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Large tumor suppressor (Lats) plays a critical role in maintaining cellular homeostasis and is the core to mediate Hippo growth-inhibitory signaling pathway. SUMOylation is a reversible and dynamic process that regulates a variety of cell functions. Here, we show that SUMOylation of Lats1 affects its kinase activity specifically towards Hippo signaling. Small ubiquitin-like modifier (SUMO) 1 interacts with and directly SUMOylates Lats1, whereas loss of SUMOylation pathway function disrupts Lats1 SUMOylation. Among potential SUMOylation sites on hLats1, K751 and K830 are conversed and essential for maintaining the transcriptional output of Hippo signaling, whereas K751 mutation more significantly abolishes SUMO1-induced Lats1 SUMOylation than K830 mutation. Though Lats1 SUMOylation at K751 affects neither its subcellular distribution nor its interactions with YAP and TAZ, it significantly destabilizes the phosphorylated Lats1 (Thr1079 but not Ser909), resulting in the attenuation of Lats1 kinase activity and inhibition of Hippo signaling. Moreover, HepG2 hepatocellular carcinoma cells express significantly more SUMOylated Lats1 than LO2 normal human hepatic cells, and in HepG2 cells or HepG2 cells xenografts, Lats1 SUMOylation at K751 consistently attenuates Lats1 kinase activity and subsequently suppresses Hippo signaling, resulting in not only the promotion of cell proliferation and colony formation but also the suppression of cell apoptosis. Together, we demonstrate that Lats1 SUMOylation at K751 suppresses its kinase activity and subsequently attenuates its tumor-suppressor functions. Thus, this study provides additional insight into how Hippo signaling is regulated and highlights the potentially critical role of Lats1 SUMOylation in tumor development. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a highly aggressive malignant tumor with limited treatment options and poor prognosis. In this study, we reveal the pivotal role of Stratifin (SFN), also recognized as 14-3-3σ, in driving HCC progression. Our investigation underscores a substantial upregulation of SFN within HCC tissues, manifesting a significant association with worse prognostic outcomes among HCC patients. In vitro and in vivo experiments reveal that SFN overexpression significantly amplifies proliferation, mitigates sorafenib-induced effects on HCC cells, and enhances tumorigenesis. While SFN silencing exerts converse effects on HCC progression. Additionally, we unveil a critical interaction between SFN and AKT, where SFN boosts AKT kinase activity by disrupting the binding of PHLPP2 and AKT, thereby intensifying the malignant progression of HCC cells. In conclusion, this study identifies the oncogenic role of SFN and elucidates the regulatory mechanism of the SFN/AKT axis in HCC, which may provide valuable insights into the mechanisms of HCC progression and potential targets for therapeutic intervention. • SFN is elevated in HCC and is associated with the worse prognosis of patients. • SFN promotes HCC cell growth and resistance to sorafenib-induced cell death. • SFN interacts with AKT, enhancing AKT's kinase activity via blocking the binding of PHLPP2 and AKT. • SFN's ability to promote HCC progression depends on its regulation of AKT kinase activity. • SFN emerges as a potential therapeutic target and a promising prognostic marker for HCC. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is one of the most prevalent and leading causes of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been demonstrated to play vital roles in cancer development and progression. The lncRNA PWRN1 (PWRN1), acts as a tumor suppressor factor, which is low expressed in some cancers. However, the molecular mechanisms underlying the effects of PWRN1 , especially the regulatory relationship with RNA binding protein in HCC remain largely unknown. In the present study, we demonstrated that PWRN1 was significantly down-regulated in HCC and correlated with better prognosis; furthermore, gain-of-function experiments showed that PWRN1 inhibited the proliferation of HCC cells. We further found that PWRN1 up-regulated pyruvate kinase activity and thus hinders the proliferation of HCC in vitro and in vivo. Mechanistically, pyruvate kinase M2 (PKM2) was bound to it and maintained the high activity state of PKM2, thereby hindering PKM2 from entering the nucleus in the form of low-activity dimers, reducing the expression of c-Myc downstream gene LDHA , leading to a decrease in lactate levels, and inhibiting the growth of tumor cells. In addition, PWRN1 was found to inhibit aerobic glycolysis. Finally, TEPP-46, a pyruvate kinase activator, appeared to inhibit HCC proliferation by maintaining tetramer stability and increasing pyruvate kinase activity. Taken together, our results provide new insights into the biology hindering HCC proliferation and indicate that PWRN1 in combination with PKM2 activators might represent a novel therapeutic target for HCC. • PWRN1 overexpression inhibits the cell proliferation of HCC. • PWRN1 physically interacts with the glycolytic enzyme PKM2, inhibits glycolysis and lactate production. • PWRN1 inhibits HCC growth through impeding PKM2 nuclear translocation and activating PKM2 activity. • The combination of PWRN1 with PKM2 activator would be promsing for the treatment of HCC. [ABSTRACT FROM AUTHOR]

