Faculty Bibliography

BACKGROUND: The human papilloma virus (HPV) is a carcinogen known for its strong association with cervical cancers and cervical lesions. It is also known to be associated with a variety of squamous cell carcinomas in other areas, such as the penis, vulva, anus and head and neck. However, the association with urothelial carcinoma remains controversial. Here, we report a case of urothelial carcinoma with squamous differentiation associated with HPV-6/HPV-11. CASE PRESENTATION: This is a case of a 70 year old man who presented with nocturia and pressure during urination. During the TURP procedure for what was clinically thought to be benign prostate hyperplasia with pathologic diagnosis as prostate carcinoma, a 2 cm papillary mass was found in the distal penile urethra. The papillary mass was found to be a high grade urothelial carcinoma positive for GATA 3 expression, with focal areas of squamous differentiation. The areas with squamous differentiation demonstrated koilocytic differentiation, which were positive for strong p16 expression. The tumor was found to harbor low risk HPV 6/11 by in situ hybridization. CONCLUSIONS: This study case demonstrates HPV infection with a low risk subtype (HPV 6/11) associated with an urothelial carcinoma with squamous differentiation and condylomatous features.

Estrogen receptors (ER) play important roles in the development and progression of breast and ovarian cancers. ERs mediate transcriptional regulation through interaction with cofactors and binding to response elements within the regulatory elements of target genes. Here, we examined the expression and function of TBLR1/TBL1XR1, a core component of NCoR (nuclear receptor corepressor) and SMRT (silencing mediator of retinoic acid and thyroid receptor) corepressor complexes, in breast and ovarian cancers. We found that although TBLR1 is present in both the nucleus and cytoplasm of normal and neoplastic breast and ovarian cells, it is expressed at significantly higher levels in the nucleus of malignant breast and ovarian cells compared to benign cells. TBLR1 functions as an ER corepressor to inhibit ER-mediated transcriptional activation in both breast and ovarian cell lines, but it has no effect on androgen receptor (AR) mediated transcriptional activation in these cells. Furthermore, ectopic expression of nuclear TBLR1 in breast and ovarian cancer cells stimulates cell proliferation. The increased cell proliferation by nuclear TBLR1 is through both ER-independent and ER-dependent mechanisms as evidenced by increased growth in hormone-free medium and estrogen medium, as well as reduced growth with ER knockdown by siRNA. Nuclear TBLR1 overexpression also increased migration and invasion in both breast and ovarian cancer cells. Determining the functional relationship between TBLR1 and ER may provide insights to develop novel treatment strategies and improve response to hormonal therapy in breast and ovarian cancers.

Treatment protocols for breast cancer depend predominantly on receptor status with respect to estrogen (estrogen receptor alpha), progesterone (progesterone receptor) and human epidermal growth factor [human epidermal growth factor receptor 2 (HER2)]. The presence of one or more of these receptors suggests that a treatment targeting these pathways might be effective, while the absence of, or in the case of HER2, lack of overexpression of, all of these receptors, termed triple negative breast cancer (TNBC), indicates a need for the more toxic chemotherapy. In an effort to develop targeted therapies for TNBC, it will be necessary to differentiate among specific TNBC subtypes. The subset of TNBC that expresses androgen receptor (AR) has been determined to express genes consistent with a luminal subtype and therefore may be amenable to therapies targeting either AR, itself, or other pathways typical of a luminal subtype. Recent investigations of the AR signal pathway within breast cancer lead to AR as a significant target for breast cancer therapy with several clinical trials currently in progress. The subclass of TNBC that lacks AR, which we have termed quadruple negative breast cancer (QNBC) currently lacks a defined targetable pathway. Unlike AR-positive TNBC, QNBC predominantly exhibits a basal-like molecular subtype. Several subtypes and related pathway proteins are preferentially expressed in QNBC that may serve as effective targets for treatment, such as ACSL4, SKP2 and EGFR. ACSL4 expression has been demonstrated to be inversely correlated with expression of hormone/growth factor receptors and may thus serve as a biomarker for QNBC as well as a target for therapy. In the following review we summarize some of the current efforts to develop alternatives to chemotherapy for TNBC and QNBC.

This study aimed to detect protein changes that can assist to understand the underlying biology of bladder cancer. The data showed forty five proteins were found to be differentially expressed comparing tumors vs non-tumor tissues, of which EGFR and cdc2p34 were correlated with muscle invasion and histological grade. Ten proteins (ss-catenin, HSP70, autotaxin, Notch4, PSTPIP1, DPYD, ODC, cyclinB1, calretinin and EPO) were able to classify muscle invasive BCa (MIBC) into 2 distinct groups, with group 2 associated with poorer survival. Finally, 3 proteins (P2X7, cdc25B and TFIIH p89) were independent factors for favorable overall survival.

Increases in fatty acid metabolism have been demonstrated to promote the growth and survival of a variety of cancers, including prostate cancer (PCa). Here, we examine the expression and function of the fatty acid activating enzyme, long-chain fatty acyl-CoA synthetase 4 (ACSL4), in PCa. Ectopic expression of ACSL4 in ACSL4-negative PCa cells increases proliferation, migration and invasion, while ablation of ACSL4 in PCa cells expressing endogenous ACSL4 reduces cell proliferation, migration and invasion. The cell proliferative effects were observed both in vitro, as well as in vivo. Immunohistochemical analysis of human PCa tissue samples indicated ACSL4 expression is increased in malignant cells compared with adjacent benign epithelial cells, and particularly increased in castration-resistant PCa (CRPC) when compared with hormone naive PCa. In cell lines co-expressing both ACSL4 and AR, proliferation was independent of exogenous androgens, suggesting that ACSL4 expression may lead to CRPC. In support for this hypothesis, ectopic ACSL4 expression induced resistance to treatment with Casodex, via decrease in apoptosis. Our studies further indicate that ACSL4 upregulates distinct pathway proteins including p-AKT, LSD1 and beta-catenin. These results suggest ACSL4 could serve as a biomarker and potential therapeutic target for CRPC.

