gefitinib-resistant cells. [ABSTRACT FROM AUTHOR]

Background/Aim: Chemotherapy resistance in triple-negative breast cancer (TNBC) cells is well documented. Therefore, it is necessary to develop safer and more effective therapeutic agents to enhance the outcomes of chemotherapeutic agents. The natural alkaloid sanguinarine (SANG) has demonstrated therapeutic synergy when coupled with chemotherapeutic agents. SANG can also induce cell cycle arrest and trigger apoptosis in various cancer cells. Materials and Methods: In this study, we investigated the molecular mechanism underlying SANG activity in MDA-MB- 231 and MDA-MB-468 cells as two genetically different models of TNBC. We employed various assays including Alamar Blue to measure the effect of SANG on cell viability and proliferation rate, Flow cytometry analysis to study the potential of the compound to induce apoptosis and cell cycle arrest, quantitative qRT PCR apoptosis array to measure the expression of different genes mediating apoptosis, and the western system was used to analyze the impact of the compound on AKT protein expression. Results: SANG lowered cell viability and disrupted cell cycle progression in both cell lines. Furthermore, S-phase cell cycle arrest-mediated apoptosis was found to be the primary contributor to cell growth inhibition in MDA-MB-231 cells. SANG-treated TNBC cells showed significantly up-regulated mRNA expression of 18 genes associated with apoptosis, including eight TNF receptor superfamily (TNFRSF), three members of the BCL2 family, and two members of the caspase (CASP) family in MDA-MB-468 cells. In MDA-MB-231 cells, two members of the TNF superfamily and four members of the BCL2 family were affected. The western study data showed the inhibition of AKT protein expression in both cell lines concurrent with up-regulated BCL2L11 gene. Our results point to the AKT/PI3K signaling pathway as one of the key mechanisms behind SANG-induced cell cycle arrest and death. Conclusion: SANG shows anticancer properties and apoptosis-related gene expression changes in the two TNBC cell lines and suggests AKT/PI3K pathway implication in apoptosis induction and cell cycle arrest. Thus, we propose SANG's potential as a solitary or supplementary treatment agent against TNBC. [ABSTRACT FROM AUTHOR]

Purpose: Selinexor is a novel XPO1 inhibitor which inhibits the export of tumor suppressor proteins and oncoprotein mRNAs, leading to cell-cycle arrest and apoptosis in cancer cells. While selinexor is currently FDA approved to treat multiple myeloma, compelling preclinical and early clinical studies reveal selinexor's efficacy in treating hematologic and non-hematologic malignancies, including sarcoma, gastric, bladder, prostate, breast, ovarian, skin, lung, and brain cancers. Current reviews of selinexor primarily highlight its use in hematologic malignancies; however, this review seeks to summarize the recent evidence of selinexor treatment in solid tumors. Methods: Pertinent literature searches in PubMed and the Karyopharm Therapeutics website for selinexor and non-hematologic malignancies preclinical and clinical trials. Results: This review provides evidence that selinexor is a promising agent used alone or in combination with other anticancer medications in non-hematologic malignancies. Conclusion: Further clinical investigation of selinexor treatment for solid malignancies is warranted. [ABSTRACT FROM AUTHOR]

Lung cancer is the most frequent type of cancer affecting both men and women globally, and it is associated with a high mortality rate. It is clinically treated with cisplatin, a platinum‐based drug that works by generating DNA lesions, which activates DNA damage response and induces cell death. However, chemoresistance by cancer cells limits the clinical usefulness of cisplatin as an anticancer drug. Here, we uncovered a role of ubiquitin‐specific protease 51 (USP51) in the chemosensitivity of lung cancer cells to cisplatin by regulating DNA damage response. USP51 was more upregulated in lung cancer tissues of chemotherapy‐resistant patients than those of chemotherapy‐sensitive patients with adjacent, nontumor tissues. USP51 overexpression in lung cancer cells in vitro reduced γ‐H2AX formation and promoted checkpoint kinase 1 (CHK1) phosphorylation, whereas USP51 knockdown showed opposite effects, indicating that USP51 played an important role in promoting DNA damage repair. Finally, USP51 knockdown weakened cisplatin resistance in A549/DDP cells and significantly suppressed tumor growth in vivo, suggesting that a USP51 inhibitor combined with cisplatin may be considered as an effective treatment strategy to eliminate drug‐resistant lung cancer cells. [ABSTRACT FROM AUTHOR]

The tumor necrosis factor (TNF) superfamily member TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells via death receptor (DR) activation with little toxicity to normal cells or tissues. The selectivity for activating apoptosis in cancer cells confers an ideal therapeutic characteristic to TRAIL, which has led to the development and clinical testing of many DR agonists. However, TRAIL/DR targeting therapies have been widely ineffective in clinical trials of various malignancies for reasons that remain poorly understood. Triple negative breast cancer (TNBC) has the worst prognosis among breast cancers. Targeting the TRAIL DR pathway has shown notable efficacy in a subset of TNBC in preclinical models but again has not shown appreciable activity in clinical trials. In this review, we will discuss the signaling components and mechanisms governing TRAIL pathway activation and clinical trial findings discussed with a focus on TNBC. Challenges and potential solutions for using DR agonists in the clinic are also discussed, including consideration of the pharmacokinetic and pharmacodynamic properties of DR agonists, patient selection by predictive biomarkers, and potential combination therapies. Moreover, recent findings on the impact of TRAIL treatment on the immune response, as well as novel strategies to address those challenges, are discussed. [ABSTRACT FROM AUTHOR]

Ovarian cancer (OC) is one of the most common gynecologic neoplasia and has the highest mortality rate, which is mainly due to late-stage diagnosis and chemotherapy resistance. There is an urgent need to explore new and better therapeutic strategies. We have previously described a family of Microtubule Destabilizing Sulfonamides (MDS) that does not trigger multidrug-mediated resistance in OC cell lines. MDS bind to the colchicine site of tubulin, disrupting the microtubule network and causing antiproliferative and cytotoxic effects. In this work, a novel microtubule-destabilizing agent (PILA9) was synthetized and characterized. This compound also inhibited OC cell proliferation and induced G2/M cell cycle arrest and apoptosis. Interestingly, PILA9 was significantly more cytotoxic than MDS. Here, we also analyzed the effect of these microtubule-destabilizing agents (MDA) in combination with Panobinostat, a pan-histone deacetylase inhibitor. We found that Panobinostat synergistically enhanced MDA-cytotoxicity. Mechanistically, we observed that Panobinostat and MDA induced α-tubulin acetylation and that the combination of both agents enhanced this effect, which could be related to the observed synergy. Altogether, our results suggest that MDA/Panobinostat combinations could represent new therapeutic strategies against OC. [ABSTRACT FROM AUTHOR]

In cancer cells, metabolic reprogramming is associated with an alteration of the O-GlcNAcylation homeostasis. This post-translational modification (PTM) that attaches O-GlcNAc moiety to intracellular proteins is dynamically and finely regulated by the O-GlcNAc Transferase (OGT) and the O-GlcNAcase (OGA). It is now established that O-GlcNAcylation participates in many features of cancer cells including a high rate of cell growth, invasion, and metastasis but little is known about its impact on the response to therapies. The purpose of this review is to highlight the role of O-GlcNAc protein modification in cancer resistance to therapies. We summarize the current knowledge about the crosstalk between O-GlcNAcylation and molecular mechanisms underlying tumor sensitivity/resistance to targeted therapies, chemotherapies, immunotherapy, and radiotherapy. We also discuss potential benefits and strategies of targeting O-GlcNAcylation to overcome cancer resistance. [ABSTRACT FROM AUTHOR]