Tumor-associated macrophages (TAMs) are important components of the tumor microenvironment (TME) and strongly associated with poor prognosis and drug resistance, including checkpoint blockade immunotherapy in solid tumor patients. However, the mechanism by which TAM affects immune metabolism reprogramming and immune checkpoint signalling pathway in the TME remains elusive. In this study we found that transforming growth factor-beta (TGF-β) secreted by M2-TAMs increased the level of glycolysis in bladder cancer (BLCA) and played important role in PD-L1-mediated immune evasion through pyruvate kinase isoenzymes M2 (PKM2). Mechanistically, TGF-β promoted high expression of PKM2 by promoting the nuclear translocation of PKM2 dimer in conjunction with phosphorylated signal transducer and activator of transcription (p-STAT3), which then exerted its kinase activity to promote PD-L1 expression in BLCA. Moreover, SB-431542 (TGF-β blocker) and shikonin (PKM2 inhibitor) significantly reduced PD-L1 expression and inhibited BLCA growth and organoids by enhancing anti-tumor immune responses. In conclusion, M2-TAM-derived TGF-β promotes PD-L1-mediated immune evasion in BLCA by increasing the PKM2 dimer-STAT3 complex nuclear translocation. Combined blockade of the TGF-β receptor and inhibition of PKM2 effectively prevent BLCA progression and immunosuppression, providing a potential targeted therapeutic strategy for BLCA. • M2-TAMs promote glycolysis and PD-L1 mediated immune evasion by TGF-β secretion. • TGF-β increases PD-L1 expression by promoting PKM2 dimer nuclear translocation. • TGF-β promotes tumor invasion and migration by promoting PKM2 tetramer. • Combined blockade of TGF-β and PKM2 enhances anti-tumor immune responses. [ABSTRACT FROM AUTHOR]

It is reported that 2'-hydroxycinnamaldehyde (HCA), isolated from cinnamon, has anti-tumor effects through the modulation of multi-target molecules. In this study, we identified pyruvate kinase M2 (PKM2) as a direct target of HCA by use of biochemical methods including affinity chromatography, drug affinity responsive target stability, and cellular thermal shift assay. PKM2 is up-regulated in multiple cancer types and is considered as a potential target for cancer therapy. HCA binds directly to PKM2 and selectively decreases the phosphorylation of PKM2 at Tyr105, indicating a potential anti-proliferative effect on prostate cancer cells. As a PKM2 activator, HCA increases pyruvate kinase activity by promoting the tetrameric state of PKM2. However, HCA suppresses protein kinase activity of PKM2 by decreasing the phosphorylation at Tyr105. Moreover, this leads to a decrease of PKM2-mediated STAT3 phosphorylation at Tyr705 and a down-regulation of target genes, including MEK5 and cyclin D1. Furthermore, HCA suppresses tumor growth and the release of tumor extracellular vesicles in vivo by inhibiting the phosphorylation of PKM2. Collectively, our results suggest that HCA may be a potential anticancer agent targeting PKM2 in cancer progression. [ABSTRACT FROM AUTHOR]

Platinum-taxane chemotherapy is the first-line standard-of-care treatment administered to patients with epithelial ovarian cancer (EOC), and faces the major challenge of cisplatin resistance. Aurora Kinase A (AURKA) is a serine/threonine kinase, acting as an oncogene by participating in microtubule formation and stabilization. In this study, we demonstrate that AURKA binds with DDX5 directly to form a transcriptional coactivator complex to induce the transcription and upregulation of an oncogenic long non-coding RNA, TMEM147-AS1, which sponges hsa-let-7b/7c-5p leading to the increasing expression of AURKA as a feedback loop. The feedback loop maintains EOC cisplatin resistance via activation of lipophagy. These findings underscore the feedback loop of AURKA/DDX5/TMEM147-AS1/let-7 provides mechanistic insights into the combined use of TMEM147-AS1 siRNA and VX-680, which can help improve EOC cisplatin treatment. Our mathematical model shows that the feedback loop has the potential to act as a biological switch to maintain on- (activated) or off- (deactivated) status, implying the possible resistance of single use of VX-680 or TMEM147-AS1 siRNA. The combined use reduces both the protein level of AURKA using TMEM147-AS1 siRNA and its kinase activity using VX-680, showing more significant effect than the use of TMEM147-AS1 siRNA or VX-680 alone, which provides a potential strategy for EOC treatment. • TMEM147-AS1 induces lipophagy to promote EOC cisplatin resistance via upregulation of ACC1 and LC3B in the downstream of AURKA. • The feedback loop of AURKA/DDX5/TMEM147-AS1/let-7 has the potential to act as a biological switch to maintain on- (activated) or off- (deactivated) status to affect EOC cisplatin resistance. • The combined use of TMEM147-AS1 siRNA in vivo and AURKA inhibitor VX-680 reduces both the protein level and kinase activity of AURKA, showing more significant effect than the use of TMEM147-AS1 siRNA or VX-680 alone, which provides a potential strategy for EOC treatment. [ABSTRACT FROM AUTHOR]

