Phosphorylation of androgen receptor by mTORC1 promotes liver steatosis and tumorigenesis.

BACKGROUND AND AIMS: Androgen receptor (AR) has been reported to play an important role in the development and progression of man's prostate cancer. Hepatocellular carcinoma (HCC) is also male-dominant, but the role of AR in HCC remains poorly understood. Mechanistic target of rapamycin complex 1 (mTORC1) also has been reported to be highly activated in HCC. In this study, we aimed to explore the role of AR phosphorylation and its relationship with mTORC1 in hepatocarcinogenesis. APPROACH AND RESULTS: In vitro experiment, we observed that mTORC1 interacts with hepatic AR and phosphorylates it at S96 in response to nutrient and mitogenic stimuli in HCC cells. S96 phosphorylation promotes the stability, nuclear localization, and transcriptional activity of AR, which enhances de novo lipogenesis and proliferation in hepatocytes and induces liver steatosis and hepatocarcinogenesis in mice independently and cooperatively with androgen. Furthermore, high ARS96 phosphorylation is observed in human liver steatotic and HCC tissues and is associated with overall survival and disease-free survival, which has been proven as an independent survival predictor for patients with HCC. CONCLUSIONS: AR S96 phosphorylation by mTORC1 drives liver steatosis and HCC development and progression independently and cooperatively with androgen, which not only explains why HCC is man-biased but also provides a target molecule for prevention and treatment of HCC and a potential survival predictor in patients with HCC.

Octreotide stimulates somatostatin receptor-induced apoptosis of SW480 colon cancer cells by activation of glycogen synthase kinase-3ß, A Wnt/ß-catenin pathway modulator.

BACKGROUND/AIMS: Peptide hormone somatostatin and its receptors (SSTRs) have a wide range of physiological functions and play a role in the treatment of numerous human diseases, including colorectal cancer. Octreotide, a somatostatin-analog peptide, inhibits growth of colonic cancer SW480 cells through Wnt/ß-catenin pathway modulation. However, the specific octreotide-stimulating SSTR subtypes and the signal-transduction mechanism responsible for the negative regulation of Wnt/ß-catenin pathway by octreotide have not been fully elucidated. METHODOLOGY: Octreotide-induced apoptosis in SW480 colon cancer cells mediated by SSTR2,SSTR5-dependent regulation of the Wnt/ß-catenin pathway components GSK-3ß and ß-catenin was investigated. Cell apoptosis of SW480 cells was measured by apoptosis-DNA ladder assay. SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5 mRNA expression levels were confirmed by RT-PCR; ß-catenin, TCF-4, cyclin D1, c-Myc, and GSK-3ß protein levels were examined by Western blot. The distribution of ß-catenin in the cell was analyzed with immunocytochemistry. RESULTS: Octreotide treatment increased SSTR2,SSTR5-induced apoptosis of SW480 colon cancer cells, promoted the plasma membrane accumulation of ß-catenin, inactivated T-cell factor-dependent transcription, and downregulated Wnt target genes cyclin D1 and c-Myc. Further, octreotide treatment mediated the activation of GSK-3. CONCLUSIONS: These preliminary findings showed the negative regulation of the Wnt/ß-catenin pathway by peptide hormone G protein-coupled receptors SSTRs.

Transgenic nude mouse with green fluorescent protein expression-based human glioblastoma multiforme animal model with EGFR expression and invasiveness.

Previously, we developed an orthotopic xenograft model of human glioblastoma multiforme (GBM) with high EGFR expression and invasiveness in Balb/c nu/nu nude mice. Now we also developed the same orthotopic xenograft model in transgenic nude mice with green fluorescent protein (GFP) expression. The present orthotopic xenografts labeled by phycoerythrin fluorescing red showed high EGFR expression profile, and invasive behavior under a bright green-red dual-color fluorescence background. A striking advantage in the present human GBM model is that the change of tumor growth can be observed visually instead of sacrificing animals in our further antitumor therapy studies.

Octreotide inhibits growth of colonic cancer SW480 cells by modulating the Wnt/P-catenin pathway.

Somatostatin can suppress the growth of various tumor cells including colonic cancer. Activated Wnt/ beta-catenin signaling pathway plays a critical role in tumorgenesis and development of colorectal cancer. However, the effect of somatostatin on Wnt/beta-catenin signaling pathway remains unknown. Thus, we investigated the effect of octreotide on Wnt/beta-catenin signaling pathway in human colonic cancer cell SW480. The results of 3-(4,5-imethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) and flow cytometric assays showed that octreotide inhibited growth, induced apoptosis and arrested the G1 cell cycle of SW480 cells in a dose-dependent manner. We demonstrated that octreotide significally up-regulated and down-regulated 13 genes and 17 genes in Wnt/beta-catenin signaling using microarray, respectively. Furthermore, as evidenced by western blot, beta-catenin protein level decreased, whereas phosphorylated beta-catenin protein level increased under octreotide. The present study reveals that octreotide can inhibit human colonic cancer cell growth through inhibition of Wnt/beta-catenin signaling pathway.