The mitochondrial enzyme hydroxymethylglutaryl-CoA synthase 2 (HMGCS2) catalyzes the rate-limiting step of ketogenesis. Although the liver constitutively expresses HMGCS2 and is considered the main ketogenic organ, HMGCS2 is induced in the kidney during fasting, leading to the proposal that the kidney contributes to fasting ketosis. We showed kidney HMGCS2 does not contribute to circulating ketones during fasting and cannot compensate for hepatic ketogenic insufficiency.

IFN gamma, a potent cytokine known to modulate tumor immunity and tumoricidal effects, is highly elevated in patients with prostate cancer after radiation. In this study, we demonstrate that IFN gamma can induce epithelial-to-mesenchymal transition (EMT) in prostate cancer cells via the JAK-STAT signaling pathway, leading to the transcription of IFN-stimulated genes (ISG) such as IFN-induced tetratricopeptide repeat 5 (IFIT5). We unveil a new function of IFIT5 complex in degrading precursor miRNAs (pre-miRNA) that includes pre-miR-363 from the miR-106a-363 cluster as well as pre-miR-101 and pre-miR-128, who share a similar 5'-end structure with pre-miR-363. These suppressive miRNAs exerted a similar function by targeting EMT transcription factors in prostate cancer cells. Depletion of IFIT5 decreased IFN gamma-induced cell invasiveness in vitro and lung metastasis in vivo. IFIT5 was highly elevated in high-grade prostate cancer and its expression inversely correlated with these suppressive miRNAs. Altogether, this study unveils a pro-metastatic role of the IFN gamma pathway via a new mechanism of action, which raises concerns about its clinical application.

Interferon-γ (IFNγ) is a potent cytokine in modulating tumor immunity and tumoricidal effects. We demonstrate a new function of IFNγ in inducing epithelial-to-mesenchymal transition (EMT) in normal and cancer cells from different cell types. IFNγ activates JAK-STAT signaling pathway leading to the transcription of IFN-stimulated genes (ISGs), such as interferon-induced tetratricopeptide repeat 5 (IFIT5). We unveil a new function of IFIT5 complex in degrading precursor microRNAs (pre-miRNA) that include pre-miR-363 from the miR-106a-363 cluster, as well as pre-miR-101 and pre-miR-128 with a similar 5’-end structure with pre-miR-363. Noticeably, these suppressive miRNAs have similar functions by targeting EMT transcription factors in prostate cancer (PCa) cells. We further demonstrated that IFIT5 plays a critical role in IFNγ-induced cell invasiveness in vitro and lung metastasis in vivo . Clinically, IFIT5 is highly elevated in high-grade PCa and its expression inversely correlates with these suppressive miRNAs. Altogether, this study unveils pro-tumorigenic role of the IFN pathway via a new mechanism of action, which certainly raises concern about its clinical application.

Targeted therapy is a standard of care for metastatic renal cell carcinoma (RCC) but the response rate is not overwhelmed, which only prolongs a short survival of patients due to the onset of therapeutic resistance.Although the mechanisms are not fully understood, the presence of cancer initiating cells (CIC) may underlie the drug resistance.Nevertheless, identifying CIC phenotypes with its biomarkers in RCC appear to be diverse and controversial from many reports.In this study, we took a different approach to focus on the regulatory mechanism in RCC-CIC and unveil DAB2IP-mediated miR-138 expression that plays a critical role in modulating stem-like phenotypes in RCC via targeting the ABC transporter (ABCA13) as well as oncogenic histone methyltransferase EZH2 while down regulation of miR-138 gene expression in RCC is due to epigenetic gene silencing by DNA methyltransferase 1 (DNMT1).We also characterize the individual mechanism by which ABCA13 in RCC-CIC contributes to its drug resistance and.EZH2 maintain stem-like phenotypes.Noticeably, elevated expression of ABCA13 and EZH2 is correlated with overall survival of RCC patients, which can be used as potential prognostic markers.Taken together, this study demonstrates a potent and unique pathway of DAB2IP-mediated miR-138 in modulating CIC phenotypes during RCC progression and also offers a new therapeutic strategy of targeting drug resistant RCC.

The current agents used for renal cell carcinoma (RCC) only exhibit the moderate response rate among patients. Development of drug resistance eventually fuels the need of either more potent drugs or new drugs to target the resistant pathways. Oridonin is a diterpenoid isolated from the Chinese medicinal herb Rabdosia rubescens and has been shown to have antitumor activities in many cancers. We previously developed new synthetic methodologies to modify structurally diversified diterpenoids and designed a series of nitrogen-enriched oridonin analogs. In this study, we screened a variety of oridonin analogs based on their cytotoxicity using MTT assay and identify the most potent candidate, namely, CYD-6-17. CYD-6-17 exhibited a high potency to inhibit the in vitro growth of several drug-resistant RCC cells as well as endothelial cells stimulated by tumor cells at nanomolar range. Delivery of CYD-6-17 significantly inhibited RCC tumor growth using xenograft model. Mechanistically, it targeted the 3-phosphoinositide-dependent protein kinase 1 gene that appeared to be a potent regulator of AKT and was associated with patient survival after targeted therapies. This offers a new rational therapeutic regimen of CYD-6-17 to drug-resistant RCC based on its novel mechanism of action.