The transient receptor potential melastatin-subfamily member 7 (TRPM7) is a ubiquitous cation channel possessing kinase activity. TRPM7 mediates a variety of physiological responses by conducting flow of cations such as Ca2+, Mg2+, and Zn2+. Here, we show that the activation of TRPM7 channel stimulated by chemical agonists of TRPM7, Clozapine or Naltriben, inhibited autophagy via mediating Zn2+ release to the cytosol, presumably from the intracellular Zn2+-accumulating vesicles where TRPM7 localizes. Zn2+ release following the activation of TRPM7 disrupted the fusion between autophagosomes and lysosomes by disturbing the interaction between Sxt17 and VAMP8 which determines fusion status of autophagosomes and lysosomes. Ultimately, the disrupted fusion resulting from stimulation of TRPM7 channels arrested autophagy. Functionally, we demonstrate that the autophagy inhibition mediated by TRPM7 triggered cell death and suppressed metastasis of cancer cells in vitro, more importantly, restricted tumor growth and metastasis in vivo, by evoking apoptosis, cell cycle arrest, and reactive oxygen species (ROS) elevation. These findings represent a strategy for stimulating TRPM7 to combat cancer. [ABSTRACT FROM AUTHOR]

Ovarian cancer (OvCa) has a dismal prognosis because of its late-stage diagnosis and the emergence of chemoresistance. Doublecortin-like kinase 1 (DCLK1) is a serine/threonine kinase known to regulate cancer cell "stemness", epithelial-mesenchymal transition (EMT), and drug resistance. Here we show that DCLK1 is a druggable target that promotes chemoresistance and tumor progression of high-grade serous OvCa (HGSOC). Importantly, high DCLK1 expression significantly correlates with poor overall and progression-free survival in OvCa patients treated with platinum chemotherapy. DCLK1 expression was elevated in a subset of HGSOC cell lines in adherent (2D) and spheroid (3D) cultures, and the expression was further increased in cisplatin-resistant (CPR) spheroids relative to their sensitive controls. Using cisplatin-sensitive and resistant isogenic cell lines, pharmacologic inhibition (DCLK1-IN-1), and genetic manipulation, we demonstrate that DCLK1 inhibition was effective at re-sensitizing cells to cisplatin, reducing cell proliferation, migration, and invasion. Using kinase domain mutants, we demonstrate that DCLK1 kinase activity is critical for mediating CPR. The combination of cisplatin and DCLK1-IN-1 showed a synergistic cytotoxic effect against OvCa cells in 3D conditions. Targeted gene expression profiling revealed that DCLK1 inhibition in CPR OvCa spheroids significantly reduced TGFβ signaling, and EMT. We show in vivo efficacy of combined DCLK1 inhibition and cisplatin in significantly reducing tumor metastases. Our study shows that DCLK1 is a relevant target in OvCa and combined targeting of DCLK1 in combination with existing chemotherapy could be a novel therapeutic approach to overcome resistance and prevent OvCa recurrence. • DCLK1 expression is elevated in platinum-resistant HGSOC cell lines. • High DCLK1 expression is associated with poor survival in HGSOC patients. • DCLK1 drives platinum-resistance and metastases in HGSOC via canonical TGF-β signaling and EMT pathways. • Combined targeting of DCLK1 and cisplatin is a novel strategy to overcome chemoresistance and metastasis in HGSOC. [ABSTRACT FROM AUTHOR]

Oesophageal cancer is associated with high morbidity and mortality rates because it is highly invasive and prone to recurrence and metastasis, with a five-year survival rate of <20%. Therefore, there is an urgent need for new methods aimed at improving therapeutic intervention. Several studies have shown that targeted therapy may be effective for the treatment of oesophageal cancer. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase with kinase activity and scaffolding function, could be overexpressed in a variety of solid tumours, including oesophageal cancer. FAK participates in survival, proliferation, progression, adhesion, invasion, migration, epithelial-to-mesenchymal transition, angiogenesis, DNA damage repair, and other biological processes through multiple signalling pathways in cancer cells. It plays an important role in the occurrence and development of tumours and has been linked to the prognosis of oesophageal cancer. FAK has been suggested as a potential therapeutic target in oesophageal cancer; thus, the combination of FAK inhibitors with chemotherapy, radiotherapy, and immunotherapy is expected to prolong the survival of patients. This paper presents a brief overview of the structure of FAK and its potential role in oesophageal cancer, providing a rationale for the future application of FAK inhibitors in the treatment of the disease. [ABSTRACT FROM AUTHOR]

