Faculty Bibliography

The degree of differentiation in human cancers generally reflects the degree of malignancy, with the most undifferentiated cancer being also the highest grade and the most aggressive. High-grade serous ovarian cancers (HGSOC) are poorly differentiated and fast-growing malignancies. The molecular mechanisms underlying the poor differentiation of HGSOC has not been completely characterized. Evidence suggests that microRNAs (miRs) are dysregulated in HGSOC. Therefore, we focused on those miRs that are relevant to tumor differentiation. Expression profiling of miRs in HGSOC, indicated miR-106a and its family members were significantly upregulated. Upregulation of miR-106a was further validated by real-time RT-PCR and miR in situ hybridization in a large cohort of HGSOC specimens. Overexpression of miR-106a in benign and malignant ovarian cells significantly increased the cellular proliferation rate and expanded the side-population fraction. In particular, SKOV3 cells with miR-106a overexpression had significantly higher tumor initial/stem cell population (CD24 and CD133 positive cells) than control SKOV3 cells. Among many miR-106a predicated target genes, p130 (RBL2), an RB tumor suppressor family member, was not only confirmed as a specific target of miR-106a but also related to tumor growth and differentiation. The importance of mir-106a and RBL2 was further demonstrated in vivo, in which, SKOV3 cells overexpressing miR-106a formed poorly differentiated carcinomas and had reduced RBL2 levels. To our knowledge, this is the first study of miR-106a mediating proliferation and tumor differentiation in HGSOC. Implications: The current study suggests that the RB tumor suppressor pathway is a critical regulator of growth and differentiation in HGSOC.

Bone morphogenetic protein (BMP) signaling has emerged as an important regulator of sensory neuron development. Using a three-generation forward genetic screen in mice we have identified Megf8 as a novel modifier of BMP4 signaling in trigeminal ganglion (TG) neurons. Loss of Megf8 disrupts axon guidance in the peripheral nervous system and leads to defects in development of the limb, heart, and left-right patterning, defects that resemble those observed in Bmp4 loss-of-function mice. Bmp4 is expressed in a pattern that defines the permissive field for the peripheral projections of TG axons and mice lacking BMP signaling in sensory neurons exhibit TG axon defects that resemble those observed in Megf8 (-/-) embryos. Furthermore, TG axon growth is robustly inhibited by BMP4 and this inhibition is dependent on Megf8. Thus, our data suggest that Megf8 is involved in mediating BMP4 signaling and guidance of developing TG axons. DOI:http://dx.doi.org/10.7554/eLife.01160.001.

Integration of cellular signaling pathways with androgen receptor (AR) signaling can be achieved through phosphorylation of AR by cellular kinases. However, the kinases responsible for phosphorylating the AR at numerous sites and the functional consequences of AR phosphorylation are only partially understood. Bioinformatic analysis revealed AR serine 213 (S213) as a putative substrate for PIM1, a kinase overexpressed in prostate cancer. Therefore, phosphorylation of AR serine 213 by PIM1 was examined using a phosphorylation site-specific antibody. Wild-type PIM1, but not catalytically inactive PIM1, specifically phosphorylated AR but not an AR serine-to-alanine mutant (S213A). In vitro kinase assays confirmed that PIM1 can phosphorylate AR S213 in a ligand-independent manner and cell type-specific phosphorylation was observed in prostate cancer cell lines. Upon PIM1 overexpression, AR phosphorylation was observed in the absence of hormone and was further increased in the presence of hormone in LNCaP, LNCaP-abl and VCaP cells. Moreover, phosphorylation of AR was reduced in the presence of PIM kinase inhibitors. An examination of AR-mediated transcription showed that reporter gene activity was reduced in the presence of PIM1 and wild-type AR, but not S213A mutant AR. Androgen-mediated transcription of endogenous PSA, Nkx3.1 and IGFBP5 was also decreased in the presence of PIM1, whereas IL6, cyclin A1 and caveolin 2 were increased. Immunohistochemical analysis of prostate cancer tissue microarrays showed significant P-AR S213 expression that was associated with hormone refractory prostate cancers, likely identifying cells with catalytically active PIM1. In addition, prostate cancers expressing a high level of P-AR S213 were twice as likely to be from biochemically recurrent cancers. Thus, AR phosphorylation by PIM1 at S213 impacts gene transcription and is highly prevalent in aggressive prostate cancer.Oncogene advance online publication, 17 September 2012; doi:10.1038/onc.2012.412.

Mouse models of prostate cancer (PCa) are critical for understanding the biology of PCa initiation, progression, and treatment modalities. Here, we summarize recent advances in PCa mouse models that led to new insights into specific gene functions in PCa. For example, the study of transgenic mice with TMPRSS2/ERG, an androgen regulated fusion protein, revealed its role in developing PCa precursor lesions, prostate intraepithelial neoplasia (PIN) but not sufficient for PCa development. Double deficiency of Pten and Smad4 leads to a high incidence of metastatic PCa. Targeted deletion of Pten in castration-resistant Nkx3-1-expressing cells (CARNs) results in rapid carcinoma formation after androgen-mediated regeneration, indicating progenitor cells with luminal characteristics can play a role in initiation of PCa. Transgenic mice with activated oncogenes, growth factors, and steroid hormone receptors or inactivated tumor suppressors continue to provide insight for disease progression from initiation to metastasis. Further development of new PCa models with spatial and temporal regulation of candidate gene expression will likely enhance our understanding of the complex events that lead to PCa initiation and progression, thereby invoking novel strategies to combat this common disease in men.

