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Osteosarcoma (OS) is a bone malignant tumor affecting children, adolescents, and young adults. Currently, osteosarcoma is treated with chemotherapy regimens established over 40 years ago. The investigation of novel therapeutic strategies for the treatment of osteosarcoma remains an important clinical need. Cyclin-dependent kinases (CDKs) have been considered promising molecular targets in cancer therapy. Among these, CDK12 has been shown to play a crucial role in the pathogenesis of malignancies, but its clinical significance and biological mechanisms in osteosarcoma remain unclear. In the present study, we aim to determine the expression and function of CDK12 and evaluate its prognostic and therapeutic value in metastatic osteosarcoma. We found that overexpression of CDK12 was associated with high tumor grade, tumor progression and reduced patient survival. The underlying mechanism revealed that knockdown of CDK12 expression with small interfering RNA or functional inhibition with the CDK12-targeting agent THZ531 effectively exhibited time- and dose-dependent cytotoxicity. Downregulation of CDK12 paused transcription by reducing RNAP II phosphorylation, interfered with DNA damage repair with increased γH2AX, and decreased cell proliferation through the PI3K-AKT pathway. This was accompanied by the promotion of apoptosis, as evidenced by enhanced Bax expression and reduced Bcl-xL expression. Furthermore, the CDK12 selective inhibitor THZ531 also hindered ex vivo 3D spheroid formation, growth of in vitro 2D cell colony, and prevented cell mobility. Our findings highlight the clinical importance of CDK12 as a potentially valuable prognostic biomarker and therapeutic target in metastatic osteosarcoma., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Mastitis typically arises from bacterial invasion, where host cell apoptosis significantly contributes to the inflammatory response. Gram-positive bacteria predominantly utilize the virulence factor lipoteichoic acid (LTA), which frequently leads to chronic breast infections, thereby impacting dairy production and animal husbandry adversely. This study employed LTA to develop models of mastitis in cow mammary gland cells and mice. Transcriptomic analysis identified 120 mRNAs associated with endocytosis and apoptosis pathways that were enriched in the LTA-induced inflammation of the Mammary Alveolar Cells-large T antigen (MAC-T), with numerous differential proteins also concentrated in the endocytosis pathway. Notably, actin-related protein 2/3 complex subunit 3 (ARPC3), actin-related protein 2/3 complex subunit 4 (ARPC4), and the heat shock protein 70 (HSP70) are closely related. STRING analysis revealed interactions among ARPC3, ARPC4, and HSP70 with components of the apoptosis pathway. Histological and molecular biological assessments confirmed that ARPC3, ARPC4, and HSP70 were mainly localized to the cell membrane of mammary epithelial cells. ARPC3 and ARPC4 are implicated in the mechanisms of bacterial invasion and the initiation of inflammation. Compared to the control group, the expression levels of these proteins were markedly increased, alongside the significant upregulation of apoptosis-related factors. While HSP70 appears to inhibit apoptosis and alleviate inflammation, its upregulation presents novel research opportunities. In conclusion, we deduced the development mechanism of ARPC3, ARPC4, and HSP70 in breast inflammation, laying the foundation for further exploring the interaction mechanism between the actin-related protein 2/3 (ARP2/3) complex and HSP70.

MS4A3 functions as a tumor suppressor in multiple cancer types. However, the roles of MS4A3 in lung cancer are still unknown. Therefore, this study aims to investigate the potentials of MS4A3 in lung cancer. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was carried out to determine mRNA expression. CCK-8 and colony formation assay are conducted to determine cell proliferation. Tube formation assay is performed to determine angiogenesis. Flow cytometry is used to determine cell apoptosis. JASPAR is used to analyze the binding motif of THAP1. Luciferase and ChIP assay are conducted to verify whether MS4A3 can interact with THAP1 to transcriptionally inactivate EGFR. The results showed that MS4A3 is downregulated in non-small-cell lung cancer (NSCLC) patients, which predicts poor clinical outcomes of NSCLC patients. Overexpressed MS4A3 enhances the chemosensitivity of NSCLC cells to osimertinib, whereas MS4A3 knockdown exerts the opposite effects. MS4A3 suppresses the proliferation and angiogenesis and promotes the apoptosis of NSCLC cells. Moreover, MS4A3 upregulates apoptosis-related THAP1 to inactivate EGFR. However, THAP1 knockdown attenuates the effects of MS4A3 and promotes the malignant behavior of NSCLC cells. In conclusion, MS4A3 functions as an anti-tumor gene in NSCLC. MS4A3/THAP1/EGFR signaling enhances the chemosensitivity of lung cancer to EGFR tyrosine kinase inhibitor (TKI).

Cytochrome c (Cyt. c) is a key initiator of the caspases that activate cell apoptosis. The spatiotemporal evaluation of the contents of Cyt. c in cellular compartments and the detection of Cyt. c delivery between cellular compartments upon apoptosis is important for probing cell viabilities. We introduce an optical probe and an electrochemical probe for the quantitative assessment of Cyt. c in cellular compartments at the single cell level. The optical or electrochemical probes are functionalized with photoresponsive o-nitrobenzylphosphate ester-caged Cyt. c aptamer constituents. These are uncaged by light stimuli at single cell compartments, allowing the spatiotemporal detection of Cyt. c through the formation of Cyt. c/aptamer complexes at non-apoptotic or apoptotic conditions. The probes are applied to distinguish the contents of Cyt. c in cellular compartments of epithelial MCF-10A breast cells and malignant MCF-7 and MDA-MB-231 breast cells under apoptotic/non-apoptotic conditions., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Enterovirus A71 (EV-A71) has emerged as a clinically important neurotropic virus following poliovirus eradication. Recent studies have shown that human tonsillar epithelial cell lines (UT-SCC-60A and UT-SCC-60B) were susceptible to EV-A71, suggesting that human tonsillar crypt epithelium could be important in EV-A71 pathogenesis. However, the mechanism about how EV-A71 infects the upper oro-digestive tract remains largely unclear. In this study, we demonstrated that the human tonsillar epithelial cells infected with EV-A71 underwent apoptotic, in which cytochrome c was released from the mitochondria to the cytosol and caspase-9 was activated, while caspase-2 and -8 were not cleaved or activated during the infection. A selective inhibitor of caspase-9, Z-LEHD-FMK, inhibited the cleavage of the executioner caspase-3 and -7, indicating that only mitochondria-mediated intrinsic apoptotic pathway was activated in EV-A71-infected tonsillar epithelial cells. No evidence of pyroptosis or necroptosis was involved in the cell death. EV-A71 infection induced interferon, pro-inflammatory cytokines and chemokines, including IFN-β, IL-6, CCL5, and TNF-α in tonsillar epithelial cells, which may play a critical role in EV-A71-caused herpangina. Our data indicated that the induction of the cytokines was partially regulated by the mitogen-activated protein kinases (MAPKs) signaling pathway. The findings unveiled the host response to EV-A71 and its regulation mechanism, and will further our understanding the significance about the tonsillar crypt epithelium as the initial and primary portal in viral pathogenesis for EV-A71 infection., Competing Interests: We have read the journal’s policy and there is no competing conflict of interest.