Advanced stage ovarian clear cell carcinoma (OCCC) is poorly responsive to platinum-based chemotherapy and has an unfavorable prognosis. Previous studies revealed heterogeneous mutations in PI3K/AKT/mTOR and MAPK pathway nodules converging in mTORC1/2 activation. Here, we aimed to identify an effective low-dose combination of PI3K/AKT/mTOR pathway and MAPK pathway inhibitors simultaneously targeting key kinases in OCCC to preclude single-inhibitor initiated pathway rewiring and limit toxicity. Small molecule inhibitors of mTORC1/2, PI3K and MEK1/2 were combined at monotherapy IC20 doses in a panel of genetically diverse OCCC cell lines (n = 7) to determine an optimal low-dose combination. The IC20 dose triple combination reduced kinase activity in PI3K/AKT/mTOR and MAPK pathways, prevented single-inhibitor induced feedback mechanisms and inhibited short and long-term proliferation in all seven cell lines. Finally, this low-dose triple drug combination treatment significantly reduced tumor growth in two genetically characterized OCCC patient-derived xenograft (PDX) models without resulting in weight loss in these mice. The effectiveness and tolerability of this combined therapy in PDX models warrants clinical exploration of this treatment strategy for OCCC and might be applicable to other cancer types with a similar genetic background. [ABSTRACT FROM AUTHOR]

DEP domain-containing mechanistic target of rapamycin (mTOR)-interacting protein (DEPTOR) is an important modulator of mTOR, a highly conserved kinase whose hyperactivation is critically involved in a variety of human tumors. The role of DEPTOR playing in pituitary adenoma (PA) is largely unknown. Here, we reported that DEPTOR was downregulated in PA tissues, especially dopamine-resistant prolactinomas. Consistently, overexpression of DEPTOR inhibited pituitary tumor GH3 and MMQ cells proliferation in vitro and in vivo, and sensitized GH3 and MMQ cells to cabergoline (CAB), a dopamine agonist (DA). Conversely, knockdown of DEPTOR promoted GH3 and MMQ cells proliferation, and conferred cells resistance to CAB. Mechanistically, DEPTOR inhibited both mTOR Complex 1 (mTORC1) and 2 (mTORC2) activities in PA cells. In addition, DEPTOR expression level was increased to suppress mTOR kinase activity via decreasing E3 ubiquitin ligase, βTrCP1, in response to CAB. Furthermore, DEPTOR enhanced autophagy-dependent cell death to confer cells sensitivity to CAB. Taken together, our results suggest that DEPTOR may be a potential target for the treatment of PAs. [ABSTRACT FROM AUTHOR]

Abstract There is increasing global incidence of highly metastatic melanoma and therapeutic strategies like those focusing on the downstream beta-catenin/MITF axis of invading melanoma cells are urgently needed. Targeting endoplasmic reticulum (ER) stress can promote cancer cell death and inhibit epithelial mesenchymal transition (EMT) in metastatic tumors. This study aimed to determine if Honokiol could promote ER stress-dependent apoptosis and regulate metastatic melanoma. The therapeutic efficacy of Honokiol was assessed using the highly metastatic melanoma xenograft mouse model for peritoneal metastasis and evaluated by computed tomography imaging. The ER stress marker, Calpain-10, delineated a novel proteolytic cleavage enzyme, while CHOP/GADD153-regulated apoptosis was used for gene silencing to determine the role of the β-catenin/MITF axis in melanoma cells. The results showed that Honokiol effectively decreased peritoneal dissemination and organ metastasis via ER stress activation and EMT marker inhibition. Knockdown Calpain-10 or CHOP/GADD153 blocked all of the biological effects in Honokiol-induced β-catenin/MITF cleavage, ERSE or TCF/LEF luciferase activity, and β-catenin kinase activity. These findings suggest that Honokiol can significantly thwart the progression of highly metastatic melanoma using the β-catenin/MITF axis via prompt Calpain-10 and CHOP/GADD153 regulated cascades. Highlights • Honokiol inhibits the growth and metastasis of melanoma both in vitro and in vivo. • Honokiol induced ER stress CHOP activation and reduced MITF, β-catenin, and CDK2 expressions in animal melanoma tissues. • Honokiol-induced CHOP/GADD153 regulated β-catenin activation. • Honokiol enhanced Calpain10 and MITF-m interaction and caused MITF-m cleavage. • High expressions of MITF, β-catenin, and CDK2 decreased the overall survival probability of melanoma. [ABSTRACT FROM AUTHOR]

