Jing Tian

New therapy targeting differential androgen receptor signaling in prostate cancer stem/progenitor vs. non-stem/progenitor cells

The androgen deprivation therapy (ADT) to systematically suppress/reduce androgens binding to the androgen receptor (AR) has been the standard therapy for prostate cancer (PCa); yet, most of ADT eventually fails leading to the recurrence of castration resistant PCa. Here, we found that the PCa patients who received ADT had increased PCa stem/progenitor cell population. The addition of the anti-androgen, Casodex, or AR-siRNA in various PCa cells led to increased stem/progenitor cells, whereas, in contrast, the addition of functional AR led to decreased stem/progenitor cell population but increased non-stem/progenitor cell population, suggesting that AR functions differentially in PCa stem/progenitor vs. non-stem/progenitor cells. Therefore, the current ADT might result in an undesired expansion of PCa stem/progenitor cell population, which explains why this therapy fails. Using various human PCa cell lines and three different mouse models, we concluded that targeting PCa non-stem/progenitor cells with AR degradation enhancer ASC-J9 and targeting PCa stem/progenitor cells with 5-azathioprine and γ-tocotrienol resulted in a significant suppression of the tumors at the castration resistant stage. This suggests that a combinational therapy that simultaneously targets both stem/progenitor and non-stem/progenitor cells will lead to better therapeutic efficacy and may become a new therapy to battle the PCa before and after castration resistant stages.

Targeting the unique methylation pattern of androgen receptor (AR) promoter in prostate stem/progenitor cells with 5-aza-2'-deoxycytidine (5-AZA) leads to suppressed prostate tumorigenesis.

Background: There is a specific silencing of AR gene expression in prostate stem cells. Results: The induction of AR gene expression inhibited the self-renewal of the prostate stem cells. Conclusion: The induction of AR expression suppressed PCa stem cell-mediated tumorigenicity. Significance: This is the first attempt to suppress prostate cancer growth via epigenetic modification of AR genes in PCa stem cells. Androgen receptor (AR) expression surveys found that normal prostate/prostate cancer (PCa) stem/progenitor cells, but not embryonic or mesenchymal stem cells, expressed little AR with high methylation in the AR promoter. Mechanism dissection revealed that the differential methylation pattern in the AR promoter could be due to differential expression of methyltransferases and binding of methylation binding protein to the AR promoter region. The low expression of AR in normal prostate/PCa stem/progenitor cells was reversed after adding 5-aza-2′-deoxycytidine, a demethylating agent, which could then lead to decreased stemness and drive cells into a more differentiated status, suggesting that the methylation in the AR promoter of prostate stem/progenitor cells is critical not only in maintaining the stemness but also critical in protection of cells from differentiation. Furthermore, induced AR expression, via alteration of its methylation pattern, led to suppression of the self-renewal/proliferation of prostate stem/progenitor cells and PCa tumorigenesis in both in vitro assays and in vivo orthotopic xenografted mouse studies. Taken together, these data prove the unique methylation pattern of AR promoter in normal prostate/PCa stem/progenitor cells and the influence of AR on their renewal/proliferation and differentiation. Targeting PCa stem/progenitor cells with alteration of methylated AR promoter status might provide a new potential therapeutic approach to battle PCa because the PCa stem/progenitor cells have high tumorigenicity.

Suppressor role of androgen receptor in proliferation of prostate basal epithelial and progenitor cells

