Department of Cancer Studies and Molecular Medicine, Biocentre, University of Leicester, UK.
Curr Cancer Drug Targets. 2013 Jan;13(1):57-68.
Effective treatments to prevent recurrence or progression of non-muscle-invasive bladder cancer, or to inhibit metastasis of muscle-invasive forms of the disease, would deliver significant patient benefit. Here the involvement of STAT signalling and the chemopreventive potential of diindolylmethane (DIM) in human bladder cancer were investigated. Muscle-invasive bladder cancer tissues were characterised by nuclear expression of phosphorylated STAT1, 3 and 5. In E-cadherin positive tumour cell lines (RT112, RT4, HT1376), STAT5 was constitutively phosphorylated, while E-cadherin negative lines (J82, T24, UMUC3) contained phosphoSTAT3. Knockdown of STAT3 induced G₀/G₁ arrest and inhibited adhesion in J82 cells. Knockdown of STAT1inhibited migration in J82 and RT112 lines. No significant increase in apoptosis was observed. In response to the Janus kinase inhibitor, AG490, RT112 and J82 cells initially underwent G₀/G₁ arrest, with RT112 cells subsequently exhibiting S phase arrest. Phosphorylation of STAT1(Tyr701), STAT3(Tyr705) and (Ser727) and STAT5(Tyr694) was inhibited by DIM, as was adhesion of J82 cells to collagen, an effect that was enhanced when STAT1 or 3 was reduced by siRNA. However, over-expression of STAT3C partially rescued the DIM inhibitory effect on collagen-mediated adhesion. Migration of both lines was inhibited by DIM, while transfection of constitutively active STAT3C enhanced migration of RT112 cells. DIM induced cell cycle arrest and apoptosis in three cell lines with different degrees of radioresistance. Taken together, these results suggest that inhibition of STAT signalling and/or treatment with DIM may decrease invasiveness of bladder cancer. DIM can induce apoptosis in cell lines which are radioresistant, so in combination with radiotherapy may be useful in overcoming such resistance.
有效治疗非肌肉浸润性膀胱癌的复发或进展，或抑制肌肉浸润性膀胱癌的转移，将为患者带来显著获益。本研究旨在探讨 STAT 信号通路在人膀胱癌中的作用以及二吲哚甲烷（DIM）的化学预防作用。在具有核磷酸化 STAT1、3 和 5 表达的肌肉浸润性膀胱癌组织中，发现了 STAT 信号通路的参与。在 E-钙黏蛋白阳性肿瘤细胞系（RT112、RT4、HT1376）中，STAT5 持续磷酸化，而在 E-钙黏蛋白阴性细胞系（J82、T24、UMUC3）中存在磷酸化 STAT3。STAT3 的敲低诱导 J82 细胞发生 G0/G1 期阻滞并抑制黏附。STAT1 的敲低抑制了 J82 和 RT112 细胞的迁移。未观察到明显的细胞凋亡增加。在 Janus 激酶抑制剂 AG490 的作用下，RT112 和 J82 细胞最初经历 G0/G1 期阻滞，随后 RT112 细胞出现 S 期阻滞。DIM 抑制了 STAT1（Tyr701）、STAT3（Tyr705 和 Ser727）和 STAT5（Tyr694）的磷酸化，同时还抑制了 J82 细胞与胶原蛋白的黏附，当 STAT1 或 3 被 siRNA 降低时，这种作用增强。然而，STAT3C 的过表达部分挽救了 DIM 对胶原介导的黏附的抑制作用。DIM 抑制了两条细胞系的迁移，而组成性激活 STAT3C 增强了 RT112 细胞的迁移。DIM 诱导三种不同放射抗性的细胞系发生细胞周期阻滞和凋亡。综上所述，这些结果表明抑制 STAT 信号通路和/或 DIM 治疗可能会降低膀胱癌的侵袭性。DIM 可诱导放射抗性细胞系发生细胞凋亡，因此与放射治疗联合使用可能有助于克服这种耐药性。
