LncRNA LINC00355招募组蛋白乙酰化酶p300/CBP通过表观调控KIF23/MKLP1表达促进胃癌增殖

Epigenetic changes contribute quite a lot to the genesis and progression of various kinds of cancer. Our work manifested that: KIF23/MKLP1 upregulates in gastric cancer in both mRNA level and protein level; KIF23/MKLP1 promotes gastric cancer cell lines growth by promoting S and G2/M cell cycle arrest; Our data indicate that KIF23/MKLP1 regulates the expression and localization of β-catenin to potentiate Wnt/β-catenin signaling pathway by competitively binding with Amer1 to block its binding with APC and disturbing the distribution of Amer1. In addition, function unknown long noncoding RNA LINC00355 and histone acetylase p300/CBP involve in KIF23/MKLP1 expression regulation in gastric cancer. According to our previous work we put forward the following hypothesis: In gastric cancer upregulation of LINC00355 recruited p300/CBP to KIF23/MKLP1 promoter, leading to homeotic imbalance of histone acetylation and deacetylation arround, then chromatin remodeling resulting in availability of KIF23/MKLP1 promoter to relative transcriptional factors such as E2F1, promoting KIF23/MKLP1 transcription. To demonstrate this hypothesis, we plan to take use of chromatin immunoprecipitation, luciferase report assay, RIP, EMSA etc. researching into epigenetic regulation mechanism of KIF23/MKLP1 expression in gastric cancer. Combine with mouse model to prove promotion effect of LINC00355 on gastric cancer growth in vivo, and KIF23/MKLP1 acts as indispensable effector molecule of LINC00355. Our work will provide useful research basis for gastric cancer genesis and development mechanism as well as new thought for gastric cancer therapy.

表观遗传学改变是肿瘤发生发展的重要原因之一。前期工作首次发现驱动蛋白KIF23在胃癌中表达升高，KIF23通过招募Amer1的异常细胞内定位解除Amer1对Wnt/β-catenin信号通路负调控实现促进胃癌增殖功能。另外，课题组发现功能不详的LncRNA LINC00355在胃癌中表达上升，干扰LINC00355表达抑制胃癌细胞增殖且抑制KIF23表达。结合干扰组蛋白乙酰化酶p300的表达KIF23的表达明显受到抑制以及LINC00355可与p300结合的预测我们提出假说：LINC00355招募染色质调节蛋白p300到KIF23启动子区，改变该区域附近的染色质结构，有助于转录因子的结合从而促进KIF23的表达。为验证此假说，课题组将应用荧光素酶报告实验、ChIP、RIP、EMSA等技术研究胃癌中KIF23表达的表观遗传学调控机制，为阐明胃癌的发生机制奠定理论基础，并对临床治疗提供新思路。

长非编码RNA（lncRNAs）在肿瘤发生发展中发挥重要作用。然而，lncRNAs在胃癌发生发展中的作用在很大程度上仍然未知。在这项研究中，我们发现长非编码RNA LINC00355在胃癌组织中表达上调，并且LINC00355的表达与胃癌的增殖、转移和预后不良相关。RNA-seq和Rescue试验表明，LINC00355可能通过调节Cdc42 GTPases的表达来激活其下游途径，从而调控胃癌的发生。已发表的大多数研究发现LINC00355通过吸附miRNA来调节下游基因表达，从而起到ceRNA的作用。我们的团队证明LINC00355主要位于胃癌细胞的细胞核，然而，LINC00355在基因表达中表观遗传调控潜力中的综合作用仍有待阐明。从机理上讲，LINC00355结合p300组蛋白乙酰转移酶，调控了CDC42启动子上的组蛋白修饰模式，激活CDC42转录，从而改变了胃癌细胞生物学。此外，LINC00355上调HNRNPA2B1表达，而HNRNPA2B1识别CDC42的m6A位点，并增强CDC42 mRNA转录物的稳定性。因此，LINC00355从机制上、功能上以及临床上都具有促进胃癌发生发展的作用。靶向LINC00355及其分子途径可能对治疗胃癌患者有意义。