Abstract Gossypetin as a hexahydroxylated flavonoid found in many flowers and Hibiscus. It exerts various pharmacological activities, including antioxidant, antibacterial and anticancer activities. However, the anticancer capacity of gossypetin has not been fully elucidated. In this study, gossypetin was found to inhibit anchorage-dependent and -independent growth of esophageal cancer cells. To identify the molecular target(s) of gossypetin, various signaling protein kinases were screened and results indicate that gossypetin strongly attenuates the MKK3/6-p38 signaling pathway by directly inhibiting MKK3 and MKK6 protein kinase activity in vitro. Mechanistic investigations showed that arginine-61 in MKK6 is critical for binding with gossypetin. Additionally, the inhibition of cell growth by gossypetin is dependent on the expression of MKK3 and MKK6. Gossypetin caused G2 phase cell cycle arrest and induced intrinsic apoptosis by activating caspases 3 and 7 and increasing the expression of BAX and cytochrome c. Notably, gossypetin suppressed patient-derived esophageal xenograft tumor growth in an in vivo mouse model. Our findings suggest that gossypetin is an MKK3 and MKK6 inhibitor that could be useful for preventing or treating esophageal cancer. Highlights • Gossypetin suppresses esophageal cancer cell growth and induces apoptosis. • Gossypetin directly binds to MKK3 and MKK6 at the ATP binding pocket. • Gossypetin directly reduces the activity of MKK3 and MKK6. • Gossypetin attenuates the growth of patient-derived esophageal xenograft tumors. [ABSTRACT FROM AUTHOR]

There is increasing global incidence of highly metastatic melanoma and therapeutic strategies like those focusing on the downstream beta-catenin/MITF axis of invading melanoma cells are urgently needed. Targeting endoplasmic reticulum (ER) stress can promote cancer cell death and inhibit epithelial mesenchymal transition (EMT) in metastatic tumors. This study aimed to determine if Honokiol could promote ER stress-dependent apoptosis and regulate metastatic melanoma. The therapeutic efficacy of Honokiol was assessed using the highly metastatic melanoma xenograft mouse model for peritoneal metastasis and evaluated by computed tomography imaging. The ER stress marker, Calpain-10, delineated a novel proteolytic cleavage enzyme, while CHOP/GADD153-regulated apoptosis was used for gene silencing to determine the role of the β-catenin/MITF axis in melanoma cells. The results showed that Honokiol effectively decreased peritoneal dissemination and organ metastasis via ER stress activation and EMT marker inhibition. Knockdown Calpain-10 or CHOP/GADD153 blocked all of the biological effects in Honokiol-induced β-catenin/MITF cleavage, ERSE or TCF/LEF luciferase activity, and β-catenin kinase activity. These findings suggest that Honokiol can significantly thwart the progression of highly metastatic melanoma using the β-catenin/MITF axis via prompt Calpain-10 and CHOP/GADD153 regulated cascades. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is a neoplastic plasma cell disorder with high disease recurrence rates. Novel therapeutic approaches capable of improving outcomes in patients with MM are urgently required. The AKT signalling plays a critical regulatory role in MM pathophysiology, including survival, proliferation, metabolism, and has emerged as a key therapeutic target. Here, we identified a novel AKT inhibitor, HS1793, and defined its mechanism of action and clinical significance in MM. HS1793 disrupted the interaction between AKT and heat shock protein 90, resulting in protein phosphatase 2A-modulated phosphorylated-AKT (p-AKT) reduction. Moreover, we observed reductions in the kinase activity of the AKT downstream target, IκB kinase alpha, and the transcriptional activity of nuclear factor kappa B, which induced mitochondria-mediated cell death in MM cells exclusively. We confirmed the cytotoxicity and specificity of HS1793 via PET-CT imaging of a metastatic mouse model generated using human MM cells. We also evaluated the cytotoxic effects of HS1793 in primary and relapsed MM cells isolated from patients. Thus, HS1793 offers great promise in eliminating MM cells and improving therapeutic responses in primary and relapsed/refractory MM patients. [ABSTRACT FROM AUTHOR]

Activating germline mutations of anaplastic lymphoma kinase (ALK) occur in most cases of hereditary neuroblastoma (NB) and the constitutively active kinase activity of ALK promotes cell proliferation and survival in NB. Therefore, ALK kinase is a potential therapeutic target for NB. In this study, we show that the novel ALK inhibitor alectinib effectively suppressed cell proliferation and induces apoptosis in NB cell lines with either wild-type ALK or mutated ALK (F1174L and D1091N) by blocking ALK-mediated PI3K/Akt/mTOR signaling. In addition, alectinib enhanced doxorubicin-induced cytotoxicity and apoptosis in NB cells. Furthermore, alectinib induced apoptosis in an orthotopic xenograft NB mouse model. Also, in the TH-MYCN transgenic mouse model, alectinib resulted in decreased tumor growth and prolonged survival time. These results indicate that alectinib may be a promising therapeutic agent for the treatment of NB. [ABSTRACT FROM AUTHOR]

