Cyclosporin A inhibits prostate cancer growth through suppression of E2F8 transcription factor in a MELK­dependent manner.

The treatment of advanced prostate cancer remains a formidable challenge due to the limited availability of effective treatment options. Therefore, it is imperative to identify promising druggable targets that provide substantial clinical benefits and to develop effective treatment strategies to overcome therapeutic resistance. Cyclosporin A (CsA) showed an anticancer effect on prostate cancer in cultured cell and xenograft models. E2F8 was identified as a master transcription factor that regulated a clinically significant CsA specific gene signature. The expression of E2F8 increased during prostate cancer progression and high levels of E2F8 expression are associated with a poor prognosis in patients with prostate cancer. MELK was identified as a crucial upstream regulator of E2F8 expression through the transcriptional regulatory network and Bayesian network analyses. Knockdown of E2F8 or MELK inhibited cell growth and colony formation in prostate cancer cells. High expression levels of E2F8 and androgen receptor (AR) are associated with a worse prognosis in patients with prostate cancer compared with low levels of both genes. The inhibition of E2F8 improved the response to AR blockade therapy. These results suggested that CsA has potential as an effective anticancer treatment for prostate cancer, while also revealing the oncogenic role of E2F8 and its association with clinical outcomes in prostate cancer. These results provided valuable insight into the development of therapeutic and diagnostic approaches for prostate cancer.

Crizotinib attenuates cancer metastasis by inhibiting TGFß signaling in non-small cell lung cancer cells.

Crizotinib is a clinically approved tyrosine kinase inhibitor for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring EML4-ALK fusion. Crizotinib was originally developed as an inhibitor of MET (HGF receptor), which is involved in the metastatic cascade. However, little is known about whether crizotinib inhibits tumor metastasis in NSCLC cells. In this study, we found that crizotinib suppressed TGFß signaling by blocking Smad phosphorylation in an ALK/MET/RON/ROS1-independent manner in NSCLC cells. Molecular docking and in vitro enzyme activity assays showed that crizotinib directly inhibited the kinase activity of TGFß receptor I through a competitive inhibition mode. Cell tracking, scratch wound, and transwell migration assays showed that crizotinib simultaneously inhibited TGFß- and HGF-mediated NSCLC cell migration and invasion. In addition, in vivo bioluminescence imaging analysis showed that crizotinib suppressed the metastatic capacity of NSCLC cells. Our results demonstrate that crizotinib attenuates cancer metastasis by inhibiting TGFß signaling in NSCLC cells. Therefore, our findings will help to advance our understanding of the anticancer action of crizotinib and provide insight into future clinical investigations.

Novel Mouse Models of Bladder Cancer Identify a Prognostic Signature Associated with Risk of Disease Progression.

To study the progression of bladder cancer from non-muscle-invasive to muscle-invasive disease, we have developed a novel toolkit that uses complementary approaches to achieve gene recombination in specific cell populations in the bladder urothelium in vivo, thereby allowing us to generate a new series of genetically engineered mouse models (GEMM) of bladder cancer. One method is based on the delivery of adenoviruses that express Cre recombinase in selected cell types in the urothelium, and a second uses transgenic drivers in which activation of inducible Cre alleles can be limited to the bladder urothelium by intravesicular delivery of tamoxifen. Using both approaches, targeted deletion of the Pten and p53 tumor suppressor genes specifically in basal urothelial cells gave rise to muscle-invasive bladder tumors. Furthermore, preinvasive lesions arising in basal cells displayed upregulation of molecular pathways related to bladder tumorigenesis, including proinflammatory pathways. Cross-species analyses comparing a mouse gene signature of early bladder cancer with a human signature of bladder cancer progression identified a conserved 28-gene signature of early bladder cancer that is associated with poor prognosis for human bladder cancer and that outperforms comparable gene signatures. These findings demonstrate the relevance of these GEMMs for studying the biology of human bladder cancer and introduce a prognostic gene signature that may help to stratify patients at risk for progression to potentially lethal muscle-invasive disease. SIGNIFICANCE: Analyses of bladder cancer progression in a new series of genetically engineered mouse models has identified a gene signature of poor prognosis in human bladder cancer.

Altered expression of fucosylation pathway genes is associated with poor prognosis and tumor metastasis in non­small cell lung cancer.

Fucosylation is a post­translational modification that attaches fucose residues to protein­ or lipid­bound oligosaccharides. Certain fucosylation pathway genes are aberrantly expressed in several types of cancer, including non­small cell lung cancer (NSCLC), and this aberrant expression is associated with poor prognosis in patients with cancer. However, the molecular mechanism by which these fucosylation pathway genes promote tumor progression has not been well­characterized. The present study analyzed public microarray data obtained from NSCLC samples. Multivariate analysis revealed that altered expression of fucosylation pathway genes, including fucosyltransferase 1 (FUT1), FUT2, FUT3, FUT6, FUT8 and GDP­L­fucose synthase (TSTA3), correlated with poor survival in patients with NSCLC. Inhibition of FUTs by 2F­peracetyl­fucose (2F­PAF) suppressed transforming growth factor ß (TGFß)­mediated Smad3 phosphorylation and nuclear translocation in NSCLC cells. In addition, wound­healing and Transwell migration assays demonstrated that 2F­PAF inhibited TGFß­induced NSCLC cell migration and invasion. Furthermore, in vivo bioluminescence imaging analysis revealed that 2F­PAF attenuated the metastatic capacity of NSCLC cells. These results may help characterize the oncogenic role of fucosylation in NSCLC biology and highlight its potential for developing cancer therapeutics.