Increased levels of interleukin-6 (IL-6) contribute to the development of polycystic ovary syndrome (PCOS); in renal cell carcinoma, the long non-coding RNA (lncRNA) SRLR upregulates IL-6. In this study, we demonstrated that the levels of the lncRNA SRLR were upregulated in PCOS patients with high expression of plasma IL-6 compared with heathy females. The levels of the lncRNA SRLR in the plasma had a positive correlation with expression of IL-6 in patients with PCOS but not in healthy females. Upregulation of the lncRNA SRLR in plasma could distinguish PCOS patients from healthy females. Overexpression of the lncRNA SRLR led to upregulation of IL-6 and promoted apoptosis of human granulosa-like tumour cells (KGN). Therefore, the lncRNA SRLR participated in PCOS by regulating cell apoptosis and IL-6 expression. SIGNIFICANCE OF THE STUDY: The lncRNA SRLR mediates its effects on apoptosis and IL-6 expression in PCOS and could be used to distinguish PCOS patients from healthy controls. Plasma circulating levels of the lncRNA SRLR may be a potential target for the treatment of PCOS., (© 2020 The Authors. Cell Biochemistry and Function published by John Wiley & Sons Ltd.)

Bile acids usually build up in patients with cholestatic liver disease. It was found that the concentration of taurocholic acid (TCA), one of the taurine conjugates of primary bile acids in serum, was elevated the most. While the role played by TCA in the disease is unclear, there is concern whether TCA contributes to the development of hepatocarcinoma from cholestasis. In the present study, the cell viability, flow cytometry, real-time polymerase chain reaction, intracellular ROS measurement, and intracellular Ca2+ measurement were used to investigate the effects of TCA on THLE-2 and HepG2 cells. The results showed that TCA is capable of inhibiting HepG2 cell growth whereas it has relatively little or no impact on that of THLE-2 cells until later stages of 16-day treatment. The growth inhibition is a result of cell apoptosis induced by the increase of Ca2+ and ROS level, and also associated with the increased expression of c-Myc, CEBPα, TNF-α, ICAM-1, VCAM-1, CXCL-2, Egr-1. HepG2 growth inhibition could contribute to the research on the treatment methods of patients already with hepatocarcinoma.

Fluorene-9-bisphenol (9,9-bis(4-hydroxyphenyl)-fluorene [BHPF]) is a bisphenol A (BPA) substitute used in the production of "BPA-free" plastics, now has been identified is harmful to living organisms. Our previous study showed that BHPF impaired mouse denuded oocyte in vitro maturation. However, there is a question that whether BHPF is still able to affect oocyte maturation in the presence of dense cumulus cells. In the present study, we checked the toxic effects of BHPF on porcine oocyte maturation which is derived from COCs in vitro culture. Our results showed that BHPF (50 μM) inhibited the expansion of cumulus cells, led to a significant decrease in polar body extrusion (PBE). Importantly, BHPF resulted in abnormal spindle assembly, ATP level decrease, reactive oxygen species (ROS) accumulation and early apoptosis in porcine oocytes, which are all negative to oocyte maturation. Furthermore, BHPF also declined porcine oocyte quality by disturbing the cortical granules (CGs) distribution. In conclusion, our study showed that BHPF still inhibited oocyte maturation even in the presence of cumulus cells leading to abnormal spindle assembly, ATP decrease, increased ROS level, early apoptosis, and disturbed CGs distribution in porcine oocytes, and also indicates that BHPF has a wide range toxic effects on oocyte in different species., (© 2019 Wiley Periodicals, Inc.)

Ginsenoside Rk1 is a substance derived from ginseng and exhibits various activities such as anti-diabetic, anti-inflammatory and anti-cancer effects; however, its anti-tumor effect and target signaling mechanism in lung adenocarcinoma are not well understood. Here, we show that Rk1, a natural drug product, can function as an antitumor modulator that induces apoptosis in lung adenocarcinoma cells by inhibiting NF-κB transcription and triggering cell cycle arrest. Mechanistically, Rk1 suppressed the proliferation and clonal formation of two lung adenocarcinoma cell lines (A549 and PC9) in vitro and caused G1 phase cell arrest. In the A549 xenograft model, Rk1 significantly inhibited tumor growth and had few toxic side effects on normal organs. Western blotting results showed that Rk1 increased the protein expression of Bax, cleaved caspase-3, -8, and -9, and PARP, decreased the expression of Bcl-2 and blocked the NF-κB signaling pathway. Furthermore, ginsenoside Rk1 also reduced the high expression of PD-L1 in lung adenocarcinoma cells by inhibiting NF-κB signaling. These data revealed a previously unreported antitumor mechanism of Rk1, providing new ideas and an experimental basis for further study of the mechanism of action of Rk1 in lung adenocarcinoma.

Objectives: The aim of the present study was to determine the effects of miRNA-103 on chondrocyte apoptosis and molecular mechanisms in osteoarthritis (OA) progression., Methods: The cell proliferation, apoptosis, and recovery ability were measured by cell counting kit-8 (CCK-8), flow cytometry, and wound healing assays. The interaction of miRNA-103 and Sphingosine kinase-1 (SPHK1) were determined by using luciferase reporter assay. The expression of mRNA and proteins were measured by qRT-PCR and Western blot. OA rat model was established by surgery stimulation., Results: miRNA-103 expression was significantly increased in the cartilage of OA patients and surgery-induced OA rat models. miRNA-103 transfection into primary rat chondrocytes reduced SPHK1 expression, induced apoptosis, inhibited cell proliferation, and impeded scratch assay wound closure. Moreover, expression of total AKT, and p-AKT were significantly reduced in miRNA-103-overexpressing chondrocytes while SPHK1 up-regulation increased the expression of phosphatidylinsitol-3-kinase (PI3K) and p-AKT, and reversed the proliferation suppression induced by the miRNA-103 mimic., Conclusions: Our studies suggest that miRNA-103 contributes to chondrocyte apoptosis, promoting OA progression by down-regulation of PI3K/AKT pathway through the reduction in SPHK1 activity., (© 2019 The Author(s).)

Objective: Exposure of oxidized low-density lipoprotein (ox-LDL) could cause dysfunction of HUVEC, thus leading to atherosclerosis development, which is a common inflammatory vascular disease. Long noncoding RNA X-inactive specific transcript (XIST) has been reported to be implicated in atherosclerosis. However, the mechanism by which this lncRNA participates in the progression of atherosclerosis is poorly defined., Materials and Methods: HUVEC challenged by ox-LDL were used as a cellular model of atherosclerosis. Cell viability, apoptosis, LDH release, and inflammatory cytokines secretion were detected by MTT, flow cytometry, and ELISA assays. The expression levels of XIST, microRNA (miR)-30c-5p, and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) were measured by quantitative Real Time-Polymerase Chain Reaction and Western blot. The target interaction between XIST and miR-30c-5p or miR-30c-5p and PTEN was validated by the Luciferase reporter assay and RNA immunoprecipitation., Results: Treatment of ox-LDL induced cell apoptosis and inflammatory cytokines release in HUVEC. XIST expression was enhanced in HUVEC treated by ox-LDL, and its knockdown decreased cell apoptosis and inflammatory response in ox-LDL-treated cells. MiR-30c-5p was a target of XIST and its overexpression suppressed cell apoptosis and inflammatory response induced by ox-LDL, which was weakened by the introduction of XIST. PTEN was a target of miR-30c-5p, and its interference led to great inhibition of cell apoptosis and inflammatory response induced by ox-LDL in HUVEC, while this effect was attenuated by miR-30c-5p deficiency or XIST overexpression., Conclusions: XIST knockdown suppresses inflammatory response and apoptosis of HUVEC stimulated by ox-LDL by increasing miR-30c-5p and decreasing PTEN.