Curcumin and related compounds are known for the large spectrum of activities. The chemical features of these compounds are important for their biological effects with a key role for the thiol-reactive α − β unsaturated carbonyl groups. Curcumin derivatives may overcome the limitation of the bioavailability of the parent compound, while maintaining the key chemical features responsible for biological activities. Curcumin and related compounds show anti-viral, anti-fungal, anti-microbial and anti-tumor activities. The therapeutic effects of curcumin, used as a supplement in cancer therapy, have been documented in various cancer types, in which inhibition of cell growth and survival pathways, induction of apoptosis and other cell death pathways have been reported. Curcumin-induced apoptosis has been linked both to the intrinsic and extrinsic apoptotic pathways. Necroptosis has also been involved in curcumin-induced toxicity. Among curcumin-induced effects, ferroptosis has also been described. The mechanism of curcumin toxicity can be triggered by reactive oxygen species-mediated endoplasmic reticulum stress. Curcumin targets have been identified in the context of the ubiquitin-proteasome system with evidence of inhibition of the proteasome proteolytic activities and cellular deubiquitinases. Curcumin has recently been shown to act on the tumor microenvironment with effects on cancer-associated fibroblasts and immune cells. The related product caffeic acid phenethyl ester has shown promising preclinical results with an effect on the inflammatory microenvironment. Here, we review the mechanisms underlying curcumin and derivatives toxicity towards cancer cells with particular emphasis on cell death pathways and the ubiquitin-proteasome system. [ABSTRACT FROM AUTHOR]

Cisplatin (CDDP) is currently employed for the treatment of several solid tumors, but cellular heterogeneity and the onset of drug resistance dictate that suitable biomarkers of CDDP sensitivity are established. Studies on triple-negative breast cancer (TNBC) have recently confirmed the involvement of gamma-glutamyltransferase 1 (GGT1), whose enzyme activity expressed at the cell surface favors the cellular resupply of antioxidant glutathione (GSH) thus offering cancer cells protection against the prooxidant effects of CDDP. However, an additional well-established mechanism depends on GGT1-mediated matabolism of extracellular GSH. It was in fact shown that glycyl-cysteine – the dipeptide originated by GGT1-mediated GSH metabolism at the cell surface – can promptly form adducts with exogenous CDDP, thus hindering its access to the cell, interactions with DNA and overall cytotoxicity. Both mechanisms: mainainance of intracellular GSH levels plus extracellular CDDP detoxication are likely concurring to determine GGT1-dependent CDDP resistance. [ABSTRACT FROM AUTHOR]

The human gonadotropin releasing hormone (GnRH-I) and its sea lamprey analogue GnRH-III specifically bind to GnRH receptors on cancer cells and can be used as targeting moieties for targeted tumor therapy. Considering that the selective release of drugs in cancer cells is of high relevance, we were encouraged to develop cleavable, self-immolative GnRH-III-drug conjugates which consist of a p-aminobenzyloxycarbonlyl (PABC) spacer between a cathepsin B-cleavable dipeptide (Val-Ala, Val-Cit) and the classical anticancer drugs daunorubicin (Dau) and paclitaxel (PTX). Alongside these compounds, non-cleavable GnRH-III-drug conjugates were also synthesized, and all compounds were analyzed for their antiproliferative activity. The cleavable GnRH-III bioconjugates revealed a growth inhibitory effect on GnRH receptor-expressing A2780 ovarian cancer cells, while their activity was reduced on Panc-1 pancreatic cancer cells exhibiting a lower GnRH receptor level. Moreover, the antiproliferative activity of the non-cleavable counterparts was strongly reduced. Additionally, the efficient cleavage of the Val-Ala linker and the subsequent release of the drugs could be verified by lysosomal degradation studies, while radioligand binding studies ensured that the GnRH-III-drug conjugates bound to the GnRH receptor with high affinity. Our results underline the high value of GnRH-III-based homing devices and the application of cathepsin B-cleavable linker systems for the development of small molecule drug conjugates (SMDCs). [ABSTRACT FROM AUTHOR]

Pirfenidone, an antifibrotic drug, has antitumor potential against different types of cancers. Our work explored whether pirfenidone sensitizes non-small cell lung cancer (NSCLC) cell lines to chemotherapeutic treatments. The cytotoxic effect of paclitaxel in combination with pirfenidone against three NSCLC cell lines (A549, NCI-H322 and NCI-H460) was evaluated using the sulforhodamine B assay. The effects of this combination on cell viability (trypan blue exclusion assay), proliferation (BrdU incorporation assay), cell cycle (flow cytometry following PI staining) and cell death (Annexin V-FITC detection assay and Western blot) were analyzed on the most sensitive cell line (NCI-H460). The cytotoxic effect of this drug combination was also evaluated against two non-tumorigenic cell lines (MCF-10A and MCF-12A). Finally, the ability of pirfenidone to sensitize NCI-H460 cells to a combination of paclitaxel plus carboplatin was assessed. The results demonstrated that pirfenidone sensitized NCI-H460 cells to paclitaxel treatment, reducing cell growth, viability and proliferation, inducing alterations in the cell cycle profile and causing an increase in the % of cell death. Remarkably, this combination did not increase cytotoxicity in non-tumorigenic cells. Importantly, pirfenidone also sensitized NCI-H460 cells to paclitaxel plus carboplatin. This work highlights the possibility of repurposing pirfenidone in combination with chemotherapy for the treatment of NSCLC. [ABSTRACT FROM AUTHOR]

Synthesis of tubulysin analogues, containing an N -methyl substituent on tubuvaline-amide together with the replacement of either the hydrophobic N -terminal N -methyl pipecolic acid (Mep) or at both N - and C - terminal peptides with available heteroaromatic acids and an unsaturated tubuphenylalanine moiety, respectively, were described. The in vitro cytotoxic activity by SRB assay on five cancer cell lines for sixteen tubulysins was evaluated. Among them, five analogues exhibited strong cytotoxic activities against five human cancer cell lines, including human breast carcinoma (MCF7), human colorectal adenocarcinoma (HT-29), HL-60, SW-480, human lung adenocarcinoma (A459). Interestingly, one analogue showed the strongest cytotoxicity on all five tested cell lines even much higher toxicity than the reference compound ellipticine. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor‐related apoptosis‐induced ligand (TRAIL) shows little or no toxicity in most normal cells and preferentially induces apoptosis in a variety of malignant cells. However, patients develop resistance to TRAIL, therefore, sensitizing agents that can sensitize the tumor cells to TRAIL‐mediated apoptosis are necessary. In this study, we investigated the effect of 2‐(3‐hydroxyphenyl)‐5‐methylnaphthyridin‐4‐one (CSC‐3436), an useful flavonoid, to overcome the TRAIL‐resistant triple negative breast cancer (TNBC) cells. We found that CSC‐3436 potentiated TRAIL‐induced apoptosis in TRAIL‐resistant TNBC cells and this correlated with the upregulation of death receptors (DR)‐5 and down‐regulation of decreased decoy receptor (DcR)‐1 expression. When examined for its mechanism, we found that the decreased expression of anti‐apoptotic proteins c‐FLIPS/L, Bcl‐Xl, Bcl‐2, Survivin, and XIAP. CSC‐3436 would increase the expression of Bax and promoted the cleavage of bid. In addition, the induction of DR5 by CSC‐3436 was found to be dependent on the modulation of reactive oxygen species (ROS)/p38/C/EBP‐homologous protein (CHOP) signaling pathways. Overall, our results indicated that CSC‐3436 could potentiate the apoptotic effects of TRAIL through down‐regulation of cell survival proteins and upregulation of DR5 via the ROS‐mediated upregulation of CHOP protein. [ABSTRACT FROM AUTHOR]

