Faculty Bibliography

IL-6 plays an important role in various inflammatory ocular diseases, including diabetic retinopathy. Muller cells are the major source of inflammatory mediators, including IL-6, in the retina. However, the mechanism of regulating IL-6 production in these cells remains unclear. Examination of signaling pathways in human retinal Muller cells (MIO-M1 cell line) cultured with IL-1beta, TNF-alpha, IL-6, IL-8, VEGF, IFN-gamma, glucose or mannitol showed that IL-1beta was the most potent stimulator of IL-6 production. In addition, IL-1 beta also increased NF-kappaB p50 protein level and phosphorylation of p38 MAPK, ERK1/2 and c-Jun. Induction of IL-6 production by IL-1beta was significantly reduced by addition of p38 MAPK (SB203580), MEK1/2 (U0126) or NF-kappaB (BAY11-7082) inhibitors, with the highest effect being observed with SB203580. To explore the specific elements in IL-6 promoter responsible for IL-1beta-induction of IL-6 expression, a series of plasmids bearing various IL-6 promoter mutations were transiently expressed in MIO-MI cells cultured in the presence or absence of IL-1beta (10ng/ml) and/or SB203580 (10microM). Results showed that IL-6 promoter activity of the parent pIL-6-Luc651 was significantly enhanced by IL-1beta, but the level was significantly attenuated by SB203580. Furthermore, the IL-6 promoter activity was also reduced upon deletion of NF-kappaB, AP-1 or C/EBP binding sites, with NF-kappaB deletion being the greatest. These results are the first demonstration that IL-1beta induces IL-6 production in Muller cells by activation of IL-6 promoter activity predominantly through the p38 MAPK/NF-kappaB pathway.

Post-translational modifications have been identified to be of great importance in cancers and lysine acetylation, which can attract the multifunctional transcription factor BRD4, has been identified as a potential therapeutic target. In this paper, we identify that BRD4 has an important role in colorectal cancer; and that its inhibition substantially wipes out tumor cells. Treatment with inhibitor MS417 potently affects cancer cells, although such effects were not always outright necrosis or apoptosis. We report that BRD4 inhibition also limits distal metastasis by regulating several key proteins in the progression of epithelial-to-mesenchymal transition (EMT). This effect of BRD4 inhibitor is demonstrated via liver metastasis in animal model as well as migration and invasion experiments in vitro. Together, our results demonstrate a new application of BRD4 inhibitor that may be of clinical use by virtue of its ability to limit metastasis while also being tumorcidal.

Lymphoid enhancer-binding factor-1 (LEF1) is a key transcription factor mediating Wnt signaling pathway. Our previous studies indicate that LEF1 is highly expressed in androgen-independent prostate cancer (PCa) and enhances invasion ability in androgen-independent PCa cells. However, the molecular mechanism of LEF1 effect on invasion remains largely unknown. Using microRNA profiling analysis comparing androgen-independent LNCaP-AI PCa cells with high levels of endogenous LEF1 to LNCaP-AI cells with LEF1 knockdown by LEF1shRNA, we found miR-181a to be increased 12.3-fold in LNCaP-AI cells. We confirmed a positive correlation between LEF1 and miR-181a expression across multiple PCa cell lines. Additionally, we showed that in PCa cells, overexpression of LEF1 increased miR-181a expression and subsequently induced EMT associated migration and invasion, whereas LEF1 knockdown decreased miR-181a expression and subsequently resulted in inhibition of EMT, migration and invasion. Mechanistically, we demonstrated by chromatin immunoprecipitation assays that LEF1 could enhance miR-181a expression via its binding to the promoter regions of hsa-miR-181a. Overall, this study identified a novel LEF1-miR-181a-EMT axis in regulation of PCa migration and invasion.

The inhibitory effects of metformin have been observed in many types of cancer. However, its effect on human salivary gland carcinoma is unknown. The effect of metformin alone or in combination with pp242 (an mTOR inhibitor) on salivary adenocarcinoma cells growth were determined in vitro and in vivo. We found that metformin suppressed HSY cell growth in vitro in a time and dose dependent manner associated with a reduced expression of MYC onco-protein, and the same inhibitory effect of metformin was also confirmed in HSG cells. In association with the reduction of MYC onco-protein, metformin significantly restored p53 tumor suppressor gene expression. The distinctive effects of metformin and PP242 on MYC reduction and P53 restoration suggested that metformin inhibited cell growth through a different pathway from PP242 in salivary carcinoma cells. Furthermore, the anti-tumor efficacy of metformin was confirmed in vivo as indicated by the increases of tumor necrosis and reduced proliferation in xenograft tumors from metformin treated group. For the first time, the inhibitory effect of metformin on human salivary gland tumor cells was documented. Moreover, metformin inhibitory effects were enhanced by mTOR inhibitor suggesting that metformin and mTOR inhibitor utilize distinctive signaling pathways to suppress salivary tumor growth.

The androgen receptor (AR) in stromal cells contributes significantly to the development and growth of prostate during fetal stages as well as during prostate carcinogenesis and cancer progression. During prostate development, stromal AR induces and promotes epithelial cell growth, as observed from tissue recombinant and mouse knockout studies. During prostate carcinogenesis and progression, the stromal cells begin to lose AR expression as early as at the stage of high-grade prostatic intraepithelial neoplasia. The extent of loss of stromal AR is directly proportional to the degree of differentiation (Gleason grade) and progression of prostate cancer (PCa). Co-culture studies suggested that stromal AR inhibits the growth of malignant epithelial cells, possibly through expression of certain paracrine factors in the presence of androgens. This functional reversal of stromal AR, from growth promotion during fetal prostate development to mediating certain growth-inhibiting effects in cancer, explains to some extent the reason that loss of AR expression in stromal cells may be crucial for development of resistance to androgen ablation therapy for PCa. From a translational perspective, it generates the need to re-examine the current therapeutic options and opens a fundamental new direction for therapeutic interventions, especially in advanced PCa.