Early studies have reported the differential roles of androgen receptor (AR) in different types (luminal, basal intermediate, and stromal) of prostate cancer cells. In vivo mouse model tumor studies using the total prostate epithelial knockout mice (pes-ARKO) also revealed that AR played a suppressive role in proliferation of the CK5(+)/CK8(+) progenitor/intermediate cells but a positive role in the CK5(-)/CK8(+) luminal epithelial cells. Using three different resources (one human basal epithelial cell line, one mouse basal epithelial originated progenitor cell line, and a basal epithelium-specific ARKO mouse model), we here demonstrated that the AR in basal epithelial cells of normal prostate plays a suppressive role in their proliferation but a positive role in differentiation into luminal epithelial cells. These results led us to conclude that ARs may play a negative role to suppress CK5(+) basal epithelial and progenitor cell proliferation, yet play an essential role to drive basal epithelial cells into more differentiated states. These results may explain why differential AR expression in different cell types within normal prostate is needed and suggest that ARs in prostate basal epithelial cells, although expressed at a very low level, are necessary to maintain the balance between progenitor cells and differentiated luminal epithelial cells.

Human kallikrein 2 (KLK2) promotes prostate cancer cell growth via function as a modulator to promote the ARA70-enhanced androgen receptor transactivation

Recent data suggested that tissue human kallikrein 2 (KLK2) might be involved in the carcinogenesis and tumor metastasis of prostate cancer (PCa). However, the detailed pathophysiological roles of KLK2 in PCa remain unclear. We report here that KLK2 may be treated as a potential therapeutic target in castration-resistant PCa (CRPC). Histologic analyses show that the increased KLK2 expression is correlated with higher cell proliferation rate and lower cell apoptosis index in CRPC specimens. Adding functional KLK2 cDNA into high passage LNCaP cells led to increased cell growth, and knockdown of KLK2 expression with KLK2-siRNA in LNCaP cells resulted in increased cell apoptosis with cell growth arrest at the G1 phase. Results from in vitro colony formation assay and in vivo xenografted PCa tissues also demonstrated that targeting KLK2 led to suppressed growth of PCa in the castration-resistant stage. Further mechanism dissection shows that KLK2 may cooperate with the AR coregulator, ARA70, to enhance AR transactivation that may result in alteration of PCa formation. Together, these results suggested KLK2 might become a new therapeutic target to battle the CRPC and KLK2-siRNA may be developed as an alternative approach to suppress PCa growth.

Association between glutathione S-transferases M1 and T1 gene polymorphisms and prostate cancer risk: a systematic review and meta-analysis

Genetic polymorphisms in glutathione S-transferases M1 (GSTM1) and T1 (GSTT1) genes have been widely reported and considered to have a significant effect on prostate cancer (PCa) risk, but the results are inconsistent. To evaluate the impact of the GSTM1 and GSTT1 polymorphism on PCa risk, we conducted a comprehensive meta-analysis based on 18 eligible studies. A total of 18 studies, including 7,119 subjects for GSTM1 and 6,454 subjects for GSTT1 between 1999 and 2012 were identified through researching MEDLINE, PubMed, Web of Science, EMBASE, Chinese National Knowledge Infrastructure database, and Chinese Biomedical Literature database. A meta-analysis was performed to obtain summary-estimated odd ratios and 95xa0% confidence intervals of GSTM1 and GSTT1 polymorphisms for PCa, with attention to study quality and publication bias. Overall, there is a significant association between GSTM1 (odds ratio (OR)u2009=u20091.407, 95xa0% confidence intervals (95xa0% CI)u2009=u20091.147–1.727, I2u2009=u200973.2xa0%, Pu2009= 0.001) genotypes and PCa susceptibility. Significant associations were also observed in subgroups of Caucasian populations (ORu2009=u20091.262, 95xa0% CIu2009=u20091.055–1.511, I2u2009=u200948.7xa0%, Pu2009=u20090.011) and Asian populations (ORu2009=u20091.776, 95xa0% CIu2009=u20091.134–2.781, I2u2009=u200983.4xa0%, Pu2009=u20090.012). However, no significant association was found (ORu2009=u20091.776, 95xa0% CIu2009=u20091.134–2.781, Pu2009=u20090.243) in African-American populations when stratified by ethnicity. While, there was no significant association seen between GSTT1 (ORu2009=u20091.003, 95xa0% CIu2009=u20090.823–1.298, I2u2009=u200968.8xa0%, Pu2009=u20090.778) genotypes and PCa risk. However, no significant associations were observed in subgroups of Caucasian populations (ORu2009=u20091.086, 95xa0% CIu2009=u20090.801–1.471, I2u2009=u200972.1xa0%, Pu2009=u20090.597) and Asian populations (ORu2009=u20090.961, 95xa0% CIu2009=u20090.644–1.434, I2u2009=u200973.0xa0%, Pu2009=u20090.846), and similar result was found among African-American populations (ORu2009=u20090.802, 95xa0% CIu2009=u20090.194–3.321, Pu2009=u20090.761) when stratified by ethnicity. Our results suggest that the GSTM1 gene polymorphism contributes to PCa susceptibility, while GSTT1 gene polymorphism is not associated with PCa in our study.