In human lung cancer progression, the EMT process is characterized by the transformation of cancer cells into invasive forms that migrate to other organs. Targeting to EMT-related molecules is emerging as a novel therapeutic approach for the prevention of lung cancer cell migration and invasion. Traf2- and Nck-interacting kinase (TNIK) has recently been considered as an anti-proliferative target molecule to regulate the Wnt signaling pathway in several types of cancer cells. In the present study, we evaluated the inhibitory effect of a tyrosine kinase inhibitor sunitinib and the integrin-αⅤβ3 targeted cyclic peptide (cRGDfK) on EMT in human lung cancer cells. Sunitinib strongly inhibited the TGF-β1-activated EMT through suppression of Wnt signaling, Smad and non-Smad signaling pathways. In addition, the cRGDfK also inhibited the expression of TGFβ1-induced mesenchymal marker genes and proteins. The anti-EMT effect of sunitinib was enhanced when cRGDfK was treated together. When sunitinib was treated with cRGDfK, the mRNA and protein expression levels of mesenchymal markers were decreased compared to the treatment with sunitinib alone. Co-treatment of cRGDfK has shown the potential to improve the efficacy of anticancer agents in combination with therapeutic agents that may be toxic at high concentrations. These results provide new and improved therapies for treating and preventing EMT-related disorders, such as lung fibrosis and cancer metastasis, and relapse. [ABSTRACT FROM AUTHOR]

One aim of cancer therapies is to induce apoptosis of tumor cells. Efficient removal of the apoptotic cells requires coordinated efforts between the processes of efferocytosis and LC3-associated phagocytosis (LAP). However, this activity has also been shown to produce anti-inflammatory and immunosuppressive signals that can be utilized by live tumor cells to evade immune defense mechanisms, resulting in tumor progression and aggressiveness. In the absence of LAP, mice exhibit suppressed tumor growth during efferocytosis, while LAP-sufficient mice show enhanced tumor progression. Little is known about how LAP or its regulators directly affect efferocytosis, tumor growth and treatment responses, and identifying the mechanisms involved has the potential to lead to the discovery of novel approaches to target cancer cells. Also incompletely understood is the direct effect of apoptotic cancer cells on LAP. This is particularly important as induction of apoptosis by current cytotoxic cancer therapies can potentially stimulate LAP following efferocytosis. Herein, we highlight the current understanding of the role of LAP and its relationship with efferocytosis in the tumor microenvironment with a view to presenting novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

As part of continuing our research on diverse C-7 derivatives of camptothecin (CPT), 16 CPT derivatives bearing piperazinyl-thiourea chemical scaffold and different substituent groups have been designed, synthesized and evaluated in vitro for cytotoxicity against five tumor cell lines (A-549, MDA-MB-231, MCF-7, KB and KBvin). As a result, all the synthesized compounds showed promising in vitro cytotoxic activity against the five tumor cell lines tested, and were more potent than irinotecan. Importantly, compounds 13 g (IC50 = 0.514 μM) and 13o (IC50 = 0.275 μM) possessed similar or better antiproliferative activity against the multidrug-resistant (MDR) KBvin subline than that of topotecan (IC50 = 0.511 μM) and merit further development as anticancer candidates for clinical trail. With these results in hand, we have a reason to conclude that incorporating piperazinyl-thiourea motifs into position-7 of camptothecin confers well cytotoxic activity against cancer cell lines, probably resulting in new anticancer drugs. [ABSTRACT FROM AUTHOR]

The transport through the nuclear pore complex is used by cancer cells to evade tumor-suppressive mechanisms. Several tumor-suppressors have been shown to be excluded from the cell nucleus in cancer cells by the nuclear export receptor CRM1 and abnormal expression of CRM1 is oncogenic. Inhibition of CRM1 has long been postulated as potential approach for the treatment of cancer and to overcome therapy resistance. Furthermore, the nuclear export of viral components mediated by the CRM1 is crucial in various stages of the viral lifecycle and assembly of many viruses from diverse families, including coronavirus. However, the first nuclear export inhibitors failed or never entered into clinical trials. More recently CRM1 reemerged as a cancer target and a successful proof of concept was achieved with the clinical approval of Selinexor. The chemical complexity of natural products is a promising perspective for the discovery of new nuclear export inhibitors with a favorable toxicity profile. Several screening campaigns have been performed and several natural product-based nuclear export inhibitors have been identified. With this review we give an overview over the role of CRM1-mediated nuclear export in cancer and the effort made to identify and develop nuclear export inhibitors in particular from natural sources. [ABSTRACT FROM AUTHOR]

In the last 15 years, pyridazinone derivatives have acquired extensive attention due to their widespread biological activities and pharmacological applications. Pyridazinones are well known for their anti-microbial, anti-viral, anti-inflammatory, anti-cancer, and cardiovascular activities, among others. In this study, we evaluated the anti-cancer activity of a new pyridazinone derivative and propose it as a potential anti-neoplastic agent in acute promyelocytic leukemia cells. Pyr-1 cytotoxicity was assessed on several human cancer and two non-cancerous cell lines by the DNS assay. Pyr-1 demonstrated potent cytotoxicity against 22 human cancer cell lines, exhibiting the most favorable selective cytotoxicity on leukemia (CEM and HL-60), breast (MDA-MB-231 and MDA-MB-468), and lung (A-549) cancer cell lines, when compared with non-cancerous breast epithelial MCF-10A cells. Analyses of apoptosis/necrosis pathways, reactive oxygen species (ROS) production, mitochondria health, caspase-3 activation, and cell cycle profile were performed via flow cytometry. Both hmox-1 RNA and protein expression levels were evaluated by quantitative real-time PCR and Western blotting assays, respectively. Pyr-1 induced apoptosis in acute promyelocytic leukemia cells as confirmed by phosphatidylserine externalization, mitochondrial depolarization, caspase-3 activation, DNA fragmentation, and disrupted cell cycle progression. Additionally, it was determined that Pyr-1 generates oxidative and proteotoxic stress by provoking the accumulation of ROS, resulting in the overexpression of the stress-related hmox-1 mRNA transcripts and protein and a marked increase in poly-ubiquitinated proteins. Our data demonstrate that Pyr-1 induces cell death via the intrinsic apoptosis pathway by accumulating ROS and by impairing proteasome activity. [ABSTRACT FROM AUTHOR]