Oval cells, a kind of hepatic progenitor cell quiescent at normal condition, activates to proliferate and differentiate into hepatocytes under severe and long-term liver injury, which usually raises severe inflammation. However, how oval cell survives in the inflammatory milieu interne is still unclear. Tumor necrosis factor α (TNFα), mimicking inflammatory hepatic milieu interne, was used to treat oval cell line, WB-F344, to test the protective function of matrilin-2. In this study, our data suggested that matrilin-2 prevented TNFα-induced apoptosis in WB-F344 cells via inhibiting ASK1/MKK7/JNK pathway. In conclusion, we determined that matrilin-2 plays the key role in maintaining the survival of oval cell and guarantees its proliferation under various injury factors., (© 2019 International Union of Biochemistry and Molecular Biology, Inc.)

Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia (EP) and responsible for major economic losses in global swine industry. After colonization of the respiratory epithelium, M. hyopneumoniae elicits a general mucociliary clearance loss, prolonged inflammatory response, host immunosuppression and secondary infections. Until now, the pathogenesis of M. hyopneumoniae is not completely elucidated. This present study explores the pathogenicity of mhp390 (P68, a membrane-associated lipoprotein) by elucidating its multiple functions. Microtitrer plate adherence assay demonstrated that mhp390 is a new cilia adhesin that plays an important role in binding to swine tracheal cilia. Notably, mhp390 could induce significant apoptosis of lymphocytes and monocytes from peripheral blood mononuclear cells (PBMCs), as well as primary alveolar macrophages (PAMs), which might weaken the host immune response. In addition, mhp390 contributes to the production of proinflammatory cytokines, at least partially, via the release of IL-1β and TNF-α. To the best of our knowledge, this is the first report of the multiple functions of M. hyopneumoniae mhp390, which may supplement known virulence genes and further develop our understanding of the pathogenicity of M. hyopneumoniae., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Intermediate-sized non-coding RNAs (imsncRNAs) have been shown to play important regulatory roles in the development of several eukaryotic organisms. In the present research, we selected imsncRNA 761 (imsnc761) as a research target. Expression analyses in a previous study showed that imsnc761 was down-regulated in maturation-arrested testis tissues as compared with the level in normal controls. In the present study, we found that imsnc761 could interact with DEAD-box helicase 6 (DDX6) to induce NTERA-2 (NT2 (testicular embryonal carcinoma cell)) cell apoptosis and proliferation inhibition via the p53 pathway. This interaction between imsnc761 and DDX6 also inhibited mitochondrial function and specific gene transcription and translation. To facilitate further research, we used label-free quantitation method to analyze the associated differences in Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways and biological processes. This confirmed the changes in several specific pathways, which matched our molecular experimental results., (© 2018 The Author(s).)

The use of ginsenosides in cancer therapy has been intensively investigated. The ginsenoside Rh4 (Rh4), a rare saponin obtained from Panax notoginseng, dissolves in water more readily than total saponins, making this compound easier to use in anti-cancer pharmaceutics. Here, we investigated the antiproliferative activity and mechanisms of Rh4 in colorectal cancer, both in vivo and in vitro. A colorectal cancer xenograft model showed that Rh4 significantly inhibited tumor growth with few side effects. CCK-8 assays, flow cytometric analysis, Western blotting and immunohistochemistry revealed that Rh4 effectively suppressed colorectal cancer cell proliferation via inducing G 0 /G 1 phase arrest, caspase-dependent apoptosis and autophagic cell death but was not significantly cytotoxic to normal colon epithelial cells. Furthermore, apoptosis played a dominant role in Rh4-induced cell death, as the pan-caspase inhibitor Z-VAD-FMK blocked cell death to a greater extent than the autophagy inhibitor 3-methyladenine. Moreover, Rh4 increased reactive oxygen species (ROS) accumulation and subsequently activated the JNK-p53 pathway. An ROS scavenger and JNK and p53 inhibitors significantly attenuated Rh4-induced apoptosis and autophagy. Thus, the present study is the first to illustrate that Rh4 triggers apoptosis and autophagy via activating the ROS/JNK/p53 pathway in colorectal cancer cells, providing basic scientific evidence that Rh4 shows great potential as an anti-cancer agent., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: It remains unknown whether blockade of c-Met signaling and epidermal growth factor receptor signaling is effective in suppressing the growth of human colorectal cancer (CRC) cells. In this study, we investigated the effects of the c-Met inhibitor PHA-665752 alone and in combination with cetuximab on the growth of human CRC cells in vitro and in mouse xenografts., Methods: Human CRC cell lines (Caco2, HCT-116, and HT-29) and mice bearing HCT-116 xenografts were treated with cetuximab in the absence or presence of PHA-665752. Cell viability and apoptosis were examined using the MTT and TUNEL assays, respectively. Vimentin was measured by immunohistochemistry as a marker for epithelial-to-mesenchymal transition. Western blotting was used to determine signaling protein expression levels., Results: The MTT assay showed that the growth of Caco2, HCT-116, and HT-29 cells was inhibited by PHA-665752 in a dose-dependent manner, but only Caco2 cell growth was suppressed by cetuximab. Combination treatment with PHA-665752 and cetuximab inhibited the proliferation of Caco2 cells and RAS mutant CRC cell lines. However, relative to the PHA-665752-alone treatment group, HT-29 cells with a BRAF mutation showed no noticeable effect. The mean tumor volume in mice treated with cetuximab in combination with PHA-665752 was significantly smaller than that in the mice treated with only cetuximab (P = 0.033) or PHA-665752 (P < 0.01). Similarly, the expression of vimentin in the mice treated with PHA-665752 in combination with cetuximab was significantly lower than that in the mice treated with cetuximab or PHA-665752 alone (P < 0.05 in each case). TUNEL assays revealed that treatment with PHA-665752 in combination with cetuximab markedly increased CRC cell apoptosis. Western blotting analysis of signaling protein expression showed that PHA- 665752 inhibited Met phosphorylation (P < 0.05). In addition, treatment with cetuximab alone or in combination with PHA-665752 effectively inhibited EGFR phosphorylation (P < 0.05)., Conclusion: Combination treatment with PHA-665752 and cetuximab suppressed in vitro and in vivo CRC cell growth more than treatment with either agent alone did., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Acute injury in the setting of liver fibrosis is an interesting and still unsettled issue. Most recently, several prominent studies have indicated the favourable effects of liver fibrosis against acute insults. Nevertheless, the underlying mechanisms governing this hepatoprotection remain obscure. In the present study, we hypothesized that macrophages and their M1/M2 activation critically involve in the hepatoprotection conferred by liver fibrosis. Our findings demonstrated that liver fibrosis manifested a beneficial role for host survival and apoptosis resistance. Hepatoprotection in the fibrotic liver was tightly related to innate immune tolerance. Macrophages undertook crucial but divergent roles in homeostasis and fibrosis: depleting macrophages in control mice protected from acute insult; conversely, depleting macrophages in fibrotic liver weakened the hepatoprotection and gave rise to exacerbated liver injury upon insult. The contradictory effects of macrophages can be ascribed, to a great extent, to the heterogeneity in macrophage activation. Macrophages in fibrotic mice exhibited M2-preponderant activation, which was not the case in acutely injured liver. Adoptive transfer of M2-like macrophages conferred control mice conspicuous protection against insult. In vitro, M2-polarized macrophages protected hepatocytes against apoptosis. Together, M2-like macrophages in fibrotic liver exert the protective effects against lethal insults through conferring apoptosis resistance to hepatocytes.

