CacyBP/SIP调控RhoA促进胰腺癌转移的分子机制研究

CacyBP / SIP (calcyclin binding protein) is a newly-discovered human-mouse coexisting gene, mainly involved in the processes of ubiquitination, cell proliferation and differentiation and backbone rearrangement, etc. However, its roles and underlying mechanisms for promoting tumorigenesis and progression remain unclear. Our previous study has desmonstrated that CacyBP / SIP was highly expressed in primary pancreatic cancer (PC) samples from patients, an event closely correlated to the metastasis of PC. Using the RNA interference approaches, we have also found that CacyBP/SIP enhanced the progression of PC via regulating the cell cycle, while promoted the PC metastasis most likley through activating RhoA. In vivo study has further revealed that both PC cell proliferation and distant PC metastasis were significantly inhibited by CacyBP/SIP downregulation in a nude mouse model. Moreover, down-regulation of CacyBP/SIP was associated with diminished expression of RhoA and other Rho-related proteins. Based on these preliminary findings, the present project is designed to explore deeper insights into the molecular mechanism(s) by which CacyBP / SIP contributes to the metastasis of PC via regulation of RhoA as well as its downstream events involving ROCK and MMPs, using genetic and phamacological appraoches including genechip microaray, co-immunoprecipitation, RNA interference, small molecule inhibitors, etc. It is expected that the proposed studies will lay down the foundation for understanding whether and by which mechanisms CacyBP/SIP promotes PC metastasis, and thus seeking the potenial molecular targets for prevention and treatment of metastasis PC.

CacyBP/SIP（钙周期素结合蛋白）是新发现的人鼠共存基因，主要参与泛素化、细胞增殖分化及骨架重排等过程，但促进肿瘤发生发展(特别是转移)的机制尚不明确。我们前期研究发现CacyBP/SIP在胰腺癌中高表达，并且与胰腺癌转移密切相关。通过基因干扰实验我们发现CacyBP/SIP通过调控细胞周期促进胰腺癌的发展；同时激活RhoA促进肿瘤的转移。体内实验发现CacyBP/SIP的表达下调后，裸鼠体内肿瘤的增殖及远处转移得到明显的抑制，同时伴有RhoA等分子的表达下调。本项目拟在前期研究基础上，通过基因芯片、免疫共沉淀、基因干扰、阻断剂等实验，深入研究CacyBP/SIP调控RhoA及其下游分子ROCK、MMPs等促进胰腺癌转移的分子机理，为阐明CacyBP/SIP在胰腺癌中的生物学功能及为胰腺癌转移防治的分子靶标筛选奠定基础。

胰腺癌是恶性程度最高的肿瘤之一，发病相对隐匿，早期诊断困难，大多数患者诊断时多为进展期，已出现转移，只有不超过 20%的患者有根治性切除的机会，5年生存期小于5%，预后极差。但是对于胰腺癌的病因及发病机制尚不清楚。因此研究与胰腺癌的发生和发展（特别是转移）有关的生物学行为，明确其分子调控机制，寻找治疗胰腺癌的分子靶点是目前临床亟需解决的问题。.在国家自然科学基金（No. 81302067）的支持下，我们通过基因干扰、侵袭转移等相关实验发现：CacyBP/SIP诱导胰腺癌细胞上皮间质转变，促进胰腺癌细胞的转移侵袭能力；免疫组化研究发现CacyBP/SIP与RhoA在胰腺癌中均为高表达；进一步实验研究发现 CacyBP/SIP通过RhoA调控胰腺癌细胞的转移侵袭能力；同时我们还发现CacyBP/SIP通过RhoA调控NFAT的转录活性诱导NFAT的表达。以上结果提示NFAT可能参与CacyBP/SIP-RhoA调控胰腺癌细胞转移的信号通路。.综上所述本研究主要的发现是CacyBP/SIP通过RhoA促进胰腺癌细胞的转移侵袭能力，并且CacyBP/SIP通过RhoA调控NFAT的转录活性诱导NFAT的表达，提示可能参与调控胰腺癌细胞转移的信号通路。因此CacyBP/SIP-RhoA-NFAT信号通路是胰腺癌细胞转移的关键分子及分子群，对筛选靶向治疗的新靶标及对胰腺癌的精准治疗具有重要意义.