Bortezomib (BTZ), a well‐established proteasome inhibitor used in the clinical therapy, leads the modulation of several biological alterations and in turn induces apoptosis. Although clinical trials with BTZ have shown promising results for some types of cancers, but not for some others, including those of the breast. The molecular basis of BTZ resistance in breast cancer remains elusive. In the present study, we found that cellular O‐GlcNAc modification was dramatically elevated by BTZ treatment in intrinsic resistant MCF‐7 and T47D cells, but not in sensitive MDA‐MB‐231 cells. A progressive increase in O‐GlcNAcylation characterized the increased acquired resistance of MDA‐MB‐231‐derived cells. We showed that elevated O‐GlcNAc subsequently modified breast cancer related pioneer factor FOXA1 and reduced its protein stability. Further, we demonstrated that FOXA1 attenuation was involved in transcriptional downregulation of proapoptotic Bim and thus suppressed breast cancer cell apoptosis. Finally, the combination of O‐GlcNAc inhibitor L01 to BTZ sensitized resistant cells. Our results have revealed a new regulatory mechanism that involves O‐GlcNAc elevation mediated Bim deficiency, which plays a key role in the apoptotic dysregulation and BTZ resistance in breast cancer cells. [ABSTRACT FROM AUTHOR]

Clinical trials of EGFR inhibitors in combination with gemcitabine for the treatment of pancreatic ductal adenocarcinoma (PDAC) have generated mixed results partially due to the poorly defined effectiveness of EGFR inhibitors in PDAC. Here, we studied a panel of PDAC cell lines to compare the IC50s of the EGFR inhibitors gefitinib and cetuximab. We found that gefitinib induced biphasic inhibition in over 50% of PDAC cells, with the initial growth inhibition occurring at nanomolar concentrations and a second growth inhibition occurring outside the clinical range. In contrast to gefitinib, cetuximab produced a single phase growth inhibition in a subset of PDAC cells. Using this sensitivity data, we screened for correlations between cell morphology proteins and EGFR ligands to EGFR inhibitor sensitivity, and found that mesothelin and the EGFR ligand TGF-α have a strong correlation to gefitinib and cetuximab sensitivity. Analysis of downstream signaling pathways indicated that plc-γ1 and c-myc were consistently inhibited by EGFR inhibitor treatment in sensitive cell lines. While an inconsistent additive effect was observed with either cetuximab or gefitinib in combination with gemcitabine, the cell pathway data indicated consistent ERK activation, leading us to pursue EGFR inhibitors in combination with trametinib, a MEK1/2 inhibitor. Both cetuximab and gefitinib in combination with trametinib produced an additive effect in all EGFR sensitive cell lines. Our results indicate that mesothelin and TGF-α can predict PDAC sensitivity to EGFR inhibitors and a combination of EGFR inhibitors with trametinib could be a novel effective treatment for PDAC. [ABSTRACT FROM AUTHOR]

Smac mimetics (SMs) are considered promising cancer therapeutics. However, the mechanisms responsible for mediating cell death by SMs are still only partly understood. Therefore, in this study, we investigated signaling pathways upon treatment with the bivalent SM BV6 using two SM-sensitive breast cancer cell lines as models. Interestingly, genetic silencing of transforming growth factor (TGF)β activated kinase (TAK)1, an upstream activator of the nuclear factor-kappaB (NF-κB) subunit RelA (p65), increased BV6-induced cell death only in EVSA-T cells, although it reduced BV6-mediated upregulation of tumor necrosis factor (TNF)α in both EVSA-T and MDA-MB-231 cells. By comparison, genetic silencing of p65, a key component of canonical NF-κB signaling, blocked BV6-induced cell death in MDA-MB-231 but not in EVSA-T cells. Similarly, knockdown of NF-κB-inducing kinase (NIK) rescued MDA-MB-231 cells from BV6-induced cell death, while it failed to do so in EVSA-T cells. Consistently, silencing of p65 or NIK reduced BV6-stimulated upregulation of TNFα in MDA-MB-231 cells. In conclusion, TAK1, receptor-interacting kinase 1 (RIPK1) as well as canonical and non-canonical NF-κB signaling are differentially involved in SM-induced cell death in breast cancer cells. These findings contribute to a better understanding of SM-induced signaling pathways. [ABSTRACT FROM AUTHOR]

Background/Aims: The ubiquitin proteasome system (UPS) is responsible for the degradation of most intracellular proteins, and proteasomal deubiquitinases (DUBs) have recently been highlighted as novel anticancer targets. It is well documented that copper complexes can inhibit UPS function through targeting both 20S proteasome and proteasomal DUBs. The antineoplastic activities of silver complexes have received much attention, but the exact mechanisms are not fully elucidated. In this study, we aim to investigate the effects of a novel silver complex [Ag(S2CN(C2H5)2)]6 (AgDT) on UPS function and its anticancer potential in non-small cell lung cancer (NSCLC). Methods: Cell viability assay (i.e., the MTS assay) and flow cytometry assay were used to analyze the cell viability and apoptosis. Proteasome inhibition was measured using 20S proteasome activity assay and 19S proteasomal DUBs activity assay. Western blot analysis and immunohistochemistry were performed to detect protein levels. The in vivo antitumor activity of AgDT was assessed with nude xenografts. Results: Silver ions, alone or in combination with disulfiram (DSF), induced UPS inhibition in NSCLC cells mainly through inhibition of proteasomal DUBs activities. Silver complex AgDT triggered intracellular accumulation of ubiquitinated proteins, and prevented the degradation of surrogate substrate GFPu. Mechanistically, AgDT potently inhibited the activities of proteasomal DUBs USP14 and UCHL5, without altering the 20S proteasome peptidases. Moreover, AgDT induced apoptosis in NSCLC cells and significantly inhibited tumor growth in xenografts. Conclusion: Our findings suggest that silver complex AgDT is a novel metal-based proteasomal DUBs inhibitor, and pharmacologic inhibition of USP14 and UCHL5 could prove to be an effective therapeutic strategy for NSCLC. [ABSTRACT FROM AUTHOR]

Inhibitor of Apoptosis Proteins (IAPs) is highly conserved negative regulators of apoptosis overexpressed in many cancer cells. Based on their endogenous antagonist, Smac/DIABLO, mimic compounds (Smac‐mimetics, SMs) have been developed to inhibit IAPs prosurvival activity, showing promising effects in advanced phases of clinical trials. Since different IAP homologs play distinctive roles in cancer cell survival and immunomodulation, SM‐induced apoptosis proceeds through diverse mechanisms. After binding to their BIR3 domain, SMs have been shown to rapidly induce auto‐ubiquitylation and degradation of cellular IAPs (cIAPs), thus leading to cell death mainly by activation of the noncanonical NF‐κB pathway. For this reason, we started the BIR3‐driven design of compounds selective for cIAP1 and with reduced affinity for X‐linked IAP (XIAP), in order to focus SMs antitumor activity on cIAPs degradation. In this work, we describe the crystal structures of the BIR3 domains of cIAP1 and XIAP, each in complex with a cIAP1‐selective SM (SM130 and SM114, respectively). The two SMs displayed 23‐ and 32‐fold higher affinity for cIAP1‐BIR3 over XIAP‐BIR3 in molecular displacement experiments based on fluorescence polarization. In vitro cell‐based assays confirmed that both selective SMs triggered apoptosis in cancer cells with different efficiencies by inducing caspases‐3, ‐8, and ‐9‐independent cIAP1 degradation. The design of cIAPs‐selective compounds represents an innovative approach in the field of anticancer drugs development, being useful to elucidate different prosurvival mechanisms and to reduce the adverse effects of pan‐IAPs compounds in cancer therapy. Database: Structural data are available in the Protein Data Bank database under the accession codes 6EXW (cIAP1‐BIR3/SM130 complex) and 6EY2 (XIAP‐BIR3/SM114 complex). [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are non-coding ~20 nucleotides long sequences that function in the initiation and development of a number of cancers. Ultrasound-targeted microbubble destruction (UTMD) is an effective method for microRNA delivery. The aim of the present study was to investigate the potential roles of UTMD-mediated miRNA (miR)-205 delivery in the development of prostate cancer (PCa). In the present study, miR-205 expression was examined by reverse transcription-quantitative polymerase chain reaction assay. miR-205 mimics were transfected into PC-3 cells using the UTMD method, and the PC-3 cells were also treated with cisplatin. Cell proliferation, apoptosis, migration and invasion abilities were detected using Cell Counting kit-8, flow cytometry, wound healing and Transwell assays, respectively. In addition, the protein expression levels of caspase-9, cleaved-caspase 9, cytochrome c (cytoc), epithelial (E)-cadherin, matrix metalloproteinase-9 (MMP-9), phosphorylated (p)-extracellular signal-regulated kinase (ERK) and ERK were measured by western blot analysis. The results of the present study demonstrated that miR-205 expression was low in human PCa cell lines compared with healthy cells and that UTMD-mediated miR-205 delivery inhibited PCa cell proliferation, migration and invasion, and promoted apoptosis modulated by cisplatin compared with UTMD-mediated miR-negative control group and miR-205-treated group. Furthermore, it was demonstrated that UTMD-mediated miR-205 transfection increased the expression of caspase-9, cleaved-caspase 9, cytochrome c and E-cadherin, and decreased the expression of MMP-9 and p-ERK. Therefore, UTMD-mediated miR-205 delivery may be a promising method for the treatment of PCa. [ABSTRACT FROM AUTHOR]