The aim of this study was to evaluate the potential cytotoxicity and the underlying mechanism of amphipathic silica nanoparticles (SiO2 NPs) exposure to human normal liver HL-7702 cells and rat normal liver BRL-3A cells. Prior to the cellular studies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X ray diffraction (XRD) were used to characterize SiO2 NPs, which proved the amorphous nature of SiO2 NPs with TEM diameter of 19.8±2.7nm. Further studies proved that exposure to SiO2 NPs dose-dependently induced cytotoxicity as revealed by cell counting kit (CCK-8) and lactate dehydrogenase (LDH) assays, with more severe cytotoxicity in HL-7702 cells than BRL-3A cells. Reactive oxygen species (ROS) and glutathione (GSH) assays showed elevated oxidative stress in both cells. Morphological studies by microscopic observation, Hochest 33258 and AO/EB staining indicated significant apoptotic changes after the cells being exposed to SiO2 NPs. Further studies by western blot indicated that SiO2 NPs exposure to both cells up-regulated p53, Bax and cleaved caspase-3 expression and down-regulated Bcl-2 and caspase-3 levels. Activated caspase-3 activity detected by colorimetric assay kit and caspase-3/7 activity detected by fluorescent real-time detection kit were significantly increased by SiO2 NPs exposure. In addition, antioxidant vitamin C significantly attenuated SiO2 NPs-induced caspase-3 activation, which indicated that SiO2 NPs-induced oxidative stress was involved in the process of HL-7702 and BRL-3A cell apoptosis. Taken together, these results suggested that SiO2 NPs-induced cytotoxicity in HL-7702 and BRL-3A cells was through oxidative stress mediated and p53, caspase-3 and Bax/Bcl-2 dependent pathway and HL-7702 cells were more sensitive to SiO2 NPs-induced cytotoxicity than BRL-3A cells., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Polycomb group (PcG) proteins are highly conserved epigenetic effectors that maintain the silenced state of genes. EZH2 is the catalytic core and one of the most important components of the polycomb repressive complex 2 (PRC2). In non-small cell lung cancer (NSCLC) cells and primary lung tumors, we found that PRC2 components, including EZH2, are overexpressed. High levels of EZH2 protein were associated with worse overall survival rate in NSCLC patients. RNA interference mediated attenuation of EZH2 expression blunted the malignant phenotype in this setting, exerting inhibitory effects on cell proliferation, anchorage-independent growth, and tumor development in a xenograft mouse model. Unexpectedly, we discovered that, in the suppression of EZH2, p53 upregulated modulator of apoptosis (PUMA) expression was concomitantly induced. This is achieved through EZH2 directly binds to the Puma promoter thus epigenetic repression of PUMA expression. Furthermore, cisplatin-induced apoptosis of EZH2-knocking down NSCLC cells was elevated as a consequence of increased PUMA expression. Our work reveals a novel epigenetic regulatory mechanism controlling PUMA expression and suggests that EZH2 offers a candidate molecular target for NSCLC therapy and EZH2-regulated PUMA induction would synergistically increase the sensitivity to platinum agents in non-small cell lung cancers., Competing Interests: The authors declare that they have no conflicts of interest.

Ovarian cancer is currently the most lethal gynecologic malignancy with limited treatment options. Improved targeted therapies are needed to combat ovarian cancer. Here, we report the identification of cyclin-dependent kinase 11 (CDK11) as a mediator of tumor cell growth and proliferation in ovarian cancer cells. Although CDK11 has not been implicated previously in this disease, we have found that its expression is upregulated in human ovarian cancer tissues and associated with malignant progression. Metastatic and recurrent tumors have significantly higher CDK11 expression when compared with the matched, original primary tumors. RNAi-mediated CDK11 silencing by synthetic siRNA or lentiviral shRNA decreased cell proliferation and induced apoptosis in ovarian cancer cells. Moreover, CDK11 knockdown enhances the cytotoxic effect of paclitaxel to inhibit cell growth in ovarian cancer cells. Systemic in vivo administration of CDK11 siRNA reduced the tumor growth in an ovarian cancer xenograft model. Our findings suggest that CDK11 may be a promising therapeutic target for the treatment of ovarian cancer patients. Mol Cancer Ther; 15(7); 1691-701. ©2016 AACR., (©2016 American Association for Cancer Research.)

Peroxisome proliferator-activated receptor α (PPARα) is a key regulator to ameliorate liver injury in cases of acute liver failure (ALF). However, its regulatory mechanisms remain largely undetermined. Endoplasmic reticulum stress (ER stress) plays an important role in a number of liver diseases. This study aimed to investigate whether PPARα activation inhibits ER stress-induced hepatocyte apoptosis, thereby protecting against ALF. In a murine model of D-galactosamine (D-GalN)- and lipopolysaccharide (LPS)-induced ALF, Wy-14643 was administered to activate PPARα, and 4-phenylbutyric acid (4-PBA) was administered to attenuate ER stress. PPARα activation ameliorated liver injury, because pre-administration of its specific inducer, Wy-14643, reduced the serum aminotransferase levels and preserved liver architecture compared with that of controls. The protective effect of PPARα activation resulted from the suppression of ER stress-induced hepatocyte apoptosis. Indeed, (1) PPARα activation decreased the expression of glucose-regulated protein 78 (Grp78), Grp94 and C/EBP-homologous protein (CHOP) in vivo; (2) the liver protection by 4-PBA resulted from the induction of PPARα expression, as 4-PBA pre-treatment promoted upregulation of PPARα, and inhibition of PPARα by small interfering RNA (siRNA) treatment reversed liver protection and increased hepatocyte apoptosis; (3) in vitro PPARα activation by Wy-14643 decreased hepatocyte apoptosis induced by severe ER stress, and PPARα inhibition by siRNA treatment decreased the hepatocyte survival induced by mild ER stress. Here, we demonstrate that PPARα activation contributes to liver protection and decreases hepatocyte apoptosis in ALF, particularly through regulating ER stress. Therefore, targeting PPARα could be a potential therapeutic strategy to ameliorate ALF., (© 2016. Published by The Company of Biologists Ltd.)