Androgen receptor enhances kidney stone-CaOx crystal formation via modulation of oxalate biosynthesis & oxidative stress.

Males develop kidney stones far more frequently than females with a ratio of 2–3:1, suggesting that androgen receptor (AR) signaling might play a key role in the development of nephrolithiasis. Using the cre-loxP system to selectively knock out AR in glyoxylate-induced calcium oxalate (CaOx) crystal mouse models, we found that the mice lacking hepatic AR had less oxalate biosynthesis, which might lead to lower CaOx crystal formation, and that the mice lacking kidney proximal or distal epithelial AR also had lower CaOx crystal formation. We found that AR could directly up-regulate hepatic glycolate oxidase and kidney epithelial NADPH oxidase subunit p22-PHOX at the transcriptional level. This up-regulation might then increase oxalate biosynthesis and oxidative stress that resulted in induction of kidney tubular injury. Targeting AR with the AR degradation enhancer ASC-J9 led to suppression of CaOx crystal formation via modulation of oxalate biosynthesis and oxidative stress in both in vitro and in vivo studies. Taken together, these results established the roles of AR in CaOx crystal formation.

Antiandrogen Therapy with Hydroxyflutamide or Androgen Receptor Degradation Enhancer ASC-J9 Enhances BCG Efficacy to Better Suppress Bladder Cancer Progression

Recent studies suggest that the androgen receptor (AR) might play important roles in influencing bladder cancer progression, yet its clinical application remains unclear. Here, we developed a new combined therapy with Bacillus Calmette–Guérin (BCG) and the AR degradation enhancer ASC-J9 or antiandrogen hydroxyflutamide (HF) to better suppress bladder cancer progression. Mechanism dissection revealed that ASC-J9 treatment enhanced BCG efficacy to suppress bladder cancer cell proliferation via increasing the recruitment of monocytes/macrophages that involved the promotion of BCG attachment/internalization to the bladder cancer cells through increased integrin-α5β1 expression and IL6 release. Such consequences might then enhance BCG-induced bladder cancer cell death via increased TNFα release. Interestingly, we also found that ASC-J9 treatment could directly promote BCG-induced HMGB1 release to enhance the BCG cytotoxic effects for suppression of bladder cancer cell growth. In vivo approaches also concluded that ASC-J9 could enhance the efficacy of BCG to better suppress bladder cancer progression in BBN-induced bladder cancer mouse models. Together, these results suggest that the newly developed therapy combining BCG plus ASC-J9 may become a novel therapy to better suppress bladder cancer progress. Mol Cancer Ther; 14(11); 2586–94. ©2015 AACR.

