BackgroundAndrogen signaling plays a critical role in the development of prostate cancer and its progression. However, androgen-independent prostate cancer cells emerge after hormone ablation therapy, resulting in significant clinical problems. We have previously demonstrated that the HOXB13 homeodomain protein functions as a prostate cancer cell growth suppressor by inhibiting androgen-mediated signals. However, the role of the HOXB13 in androgen-independent growth of prostate cancer cells remains unexplained.ResultsIn this report, we first demonstrated that HOXB13 was highly overexpressed in hormone-refractory tumors compared to tumors without prostate-specific antigen after initial treatment. Functionally, in an androgen-free environment minimal induction of HOXB13 in LNCaP prostate cancer cells, to the level of the normal prostate, markedly promoted cell proliferation while suppression inhibited cell proliferation. The HOXB13-mediated cell growth promotion in the absence of androgen, appears to be mainly accomplished through the activation of RB-E2F signaling by inhibiting the expression of the p21waf tumor suppressor. Indeed, forced expression of HOXB13 dramatically decreased expression of p21waf; this inhibition largely affected HOXB13-mediated promotion of E2F signaling.ConclusionsTaken together, the results of this study demonstrated the presence of a novel pathway that helps understand androgen-independent survival of prostate cancer cells. These findings suggest that upregulation of HOXB13 is associated with an additive growth advantage of prostate cancer cells in the absence of or low androgen concentrations, by the regulation of p21-mediated E2F signaling.

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Purpose: The purpose of this study was to determine whether periurethral injection of allogenic mesenchymal stem cells (MSCs) could increase the leak point pressure (LPP) in a rat model of stress urinary incontinence. Materials and Methods: Female Sprague-Dawley rats (230–240 g, n = 30) were divided into 3 groups: sham operation (group C), saline-treated (group S) and MSC-treated (group M). Bilateral pudendal nerve dissection followed by normal saline or MSC injection on both sides of the urethra was done. LPP and closing pressure (CP) testing was performed after the treatment. The specific markers for smooth muscle cells in the transplantation sites of the urethra were determined. Results: Both the LPP and CP were significantly lower in group S than controls. However, these were restored to the control values in group M (p < 0.05). The LPPs of groups C, S and M were 29.1 ± 2.1, 22.0 ± 2.2 and 43.1 ± 3.2 cm H₂O, respectively. The CPs of groups C, S and M were 27.1 ± 3.1, 21.1 ± 3.2, and 32.1 ± 2.1 cm H₂O, respectively. The injected MSCs stained positive for muscle-specific markers. Conclusion: This study suggests that MSCs might differentiate into muscle lineage cells and may contribute to the repair of damaged muscle tissue.