Bax inhibitor 1 (BI-1) is a highly conserved protein originally identified as a suppressor of the proapoptotic protein Bax to inhibit cell death in animals and plants. The orthologs of BI-1 are widely distributed in filamentous fungi but their functions remain largely unknown. Herein, we report the identification and characterizations of MrBI-1, an ortholog of BI-1, in the entomopathogenic fungus Metarhizium robertsii. First, we found that MrBI-1 could partially rescue mammalian Bax-induced cell death in yeast. Deletion of MrBI-1 impaired fungal development, virulence and heat tolerance in M. robertsii. We also demonstrated that inactivation of MrBI-1 reduced fungal resistance to farnesol but not to hydrogen peroxide, suggesting that MrBI-1 contributes to antiapoptotic-like cell death via the endoplasmic reticulum stress-signaling pathway rather than the classical mitochondrium-dependent pathway. In particular, we found that unlike the observations in yeasts and plants, expression of mammalian Bax did not lead to a lethal effect in M. robertsii; however, it did aggravate the fungal apoptotic effect of farnesol. The results of this study advance our understanding of BI-1-like protein functions in filamentous fungi.

Epidemiological studies have revealed an association between vitamin D deficiency and various chronic liver diseases. However, it is not known whether lack of vitamin D can induce spontaneous liver fibrosis in an animal model. To study this, mice were fed either a control diet or a vitamin D deficient diet (VDD diet). For the positive control, liver fibrosis was induced with carbon tetrachloride. Here we show, for the first time, that liver fibrosis spontaneously developed in mice fed the VDD diet. Long-term administration of a VDD diet resulted in necro-inflammation and liver fibrosis. Inflammatory mediators including tumor necrosis factor-α, interleulin-1, interleukin-6, Toll-like-receptor 4, and monocyte chemotactic protein-1 were up-regulated in the livers of the mice fed the VDD diet. Conversely, the expression of Th2/M2 markers such as IL-10, IL-13, arginase 1, and heme oxygenase-1 were down-regulated in the livers of mice fed the VDD diet. Transforming growth factor-β1 and matrix metalloproteinase 13, which are important for fibrosis, were induced in the livers of mice fed the VDD diet. Moreover, the VDD diet triggered apoptosis in the parenchymal cells, in agreement with the increased levels of Fas and FasL, and decreased Bcl2 and Bclx. Thus, long-term vitamin D deficiency can provoke chronic inflammation that can induce liver apoptosis, which consequently activates hepatic stellate cells to initiate liver fibrosis.

Objective: To analyze the role of glycogen synthase kinase 3β (GSK3β) in hepatocyte apoptosis induced by oxidative stress., Methods: Human HL-7702 hepatoma cells were induced by H₂O₂/antimycin A to establish oxidative stress-induced cell apoptosis models. SB216763, a specific inhibitor of GSK3β, was given to the cells two hours before H₂O₂/antimycin A induction. Cell survival was observed using calcein acetoxymethyl ester/propidium iodide (PI) double staining, and cell apoptosis was detected using annexin V-FITC/PI staining combined with flow cytometry. In the meanwhile, the cell culture supernatant was subjected to lactate dehydrogenase (LDH) assay to evaluate the extent of cell death. The expressions of p-GSK3β, GSK3β, caspase-3, cleaved caspase-3, c-Jun N-terminal kinase (JNK) and cytochrome C (CytC) proteins were examined using Western blotting., Results: Oxidative stress triggered by H₂O₂/antimycin A promoted GSK3β activity; inhibition of GSK3β activity by SB216763 relieved oxidative stress and reduced cell apoptosis induced by oxidative stress. Compared with the model groups, SB216763 intervened group showed that the cell apoptosis rate and the level of LDH were reduced significantly, and that the expressions of cleaved caspase-3, JNK, CytC proteins decreased., Conclusion: GSK3β is an important signaling molecule in the apoptosis pathway induced by oxidative stress. The inhibition on GSK3β may alleviate the oxidative stress-induced hepatocyte apoptosis.

Studies have shown that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces apoptotic cell death in neuronal cells. However, whether this is the result of endoplasmic reticulum (ER) stress-mediated apoptosis remains unknown. In this study, we determined whether ER stress plays a role in the TCDD-induced apoptosis of pheochromocytoma (PC12) cells and primary neurons. PC12 cells were exposed to different TCDD concentrations (1, 10, 100, 200, or 500nM) for varying lengths of time (1, 3, 6, 12, or 24h). TCDD concentrations much higher than 10nM (100, 200, or 500nM) markedly increased glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP) levels, which are hallmarks of ER stress. We also evaluated the effects of TCDD on ER morphology in PC12 cells and primary neurons that were treated with different TCDD concentrations (1, 10, 50, or 200nM) for 24h. Ultrastructural ER alterations were observed with transmission electron microscopy in PC12 cells and primary neurons treated with high concentrations of TCDD. Furthermore, TCDD-induced ER stress significantly promoted the activation of the PKR-like ER kinase (PERK), a sensor for the unfolded protein response (UPR), and its downstream target eukaryotic translation initiation factor 2 α (eIF2α); in contrast, TCDD did not appear to affect inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6), two other UPR sensors. Importantly, TCDD significantly inhibited eIF2α phosphorylation and triggered apoptosis in PC12 cells after 6-24h of treatment. Salubrinal, which activates the PERK-eIF2α pathway, significantly enhanced eIF2α phosphorylation in PC12 cells and attenuated the TCDD-induced cell death. In contrast, knocking down eIF2α using small interfering RNA markedly enhanced TCDD-induced cell death. Together, these results indicate that the PERK-eIF2α pathway plays an important role in TCDD-induced ER stress and apoptosis in PC12 cells., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: To determine the roles of mitochondrial apoptosis and energy metabolism in hepatocytes during the pathogenic process of acute renal failure (ALF) by assessing disease-related differential activities of several key mitochondrial enzymes, including citrate synthase (CS), carnitine palmitoyltransferase-1 (CPT-1) and cytochrome c oxidase (COX)., Methods: Thirty-two male Sprague Dawley rats were given D-galactosamine followed by and lipopolysaccharide (LPS) to induce acute liver failure and sacrificed after 4 (4 h group), 8 (8 h group) 12 (12 h group) and 24 hours (24 h group) of treatment. Eight unmodeled rats served as controls. Effects related to apoptosis were evaluated by pathological analysis of hepatic tissues and TUNEL staining. Ultrastructural changes in mitochondria were assessed by electron microscopy. The activity and expression of CS, CPT-1 and COX were measured., Results: Hepatocyte apoptosis was present in the 4 h treatment group and was increased obviously in the 8 h treatment group. Hepatocyte necrosis was first observed in the 12 h treatment group and was significantly higher in the 24 h treatment group, with inflammatory cell invasion. Ultrastructural changes in mitochondria were present in the 4 h treatment group, and the 24 h treatment group showed mitochondria with completely destroyed outer membranes, which resulted in mitochondrial collapse. Activity and protein expression of CS, CPT-1 and COX were increased in the 4 h group (vs. controls), were at their peak in the 8 h group (CS:t =1.481, P less than 0.01; CPT-1:t =2.619, P less than 0.05; COX:t =1.014, P less than 0.01) and showed a decreasing trend in the 12 h group. In addition, the activities of CS, CPT-1 and COX were enhanced at the stage of hepatocyte apoptosis, suggesting that these enzymes were involved in the initiation and development of ALF., Conclusion: Energy metabolism plays an important role in hepatocyte apoptosis during ALF.