Background: Docetaxel-based chemotherapy failure in advanced prostate carcinoma has partly been attributed to the resistance of prostate cancer (PC) cells to docetaxel-induced apoptosis. Hence, there is an urgent need to identify mechanisms of docetaxel chemoresistance and to develop new combination therapies. Methods: miR-193a-5p level was evaluated by qPCR in prostate tissues and cell lines, and its expression in the tissues was also examined by in situ hybridization. PC cell line (PC3 cell) was transfected with miR-193a-5p mimic or its inhibitor, and then cell apoptosis and the expression of its downstream genes Bach2 and HO-1 were detected by TUNEL staining and Western blotting. Luciferase reporter assay was used to detect the effect of miR-193a-5p and Bach2 on HO-1 expression. Xenograft animal model was used to test the effect of miR-193a-5p and docetaxel on PC3 xenograft growth. Results: miR-193a-5p was upregulated in PC tissues and PC cell lines, with significant suppression of PC3 cell apoptosis induced by oxidative stress. Mechanistically, miR-193a-5p suppressed the expression of Bach2, a repressor of the HO-1 gene, by directly targeting the Bach2 mRNA 3'-UTR. Docetaxel treatment modestly decreased Bach2 expression and increased HO-1 level in PC3 cells, whereas a modest increase of HO-1 facilitated docetaxel-induced apoptosis. Notably, docetaxel-induced miR-193a-5p upregulation, which in turn inhibits Bach2 expression and thus relieves Bach2 repression of HO-1 expression, partly counteracted docetaxel-induced apoptosis, as evidenced by the increased Bcl-2 and decreased Bax expression. Accordingly, silencing of miR-193a-5p enhanced sensitization of PC3 cells to docetaxel-induced apoptosis. Finally, depletion of miR-193a-5p significantly reduced PC xenograft growth in vivo. Conclusions: Silencing of miR-193a-5p or blockade of the miR-193a-5p-Bach2-HO-1 pathway may be a novel therapeutic approach for castration-resistant PC. [ABSTRACT FROM AUTHOR]

Ovarian cancer is the most lethal disease among gynecological malignancies. More effective therapy is required to counter high recurrence rates and chemotherapy resistance. We investigated the efficacy and molecular mechanisms of three combined treatments (TCTs)--a novel histone deacetylase (HDAC) inhibitor OBP-801/YM753, 5-fluorouracil (5-FU), and paclitaxel (PTX)--in human ovarian cancer SKOV-3 and OVCAR-3 cells. The inhibition of cell growth was stronger with TCTs than with each single agent and with two combined treatments. The TCTs significantly induce G2 phase arrest in both cell lines. We then analyzed the molecular mechanisms and found that the TCTs increased the phosphorylation of p38 (Thr180/Tyr182), decreased the expression of CDC25C, and increased the phosphorylation of CDC2 (Tyr15), an inactive form of CDC2. To examine the responsibilities of the p38 pathway for G2 phase arrest induced by the TCTs, we employed the p38 inhibitor SB203580. SB203580 inhibited G2 phase arrest, suppression of CDC25C, and phosphorylation of CDC2 (Tyr15) induced by the TCTs. These results suggest that the TCTs can induce G2 phase arrest through activation of the p38 signaling pathway. We therefore believe that this combination is promising as a novel therapeutic strategy against ovarian cancer. [ABSTRACT FROM AUTHOR]

Tripentones represent an interesting class of compounds due to their significant cytotoxicity against different human tumor cells in the submicro-nanomolar range. New tripentone analogs, in which a pyridine moiety replaces the thiophene ring originating the fused azaindole system endowed with anticancer activity viz 8H-thieno[2,3-b]pyrrolizinones, were efficiently synthesized in four steps with fair overall yields (34-57%). All tripentone derivatives were tested in the range of 0.1-100 μM for cytotoxicity against two human tumor cell lines, HCT-116 (human colorectal carcinoma) and MCF-7 (human breast cancer). The most active derivative, with GI50 values of 4.25 μM and 20.73 μM for HCT-116 and MCF-7 cells, respectively, did not affect the viability of Caco-2 differentiated in normal intestinal-like cells, suggesting tumor cells as the main target of its cytotoxic action. The same compound was further investigated in order to study its mode of action. Results showed that it did not exert necrotic effects, while induced a clear shift of viable cells towards early apoptosis. Flow cytometric analysis demonstrated that this compound caused cell cycle alteration, inhibiting its progression in S and G2/M phases. [ABSTRACT FROM AUTHOR]

Background: The prognosis for patients with disseminated lung cancer is poor and current treatments have limited survival benefit as resistance often occurs, and is often associated with significant toxicity. A possible strategy to improve treatment and evade chemoresistance may be to find new combinations of drugs. The aim of this study was to analyze the potential of combining proteasome inhibitors (PIs) with chemotherapeutic drugs used in the routine treatment for lung cancer patients. Results: The median-effect method was applied to the Fluorometric Microculture Cytotoxicity Assay (FMCA) to evaluate effects of combining two different PIs (bortezomib and b-AP15) with clinically used chemotherapeutic drugs representing different mechanisms of action (cisplatin, gefitinib, gemcitabine and vinorelbine) in two lung cancer cell lines (one sensitive and one resistant). Proteasome inhibition in combination with cisplatin, gemcitabine or vinorelbine had synergistic effects in at least one of the tested cell lines. Furthermore, the effect of gefitinib appeared strongly potentiated by the PI in the least resistant lung cancer cell line, although the level of synergy could not be determined with the median-effect method. Conclusions: Combining PIs with cisplatin, gefitinib, gemcitabine or vinorelbine show potential as new combination chemotherapy for the treatment of lung cancer. [ABSTRACT FROM AUTHOR]

