IL-4 induces proliferation in prostate cancer PC3 cells under nutrient-depletion stress through the activation of the JNK-pathway and survivin up-regulation

Interleukin (IL)-4 plays a critical role in the regulation of immune responses and has been detected at high levels in the tumor microenvironment of cancer patients where it correlates with the grade of malignancy. The direct effect of IL-4 on cancer cells has been associated with increased cell survival; however, its role in cancer cell proliferation and related mechanisms is still unclear. Here it was shown that in a nutrient-depleted environment, IL-4 induces proliferation in prostate cancer PC3 cells. In these cells, under nutrient-depletion stress, IL-4 activates mitogen-activated protein kinases (MAPKs), including Erk, p38, and JNK. Using MAP-signaling-specific inhibitors, it was shown that IL-4-induced proliferation is mediated by JNK activation. In fact, JNK-inhibitor-V (JNKi-V) stunted IL-4-mediated cell proliferation. Furthermore, it was found that IL-4 induces survivin up-regulation in nutrient-depleted cancer cells. Using survivin-short-hairpin-RNAs (shRNAs), it was demonstrated that in this milieu survivin expression above a threshold limit is critical to the mechanism of IL-4-mediated proliferation. In addition, the significance of survivin up-regulation in a stressed environment was assessed in prostate cancer mouse xenografts. It was found that survivin knockdown decreases tumor progression in correlation with cancer cell proliferation. Furthermore, under nutrient depletion stress, IL -4 could induce proliferation in cancer cells from multiple origins: MDA-MB-231 (breast), A253 (head and neck), and SKOV-3 (ovarian). Overall, these findings suggest that in a tumor microenvironment under stress conditions, IL-4 triggers a simultaneous activation of the JNK-pathway and the up-regulation of survivin turning on a cancer proliferation mechanism.     

HCMV感染对恶性胶质瘤U87细胞增殖及ATF5表达的影响

人巨细胞病毒(HCMV)能够诱导肿瘤细胞的恶性转化,但其分子机制尚有待进一步探索。探讨HCMV是否通过调控转录激活因子5(ATF5)的表达变化促进胶质瘤细胞的增殖。采用HCMV AD169株(MOI=5)感染神经胶质瘤U87细胞株,MTT方法观察HCMV感染0、12、24、48 h后细胞的增殖活性。Real-time PCR及Western-blot检测HCMV感染U87细胞后ATF5基因及蛋白的表达水平变化。以慢病毒为载体的靶向ATF5小干扰RNA构建载体,敲低ATF5表达水平后感染HCMV,MTT检测病毒感染细胞的增殖活性变化。HCMV感染神经胶质瘤U87细胞后,与未感染组比较,增值活性明显升高(P0.05),ATF5表达水平上升,表明HCMV感染使胶质瘤细胞增殖活性提高,细胞抗凋亡能力增强。成功构建沉默ATF5细胞系siATF5 U87,HCMV感染siATF5 U87细胞后使细胞增殖活性减弱,抗凋亡能力下降。以上实验结果表明,HCMV感染上调胶质瘤U87细胞ATF5的表达水平,促进细胞的增殖。因此HCMV感染可能通过调控ATF5信号通路增加细胞恶性性状,为治疗胶质瘤提供一个新的思路。     

HoxA10 Induces Proliferation in Human Prostate Carcinoma PC-3 Cell Line

The objectives of this study were to examine the expression levels of Homeobox A10 (HoxA10) in prostate cancer cells and to study the molecular mechanism of HoxA10-mediated regulation of prostate cancer cell growth and development. We investigated the effect of HoxA10 on cell proliferation by stably overexpressing or silencing HoxA10 in prostate cancer PC-3 cell line using lentiviral vectors. Quantitative real-time PCR and western blotting analysis were used to compare the expressions of HoxA10 in prostate cancer cell lines and normal prostate epithelium. Cancer cell proliferation was examined by MTT assay and colony formation assay. The levels of HoxA10 expression were significantly increased in prostate cancer cell lines and tissues compared to those in normal prostate epithelium. Overexpression of HoxA10 in PC-3 cells induced significant cancer cell proliferation, whereas silencing of HoxA10 expression by RNAi resulted in decreased proliferation rates. HoxA10 was highly expressed in prostate cancer cells and tissues, suggesting its functional involvement in cancer cell proliferation. We successfully overexpressed or silenced HoxA10 in prostate cancer PC-3 cell line and discovered that the levels of HoxA10 directly correlate with cancer cell proliferation. These findings contribute to a better understanding of the regulatory mechanism of HoxA10 in prostate cancer.     

5alpha-androstane-3alpha,17beta-diol selectively activates the canonical PI3K/AKT pathway: a bioinformatics-based evidence for androgen-activated cytoplasmic signaling

5alpha-Androstane-3alpha,17beta-diol (3alpha-diol) is reduced from the potent androgen, 5alpha-dihydrotestosterone (5alpha-DHT), by reductive 3alpha-hydroxysteroid dehydrogenases (3alpha-HSDs) in the prostate. 3alpha-diol is recognized as a weak androgen with low affinity toward the androgen receptor (AR), but can be oxidized back to 5alpha-DHT. However, 3alpha-diol may have potent effects by activating cytoplasmic signaling pathways, stimulating AR-independent prostate cell growth, and, more importantly, providing a key signal for androgen-independent prostate cancer progression. A cancer-specific, cDNA-based membrane array was used to determine 3alpha-diol-activated pathways in regulating prostate cancer cell survival and/or proliferation. Several canonical pathways appeared to be affected by 3alpha-diol-regulated responses in LNCaP cells; among them are apoptosis signaling, PI3K/AKT signaling, and death receptor signaling pathways. Biological analysis confirmed that 3alpha-diol stimulates AKT activation; and the AKT pathway can be activated independent of the classical AR signaling. These observations sustained our previous observations that 3alpha-diol continues to support prostate cell survival and proliferation regardless the status of the AR. We provided the first systems biology approach to demonstrate that 3alpha-diol-activated cytoplasmic signaling pathways are important components of androgen-activated biological functions in human prostate cells. Based on the observations that levels of reductive 3alpha-HSD expression are significantly elevated in localized and advanced prostate cancer, 3alpha-diol may, therefore, play a critical role for the transition from androgen-dependent to androgen-independent prostate cancer in the presence of androgen deprivation.