Constitutively-active androgen receptor splice variants (AR-V) lacking the ligand-binding domain have been implicated in the pathogenesis of castration-resistant prostate cancer and in mediating resistance to newer drugs that target the androgen axis. AR-V regulate expression of both canonical AR targets and a unique set of cancer-specific targets that are enriched for cell cycle functions. However, little is known about how AR-V control gene expression. Here we report that two major AR-V, termed AR-V7 and ARv567es, not only homodimerize and heterodimerize with each other but also heterodimerize with full-length androgen receptor (AR-FL) in an androgen-independent manner. We found that heterodimeration of AR-V and AR-FL was mediated by N- and C-terminal interactions and by the DNA-binding domains of each molecule, whereas AR-V homoimerization was mediated only by DNA-binding domain interactions. Notably, AR-V dimerization was required to transactivate target genes and to confer castration-resistant cell growth. Our results clarify the mechanism by which AR-V mediate gene regulation and provide a pivotal pathway for rational drug design to disrupt AR-V signaling, as a rational strategy for effective treatment of advanced prostate cancer.

Androgen receptor (AR) signaling in stromal cells is important in prostate cancer, yet the mechanisms underpinning stromal AR contribution to disease development and progression remain unclear. Using patient-matched benign and malignant prostate samples, we show a significant association between low AR levels in cancer associated stroma and increased prostate cancer-related death at one, three and five years post-diganosis, and in tissue recombination models with primary prostate cancer cells that low stromal AR decreases castration-induced apoptosis. AR-regulation was found to be different in primary human fibroblasts isolated from adjacent to cancerous and non-cancerous prostate epithelia, and to represent altered activation of myofibroblast pathways involved in cell cycle, adhesion, migration, and the extracellular matrix (ECM). Without AR signaling, the fibroblast-derived ECM loses the capacity to promote attachment of both myofibroblasts and cancer cells, is less able to prevent cell-matrix disruption, and is less likely to impede cancer cell invasion. AR signaling in prostate cancer stroma appears therefore to alter patient outcome by maintaining an ECM microenvironment inhibitory to cancer cell invasion. This paper provides comprehensive insight into AR signaling in the non-epithelial prostate microenvironment, and a resource from which the prognostic and therapeutic implications of stromal AR levels can be further explored.

Although the antitumor role of metformin has been widely reported, the molecular mechanism of this biguanide agent in the inhibition of tumor progression remains unclear. Here, we identified miR-708-5p as a novel target of metformin in prostate cancer cells. Metformin promotes increased expression of miR-708-5p, leading to suppression of endoplasmic reticulum (ER) membrane protein neuronatin (NNAT) expression and subsequently induces apoptosis of prostate cancer cells through the ER stress pathway. Further, miR-708-5p-induced knockdown of NNAT is associated with downregulated intracellular calcium levels and induced malformation of ER-ribosome structure revealed by electronic microscopy. Meanwhile, the unfolded protein response regulator CHOP, p-eIF2alpha, calreticulin, GRP78 and ATP2A1, all of which are also considered as ER stress markers, are upregulated by metformin and miR-708-5p. Taken together, our findings clearly demonstrate that metformin stimulates increased expression of miR-708-5p to target the NNAT-mediated response to ER stress and apoptosis. This novel regulatory mechanism of metformin in prostate cancer cells not only advances our knowledge on the molecular mechanism of metformin but also provides a promising therapeutic strategy by targeting miR-708-5p and NNAT for prostate cancer treatment.

The microRNA-34a (miR-34a), a tumor suppressive microRNA (miRNA), is implicated in epithelial-mesenchymal transition (EMT) and cancer stem cells. Lymphoid enhancer-binding factor-1 (LEF1) is a key transcription factor in the Wnt signaling pathway, and has been suggested to be involved in regulation of cell proliferation and invasion. Here, the molecular mechanism of miR-34a and LEF1 in cooperatively regulating prostate cancer (PCa) cell invasion is described. Molecular profiling analysis of miRNA levels in PCa cells revealed a negative correlation between miR-34a and LEF1 expression, and the downregulation of LEF1 by miR-34a was confirmed by luciferase assays. Further, miR-34a specifically repressed LEF1 expression through direct binding to its 3'-untranslated (3'-UTR) regions. miR-34a modulated the levels of LEF1 to regulate EMT in PCa cells. Functionally, miR-34a negatively correlated with the migration and invasion of PCa cells through LEF1. An analysis of miR-34a expression levels in matched human tumor and benign tissues demonstrated consistent and statistically significant downregulation of miR-34a in primary prostate cancer specimens. These data strongly suggest that miR-34a/LEF1 regulation of EMT plays an important role in PCa migration and invasion. Implications: The miR-34a/LEF1 axis represents a potential molecular target for novel therapeutic strategies in PCa.