Division of Translational and Clinical Oncology, Cancer Research Institute, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
Clin Cancer Res. 2009 Nov 15;15(22):6810-9. doi: 10.1158/1078-0432.CCR-09-0973. Epub 2009 Nov 10.
Glycogen synthase kinase-3beta (GSK3beta) regulates multiple cell signaling pathways and has been implicated in glucose intolerance, neurodegenerative disorders, and inflammation. We investigated the expression, activity, and putative pathologic role of GSK3beta in gastrointestinal, pancreatic, and liver cancers.
Colon, stomach, pancreatic, and liver cancer cell lines; nonneoplastic HEK293 cells; and matched pairs of normal and tumor tissues of stomach and colon cancer patients were examined for GSK3beta expression and its phosphorylation at serine 9 (inactive form) and tyrosine 216 (active form) by Western immunoblotting and for GSK3beta activity by in vitro kinase assay. The effects of small-molecule GSK3beta inhibitors and of RNA interference on cell survival, proliferation, and apoptosis were examined in vitro and on human colon cancer cell xenografts in athymic mice. The effects of GSK3beta inhibition on human telomerase reverse transcriptase (hTERT) expression and telomerase activity were compared between colon cancer and HEK293 cells.
Cancer cell lines and most cancer tissues showed increased GSK3beta expression and increased tyrosine 216 phosphorylation and activity but decreased serine 9 phosphorylation compared with HEK293 cells and nonneoplastic tissues. Inhibition of GSK3beta resulted in attenuated cell survival and proliferation and increased apoptosis in most cancer cell lines and in HT-29 xenografts in rodents but not in HEK293 cells. GSK3beta inhibition in colon cancer cells was associated with decreased hTERT expression and telomerase activity.
The results indicate that deregulated GSK3beta sustains gastrointestinal cancer cells survival through modulation of hTERT and telomerase.
糖原合酶激酶-3β（GSK3β）调节多种细胞信号通路，与葡萄糖耐量异常、神经退行性疾病和炎症有关。我们研究了 GSK3β在胃肠道、胰腺和肝癌中的表达、活性和潜在的病理作用。
通过 Western 免疫印迹检测结肠、胃、胰腺和肝癌细胞系；非肿瘤性 HEK293 细胞；以及胃和结肠癌患者的配对正常和肿瘤组织中 GSK3β的表达及其丝氨酸 9 位（无活性形式）和酪氨酸 216 位（活性形式）的磷酸化，并通过体外激酶测定检测 GSK3β的活性。在体外研究小分子 GSK3β抑制剂和 RNA 干扰对细胞存活、增殖和凋亡的影响，并在裸鼠中研究其对人结肠癌细胞异种移植物的影响。比较了 GSK3β抑制对结肠癌细胞和 HEK293 细胞中人类端粒酶逆转录酶（hTERT）表达和端粒酶活性的影响。
与 HEK293 细胞和非肿瘤组织相比，癌细胞系和大多数肿瘤组织中 GSK3β的表达增加，酪氨酸 216 的磷酸化和活性增加，但丝氨酸 9 的磷酸化减少。在大多数癌细胞系和 HT-29 异种移植瘤中，抑制 GSK3β导致细胞存活和增殖减少，凋亡增加，但在 HEK293 细胞中则不然。结肠癌细胞中 GSK3β的抑制与 hTERT 表达和端粒酶活性降低有关。
研究结果表明，失调的 GSK3β 通过调节 hTERT 和端粒酶维持胃肠道癌细胞的存活。