While the mechanisms of human cancer development are not fully understood, evidence of microRNA (miRNA, miR) dysregulation has been reported in many human diseases, including cancer. miRs are small noncoding RNA molecules that regulate posttranscriptional gene expression by binding to complementary sequences in the specific region of gene mRNAs, resulting in downregulation of gene expression. Not only are certain miRs consistently dysregulated across many cancers, but they also play critical roles in many aspects of cell growth, proliferation, metastasis, apoptosis, and drug resistance. Recent studies from our group and others revealed that miR-1 is frequently downregulated in various types of cancer. Through targeting multiple oncogenes and oncogenic pathways, miR-1 has been demonstrated to be a tumor suppressor gene that represses cancer cell proliferation and metastasis and promotes apoptosis by ectopic expression. In this review, we highlight recent findings on the aberrant expression and functional significance of miR-1 in human cancers and emphasize its significant values for therapeutic potentials.

Osteosarcoma (OS) is a malignant tumor mainly occurring in children and adolescents. Methotrexate (MTX), a chemotherapy agent, is widely used in treating OS. However, treatment failures are common due to acquired chemoresistance, for which the underlying molecular mechanisms are still unclear. In this study, we report that overexpression of estrogen-related receptor alpha (ERR α ), an orphan nuclear receptor, promoted cell survival and blocked MTX-induced cell death in U2OS cells. We showed that MTX induced ROS production in MTX-sensitive U2OS cells while ERR α effectively blocked the ROS production and ROS associated cell apoptosis. Our further studies demonstrated that ERR α suppressed ROS induction of tumor suppressor P53 and its target genes NOXA and XAF1 which are mediators of P53-dependent apoptosis. In conclusion, this study demonstrated that ERR α plays an important role in the development of MTX resistance through blocking MTX-induced ROS production and attenuating the activation of p53 mediated apoptosis signaling pathway, and points to ERR α as a novel target for improving osteosarcoma therapy.

It has been widely accepted that microglia, which are the innate immune cells in the brain, upon activation can cause neuronal damage. In the present study, we investigated the role of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in regulating microglial nitric oxide production and its role in causing neuronal damage. The study revealed that TCDD stimulates the expression of inducible nitric oxide synthase (iNOS) as well as the production of nitric oxide (NO) in a dose- and time-dependent manner. Further, a rapid activation of p38 and JNK MAPKs was found in HAPI microglia following TCDD treatment. Blockage of p38 and JNK kinases with their specific inhibitors, SB202190 and SP600125, significantly reduced TCDD-induced iNOS expression and NO production. In addition, it was demonstrated through treating rat primary cortical neurons with media conditioned with TCDD treated microglia that microglial iNOS activation mediates neuronal apoptosis. Lastly, it was also found that p38 and JNK MAPK inhibitors could attenuate the apoptosis of rat cortical neurons upon exposure to medium conditioned by TCDD-treated HAPI microglial cells. Based on these observations, we highlight that the p38/JNK MAPK pathways play an important role in TCDD-induced iNOS activation in rat HAPI microglia and in the subsequent induction of apoptosis in primary cortical neurons., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1) was originally identified as a receptor for oxLDL predominantly expressed in endothelial cells. Recently up-regulation of LOX-1 has been implicated in oxidative stress and cell apoptosis in many cell types. However, LOX-1 expression in neurons or regulation of neuronal apoptosis by LOX-1 has not been reported. To investigate the possible roles of LOX-1 in hypertension induced brain damage, we examined the distribution of LOX-1 in cortex and hippocampus and compared its expression in 32-week-old SHR and WKY rats. Immunofluorescence revealed that LOX-1 positive cells were located principally at the cortex involved in sensory information processing and were mainly expressed in neurons. We also found up-regulated mRNA expression of LOX-1, Bax and caspase-3 and down-regulated mRNA expression of Bcl-2 in SHR group. Compared with WKY group, SHR group showed increased LOX-1 positive cells and TUNEL positive cells. Furthermore, double-labeling method indicated that LOX-1 expression was colocalized with TUNEL positive cells, which means that LOX-1 expression was involved in hypertension related cell apoptosis. These findings indicated that LOX-1 expression was up-regulated in the cortex of SHR and its expression has implication in neuronal apoptosis. Elevated Bax/Bcl-2 ratio may be involved under this event., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Telomerase reverse transcriptase (TERT) can regulate cell apoptosis and proliferation. It has been shown that TERT expression can be induced in models of adult brain ischemia. In the present study, we investigated the role of TERT in ischemic neuronal death in neonatal hypoxic-ischemic rats model. Postnatal day 10 Sprague-Dawley rats were used to establish hypoxia-ischemia (HI) model and hypoxia alone (H) model. Pups were killed at 4, 8, 12, 24, or 48 h after the insult. Plasmid containing mock, TERT antisense or sense fragment mixed with Fugene HD was injected to the right lateral ventricle immediately after the insult respectively. Additional injection was performed after 24 h. Pups were sacrificed 24h after the administration. TERT and cleaved caspase-3 (CC3) expression were measured by Western blot. Apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. We found that H/HI treatment induced neuronal apoptosis and expression of TERT and CC3. However, TERT was higher in H than in HI pups whereas CC3 and apoptosis were opposite, TERT antisense plasmid markedly attenuated TERT expression induced by HI, upregualted CC3 expression, and increased apoptosis. Our results indicate that TERT might function as an anti-apoptotic protein by inhibiting activation of caspase-3, while further studies are needed to evaluate underlying mechanisms., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Epidemiological studies have indicated that obesity is associated with colorectal cancer. The obesity hormone leptin is considered as a key mediator for cancer development and progression. The present study aims to investigate regulatory effects of leptin on colorectal carcinoma. The expression of leptin and its receptor Ob-R was examined by immunohistochemistry in 108 Chinese patients with colorectal carcinoma. The results showed that leptin/Ob-R expression was significantly associated with T stage, TNM stage, lymph node metastasis, distant metastasis, differentiation and expression of p-mTOR, p-70S6 kinase, and p-Akt. Furthermore, the effects of leptin on proliferation and apoptosis of HCT-116 colon carcinoma cells were determined. The results showed that leptin could stimulate the proliferation and inhibit the apoptosis of HCT-116 colon cells through the PI3K/Akt/mTOR pathway. Ly294002 (a PI3K inhibitor) and rapamycin (an mTOR inhibitor) could prevent the regulatory effects of leptin on the proliferation and apoptosis of HCT-116 cells via abrogating leptin-mediated PI3K/Akt/mTOR pathway. All these results indicated that leptin could regulate proliferation and apoptosis of colorectal carcinoma through the PI3K/Akt/ mTOR signalling pathway.

