GGN基因调控MAPK信号促进膀胱癌细胞生长并抑制该细胞凋亡的分子机制研究

Bladder cancer, with increasing mortality and morbility, is the most common malignant tumor in urinary system. The traditional therapy including surgery, BCG vaccine and cisplatin couldn’t improve the prognosis of patients. Recently, target therapy is hot spot in the field of cancer therapy. In our early study, GGN was shown to be expressed higher in bladder cancer tissues than the control and was reversely correlated with overall survival. When GGN was reduced in bladder cancer cells T24, both growth and proliferation were inhibited. Moreover, the cells in S phase increased significantly while it was decreased reversely in G1 or G2/M phase, which indicated that GGN downregulation blocked cell division. Furthermore, the expression of Bcl-2 was greatly upregulated and the expression of ERK1/2 was downregulated in GGN-knockdown T24 cells. Additionally, the activity of Caspase3/7 was about two folds higher in T24 cells with GGN knockdown than that in wild T24 cells. Based on the above data, we hypothesized that GGN promoted cell growth and inhibited cell apoptosis in T24 cells by regulating MAPK signaling. Accordingly, we designed experiments as below. To analyze the association between GGN and bladder cancer, we will determine the expression of GGN in bladder cancer tissues and normal bladder tissues, and search relative information in TCGA databank. To detect the effects of GGN on cell apoptosis signaling and proliferation signaling in T24 cells and analyze the association among GGN gene, platinum and bladder cancer. We will also verify the role of GGN in T24 cells and observe the effects of GGN on nude mice model bearing xenograft bladder cancer. The molecular mechanism of proliferation and apoptosis of bladder cancer cells will be elucidated through GGN-mediated MAPK signaling. This study will provide some useful information for the diagnosis and therapy of bladder cancer.

膀胱癌发病机制尚不完全清楚。传统的膀胱癌治疗均存在一定缺陷，靶向治疗前景良好。我们前期研究发现GGN基因在膀胱癌中高表达，且与膀胱癌预后呈负相关。下调膀胱癌细胞T24中GGN后，T24细胞增殖速率降低；处于S期细胞增加，而G1、G2/M期细胞减少；MAPK信号通路关键分子ERK1/2表达降低，Bcl-2等抗凋亡基因表达上调，Caspase3/7活性增高。结合文献，推测在膀胱癌中GGN基因通过MAPK信号促进细胞增殖、抑制细胞凋亡，发挥对顺铂化疗药物耐药的作用。为此，拟检测膀胱癌中GGN基因的表达，结合TCGA数据库，分析GGN基因与膀胱癌及顺铂耐药的关系；通过实验观察GGN基因对细胞增殖、周期、迁移、侵袭、凋亡以及癌细胞顺铂敏感性的影响；通过体内实验观察GGN基因对膀胱癌生长、转移以及顺铂耐药的影响； 从MAPK信号通路入手探讨GGN基因影响膀胱癌细胞增殖和凋亡的分子机制。

膀胱癌是与性别相关的疾病之一，复发率高，男性的发病率约为女性的两倍。作为一类生殖特异性基因，gamtogenin (GGN)被报道与膀胱癌的不良预后相关，并与NF-kB信号相互作用，但其潜在机制以及是否与男性发病率更高有关尚不清楚。前期研究证实了GGN通过调节MAPK信号通路，参与调节膀胱癌细胞的增殖、凋亡和细胞周期。为进一步探讨其在膀胱癌(BCa)中的作用，课题组采集了64例膀胱癌患者的标本，免疫组化检测GGN的表达水平，并对患者进行了术后5年随访，结果显示GGN在男性的表达显著高于女性的表达，并且与不良预后相关。在干扰了GGN表达的膀胱癌细胞中，我们发现GGN可以调节NF-KB信号通路，并影响以CCL2为代表的相关炎症因子的表达。综上所述，本研究揭示了GGN与BCa细胞增殖和CCL2之间的关系，GGN可能是男性BCa的驱动因素。此外，我们还观察到AR参与调节GGN蛋白。其可能作为AR信号通的一个辅助因子，在膀胱癌的进展中发挥重要的协同促进作用。该现象可能为解释膀胱癌的性别差异提供数据，该数据能为未来的精准治疗提供依据。