Transforming growth factor-β1 (TGF-β1) promotes tumor metastasis by inducing an epithelial-to-mesenchymal transition (EMT) in cancer cells. In this study, we investigated the effects of BIX02189 and XMD8-92, pharmacologic inhibitors of the MEK5 [mitogen-activated protein kinase/extracellular-signal-regulated kinase (ERK)5] signaling pathway, on the EMT and migration of cancer cells induced by TGF-β1. In human A549 lung cancer cells, TGF-β1-induced EMT, cell motility, and expression of matrix metalloproteinase-2 were completely inhibited by BIX02189, but not by XMD8-92 or small interference RNAs specific to MEK5 and ERK5. Interestingly, BIX02189 strongly blocked the activation of TGF-β1 signaling components, and this inhibitory effect was not reproduced by MEK5 inhibition. Molecular docking simulation and kinase assays revealed that BIX02189 binds directly to the ATP-binding site of the TGF-β receptor type I (TβRI) and suppresses its kinase activity. Finally, the anti-metastatic effect of BIX02189 was validated in a TβRI-derived A549 xenograft mouse model. Collectively, these findings newly characterize BIX02189 as a potent inhibitor of TβRI that can block the tumor metastatic activity of TGF-β1. [ABSTRACT FROM AUTHOR]

Dysregulation in iron metabolism can lead to a wide range of diseases including cancer. Iron-regulatory proteins (IRPs) and iron responsive elements (IREs) have been established as post-transcriptional regulators of intracellular iron homeostasis. The roles of other pathways involved in this process, however, remain largely unknown. Here we report that epidermal growth factor receptor (EGFR), an oncogenic driver, binds to and regulates the subcellular distribution of transferrin receptor 1(TfR1) through its tyrosine kinase activity and thus is required for cellular iron import. Inactivation of EGFR reduces the cell surface TfR1 expression, which leads to decreased iron import due to impaired TfR1-mediated iron uptake. This damaged iron assimilation results in cell cycle arrest and growth inhibition, which can be partially rescued by non-Tf-bound iron supplements. Evaluation of non-small cell lung cancer samples reveals a positive correlation between EGFR activation and membrane TfR1 expression. Our findings uncover a new role of EGFR in modulating cellular iron homeostasis through redistribution of TfR1, which is essential for cancer development and progression. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor I receptor (IGF1R) is frequently upregulated in breast cancer. Due to its intrinsic tyrosine kinase activity, aberrant activation of the IGF1R signaling axis may enhance tumor cell proliferation and cancer stemness, causing tumor relapse, metastasis and resistance to chemotherapy. We utilized a chromatin RNA in situ reverse transcription (CRIST) approach to characterize molecular factors that regulate the IGF1R network. We identified lncRNA HULC (Highly Upregulated in Liver Cancer) as a key trans-regulator of IGF1R in breast cancer cells. Loss of HULC suppressed the expression of IGF1R and the activation of its downstream PI3K/AKT pathway, while HULC overexpression activated the axis in breast cancer cells. Using a transcription-associated trap (RAT) assay, we demonstrated that HULC functioned as a nuclear lncRNA and epigenetically activated IGF1R by directly binding to the intragenic regulatory elements of the gene, orchestrating intrachromosomal interactions, and promoting histone H3K9 acetylation. The activated HULC-IGF1R/PI3K/AKT pathway mediated tumor resistance to cisplatin through the increased expression of cancer stemness markers, including NANOG, SOX2, OCT4, CD44 and ALDH1A1. In immunodeficient mice, stimulation of the HULC-IGF1R pathway promoted tumor metastasis. These data suggest that HULC may be a new epigenetic target for IGF1R axis-targeted therapeutic intervention. [ABSTRACT FROM AUTHOR]

