细胞凋亡在结肠腺癌组织中的变化及其相关蛋白的表达

目的:观察结肠腺癌组织细胞凋亡的变化,探讨抑制凋亡蛋白Bcl-2、Bcl-xL及Bcl-w在结肠腺癌中的作用.方法:收集14例我院手术切除结肠腺癌标本,肠镜取正常结肠黏膜组织27例,所有标本均经病理明确诊断.用TUNEL法检测其组织细胞凋亡水平,并用免疫组织化学PV法检测蛋白Bcl-2、Bcl-xL及Bcl-w的表达水平.结果:正常结肠黏膜组织的细胞凋亡指数明显高于结肠腺癌,有统计学显著性差异(t=3.35,P=0.002);结肠腺癌中Bcl-xL与Bcl-w的表达均高于正常结肠黏膜组织,有统计学差异(92.86% vs 11.11%;85.71% vs 0%,P<0.01或P<0.05);Bcl-2的表达与正常结肠黏膜组织没有统计学差异(P>0.05).结论:结肠腺癌的组织细胞凋亡明显低于正常结肠组织:结肠腺癌中抑制凋亡蛋白Bcl-xL与Bcl-w的高表达可能发挥了重要的作用.     

Signaling components involved in Bcl-w-induced migration of gastric cancer cells

We have previously reported that Bcl-w enhances the invasiveness of gastric cancer cells by inducing MMP-2 expression via phosphoinositide 3-kinase (PI3K), Akt and Sp1. This study demonstrates that Bcl-w additionally induces uPA expression and FAK activation. Analyses of the hierarchical relationship and functions of these components showed that the PI3K-Akt-Sp1 pathway also mediates the induction of uPA, and that both uPA and MMP-2 contribute to Bcl-w-induced invasion via the stimulation of the FAK-dependent migratory pathway. These findings significantly advance our understandings of the Bcl-w-induced signaling processes that results in the migration and invasion of cancer cells.     

Synchronised phosphorylation of BNIP3, Bcl-2 and Bcl-xL in response to microtubule-active drugs is JNK-independent and requires a mitotic kinase

BNIP3 is a hypoxia-inducible BH3-only member of the Bcl-2 family of proteins that regulate apoptosis and autophagy. However the role of BNIP3 in the hypoxia response has proved difficult to define and remains controversial. In this study we show that in cancer cells, knockdown or forced expression of BNIP3 fails to modulate cell survival under hypoxic or normoxic conditions. However, we demonstrate that BNIP3 is regulated post-translationally, existing as multiple monomeric and dimeric phosphorylated forms. Upon treatment with microtubule inhibitors, but not other classes of chemotherapeutics, BNIP3 becomes hyperphosphorylated. We demonstrate that the phosphorylation of BNIP3 occurs in synchrony with phosphorylation of its binding partners Bcl-2 and Bcl-xL. Microtubule inhibitor-induced phosphorylation of these proteins occurs independently of the AKT/mTor and JNK kinase pathways and requires Mps1 mitotic checkpoint kinase activity. Inhibition of mitotic arrest in the presence of paclitaxel blocks the phosphorylation of BNIP3, Bcl-2 and Bcl-xL, demonstrating that these proteins are phosphorylated by a mitochondrially active mitotic kinase. We show that phosphorylation increases the stability of BNIP3 and that BNIP3 predominantly interacts with the phosphorylated form of Bcl-2. This study provides new insight into the post-translational functional control of these Bcl-2 family members.