Min Hye-Jin, Koh Sang Seok, Cho Il-Rae, Srisuttee Ratakorn, Park Eun-Hee, Jhun Byung Hak, Kim Yong-Gyun, Oh Sangtaek, Kwak Ju Eun, Johnston Randal N, Chung Young-Hwa
Department of Nanomedical Engineering, BK21 Nanofusion Technology Team, Pusan National University, Miryang, Gyeongnam, Korea.
Int J Oncol. 2009 Sep;35(3):617-24.
Reovirus functions as an oncolytic agent for many types of cancer including colon cancer. Although most studies have emphasized the role of activated Ras signaling in enhancing reoviral oncolysis in susceptible cells, we note that many colon cancers also display elevated beta-catenin. Thus, it is possible that enhanced beta-catenin may augment reoviral susceptibility in colon cancer cells. To explore this hypothesis, HEK293 cells were treated with the glycogen synthase kinase (GSK)-3beta inhibitor LiCl, thereby inducing beta-catenin, followed by reoviral infection. Co-administration with LiCl indeed enhanced cell death compared to reovirus infection alone, but this was not associated with elevated reoviral replication. Similarly, HEK293 cells expressing the Frizzled-1 receptor in Wnt3a-conditioned medium also showed reovirus replication equivalent to that in cells in control medium, further suggesting that up-regulation of beta-catenin does not enhance the replication of reovirus. Instead, we observed that inhibition of GSK-3beta with LiCl decreased reovirus-induced NF-kappaB activation, leading to accelerated apoptosis via caspase 8 activation. We further found that colon cancer HCT116 cells were sensitized to apoptosis by co-treatment with reovirus and a GSK-3beta inhibitor, AR-A014418. Finally, we identified that inhibition of NF-kappaB sensitized apoptosis of HEK293 or HCT 116 cells during reovirus infection. Taken together, we propose that inhibition of GSK-3beta sensitizes reovirus-induced apoptosis of colon cancer cells by down-regulation of NF-kappaB activity, offering a potentially improved therapeutic strategy for the treatment of colon cancer.
呼肠孤病毒可作为包括结肠癌在内的多种癌症的溶瘤剂。尽管大多数研究都强调了激活的Ras信号在增强易感细胞中呼肠孤病毒溶瘤作用方面的作用，但我们注意到许多结肠癌中β-连环蛋白也有升高。因此，增强的β-连环蛋白可能会增加结肠癌细胞对呼肠孤病毒的敏感性。为了探究这一假设，用糖原合酶激酶（GSK）-3β抑制剂氯化锂处理人胚肾293（HEK293）细胞，从而诱导β-连环蛋白表达，随后进行呼肠孤病毒感染。与单独的呼肠孤病毒感染相比，联合使用氯化锂确实增强了细胞死亡，但这与呼肠孤病毒复制增加无关。同样，在Wnt3a条件培养基中表达卷曲蛋白-1受体的HEK293细胞的呼肠孤病毒复制水平也与对照培养基中的细胞相当，这进一步表明β-连环蛋白的上调并不会增强呼肠孤病毒的复制。相反，我们观察到用氯化锂抑制GSK-3β可降低呼肠孤病毒诱导的核因子κB（NF-κB）激活，通过激活半胱天冬酶8导致细胞凋亡加速。我们进一步发现，结肠癌细胞HCT116经呼肠孤病毒和GSK-3β抑制剂AR-A014418联合处理后对细胞凋亡更敏感。最后，我们确定抑制NF-κB可使HEK293或HCT 116细胞在呼肠孤病毒感染期间对细胞凋亡更敏感。综上所述，我们提出抑制GSK-3β可通过下调NF-κB活性使呼肠孤病毒诱导的结肠癌细胞凋亡更敏感，为结肠癌的治疗提供了一种潜在的改良治疗策略。