Toll-like receptor 3 (TLR3), a member of the pathogen recognition receptors, is widely expressed in various cells and has been shown to activate immune signaling pathways by recognizing viral double-stranded RNA. Recently, it was reported that the activation of TLR3 induced apoptosis in some cells, but the detailed molecular mechanism is not fully understood. In this study, we found that in endothelial cells polyinosinic-polycytidylic acid (poly(I-C)) induced dose- and time-dependent cell apoptosis, which was elicited by TLR3 activation, as TLR3 neutralization and down-regulation repressed the apoptosis. Poly(I-C) induced the activation of both caspases 8 and 9, indicating that TLR3 triggered the signaling of both the extrinsic and intrinsic apoptotic pathways. Poly(I-C) up-regulated tumor necrosis factor-related apoptosis-inducing ligand and its receptors, death receptors 4/5, resulting in initiating the extrinsic pathway. Furthermore, poly(I-C) down-regulated anti-apoptotic protein, B cell lymphoma 2 (Bcl-2), and up-regulated Noxa, a key Bcl-2 homology 3-only antagonist of Bcl-2, leading to the priming of the intrinsic pathway. A p53-related protein, the transactivating p63 isoform α (TAp63α), was induced by TLR3 activation and contributed to the activation of both the intrinsic and extrinsic apoptotic pathways. Both the cells deficient in p63 gene expression by RNA interference and cells that overexpressed the N-terminally truncated p63 isoform α (ΔNp63α), a dominant-negative variant of TAp63α, by gene transfection, survived TLR3 activation. Taken together, TAp63α is a crucial regulator downstream of TLR3 to induce cell death via death receptors and mitochondria.

The antitumor activity of histone deacetylase inhibitors (HDACI) on multidrug-resistant sarcoma cell lines has not been previously described. Treatment of multidrug-resistant sarcoma cell lines with HDACI PCI-24781 resulted in dose-dependent accumulation of acetylated histone, p21 and poly(ADP-ribose)polymerase (PARP) cleavage products. Growth of these cell lines was inhibited by PCI-24781 at IC(50) of 0.43 to 2.7. When we looked for synergy of PCI-24781 with chemotherapeutic agents, we found that PCI-24781 reverses drug resistance in all four multidrug-resistant sarcoma cell lines and synergizes with chemotherapeutic agents to enhance caspase-3/-7 activity. Expression of RAD51 (a marker for DNA double-strand break repair) was inhibited and the expression of GADD45α (a marker for growth arrest and DNA-damage) was induced by PCI-24781 in multidrug-resistant sarcoma cell lines. In conclusion, HDACI PCI-24781 synergizes with chemotherapeutic drugs to induce apoptosis and reverses drug resistance in multidrug-resistant sarcoma cell lines.

Background: The activation of signal transducer and activator of transcription 3 (Stat3) pathway correlates with tumor growth, survival, drug resistance and poor prognosis in osteosarcoma. To explore the potential therapeutic values of this pathway, we assessed both the expression and the activation of Stat3 pathway in several pairs of multidrug resistant (MDR) osteosarcoma cell lines, and tissues. To explore the potential therapeutic values of this pathway, we analyzed the ability of the synthetic oleanane triterpenoid, C-28 methyl ester of 2-cyano-3,12-dioxoolen-1,9-dien-28-oic acid (CDDO-Me), to inhibit Stat3 expression and activation as well as its effects on doxorubicin sensitivity in osteosarcoma cells., Methods: Expression of Stat3, phosphorylated Stat3 (pStat3) and Stat3 targeted proteins, including Bcl-XL, Survivin and MCL-1 were determined in drug sensitive and MDR osteosarcoma cell lines and tissues by Western blot analysis. The effect of CDDO-Me on osteosarcoma cell growth was evaluated by MTT and apoptosis by PARP cleavage assay and caspase-3/7 activity., Results: Stat3 pathway was activated in osteosarcoma tissues and in MDR cell lines. CDDO-Me inhibited growth and induced apoptosis in osteosarcoma cell lines. Treatment with CDDO-Me significantly decreased the level of nuclear translocation and phosphorylation of Stat3. The inhibition of Stat3 pathway correlated with the suppression of the anti-apoptotic Stat3 targeted genes Bcl-XL, survivin, and MCL-1. Furthermore, CDDO-Me increased the cytotoxic effects of doxorubicin in the MDR osteosarcoma cell lines., Conclusions: Stat3 pathway is overexpressed in MDR osteosarcoma cells. CDDO-Me significantly inhibited Stat3 phosphorylation, Stat3 nuclear translocation and induced apoptosis in osteosarcoma. This study provides the framework for the clinical evaluation of CDDO-Me, either as monotherapy or perhaps even more effectively in combination with doxorubicin to treat osteosarcoma and overcome drug resistance.

Purpose: To identify the apoptosis genes involved in the multidrug resistant phenotype of osteosarcoma., Methods: Multidrug resistant human osteosarcoma cell line (U-2 OS MR) and a drug sensitive parental cell line (U-2 OS) were both treated with paclitaxel and analyzed by the gene array containing 96 apoptosis associated genes. The different expression of the special apoptosis associated genes were further analyzed by Western blot in the multidrug resistant osteosarcoma cell lines (U-2 OS MR, KH OS R2) and the drug sensitive parental cell lines (U-2 OS, KH OS). One of the disregulated gene, RAIDD, was transfected into the multidrug resistant osteosarcoma cells for functional studies., Results: RAIDD showed signs of significant expression in the U-2 OS cells after being treated with paclitaxel (P < 0.01). However, the induction of RAIDD did not occur in U-2 OS MR cells (P = 0.2). Subsequent analysis by Western blot confirmed the deficiency of the expression of RAIDD protein in U-2 OS MR. On the contrary, the expression of RAIDD could be significantly induced by paclitaxel and doxorubicin in U-2 OS cells as both time and dosage were deciding factors. It also demonstrated the cleavage of PARP associated with RAIDD expression in U-2 OS cells, but not however in U-2 OS MR cells after being treated with paclitaxel or doxorubicin. Similar results were found in osteosarcoma multidrug resistant cell line KH OS R2 and the drug sensitive parental cell line KH OS. Furthermore, over-expression of RAIDD in multidrug resistant cell lines could possibly reverse drug resistant phenotypes., Conclusion: This study indicate that impaired expression of RAIDD in drug induced apoptosis may play a role in the multidrug resistance of osteosarcoma cells.

