Faculty Bibliography

Androgen receptor splice variants (AR-Vs) are implicated in resistance of prostate cancer to androgen-directed therapies. When expressed alone in cells, some AR-Vs (e.g., AR-V7) localize primarily to the nucleus, whereas others (e.g., AR-V1, AR-V4, and AR-V6) localize mainly to the cytoplasm. Significantly, the latter are often co-expressed with the nucleus-predominant AR-Vs and the full-length AR (AR-FL). An important question to be addressed is whether the cytoplasmic-localized AR-Vs play a role in castration-resistant prostate cancer (CRPC) through interaction with the nucleus-predominant AR-Vs and AR-FL. Here, it is demonstrated that AR-V1, -V4, and -V6 can dimerize with both AR-V7 and AR-FL. Consequently, AR-V7 and androgen-bound AR-FL induced nuclear localization of AR-V1, -V4, and -V6, and these variants, in turn, mitigated the ability of the anti-androgen enzalutamide to inhibit androgen-induced AR-FL nuclear localization. Interestingly, the impact of nuclear localization of AR-V4 and -V6 on AR transactivation differs from that of AR-V1. Nuclear localization leads to an increased ability of AR-V4 and -V6 to transactivate both canonical AR targets and AR-V-specific targets and to confer castration-resistant cell growth. However, while AR-V1, which lacks inherent transcriptional activity, appears to activate AR-FL in an androgen-independent manner, it significantly antagonizes AR-V7 transactivation. Together, these data demonstrate that the complex interactions among different AR-Vs and AR-FL play a significant role in castration resistant disease. IMPLICATIONS: This study suggests important consequences for clinical castration resistance due to simultaneous expression of AR-FL and AR-Vs in patient tumors and suggests that dissecting these interactions should help develop effective strategies to disrupt AR-V signaling.

Carcinosarcoma of the anus is rare and has yet to be reportedly associated with the keratinocyte-specific Human Papilloma Virus (HPV). We describe a case of anal carcinosarcoma with HPV infection in both the epithelial and mesenchymal components of the tumor by immunohistochemistry, chromogenic in-situ hybridization (CISH) and further supported by electron microscopy (EM). Microscopic examination of the tumor showed nests of poorly-differentiated invasive squamous cell carcinoma with basaloid features intermixed with a hypercellular, atypical spindle cell proliferation. Immunohistochemistry demonstrated that the epithelial component was positive for AE1/AE3, p63, CK5/6 and p16, whilst the mesenchymal component was positive for smooth muscle actin, vimentin, and focally positive for desmin and p16, consistent with carcinosarcoma. The tumor was negative for GATA-3, CK7 and CK20. CISH demonstrated that the tumor was positive for high risk HPV (subtype 16/18) in both tumor components. EM further supported the presence of intracellular virus particles (~50 nm) that is compatible with HPV infection. Infection of both epithelial and mesenchymal tumor components by HPV has not been previously observed in the gastrointestinal tract. This finding may represent initial epithelial HPV infection with subsequent divergent tumoral differentiation and suggests the presence of viral replication in both biphasic tumor components.

We recently demonstrated that anti-SSA/52kD-Ro antibodies (Abs) from patients with autoimmune-diseases and QTc prolongation directly target and inhibit HERG-K channel at the extracellular pore region (E-pore) where homology with SSA/52kD-Ro antigen was demonstrated. We tested the hypothesis that immunization of guinea-pigs with a peptide corresponding to the E-pore region (E-pore peptide) will generate pathogenic inhibitory Abs and cause QTc prolongation. Guinea-pigs were immunized with a 31-amino-acid peptide corresponding to E-pore region of HERG. At days 10 to 62 post-immunization, ECGs were recorded and blood drawn for the detection of E-pore peptide Abs. Sera from patients with autoimmune-diseases was evaluated for reactivity to E-pore peptide by ELISA and histology was performed on hearts using Masson's trichrome. HERG channel inhibition was assessed by electrophysiology and by computational modelling of Human ventricular action potential (AP). ELISA results revealed the presence of high-titers of E-pore peptide Abs and significant QTc prolongation post-immunization. High reactivity to E-pore peptide was found using anti-SSA/Ro Ab positive-sera from patients with QTc prolongation. Histology data showed no evidence of fibrosis in immunized hearts. Simulations of simultaneous inhibition of repolarizing currents by anti-SSA/Ro Ab positive-sera showed predominance of HERG channel in controlling AP duration and QT-interval. The results are first to demonstrate that inhibitory Abs to HERG E-pore region induced QTc prolongation in immunized guinea-pigs by targeting HERG channel independently from fibrosis. The reactivity of anti-SSA/Ro Ab positive-sera from patients with connective tissue diseases with the E-pore peptide opens novel pharmacotherapy avenues in the diagnosis and management of autoimmune-associated QTc prolongation