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Gong Y.,Peking University | Gong Y.,National Urological Cancer Center | Wang D.,University of Pittsburgh | Dar J.A.,University of Pittsburgh | And 10 more authors.
Endocrinology | Year: 2012

Androgen receptor (AR) plays a key role in prostate development and carcinogenesis. Increased expression and/or stability of AR is associated with sensitization of prostate cancer cells to low levels of androgens, leading to castration resistance. Hence, understanding the mechanisms regulating AR protein stability is clinically relevant and may lead to new approaches to prevent and/or treat prostate cancer. Using fluorescence microscopy, Western blot, and pulse chase assay, we showed that nuclear export signal (NES)AR, a nuclear export signal in the ligand binding domain (LBD) of AR, can significantly enhance the degradation of fusion protein constructs in PC3 prostate cancer cells. The half-life of GFP-NESAR was less than 3 h, which was 10 times shorter than that of green fluorescent protein (GFP) control. Further analysis showed that NESAR can signal for polyubiquitination and that degradation of NESAR-containing fusion proteins can be blocked by proteasome inhibitor MG132. Ubiquitination of GFP-AR or GFP-LBD was suppressed in the presence of dihydrotestosterone, which isknownto suppress NESAR while inducing nuclear localization signal 2 in AR or LBD, suggesting that the export activity of NESAR is required for NES AR-mediated polyubiquitination. Treatment with MG132 also induced aggresome formation of NESAR-containing fusion proteins in perinuclear regions of the transfected PC3 cells, indicating a role for NES AR in inducing unfolded protein responses. The above observations suggest that NESAR plays a key role in AR ubiquitination and proteasome-dependent degradation in prostate cancer cells. Copyright © 2012 by The Endocrine Society.

Qiu W.,Peking University | Qiu W.,National Urological Cancer Center | Su M.,Peking Union Medical College | Xie F.,Peking University | And 12 more authors.
Cell Death and Disease | Year: 2014

Lysosomes are acidic organelles that have a crucial role in degrading intracellular macromolecules and organelles during the final stage of autophagy. Tetrandrine (Tet), a bisbenzylisoquinoline alkaloid, was reported as an autophagy activator. Here, in contrast with previous studies, we show that Tet is a potent lysosomal deacidification agent and is able to block autophagic flux in the degradation stage. Single-agent Tet induces significant apoptosis both in vitro and in xenograft models. In the presence of Tet, apoptosis was preceded by a robust accumulation of autophagosomes and an increased level of microtubule-associated protein 1 light chain 3, type II (LC3-II). However, Tet increased the level of sequestosome 1 and decreased the turnover of LC3, indicating the blockade of autophagic flux in the degradation stage. As blockade of autophagic flux decreases the recycling of cellular fuels, Tet reduces the uptake of glucose in cancer cells. These effects lead to insufficient substrates for tricarboxylic acid (TCA) cycle and impaired oxidative phosphorylation. Blunting autophagosome formation using 3-methyladenine or genetic knockdown of Beclin-1 failed to rescue cells upon Tet treatment. By contrast, addition of methyl pyruvate to supplement TCA substrates protected Tet-treated tumor cells. These results demonstrate that energetic impairment is required in Tet-induced apoptosis. Tet, as a potent lysosomal inhibitor, is translatable to the treatment of malignant tumor patients. © 2014 Macmillan Publishers Limited All rights reserved.