Insulin-like growth factor-I receptor (IGF-IR) is an important mediator of tumor cell survival and shows prognostic significance in sarcoma. To explore potential therapeutic strategies for interrupting signaling through this pathway, we assessed the ability of cyclolignan picropodophyllin (PPP), a member of the cyclolignan family, to selectively inhibit the receptor tyrosine kinase activity of IGF-IR in several sarcoma cell line model systems. Of the diverse sarcoma subtypes studied, osteosarcoma cell lines were found to be particularly sensitive to IGF-IR inhibition, including several multidrug resistant osteosarcoma cell lines with documented resistance to various conventional anticancer drugs. PPP shows relatively little toxicity in human osteoblast cell lines when compared with osteosarcoma cell lines. These studies show that PPP significantly inhibits IGF-IR expression and activation in both chemotherapy-sensitive and chemotherapy-resistant osteosarcoma cell lines. This inhibition of the IGF-IR pathway correlates with suppression of proliferation of osteosarcoma cell lines and with apoptosis induction as measured by monitoring of poly(ADP-ribose) polymerase and its cleavage product and by quantitative measurement of apoptosis-associated CK18Asp396. Importantly, PPP increases the cytotoxic effects of doxorubicin in doxorubicin-resistant osteosarcoma cell lines U-2OS(MR) and KHOS(MR). Furthermore, small interfering RNA down-regulation of IGF-IR expression in drug-resistant cell lines also caused resensitization to doxorubicin. Our data suggest that inhibition of IGF-IR with PPP offers a novel and selective therapeutic strategy for ostosarcoma, and at the same time, PPP is effective at reversing the drug-resistant phenotype in osteosarcoma cell lines.

To identify apoptosis genes involved in the multidrug resistance of osteosarcoma, a multidrug resistant human osteosarcoma cell line (U-2 OS MR) was established. Apoptosis gene microarray analysis demonstrated that GADD45alpha was significantly induced in U-2 OS cells after exposure to paclitaxel (P < 0.0001). However, the induction of GADD45alpha did not occur in U-2 OS MR cells. Subsequent analysis by Western blot confirmed that the expression of GADD45alpha could be significantly induced by paclitaxel and doxorubicin in U-2 OS cells but not in U-2 OS MR cells. Furthermore, the paclitaxel or doxorubicin treated U-2 OS and KH OS cells have a higher percentage of apoptotic cells when compared with U-2 OS MR and KH OS R2 cells treated with the same drugs. When GADD45alpha was transfected into U-2 OS MR or KH OS R2 and expressed, the cells became more sensitive to chemotherapeutic drugs. These results suggest that GADD45alpha may play a role in drug-induced apoptosis, as well as multidrug resistance in osteosarcoma cells.

Neural stem/progenitor cells (NPCs) are present in the developing and adult central nervous system. NPC apoptosis is an important aspect of normal brain development. We show that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 2 is highly expressed on human NPCs derived from fetal cortex, yet TRAIL induces only minimal levels of apoptosis in NPCs. Caspase-8 mRNA and protein, an important factor in the TRAIL-mediated death pathway, is present at low levels in human NPCs. In contrast, inhibitors of apoptosis proteins (IAP), such as c-IAP1, are highly expressed. The transcription inhibitor actinomycin D sensitized human NPCs to TRAIL-induced apoptosis. Further, inhibition of cellular inhibitors of apoptosis protein 1 (c-IAP1) expression by small interfering RNA (siRNA) increased TRAIL-mediated caspase-3 activation and apoptosis; thus, c-IAP1 protects NPCs against TRAIL-induced apoptosis and suppresses caspase-3 activation. These findings illustrate the mechanisms for NPC resistance to apoptotic agonists such as TRAIL, and demonstrate a potentially important mechanism in CNS disease states., (Copyright (c) 2005 Wiley-Liss, Inc.)

Objective: To evaluate the effect of beta irradiation on intimal proliferation and apoptosis in vein grafts., Methods: Autogenous vein graft model was established in 80 rats by transplanting the internal branch of the jugular vein to the carotid artery by end to end anastomosis. The veins were irradiated by (32)P solution before anastomosis. Two dose schedules were studied: control group (graft, nonirradiated) and radiation group (20 Gy). The grafted veins were harvested at 3, 1, 2 and 4 week respectively after the operation. intimal hyperplasia (IH), smooth muscle cell (SMC), proliferation, p53, bcl-2 and bax were observed pathologically and immunohistochemically. They were analyzed by a computerized system. The presence of apoptotic VSMC was demonstrated by TUNEL method., Result: There was a significant decrease in the average intimal thickness at 7, 14 and 28 days (t = 15.694, P < 0.05) in the radiation group. Immunohistochemical analysis of PCNA indicated decreased positive cells in the radiation group compared with the controls at 1 and 2 weeks (t = 60.157, P < 0.01). Apoptosis of VSMC was higher in the radiation group than in the control group at 2 weeks (t = 56.176, P < 0.01). There was no significant difference in expression of P(53) between the two groups, and there was a significant increase in bax/bcl-2 in the radiation group at 2 weeks (t = 9.783, P < 0.05)., Conclusion: These preliminary results demonstrated that low dose of beta irradiation in the vein graft inhibits SMC proliferation and induces the apoptosis of VSMC in rats.

Objective: To study the mechanism of graft vein stenosis., Methods: A rat experimental model of autogenous vein graft was established by transplanting the right external jungular vein into the infrarenal abdominal aorta in 100 Wister rats. Electric microscope, TUNEL and immunohistochemical S-P technique were used to detect the apoptosis, the expression of apoptosis related-gene bcl-2 and bax and proliferation cell nuclear antigen (PCNA) of smooth muscle cells(SMCs) in vein graft., Results: From 1 to 8 weeks after replacement, the expression of apoptosis and PCNA of SMCs was continuously higher than the control group (P < 0.01). From 1 to 2 weeks, the expression of TUNEL and PCNA showed peak value. From 1 to 2 weeks, the positive rate of apoptosis was lower than that of PCNA, but from 4 to 8 weeks, the positive rate of TUNEL was higher than that of PCNA. There was obvious positive correlation between the expression of TUNEL and PCNA (r = 0.813 P < 0.05). One to 2 weeks after vein grafting, bcl-2 positive rate increased and was more different than the control group and the group of 4 to 8 weeks after vein grafting (P < 0.010)., Conclusions: The imbalance of proliferation and apoptosis may be related to the vessel remodeling and vein graft stenosis, and bcl-2 and bax protein may involve in the regulation of apoptosis of VSMC. Adopting the mixed strategy to regulate the balance between proliferation and apoptosis may be useful to prevent vein graft stenosis.

Mitogen-activated protein kinases (MAPKs) are involved in neuronal death caused by many cytotoxins. Conventional MAPKs consist of three family members: extracellular signal-regulated kinase-1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38. It has been originally shown that ERK1/2 is important for cell survival, whereas JNK and p38 are deemed stress responsive and thus involved in apoptosis. However, information describing the role of MAPKs in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced neurotoxicity is insufficient. The aim of this study was to identify the role of MAPK cascades in TCDD-induced neurotoxicity using differentiated pheochromocytoma (PC12) cells as a model for neuronal cells. Cell viability assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and flow cytometry analysis showed that TCDD attenuated cell viability with a dose- and time-dependent manner and significantly induced apoptosis in primary cortical neurons and PC12 cells. Western blot analysis indicated that TCDD markedly activated the expression of ERK1/2, JNK and p38 in TCDD-treated PC12 cells. Furthermore, PD98059 (ERK1/2 inhibitor), SP600125 (JNK inhibitor) and SB202190 (p38 inhibitor) notably blocked the effect of TCDD on cell apoptosis. Based on the findings above, it is concluded that the activation of MAPK signaling pathways may be associated with TCDD-mediated neuronal apoptosis. [ABSTRACT FROM AUTHOR]