Human U three protein 14a (hUTP14a) binds p53 and promotes p53 degradation. Here, we report that hUTP14a plays an anti-apoptotic role in tumor cells through a p53-independent pathway. Knockdown of hUTP14a activated the intrinsic pathway of apoptosis and sensitized tumor cells to chemotherapeutic drug-induced apoptosis. In addition, the protein level of hUTP14a decreased upon chemotherapeutic drug- or irradiationinduced apoptosis. Importantly, the decrease of hUTP14a during induced apoptosis was not blocked by pan-caspase inhibitor z-VAD-FMK, indicating that the down-regulation of hUTP14a is an upstream event in apoptosis. Furthermore, ectopically expressed hUTP14a protected tumor cells from chemotherapeutic drug-induced apoptosis. In summary, our data showed that hUTP14a protected tumor cells from chemotherapeutic drug-induced apoptosis and thus might possess a potential as a target for anti-tumor therapy. [ABSTRACT FROM AUTHOR]

Cell-based assays in multiwell plates are widely used for radiosensitivity and chemosensitivity assessment with different mammalian cell types. Despite their relative ease of performance, such assays lack specificity as they do not distinguish between the cytostatic (reversible/sustained growth arrest) and cytotoxic (loss of viability) effects of genotoxic agents. We recently reported studies with solid tumor-derived cell lines demonstrating that radiosensitivity as measured by multiwell plate colorimetric (e.g., XTT) and fluorimetric (e.g., CellTiter-Blue) assays reflects growth arrest but not loss of viability. Herein we report similar observations with cancer cell lines expressing wild-type p53 (A549 lung carcinoma) or mutant p53 (MDA-MB-231 breast carcinoma) after treatment with the chemotherapeutic drug cisplatin. Importantly, we show that treatment of cancer cells with concentrations of cisplatin that result in 50% effect (i.e., IC50) in multiwell plate assays trigger the emergence of growth-arrested cells that exhibit highly enlarged morphology, remain viable and adherent to the culture dish, and metabolize the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) to its formazan derivative. The emergence of markedly enlarged viable cells complicates the interpretation of chemosensitivity data obtained with multiwell plate high throughput assays. Relying solely on IC50 values could be misleading. [ABSTRACT FROM AUTHOR]

MDL-12330A is a widely used adenylyl cyclase (AC) inhibitor that blocks AC/cAMP signaling. In this study, we demonstrated a novel antitumor activity of this drug in gastric carcinoma (GC) cell lines. In these GC cells, MDL-12330A reduced cell viability and induced cell death in a concentration-dependent manner. At a moderate concentration (∼20 μM), MDL-12330A mainly induced apoptotic death whereas at concentrations greater than 20 μM, it increased non-apoptotic cell death. The induction of apoptosis was at least partially regulated by CHOP-mediated DR5 upregulation, as detected by immunoblotting and gene interference assays. More importantly, low concentrations of MDL-12330A effectively enhanced recombinant human tumor necrosis factor (TNF)-related apoptosis-inducing ligand (rhTRAIL)- induced apoptosis and clonogenicity in these gastric cancer cells. This study demonstrates a possible role of MDL-12330A as a potential sensitizer to TRAIL, and suggests a novel therapeutic strategy targeting gastric cancer cells. [ABSTRACT FROM AUTHOR]

Loss of wild-type p53 function is widely accepted to be permissive for the development of multinucleated giant cells. However, whether therapy-induced multinucleation is associated with cancer cell death or survival remains controversial. Herein, we demonstrate that exposure of p53-deficient or p21WAF1 (p21)-deficient solid tumor-derived cell lines to ionizing radiation (between 2 and 8 Gy) results in the development of multinucleated giant cells that remain adherent to the culture dish for long times post-irradiation. Somewhat surprisingly, single-cell observations revealed that virtually all multinucleated giant cells that remain adherent for the duration of the experiments (up to three weeks post-irradiation) retain viability and metabolize 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT), and the majority (>60%) exhibit DNA synthesis. We further report that treatment of multinucleated giant cells with pharmacological activators of apoptosis (e.g., sodium salicylate) triggers their demise. Our observations reinforce the notion that radiation-induced multinucleation may reflect a survival mechanism for p53/p21-deficient cancer cells. With respect to evaluating radiosensitivity, our observations underscore the importance of single-cell experimental approaches (e.g., single-cell MTT) as the creation of viable multinucleated giant cells complicates the interpretation of the experimental data obtained by commonly-used multi-well plate colorimetric assays. [ABSTRACT FROM AUTHOR]

We have synthesized a novel derivative of Digitoxin, termed "MonoD", which demonstrates cytotoxic effects in lung cancer cells with much higher potency as compared to Digitoxin. Our data show that within 1 h of MonoD treatment, H460 cells showed increased oxidative stress, increased formation of autophagic vacuoles, and increased expression of pro-autophagic markers Beclin-1 and LC3-II. Cells pretreated with MnTBAP, a superoxide scavenger not only lowered superoxide production, but also had lower levels of LC3-II and Beclin-1. Prolonged treatment with MonoD-induced apoptosis in lung cancer cells. We investigated MonoD-dependent regulation of Akt and Bcl2, proteins that are known regulators of both autophagy and apoptosis. Molecular and pharmacologic inhibitors of Bcl2 and Akt, when combined with MonoD, led to higher expression of LC3-II and Beclin-1 as compared to MonoD alone, suggesting a repressive effect for these proteins in MonoD-dependent autophagy. Pretreatment of cells with an autophagy inhibitor repressed the apoptotic potential of MonoD, confirming that early autophagic flux is important to drive apoptosis. Therapeutic entities such as MonoD that target multiple pathways such as autophagy and apoptosis may prove advantageous over current therapies that have unimodal basis for action and may drive sustained tumor regression, which is highly desirable. [ABSTRACT FROM AUTHOR]

The synthesis of new 3-cyano-2-substituted pyridines bearing various pharmacophores and functionalities at position 2 is described. The synthesized compounds were evaluated for their in vitro anti-cancer activities on five cancer cell lines using 5-FU as reference compound. The results revealed that the benzohydrazide derivative 9a induced growth inhibition in human breast cancer cell line MCF-7 with an IC50 value of 2 μM and it showed lower cytotoxicity on MCF-12a normal breast epithelial cells. Additionally, 9a induced apoptotic morphological changes and induced apoptosis in MCF-7 in a dose and time-dependent manner according to an enzyme linked immunosorbent apoptosis assay which is further confirmed by a TUNEL assay. Flow cytometric analysis indicated that 9a arrested MCF-7 cells in the G1 phase, which was further confirmed by increased expression of p21 and p27 and reduced expression of CDK2 and CDK4. Western blot data revealed significant upregulation of the expression of p53, Bax, caspase-3 and down-regulation of Bcl-2, Mdm-2 and Akt. Additionally, 9a increased the release of cytochrome c from mitochondria to cytoplasm which provokes the mitochondrial apoptotic pathway while it showed no significant change on the expression of the death receptor proteins procaspase-8, caspase-8 and FAS. Furthermore, 9a reduced the expression of phospho AKT and -catenin in dose dependent manner while inhibiting the expression of migration-related genes such as matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF). Our findings suggest that compound 9a could be considered as a lead structure for further development of more potent apoptosis inducing agents with anti-metastatic activities. [ABSTRACT FROM AUTHOR]