The prognosis of metastatic or relapsed renal cell carcinoma (RCC) is still very poor, highlighting the need for new treatment strategies. Here, we identify a cooperative antitumor activity of interferon-α (IFNα) together with the Smac mimetic BV6 that antagonizes antiapoptotic IAP proteins. BV6 and IFNα act together to reduce cell viability and to induce apoptosis in various RCC cell lines. Molecular studies revealed that BV6/IFNα co-treatment triggers apoptosis independently of autocrine/paracrine Tumor Necrosis Factor (TNF)α signaling, since the TNFα-blocking antibody Enbrel fails to rescue cell death. Importantly, knockdown of Receptor-Interacting Protein (RIP)1 significantly decreases BV6/IFNα-mediated apoptosis, whereas the RIP1 kinase inhibitor necrostatin-1 (Nec-1) provides no protection. This demonstrates that RIP1 protein is critically required for BV6/IFNα-induced apoptosis, while RIP1 kinase activity is dispensable, pointing to a scaffold function of RIP1. Consistently, BV6 and IFNα cooperate to trigger the interaction of RIP1, Fas-Associated Death Domain protein (FADD) and caspase-8 to form a cytosolic cell death complex that drives caspase activation. Addition of the broad-range caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) significantly protects RCC cells against BV6/IFNα-induced apoptosis, demonstrating that caspase activity is required for apoptosis. In conclusion, the combination approach of IFNα and BV6 represents a promising strategy for cooperative induction of apoptosis in RCC cells, which warrants further investigation. [ABSTRACT FROM AUTHOR]

Platelet-derived growth factor receptors (PDGFRα/β) play critical roles in the autocrine-stimulated growth and recruitment of cancer-associated fibroblasts (CAFs) of human lung cancer cells. We have identified GZD856 as a new PDGFR inhibitor that potently inhibits PDGFRα/β kinase activity and blocks this signaling pathway in lung cancer cells both in vitro and in vivo. GZD856 strongly suppresses the proliferation of PDGFRα-amplified H1703 (PDGFRβ(-)) human lung cancer cells and demonstrates significant in vivo antitumor efficacy in a xenograft mouse model. Although GZD856 displays only limited in vitro antiproliferative efficiency against PDGFRα(-)/PDGFRβ(+) A549 lung cancer cells, it efficiently inhibits the in vivo growth and metastasis of A549 cancer cells in xenograft and orthotopic models, respectively. The promising in vivo antitumor activity of GZD856 in A549 models may result from its suppression of PDGFR-related microenvironment factors, such as recruitment of CAFs and collagen content in stromal cells. GZD856 may be considered as a promising new candidate for anti-lung cancer drug development. [ABSTRACT FROM AUTHOR]

Mutant Kras and chronic pancreatitis are the most common pathological events involved in human pancreatic cancer. It has been demonstrated that c-Raf is responsible for transmitting signals from mutant Ras to its downstream signals including MEK-ERK and for initiating carcinogenesis. The soluble epoxide hydrolase (sEH), a pro-inflammatory enzyme, generally inactivates anti-inflammatory and anti-pain epoxyeicosatrienoic acids (EETs). Herein, we have synthesized a novel compound of trans-4-{4-[3-(4-chloro-3-trifluoromethyl-phenyl)-ureido]-cyclohexyloxy}-pyridine-2-carboxylic acid methylamide (t-CUPM) via modifying the central phenyl ring of sorafenib and confirmed its dual inhibition of sEH and c-Raf by recombinant kinase activity assay. Pharmacokinetic analysis revealed that oral dosing of t-CUPM resulted in higher blood levels than that of sorafenib throughout the complete time course (48 h). The effect of t-CUPM on the inhibition of mutant Kras(G12D)-initiated murine pancreatic cancer cell growth was determined using the mouse pancreatic carcinoma cell model obtained from LSL-Kras(G12D)/Pdx1-Cre mice and showed that t-CUPM significantly inhibited this murine pancreatic carcinoma cell growth both in vitro and in mice in vivo. Inhibition of mutant Kras-transmitted phosphorylations of cRAF/MEK/ERK was demonstrated in these pancreatic cancer cells using Western blot assay and immunohistochemical approach. Modulation of oxylipin profile, particularly increased EETs/DHET ratio by sEH inhibition, was observed in mice treated with t-CUPM. These results indicate that t-CUPM is a highly potential agent to treat pancreatic cancer via simultaneously targeting c-Raf and sEH. [ABSTRACT FROM AUTHOR]

SH3 domain plays an important role in maintaining autoinhibition of BCR-ABL protein. RIN1 interacts with BCR-ABL SH3 domain via PxxP motifs to promote autophosphorylation as well as activation of BCR-ABL tyrosine kinase, suggesting using exogenous SH3 domain which blocks the interaction of BCR-ABL and RIN1 could be an adjunct therapy for CML. Here, we reported a novel p-BCR-ABL inhibitor, designed as ABL SH3 mutant, and identified its effects on inhibiting the tyrosine kinase activity of BCR-ABL without or with imatinib (IM) in vitro and in vivo. Our results demonstrated that ABL SH3 mutant T79Y markedly repressed the expression of BCR-ABL signaling pathways in IM-resistant cell lines KCL22 and K562/G01 as well as IM-sensitive cell line K562. Moreover, combination of T79Y with IM considerably decreased the proliferation of leukemia cells in vivo. Inhibition of BCR-ABL and RIN1 interaction using exogenous modified BCR-ABL SH3 domain provides a feasible and alternative option of small molecule inhibitors for CML treatment. [ABSTRACT FROM AUTHOR]