Xie F.,Peking University | Xie F.,National Urological Cancer Center | Su M.,Peking Union Medical College | Qiu W.,Peking University | And 12 more authors.
International Journal of Molecular Sciences | Year: 2013

Kaempferol (Kae), a natural flavonoid, is widely distributed in fruits and vegetables. Previous studies have identified Kae as a possible cancer preventive and therapeutic agent. We found Kae to exhibit potent antiproliferation and anti-migration effects in human bladder cancer EJ cells. Kaempferol robustly induced apoptosis in EJ cells in a dose-dependent manner, as evidenced by increased cleavage of caspase-3. Furthermore, we found Kae-induced apoptosis in EJ cells to be associated with phosphatase and the tensin homolog deleted on the chromosome 10 (PTEN)/PI3K/Akt pathway. Kae significantly increased PTEN and decreased Akt phosphorylation. Kae-induced apoptosis was partially attenuated in PTEN-knockdown cells. Our findings indicate that Kae could be an alternative medicine for bladder cancer, based on a PTEN activation mechanism. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Wu P.,Peking University | Wu P.,National Urological Cancer Center | Zhang N.,Capital University of Medicine science | Wang X.,Peking University | And 8 more authors.
Journal of Human Genetics | Year: 2012

Von Hippel-Lindau (VHL) disease is an autosomal dominant familial cancer syndrome caused by germline mutations in VHL tumor suppressor gene. It is characterized by hemangioblastoma in central nervous system and retina, renal cell carcinoma or cyst, pheochromocytoma, pancreatic cyst and tumor, endolymphatic-sac tumor, and papillary cystadenoma in epididymis and broad ligament. Here, we used PCR-direct sequencing and universal primer quantitative fluorescent multiplex PCR (UPQFM-PCR) to detect VHL mutations in 16 patients clinically diagnosed with VHL disease. PCR-direct sequencing detected 12 germline mutations (75%, 12/16), in which a novel mutation of c.451A>T/p.Ile151Phe found in one proband had not been reported previously. UPQFM-PCR found two large deletions (12.5%, 2/16). The two remaining patients carried non-typical disease-causing mutations, including one silent mutation (c.481C>A/p.Arg161Arg) and one mutation in 3′-UTR (c.642+70C>A). Remarkably, 56.3% (9/16) probands did not have family history of VHL disease, suggesting the higher frequency of de novo mutations in Chinese patients. We also summarized Chinese VHL disease patients with VHL mutation findings published in the literature to provide information about the spectrum of VHL mutations in Chinese VHL disease patients. © 2012 The Japan Society of Human Genetics All rights reserved.

Zhang B.,Peking University | Zhang B.,National Urological Cancer Center | Shen C.,Peking University | Shen C.,National Urological Cancer Center | And 4 more authors.
Transplantation | Year: 2014

BACKGROUND: Urothelial carcinoma (UC) is a common complication after renal replacement therapy (RRT) among Chinese end-stage renal disease (ESRD) patients. It is unclear whether there are any differences in the clinicopathologic characteristics of UC between renal transplantation (RT) and dialysis patients; such differences could impact RRT modality selection. METHODS: We retrospectively reviewed clinicopathologic data for 27 RT patients and 40 dialysis patients who were diagnosed with UC in our center to explore differences in the clinicopathologic characteristics of UC and prognoses between the two groups. RESULTS: The median follow-up period was 92 months (2-137) for the RT group and 71 months (18-155) for the dialysis group. The demographic and baseline data showed no significant differences between the two groups. Upper urinary tract UC (UUC) occurred more frequently in the RT group (22 UUCs in 39 UCs), whereas bladder UC (BUC) predominated in the dialysis group (33 BUCs in 49 UCs) (P=0.025). The pathologic grading in the RT group was significantly higher than that in the dialysis group (P=0.046 for WHO1973 grading, P=0.026 for WHO2004 grading), whereas the difference in tumor stage was not significant (P=0.089). The RT group manifested a higher recurrence rate than the dialysis group (P=0.024). However, the overall and cancer-specific survival rates between the two groups were not significantly different (P=0.239 and P=0.818, respectively). CONCLUSION: Certain traits of UC, including tumor site, pathologic grading, and recurrence-free survival, were notably different between RT and dialysis patients, but the overall and cancer-specific survival rates were similar. © 2014 by Lippincott Williams and Wilkins.

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