The conflicting role of E2F1 in prostate cancer: A matter of cell context or interpretational flexibility?

The transcription factor E2F1 plays a crucial role in mediating multiple cancer hallmark capabilities that regulate cell cycle, survival, apoptosis, metabolism, and metastasis. Aberrant activation of E2F1 is closely associated with a poor clinical outcome in various human cancers. However, E2F1 has conflictingly been reported to exert tumor suppressive activity, raising a question as to the nature of its substantive role in the control of cell fate. In this review, we summarize deregulated E2F1 activity and its role in prostate cancer. We highlight the recent advances in understanding the molecular mechanism by which E2F1 regulates the development and progression of prostate cancer, providing insight into how cell context or data interpretation shapes the role of E2F1 in prostate cancer. This review will aid in translating biomedical knowledge into therapeutic strategies for prostate cancer.

PI3K pathway in prostate cancer: All resistant roads lead to PI3K.

The phosphoinositide 3-kinase (PI3K) pathway integrates multifarious environmental cues to regulate cell survival, growth, and metabolism. Hyperactivation of the PI3K pathway increases biological fitness by offering a high degree of adaptability to and resilience against diverse perturbations, thus conferring survival benefits on premalignant and transformed cells. In prostate cancer, the PI3K pathway is aberrantly activated by various genetic and epigenetic alterations and its hyperactivation is closely associated with a poor clinical outcome. In this review, we discuss the challenges encountered with clinically effective therapies targeting the PI3K pathway in prostate cancer, highlighting the clinical importance of combination therapies. In particular, we address how prostate cancer cells utilize the PI3K pathway for the development of resistance to a broad range of anticancer treatments. In addition, we describe the molecular mechanisms by which prostate cancer cells become resistant to PI3K pathway inhibitors. This review will be helpful in translating biological knowledge into therapeutic strategies for the treatment of prostate cancer and provide insight into overcoming therapeutic challenges associated with prostate cancer.

Schisandrol B and schisandrin B inhibit TGFß1-mediated NF-κB activation via a Smad-independent mechanism.

Aberrant transforming growth factor ß1 (TGFß1) signaling plays a pathogenic role in the development of vascular fibrosis. We have reported that Schisandra chinensis fruit extract (SCE), which has been used as a traditional oriental medicine, suppresses TGFß1-mediated phenotypes in vascular smooth muscle cells (VSMCs). However, it is still largely unknown about the pharmacologic effects of SCE on various TGFß1 signaling components. In this study, we found that SCE attenuated TGFß1-induced NF-κB activation and nuclear translocation in VSMCs. Among the five active ingredients of SCE that were examined, schisandrol B (SolB) and schisandrin B (SchB) most potently suppressed TGFß1-mediated NF-κB activation. In addition, SolB and SchB effectively inhibited IKKα/ß activation and IκBα phosphorylation in TGFß1-treated VSMCs. The pharmacologic effects of SolB and SchB on NF-κB activation were independent of the Smad-mediated canonical pathway. Therefore, our study demonstrates that SCE and its active constituents SolB and SchB suppress TGFß1-mediated NF-κB signaling pathway in a Smad-independent mechanism. Our results may help further investigations to develop novel multi-targeted therapeutic strategies that treat or prevent vascular fibrotic diseases.

TGFß1 induces stress fiber formation through upregulation of TRPC6 in vascular smooth muscle cells.

Aberrant transforming growth factor ß1 (TGFß1) signaling plays a crucial role in the pathogenesis of vascular fibrosis. On the other hand, deregulated transient receptor potential canonical 6 (TRPC6) channel expression shows impaired vascular physiology and wound healing. However, it has little been known about the functional association between TGFß1 and TRPC6 in vascular smooth muscle cells (VSMCs). In this study, we analyzed the microarray data obtained from TGFß1-treated A7r5 VSMCs. We found that TGFß1 specifically elevates the expression level of TRPC6 mainly through Smad-dependent canonical pathway. The siRNA against TRPC6 abolished TGFß1-induced molecular and cellular phenotype changes, including myosin light chain phosphorylation, actin stress fiber formation, and cell migration. These results demonstrate that TRPC6 is an important component of TGFß1 signaling pathway in VSMCs. Therefore, our findings provide a basis for future investigation aimed at developing novel therapeutic strategies for treatment of vascular fibrosis.

Cyclosporin A suppresses prostate cancer cell growth through CaMKKß/AMPK-mediated inhibition of mTORC1 signaling.

Cyclosporin A (CsA) has antitumor effects on various cancers including prostate cancer. However, its antitumor mechanism is poorly understood. In this study, we showed that AMP-activated protein kinase (AMPK) mediates the antitumor effect of CsA on prostate cancer cells. CsA attenuated cell growth by inducing a G1 arrest through the inhibition of mTOR complex 1 (mTORC1) signaling. In this context, Akt was paradoxically activated downstream of the EGF receptor (EGFR)-mediated increase in phosphatidylinositol 3,4,5-trisphosphate (PIP3) production. However, CsA also caused a Ca²âº/calmodulin-dependent protein kinase kinase ß (CaMKKß)-dependent activation of AMPK, which inhibits mTORC1 signaling; this led to ineffective Akt signaling. An EGFR or Akt inhibitor increased the growth suppressive activity of CsA, whereas the combination of an AMPK inhibitor and CsA markedly rescued cells from the G1 arrest and increased cell growth. These results provide novel insights into the molecular mechanisms of CsA on cancer signaling pathways.