The presence of androgen receptor variant 7 (AR‐V7) variants becomes a significant hallmark of castration‐resistant prostate cancer (CRPC) relapsed from hormonal therapy and is associated with poor survival of CRPC patients because of lacking a ligand‐binding domain. Currently, it still lacks an effective agent to target AR‐V7 or AR‐Vs in general. Here, we showed that a novel class of agents (thailanstatins, TSTs and spliceostatin A analogs) can significantly suppress the expression of AR‐V7 mRNA and protein but in a less extent on the full‐length AR expression. Mechanistically, TST‐D is able to inhibit AR‐V7 gene splicing by interfering the interaction between U2AF65 and SAP155 and preventing them from binding to polypyrimidine tract located between the branch point and the 3′ splice site. In vivo, TST‐D exhibits a potent tumor inhibitory effect on human CRPC xenografts leading to cell apoptosis. The machinery associated with AR gene splicing in CRPC is a potential target for drugs. Based on their potency in the suppression of AR‐V7 responsible for the growth/survival of CRPC, TSTs representing a new class of anti‐AR‐V agents warrant further development into clinical application.

Conventional chemotherapy is commonly used for advanced stages of transitional cell carcinoma (TCC) with modest success and high morbidity; however, TCC eventually develops resistance. Muscle invasive bladder cancer (MIBC) is recognized as a lethal disease due to its poor response to traditional chemotherapy. Numerous studies have implicated β-catenin, a critical effector in Wnt-mediated pathway associated with epithelial-mesenchymal transition and cancer stem cell, is involved in TCC progression, and furthermore closely associated with chemo-resistance. In this study, we discovered a novel natural product analogue CYD 6-17 that has a potent inhibitory effect on TCC cells exhibiting drug resistance to various chemotherapeutics, with an IC50 at nM range. Delivery of CYD 6-17 significantly inhibited the tumor growth using xenograft model but without detectable side effects. Mechanistically, it targeted β-catenin gene transcription by decreasing the binding of XBP1 to the promoter region, which appeared to be a new regulatory mechanism for β-catenin gene expression. Clinically, XBP1 expression correlated with the poor overall survival of patients. Overall, this study unveils unique mechanism of β-catenin gene regulation in advanced TCC and also offers a potential rational therapeutic regimen to MIBC.

Chemotherapy is the standard care for metastatic disease, in renal cell carcinoma (RCC), the outcome of chemotherapy only prolongs short survival of patients. The reason for the resistance of RCC to chemotherapy is not fully understood, although it has been speculated that overabundance of ATP-binding cassette (ABC)/p-glycoprotein transporter system in RCC might be the reason to repel various chemotherapeutic agents away from the cancer cell. Meanwhile, cancer stem cells (CSC) theory has also focused a significant attention in recent years as a potential explanation for drug resistance and metastasis of RCC. In this study, we demonstrate that drug resistant RCC cells exhibit CSC phenotypes and miR-138 that is significantly downregulated in RCC acted critical role in suppressing CSC phenotype by targeting ABC transporter ABCA13 and oncogenic histone methyltransferase EZH2. Importantly, miR-138 levels were significantly enhanced by treatment of DNA hypomethylating agent (i.e., 5-aza) or histone deactylases inhibitor (i.e., TSA). Epigenetic silencing of tumor-suppressive micro-RNAs has been shown a key oncogenic mechanism for the activation of oncogenes in tumors. Indeed, depletion of miR-138 promoted CSC phenotype followed by enhanced expressions of ABCA13 and EZH2. Furthermore, a novel tumor suppressor DAB2IP can inhibit DNA methyltransferase 1 (DNMT1) activity, which results in miR-138 expression. Taken together, this study identifies the new role of miR-138 in RCC-CSC and unveils a unique regulation of tumor suppressor protein in DNMT1. Overall study provides not only a new biomarker of RCC-CSC and but also potential therapeutic strategy of targeting drug resistant RCC. Citation Format: Eun-Jin Yun, Jiancheng Zhou, Chun-Jung Lin, Elizabeth Hernandez, John Santoyo, Jer-Tsong Hsieh. Epigenetic regulation of miR-138 confers cancer stem cell characteristics of renal cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3078. doi:10.1158/1538-7445.AM2015-3078

Histone lysine demethylase KDM4/JMJD2s are overexpressed in many human tumors including prostate cancer (PCa). KDM4s are co-activators of androgen receptor (AR) and are thus potential therapeutic targets. Yet to date few KDM4 inhibitors that have anti-prostate tumor activity in vivo have been developed. Here, we report the anti-tumor growth effect and molecular mechanisms of three novel KDM4 inhibitors (A1, I9, and B3). These inhibitors repressed the transcription of both AR and BMYB-regulated genes. Compound B3 is highly selective for a variety of cancer cell lines including PC3 cells that lack AR. B3 inhibited the in vivo growth of tumors derived from PC3 cells and ex vivo human PCa explants. We identified a novel mechanism by which KDM4B activates the transcription of Polo-like kinase 1 (PLK1). B3 blocked the binding of KDM4B to the PLK1 promoter. Our studies suggest a potential mechanism-based therapeutic strategy for PCa and tumors with elevated KDM4B/PLK1 expression.