TGFβ1 Leu10Pro polymorphism contributes to the development of prostate cancer: evidence from a meta-analysis

Transforming growth factor-β1 (TGFβ1) plays a significant role in regulating cellular proliferation and apoptosis. A large number of studies related to the association between TGFβ1 Leu10Pro polymorphism and prostate cancer (PC) risk, but get conflicting results. We performed a meta-analysis based on six studies, assessing the strength of the association using odds ratios (OR) with 95xa0% confidence intervals (CI). Overall, our evidence has indicated that TGFβ1 Leu10Pro polymorphism had significantly increased PC risk in the allele comparison model (ORu2009=u20091.081, 95xa0% CIu2009=u20091.003–1.165, Pheterogeneityu2009=u20090.141, Pu2009=u20090.041). In the stratified analysis by ethnicity, the same results were found among Caucasians (for heterozygote model, ORu2009=u20091.741, 95xa0% CIu2009=u20091.004–3.020, Pheterogeneityu2009=u20090.000, Pu2009=u20090.049; recessive model, ORu2009=u20091.339, 95xa0% CIu2009=u20091.045–1.717, Pheterogeneityu2009=u20090.020, Pu2009=u20090.021; allele comparison model, ORu2009=u20091.091, 95xa0% CIu2009=u20091.005–1.184, Pheterogeneityu2009=u20090.048, Pu2009=u20090.037). In conclusion, this meta-analysis suggested that TGFβ1 Leu10Pro polymorphism contributed to the development of PC. A well-designed and larger study is still required to evaluate this polymorphism and PC risk.

Targeting estrogen/estrogen receptor alpha enhances Bacillus Calmette-Guérin efficacy in bladder cancer

Recent studies showed the potential linkage of estrogen/estrogen receptor signaling with bladder tumorigenesis, yet detailed mechanisms remain elusive. Here we found a new potential therapy with the combination of Bacillus Calmette Guerin (BCG) and the anti-estrogen ICI 182,780 led to better suppression of bladder cancer (BCa) than BCG alone. Mechanism dissection found ICI 182,780 could promote BCG attachment/internalization to the BCa cells through increased integrin-α5β1 expression and IL-6 release, which may enhance BCG-induced suppression of BCa cell growth via recruiting more monocytes/macrophages to BCa cells and increased TNF-α release. Consistently, in vivo studies found ICI 182,780 could potentiate the anti-BCa effects of BCG in the carcinogen-induced mouse BCa models. Together, these in vitro and in vivo results suggest that combining BCG with anti-estrogen may become a new therapeutic approach with better efficacy to suppress BCa progression and recurrence.

Sox5 contributes to prostate cancer metastasis and is a master regulator of TGF-β-induced epithelial mesenchymal transition through controlling Twist1 expression

Background:Metastatic castration-resistant prostate cancer (mCRPC) is one of the main contributors to the death of prostate cancer patients. To date, the detailed molecular mechanisms underlying mCRPC are unclear. Given the crucial role of epithelial–mesenchymal transition (EMT) in cancer metastasis, we aimed to analyse the expression and function of Transforming growth factor-beta (TGF-β) signal-associated protein named Sox5 in mCRPC.Methods:The protein expression levels were analysed by western blot, immunohistochemistry and immunofluorescence. Luciferase reporter assays and chromatin immunoprecipitation were employed to validate the target of Sox5. The effect of Smad3/Sox5/Twist1 on PCa progression was investigated in vitro and in vivo.Results:Here, we found that TGF-β-induced EMT was accompanied by increased Sox5 expression. Interestingly, knockdown of Sox5 expression attenuated EMT induced by TGF-β signalling. Furthermore, we demonstrated that Smad3 could bind to the promoter of Sox5 and regulate its expression. Mechanistically, Sox5 could bind to Twist1 promoter and active Twist1, which initiated EMT. Importantly, knockdown of Sox5 in prostate cancer cells resulted in less of the mesenchymal phenotype and cell migration ability. Furthermore, targeting Sox5 could inhibit prostate cancer progression in a xenograft mouse model. In clinic, patients with high Sox5 expression were more likely to suffer from metastases, and high Sox5 expression also has a lower progression-free survival and cancer specific-survival in clinic database.Conclusions:Therefore, we propose a new mechanism in which Smad3/Sox5/Twist1 promotes EMT and contributes to PCa progression.