Functional upregulation of the H₂S/Ca_v3.2 channel pathway accelerates secretory function in neuroendocrine-differentiated human prostate cancer cells

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• 作者：Kazuki Fukami^a ; ^{a_smile_bring_up_a_happy_mind9@yahoo.co.jp" class="auth_mail" title="E-mail the corresponding author} ; Fumiko Sekiguchi^a ; ^{fumiko@phar.kindai.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Miku Yasukawa^a ; ^{raintree.blossom.57@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Erina Asano^a ; ^{1111610150f@kindai.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Ryuji Kasamatsu^a ; ^{cfado303@jtw.zaq.ne.jp" class="auth_mail" title="E-mail the corresponding author} ; Mai Ueda^a ; ^{1211610011n@kindai.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Shigeru Yoshida^b ; ^{physiology@life.kindai.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Atsufumi Kawabata^a ; ^{kawabata@phar.kindai.ac.jp" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Hydrogen sulfide ; T-type calcium channel ; Prostate cancer ; Neuroendocrine differentiation
• 刊名：Biochemical Pharmacology
• 出版年：2015
• 出版时间：1 October 2015
• 年：2015
• 卷：97
• 期：3
• 页码：300-309
• 全文大小：2414 K

文摘

Neuroendocrine-differentiated prostate cancer cells may contribute to androgen-independent proliferation of surrounding cells through Ca²⁺-dependent secretion of mitogenic factors. Human prostate cancer LNCaP cells, when neuroendocrine-differentiated, overexpress Ca_v3.2 T-type Ca²⁺ channels that contribute to Ca²⁺-dependent secretion. Given evidence for the acceleration of Ca_v3.2 activity by hydrogen sulfide (H₂S), we examined the roles of the H₂S/Ca_v3.2 pathway and then analyzed the molecular mechanisms of the Ca_v3.2 overexpression in neuroendocrine-differentiated LNCaP cells. LNCaP cells were differentiated by dibutyryl cyclic AMP. Protein levels and T-type Ca²⁺ channel-dependent currents (T-currents) were measured by immunoblotting and whole-cell pacth-clamp technique, respectively. Spontaneous release of prostatic acid phosphatase (PAP) was monitored to evaluate secretory function. The differentiated LNCaP cells exhibited neurite outgrowth, androgen-independent proliferation and upregulation of mitogenic factors, and also showed elevation of Ca_v3.2 expression or T-currents. Expression of cystathionine-纬-lyase (CSE) and cystathionine-尾-synthase (CBS), H₂S-forming enzymes, and spontaneous secretion of PAP increased following the differentiation. The augmented T-currents were enhanced by H₂S donors and suppressed by inhibitors of CSE, but not CBS. The PAP secretion was reduced by inhibition of CSE or T-type Ca²⁺ channels. During differentiation, Egr-1 and REST, positive and negative transcriptional regulators for Ca_v3.2, were upregulated and downregulated, respectively, and Egr-1 knockdown prevented the Ca_v3.2 overexpression. Our data suggest that, in neuroendocrine-differentiated LNCaP cells, H₂S formed by the upregulated CSE promotes the activity of the upregulated Ca_v3.2, leading to the elevated secretory functions. The overexpression of Ca_v3.2 appears to involve upregulation of Egr-1 and downregulation of REST.