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand- receptor (TRAIL-R) family has emerged as a key mediator of cell fate and survival. Ligation of TRAIL ligand to TRAIL-R1 or TRAIL-R2 initiates the extrinsic apoptotic pathway characterized by the recruitment of death domains, assembly of the death-inducing signaling complex (DISC), caspase activation and ultimately apoptosis. Conversely the decoy receptors TRAIL-R3 and TRAIL-R4, which lack the pro-apoptotic death domain, function to dampen the apoptotic response by competing for TRAIL ligand. The tissue restricted expression of the decoy receptors on normal but not cancer cells provides a therapeutic rational for the development of selective TRAIL-mediated anti-tumor therapies. Recent clinical trials using agonistic antibodies against the apoptosis-inducing TRAIL receptors or recombinant TRAIL have been promising; however the number of patients in complete remission remains stubbornly low. The mechanisms of TRAIL resistance are relatively unexplored but may in part be due to TRAIL-R down-regulation or shedding of TRAIL-R by tumor cells. Therefore a better understanding of the mechanisms underlying TRAIL resistance is required. The ubiquitin-proteasome system (UPS) has been shown to regulate TRAIL-R members suggesting that pharmacological inhibition of the UPS may be a novel strategy to augment TRAIL-based therapies and increase efficacies. We recently identified b-AP15 as an inhibitor of proteasome deubiquitinase (DUB) activity. Interestingly, exposure of tumor cell lines to b-AP15 resulted in increased TRAIL-R2 expression and enhanced sensitivity to TRAIL-mediated apoptosis and cell death in vitro and in vivo. In conclusion, targeting the UPS may represent a novel strategy to increase the cell surface expression of pro-apoptotic TRAIL-R on cancer cells and should be considered in clinical trials targeting TRAIL-receptors in cancer patients. [ABSTRACT FROM AUTHOR]

The proteasome inhibitor bortezomib simultaneously renders tumor cells sensitive to killing by natural killer (NK) cells and resistant to killing by tumor-specific T cells. Here, we show that b-AP15, a novel inhibitor of proteasome deubiquitinating activity, sensitizes tumors to both NK and T cell-mediated killing. Exposure to b-AP15 significantly increased the susceptibility of tumor cell lines of various origins to NK ( p < 0.0002) and T cell ( p = 0.02)-mediated cytotoxicity. Treatment with b-AP15 resulted in increased tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor-2 expression ( p = 0.03) and decreased cFLIP expression in tumor cells in vitro. In tumor-bearing SCID/Beige mice, treatment with b-AP15 followed by infusion of either human NK cells or tumor-specific T cells resulted in a significantly delayed tumor progression compared with mice treated with NK cells ( p = 0.006), T cells ( p < 0.0001) or b-AP15 alone ( p = 0.003). Combined infusion of NK and T cells in tumor-bearing BALB/c mice following treatment with b-AP15 resulted in a significantly prolonged long-term survival compared with mice treated with b-AP15 and NK or T cells ( p ≤ 0.01). Our findings show that b-AP15-induced sensitization to TRAIL-mediated apoptosis could be used as a novel strategy to augment the anticancer effects of adoptively infused NK and T cells in patients with cancer. [ABSTRACT FROM AUTHOR]

The tumor microenvironment is a key determinant for radio-responsiveness. Immune cells play an important role in shaping tumor microenvironments; however, there is limited understanding of how natural killer (NK) cells can enhance radiation effects. This study aimed to assess the mechanism of reciprocal complementation of radiation and NK cells on tumor killing. Various tumor cell lines were co-cultured with human primary NK cells or NK cell line (NK-92) for short periods and then exposed to irradiation. Cell proliferation, apoptosis and transwell assays were performed to assess apoptotic efficacy and cell viability. Western blot analysis and immunoprecipitation methods were used to determine XIAP (X-linked inhibitor of apoptosis protein) and Smac (second mitochondria-derived activator of caspase) expression and interaction in tumor cells. Co-culture did not induce apoptosis in tumor cells, but a time- and dose-dependent enhancing effect was found when co-cultured cells were irradiated. A key role for caspase activation via perforin/granzyme B (Grz B) after cell-cell contact was determined, as the primary radiation enhancing effect. The efficacy of NK cell killing was attenuated by upregulation of XIAP to bind caspase-3 in tumor cells to escape apoptosis. Knockdown of XIAP effectively potentiated NK cell-mediated apoptosis. Radiation induced Smac released from mitochondria and neutralized XIAP and therefore increased the NK killing. Our findings suggest NK cells in tumor microenvironment have direct radiosensitization effect through Grz B injection while radiation enhances NK cytotoxicity through triggering Smac release. [ABSTRACT FROM AUTHOR]

Preclinical studies support the therapeutic potential of histone deacetylases inhibitors (HDACi) in combination with taxanes. The efficacy of combination has been mainly ascribed to a cooperative effect on microtubule stabilization following tubulin acetylation. In the present study we investigated the effect of paclitaxel in combination with two novel HDACi, ST2782 or ST3595, able to induce p53 and tubulin hyperacetylation. A synergistic effect of the paclitaxel/ST2782 (or ST3595) combination was found in wild-type p53 ovarian carcinoma cells, but not in a p53 mutant subline, in spite of a marked tubulin acetylation. Such a synergistic interaction was confirmed in additional human solid tumor cell lines harboring wildtype p53 but not in those expressing mutant or null p53. In addition, a synergistic cytotoxic effect was found when ST2782 was combined with the depolymerising agent vinorelbine. In contrast to SAHA, which was substantially less effective in sensitizing cells to paclitaxel-induced apoptosis, ST2782 prevented up-regulation of p21WAF1/Cip1 by paclitaxel, which has a protective role in response to taxanes, and caused p53 down-regulation, acetylation and mitochondrial localization of acetylated p53. The synergistic antitumor effects of the paclitaxel/ST3595 combination were confirmed in two tumor xenograft models. Our results support the relevance of p53 modulation as a major determinant of the synergistic interaction observed between paclitaxel and novel HDACi and emphasize the therapeutic interest of this combination. [ABSTRACT FROM AUTHOR]

Anthracycline antibiotic doxorubicin (DOX) belongs among the most important antineoplastics used in cancer therapy. Unfortunately, its cytostatic effect in therapeutic doses is frequently insufficient; but the use of higher DOX doses is limited by the development of systemic toxicity, especially cardiotoxicity. Therefore, a searching for some possibilities of how to increase DOX efficacy in cancer cells, and minimizing associated toxicities to noncancerous tissues, is in the forefront of scientific research. Many approaches are based on altered DOX metabolism. The classical strategies include an enhancing of DOX uptake by cancer cells and/or an activation of DOX prodrug within cancer cells via liposomal encapsulation or conjugation with antibodies, peptides, or synthetic polymers. The diminishing of DOX deactivation, restriction of DOX efflux from cancer cells, decreased antioxidant defense of cancer cells, changes in cell cycle, or modulation of signaling pathways represent newer approaches in increasing DOX toxicity in tumors. Each way has certain advantages and limitations. The aim of this review was not to collect all reported results, but to bring an overview of various approaches and a summary of their principles. Possible advantages, disadvantages, and further perspectives are discussed and evaluated. [ABSTRACT FROM AUTHOR]

To further enhance anticancer effect of Shepherdin and overcome limitation of peptide therapy, recombinant adeno-associated virus (rAAV) was constructed with following strategies: therapeutic peptide secretory expression and adeno-associated virus gene transfer system. MTT assay and flow cytometric analysis revealed that rAAV harboring fusion gene NT4-Ant-Shepherdin significantly suppressed A549 cell growth in a time-dependent manner and induced apoptosis. In the infected A549 cells, survivin expression level decreased strongly while Caspase-3/7 activities increased significantly. These results indicated that rAAV harboring fusion gene NT4-Ant-Shepherdin may be a novel strategy in lung cancer peptide therapy. [ABSTRACT FROM AUTHOR]