Chromosomal rearrangements of the NTRK1 gene, which encodes the high affinity nerve growth factor receptor (tropomyosin related kinase, TRKA), have been observed in several epithelial cancers, such as colon cancer, papillary thyroid carcinoma or non small cell lung cancer. The various NTRK1 fusions described so far lead to constitutive activation of TRKA kinase activity and are oncogenic. We further investigated here the existence and the frequency of NTRK1 gene rearrangements in colorectal cancer. Using immunohistochemistry and quantitative reverse transcriptase PCR, we analyzed a series of human colorectal cancers. We identified two TRKA positive cases over 408, with NTRK1 chromosomal rearrangements. One of these rearrangements is a TPM3–NTRK1 fusion already observed in colon cancer, while the second one is a TPR–NTRK1 fusion never described in this type of cancer. These findings further confirm that translocations in the NTRK1 gene are recurring events in colorectal cancer, although occurring at a low frequency (around 0.5%). [ABSTRACT FROM AUTHOR]

Overexpression of human epithelial growth factor receptor 2 (HER2) is a poor prognostic factor in breast cancer. HER2 is a transmembrane receptor comprising an extracellular domain (ECD), a single transmembrane domain, and an intracellular domain (ICD) with tyrosine-kinase activity. Receptor dimerization triggers pivotal effector pathways in cancer, such as phosphatidylinositol 3-kinase (PI3K) signaling. Currently, screening of HER2 in breast tumors for prognostic and therapeutic purposes involves immunohistochemical (IHC) phenotyping for the ECD, in which tumors with IHC scores below 2+ are reported as HER2-negative. We used a label-free liquid chromatography–mass spectrometry (LC–MS) proteomic approach to compare plasma samples from patients with HER2-positive breast tumors and patients with HER2-negative tumors. Patients with HER2-negative tumors expressed higher circulating levels of calpain-10 than patients with HER2-positive tumors. Calpains cleave HER2, releasing its ECD and transforming phenotypically positive tumors into phenotypically negative tumors. Therefore, we investigated the expression of the ICD in HER2-negative samples that overexpressed calpain-10. We found that 16% of HER2-negative tumors were positive for HER2-ICD, which was associated with circulating HER2-ECD. HER2 gene amplification was also observed in some HER2-negative tumors. Positive staining for the PI3K pathway was observed in the HER2-negative, ICD-positive tumors, similar to the HER2-positive cohort. Microarray analysis revealed that HER2-negative, ICD-positive samples clustered between HER2-positive tumors and triple-negative tumors. Survival analysis revealed that outcome in women with HER2-negative, ICD-positive tumors was better than in women bearing HER2-negative, ICD-negative (triple negative) tumors but was quite similar to HER2-positive tumors and worse than women with luminal A tumors. Moreover, in vitro analyses revealed that MDA-MB 231, a triple negative cell line, possesses calpain-10 and HER2-p-ICD up-regulation and blockage of calpain-10 activity promoted an increase in HER2-p-ICD and p-AKT levels, suggesting an increase in these pathways signaling. These data indicate that HER2-negative tumors with HER2-ICD positivity exhibit clinical behavior closer to that of HER2-positive tumors. This indicates a need for HER2-ICD screening when determining the molecular profile of breast tumors. These findings further indicate that lapatinib should be investigated as a target therapy for HER2-ICD-positive breast tumors. [ABSTRACT FROM AUTHOR]

Gossypetin as a hexahydroxylated flavonoid found in many flowers and Hibiscus. It exerts various pharmacological activities, including antioxidant, antibacterial and anticancer activities. However, the anticancer capacity of gossypetin has not been fully elucidated. In this study, gossypetin was found to inhibit anchorage-dependent and -independent growth of esophageal cancer cells. To identify the molecular target(s) of gossypetin, various signaling protein kinases were screened and results indicate that gossypetin strongly attenuates the MKK3/6-p38 signaling pathway by directly inhibiting MKK3 and MKK6 protein kinase activity in vitro. Mechanistic investigations showed that arginine-61 in MKK6 is critical for binding with gossypetin. Additionally, the inhibition of cell growth by gossypetin is dependent on the expression of MKK3 and MKK6. Gossypetin caused G2 phase cell cycle arrest and induced intrinsic apoptosis by activating caspases 3 and 7 and increasing the expression of BAX and cytochrome c. Notably, gossypetin suppressed patient-derived esophageal xenograft tumor growth in an in vivo mouse model. Our findings suggest that gossypetin is an MKK3 and MKK6 inhibitor that could be useful for preventing or treating esophageal cancer. [ABSTRACT FROM AUTHOR]