The microbiome is a new center of attention for studies on the pathogenesis of human disease by focusing on the alterations of all microorganisms living in a particular site or system of human body, referred as microbiota. Evidence suggests that microbiota could contribute to the pathogenesis of a number of chronic diseases, including cancers, both locally and remotely. Multiple mechanisms have been proposed and/or proven for the microbiota's role in tumorigenesis, such as via induction of chronic inflammation, genotoxicity, bacterium-mediated cell proliferation, and activation of procarcinogens. Emerging data suggest that indigenous microbiota in the urinary tract may play an important role in the tumorigenesis of urothelial carcinoma, similar to other tumors. Future studies are needed to adequately define the microbiota composition and correlate its change with urothelial carcinoma.

Androgen receptor (AR), a steroid hormone receptor, is critical for prostate cancer growth. However, activation of AR by androgens can also lead to growth suppression and differentiation. Transcriptional cofactors play an important role in this switch between proliferative and anti-proliferative AR target gene programs. Transducin beta-like-related protein 1 (TBLR1), a core component of the nuclear receptor corepressor complex, shows both corepressor and coactivator activities on nuclear receptors, but little is known about its effects on AR and prostate cancer. We characterized TBLR1 as a coactivator of AR in prostate cancer cells and determined that the activation is dependent on both phosphorylation and 19S proteosome. We showed that TBLR1 physically interacts with AR and directly occupies the androgen-response elements of the affected AR target genes in an androgen-dependent manner. TBLR1 is primarily localized in the nucleus in benign prostate cells and nuclear expression is significantly reduced in prostate cancer cells in culture. Similarly, in human tumor samples, the expression of TBLR1 in the nucleus is significantly reduced in the malignant glands compared with the surrounding benign prostatic glands (P<0.005). Stable ectopic expression of nuclear TBLR1 leads to androgen-dependent growth suppression of prostate cancer cells in vitro and in vivo by selective activation of androgen-regulated genes associated with differentiation (e.g. KRT18) and growth suppression (e.g. NKX3-1), but not cell proliferation of the prostate cancer. Understanding the molecular switches involved in the transition from AR-dependent growth promotion to AR-dependent growth suppression will lead to more successful treatments for prostate cancer.

BACKGROUND: The goal of the Prostate Cancer Biorepository Network (PCBN) is to develop a biorepository with high-quality, well-annotated specimens obtained in a systematic, reproducible fashion using optimized and standardized protocols, and an infrastructure to facilitate the growth of the resource and its wide usage by the prostate cancer research community. An emerging area of concern in the field of prostate cancer biobanking is an apparent shift in the proportion of surgical procedures performed for prostate cancer treatment from radical retropubic prostatectomy (RRP) to robot-assisted laparoscopic prostatectomy (RALP). Our study aimed to determine the potential impact of the RALP procedure on the detection of known prostate cancer biomarkers, and the subsequent suitability of RALP-derived specimens for prostate cancer biomarker studies. METHODS: DNA and RNA were extracted from RRP and RALP specimens. Quality assessment was conducted using spectrophotometric analysis and RNA was analyzed for RNA integrity number (RIN) and by real-time reverse-transcription PCR (qRT-PCR) for racemase, hepsin, ERG, TMPRSS2-ERG gene fusions, and the microRNAs miR-26a, miR-26b, miR-141, and miR-221. RESULTS: We demonstrate that extraction of derivatives from frozen tissues from RRP and RALP specimens yields samples of equally high quality as assessed by spectrophotometric and RIN analysis. Likewise, expression levels of genes analyzed by qRT-PCR did not differ between RRP and RALP-derived tissues. CONCLUSIONS: Our studies indicate that samples obtained from RALP specimens may be suitable for prostate cancer biomarker studies-an important finding given the current shift in surgical procedures for prostate cancer treatment. Prostate 9999: XX-XX, 2013. (c) 2013 Wiley Periodicals, Inc.

Global microRNA (miRNA) profile may predict prostate cancer (PCa) behaviors. In this study, we examined global miRNA expression by miRNA profiling as well as specific miRNA expression levels in PCa epithelium and stroma by in situ hybridization (ISH) and correlated with various clinicopathological features. We first performed comprehensive miRNA profiling on 27 macrodissected cases of PCa by miRNA microarray. A total of 299 miRNAs were significantly dysregulated in high grade and advanced stage PCa. We demonstrated that PCa can be readily classified into high grade/stage and low-grade/stage groups by its global miRNA expression profile. Next, we examined the expression of several selected dysregulated miRNAs, including let-7c, miR-21, miR-27a, miR-30c, and miR-219, in PCa by ISH. The levels of miRNA expression in epithelial and stromal cells were scored semiquantitatively and compared with clinicopathological features, including age, race, Gleason score, stage, PSA recurrence, metastasis, hormone resistance and survival. We found that the expression of miR-30c and miR-219 were significantly down-regulated in PCa. miR-21 and miR-30c were significantly down-regulated in PCa in African Americans compared to Caucasian Americans. In addition, down-regulation of let-7c, miR-21, miR-30c, and miR-219 are associated with metastatic disease. Furthermore, down-regulation of miR-30c and let-7c are significantly associated with androgen-dependent PCa. In PCa stromal cells, let-7c downregulation is significantly associated with extraprostatic extension. Our data suggest that selected miRNAs may serve as potential biomarkers to predict cancer progression.