The vast majority of anticancer drugs in clinical use are limited by systemic host toxicity due to their non-specific side effects. These shortcomings have led to the development of tumour specific drugs which target a single-deregulated pathway or over expressed receptor in cancer cells. Whilst this approach has achieved clinical success, we have also learnt that targeting a single entity in cancer is rarely curative due to the large number of deregulated pathways, receptors and kinases which are also present, in addition to the target. An attractive alternative to improve targeting would be to harness the already established activity of known anticancer drugs by attaching them to a molecule that is transported into cancer cells via a selective transport system. One possibility for this approach is the polyamine pathway. This review provides a brief overview of the polyamine pathway and how, over the years, it has proved an exciting target for the development of novel anticancer agents. However, the focus of this article will be on the properties of the polyamine transport system and how these features could potentially be exploited to develop a novel and selective anticancer drug delivery system. [ABSTRACT FROM AUTHOR]

Serum γ-glutamyltransferase (GGT) is thought to derive from the liver, but its values predict morbidity and mortality for several diseases, such as cardiac infarction, stroke, diabetes, renal failure and cancer. We assessed total GGT and its fractions in the culture supernatants of human cell lines (melanoma, prostate cancer, bronchial epithelium) by gel filtration chromatography. We also compared the GGT elution profile in plasma and the corresponding very-low-density lipoprotein (VLDL) fraction. All the cell lines tested released soluble GGT whose activity increased in parallel with the cell growth. Released GGT presented a molecular weight of 2000 kDa, identical to the b-GGT fraction of human plasma and corresponding to that of VLDL. But ultracentrifugation studies showed that b-GGT had a higher density than VLDL. The b-GGT present in human plasma can be produced by tissues other than the liver, thus explaining the increase of serum GGT observed in diseases of other organs. [ABSTRACT FROM AUTHOR]

In normal tissues, the expression of folate receptors is low and limited to cells that are important for embryonic development or for folate reabsorption. However, in several pathological conditions some cells, such as cancer cells and activated macrophages, overexpress folate receptors (FRs). This overexpression makes them a potential therapeutic target in the treatment of cancer and inflammatory diseases to obtain a selective delivery of drugs at altered cells level, and thus to improve the therapeutic efficacy and decrease the systemic toxicity of the pharmacological treatments. Two strategies have been used to achieve this folate receptor targeting: (i) the use of ligands with high affinity to FRs (e.g., folic acid or anti-FRs monoclonal antibodies) linked to the therapeutic agents or (ii) the use of nanocarriers whose surface is decorated with these ligands and in which the drug is encapsulated. This manuscript analyzes the use of FRs as a target to develop new therapeutic tools in the treatment of cancer and inflammatory diseases with an emphasis on the nanoformulations that have been developed for both therapeutic and imaging purposes. [ABSTRACT FROM AUTHOR]

Background: Doxorubicin is an effective breast cancer drug but is hampered by a severe, dose-dependent toxicity. Concomitant administration of doxorubicin and another cancer drug may be able to sensitize tumor cells to the cytotoxicity of doxorubicin and lowers the therapeutic dosage. In this study, we examined the combined effect of low-dose doxorubicin and siRNA inhibition of telomerase on breast cancer cells. We found that when used individually, both treatments were rapid and potent apoptosis inducers; and when the two treatments were combined, we observed an enhanced and sustained apoptosis induction in breast cancer cells. Methods: siRNA targeting the mRNA of the protein component of telomerase, the telomerase reverse transcriptase (hTERT), was transfected into two breast cancer cell lines. The siRNA inhibition was confirmed by RT-PCR and western blot on hTERT mRNA and protein levels, respectively, and by measuring the activity level of telomerase using the TRAP assay. The effect of the hTERT siRNA on the tumorigenicity of the breast cancer cells was also studied in vivo by injection of the siRNA-transfected breast cancer cells into nude mice. The effects on cell viability, apoptosis and senescence of cells treated with hTERT siRNA, doxorubicin, and the combined treatment of doxorubicin and hTERT siRNA, were examined in vitro by MTT assay, FACS and SA-β-galactosidase staining. Results: The hTERT siRNA effectively knocked down the mRNA and protein levels of hTERT, and reduced the telomerase activity to 30% of the untreated control. In vivo, the tumors induced by the hTERT siRNA-transfected cells were of reduced sizes, indicating that the hTERT siRNA also reduced the tumorigenic potential of the breast cancer cells. The siRNA treatment reduced cell viability by 50% in breast cancer cells within two days after transfection, while 0.5 µM doxorubicin treatment had a comparable effect but with a slower kinetics. The combination of hTERT siRNA and 0.5 µM doxorubicin killed twice as many cancer cells, showing a cumulative effect of the two treatments. Conclusion: The study demonstrated the potential of telomerase inhibition as an effective treatment for breast cancer. When used in conjunction to doxorubicin, it could potentiate the cytotoxic effect of the drug to breast cancer cells. [ABSTRACT FROM AUTHOR]

Sabarubicin (MEN 10755), a new disaccaride anthracycline, has shown greater efficacy than Doxorubicin in a large panel of preclinical models and now it is in phase II clinical trials. Its promising antitumour activity promoted considerable interest to combine Sabarubicin with other antitumour agents. Thus, the purpose of this study was to evaluate in vitro cytotoxic effects and in vivo antitumour activities produced by the combination of Sabarubicin and cisplatin (DDP). The antitumour effect of Sabarubicin and DDP association was investigated, in vitro and in vivo, in preclinical models of lung cancer i.e.: the non-small cell lung carcinoma (NSCLC) H460 and the small-cell lung carcinoma (SCLC) GLC4 in terms of synergism, additivity or antagonism in order to establish the best schedule for the combined treatment. Further, the correlation between antitumour activity and the pharmacokinetic parameters of the studied combination was also evaluated. The drug combination in vitro was in general more cytotoxic than the single drug alone, indicating the presence of a synergistic effect in both tumour cell lines. Also, in the xenograft experiments a superior antitumoral effect was observed when Sabarubicin was combined with DDP. The antitumour efficacy of Sabarubicin (6 mg/kg q4d × 5) combined with DDP (6 mg/kg q4d × 3) greatly depended on the schedule of administration. In H460 tumour line, the sequential combination was more effective than the simultaneous administration of the two agents, although the antitumour efficacy was not dependent on the sequence of combination. On the other hand, a strong sequence-dependent effect was observed when Sabarubicin was combined with DDP in SCLC, GLC4. In particular, the highest value of LCK = 6.7 was obtained when administration of DDP followed by 24 h that of Sabarubicin. Pharmacokinetics of Sabarubicin in combination with DDP was evaluated at 6 mg/kg for both drugs with different sequential schedule. The experimental data showed no evidence for pharmacokinetics drug–drug interaction. These preclinical results indicate the potential for a strong antitumour activity in lung tumours of the combination Sabarubicin and DDP. In particular, in SCLC the best response should be given by a sequence with administration of Sabarubicin followed 24 h later by that of DDP. Clinical trials based on these results are ongoing. [ABSTRACT FROM AUTHOR]