University of Turku, Department of Ophthalmology, Turku, Finland.
Anticancer Res. 2010 Oct;30(10):3995-9.
Rb functions as a key controller of the G(1)-S transition of the cell cycle, and its inactivation leads to a defective G(1) checkpoint. Bladder cancer frequently displays alterations in Rb such as constitutive hyperphosphorylation which results in inactive Rb and progression of cells to the S-phase. Several protein kinase C (PKC) inhibitors are currently undergoing clinical trials as anticancer drugs.
T24 urinary bladder carcinoma cells, known to express hyperphosphorylated Rb, were treated with PKCα/βI inhibitor Go6976. The treated cells were subjected to cell cycle analysis, cell growth assay and Western blots for Rb and cdc2 phosphorylation.
The treatment resulted in Rb dephosphorylation at Ser 795 and Ser 807/811, and cdc2 dephosphorylation at Tyr15. Subsequent G(0/1) arrest and reduced proliferation rates were observed.
The results show that Go6976 can be used to restore constantly hyperphosphorylated and therefore constantly inactive Rb function in cancer cells.
Rb 作为细胞周期 G(1)-S 转换的关键控制器，其失活导致 G(1)检验点缺陷。膀胱癌经常显示 Rb 的改变，如组成性过度磷酸化，导致失活的 Rb 和细胞进入 S 期的进展。几种蛋白激酶 C（PKC）抑制剂目前正在作为抗癌药物进行临床试验。
已知表达高磷酸化 Rb 的 T24 膀胱癌细胞用 PKCα/βI 抑制剂 Go6976 处理。用细胞周期分析、细胞生长测定和 Rb 和 cdc2 磷酸化的 Western blot 对处理过的细胞进行分析。
治疗导致 Rb 在 Ser 795 和 Ser 807/811 去磷酸化，cdc2 在 Tyr15 去磷酸化。随后观察到 G(0/1) 期阻滞和增殖率降低。
结果表明，Go6976 可用于恢复癌细胞中持续高磷酸化且因此持续失活的 Rb 功能。