BACKGROUND: Androgen receptor (AR) expression in breast cancers may serve as a prognostic and predictive marker. We examined the expression pattern of AR and its phosphorylated forms, Ser-213 (AR-Ser[P]-213) and Ser-650 (AR-Ser[P]-650), in breast cancer and evaluated their association with clinicopathological parameters. METHODS: Immunohistochemistry was performed on primary and distant metastatic breast cancers and benign breast tissue using antibodies against AR, AR-Ser(P)-213, and AR-Ser(P)-650. The levels of cytoplasmic and nuclear expression were scored semiquantitatively using a histoscore. RESULTS: Nuclear staining of AR was observed in all benign breast tissue and 67% of cancer cases. Nuclear and cytoplasmic AR-Ser(P)-213 was increased in breast cancers 2-fold (P = .0014) and 1.7-fold (P = .05), respectively, compared with benign controls, whereas nuclear and cytoplasmic AR-Ser(P)-650 expression was decreased in tumors by 1.9-fold and 1.7-fold (both P < .0001), respectively. Increased expression of nuclear or cytoplasmic AR-Ser(P)-213 was observed in metastatic breast cancers (1.3-fold, P = .05), ER-negative (2.6-fold, P = .001), and invasive ductal carcinoma (6.8-fold, P = .04). AR-Ser(P)-650 expression was downregulated in lymph node-positive breast cancers (1.4-fold, P = .02) but was upregulated in invasive ductal carcinomas (3.2-fold, P < .0001) and metastases (1.5-fold, P = .003). Moreover, in ER-negative breast cancers, nuclear AR-Ser(P)-650 was decreased (1.4-fold, P = .005), and cytoplasmic AR-Ser(P)-650 was increased (1.4-fold, P = .003). CONCLUSIONS: AR and its phosphorylation at serines 213 and 650 are differentially expressed in breast cancer tumorigenesis and progression. Phosphorylation of AR at serines 213 and 650 is increased in ER-negative breast cancers, ductal carcinomas, and metastases and may have predictive value in breast cancer prognosis. Cancer 2013;000:000-000. (c) 2013 American Cancer Society.

AIM: To develop and validate a technique for construction of intermediate density tissue microarray (TMA) slides based on the transfer of tissue from pre-existing routine slides provided for pathology diagnosis with validation to show preservation of morphology and antigenicity of the transferred tissue. METHODS: A prostate cancer TMA was constructed using 20 cores from radical prostatectomy slides. This technique entails removal of the coverslip on each slide and reinforcement of the tissue by covering with Mount-Quick liquid mounting medium. The attached tissue with its new scaffold is 'biopsied' using a TMA needle (1.5 mm in diameter). The resultant biopsy disc is then transferred onto a recipient slide, with adhesion of the disc to the slide accomplished using heavy pressure. The preservation of morphology and antigenicity of this TMA is tested in comparison to a traditional TMA. RESULTS: After immunohistochemical staining, 35 of 39 cores (89.7%) on the patch TMA were intact compared with 39 of 40 cores (97.5%) on the traditional TMA (p>0.1). Expression patterns and density of the antigens (34betaE12, p63 and AMACR) on the patch TMA were almost identical to the traditional TMA. CONCLUSIONS: Patch TMA represents a viable alternative for tissue-based immunohistochemistry studies when paraffin blocks are unavailable. This may be a valuable tool for allowing the use of archival slide material for immunohistochemistry and enabling a standardised TMA platform to be used when the slides sent for review from other institutions are the only source of tissue available.

OBJECTIVE: To study the histopathology changes and clinical features of vesical diverticula, focusing on the neoplastic entities. MATERIALS AND METHODS: We retrieved data for 108 patients with vesical diverticula from the archives of our institute during the past 15 years (1998 to 2012) and reviewed their clinical and pathologic characteristics. RESULTS: Diverticula most often involved the lateral wall, followed by the posterolateral and posterior walls of the urinary bladder. Nonneoplastic processes were found in 70 of 108 patients (65%), including inflammation, metaplasia, and urothelial hyperplasia, with or without atypia/dysplasia. Primary carcinomas arising within the diverticula were found in 36 patients (33.3%), of which 33 were urothelial carcinoma, including 5 with divergent differentiation, 2 with squamous carcinoma, and 1 with adenocarcinoma. Patient follow-up for neoplastic diverticula (mean, 59 months; range, 1-108 months) showed that no patients died of disease progression. Concurrent or subsequent urothelial carcinoma was present in the nondiverticular bladder in 19 of 36 patients (53%). Four patients with subsequent extradiverticular urothelial carcinoma showed progression, with pathology upstaging. CONCLUSION: Inflammation, metaplasia, and dysplasia are commonly seen in vesical diverticula. In our series, which includes patients who underwent endoscopic or surgical intervention and microscopic examination, those with vesical diverticula appeared to have a significantly higher risk for development of urothelial carcinoma, which can occur synchronously or precede carcinoma of the nondiverticular bladder. Compared with their non-diverticulum-associated counterparts, a significantly higher percentage of diverticulum-associated bladder carcinomas are high-grade and invasive. Conservative approaches are suggested for tumors confined within diverticula, after extensive investigation of the nondiverticular bladder.