Centre for Digestive Diseases, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark St, Whitechapel, London, UK.
Exp Mol Pathol. 2013 Feb;94(1):103-8. doi: 10.1016/j.yexmp.2012.09.001. Epub 2012 Sep 12.
Colorectal adenomas display features of senescence, but these are often lost upon progression to carcinoma, indicating that oncogene induced senescence (OIS) could be a roadblock in colorectal cancer (CRC) development. Heat shock proteins (HSPs) have been implicated in the prognosis of CRC and HSP based therapy is a current interest for drug development. Recent cell culture studies have suggested that in the absence of a TP53 mutation, OIS mediated by PI3K/AKT activation can be circumvented by high expression of HSPs. Furthermore, while PI3K/AKT activation and KRAS mutations are independent inducers of OIS, PI3K/AKT activation can suppress KRAS-induced OIS when both are present in cultured cells. As KRAS mutations, PI3K/AKT activation and TP53 mutations are all common features of CRC, it is possible that the requirement for HSP to inhibit OIS in CRC is dependent on the mutation spectrum of a tumour. However, work on HSP that utilised mutation profiled human tumour tissues has been limited. Here, we characterised the expression of two major HSP proteins (HSP27 and 72) by immunohistochemistry (IHC), the mutation status of TP53, KRAS and PIK3CA genes by direct sequencing and the activation status of AKT by IHC in a cohort of unselected primary CRC (n=74). We compare our data with findings generated from cell-based studies. Expression of HSP27 and HSP72 was correlated to clinicopathological and survival data but no significant association was found. We also established the mutation status of TP53, KRAS and PIK3CA genes and the activation status of AKT in our CRC panel. We did not detect any associations between HSP27 or HSP72 expression with TP53 mutation status. However, HSP27 expression in CRCs was strongly associated with the co-presence of wildtype KRAS and activated PI3K/AKT (p=0.004), indicating a possible role of HSP27 in overcoming PI3K/AKT induced OIS in tumours. Our studies suggest a role for using archival tissues in validating hypotheses generated from cell culture based investigations.
结直肠腺瘤具有衰老的特征，但在进展为癌时这些特征往往会丢失，这表明癌基因诱导的衰老（OIS）可能是结直肠癌（CRC）发展的障碍。热休克蛋白（HSPs）已被牵涉到 CRC 的预后中，并且基于 HSP 的治疗是药物开发的当前热点。最近的细胞培养研究表明，在不存在 TP53 突变的情况下，通过高水平表达 HSP 可以绕过由 PI3K/AKT 激活介导的 OIS。此外，虽然 PI3K/AKT 激活和 KRAS 突变是 OIS 的独立诱导因素，但在培养细胞中同时存在这两种因素时，PI3K/AKT 激活可以抑制 KRAS 诱导的 OIS。由于 KRAS 突变、PI3K/AKT 激活和 TP53 突变都是 CRC 的常见特征，因此，抑制 CRC 中 OIS 所需的 HSP 可能依赖于肿瘤的突变谱。然而，利用突变谱分析人类肿瘤组织的 HSP 研究工作受到了限制。在这里，我们通过免疫组织化学（IHC）检测了两种主要 HSP 蛋白（HSP27 和 72）的表达，通过直接测序检测了 TP53、KRAS 和 PIK3CA 基因的突变状态，通过 IHC 检测了 AKT 的激活状态，在一组未经选择的原发性 CRC（n=74）中进行了分析。我们将我们的数据与基于细胞的研究产生的结果进行了比较。HSP27 和 HSP72 的表达与临床病理和生存数据相关，但未发现显著相关性。我们还确定了我们 CRC 组中 TP53、KRAS 和 PIK3CA 基因的突变状态以及 AKT 的激活状态。我们没有检测到 HSP27 或 HSP72 表达与 TP53 突变状态之间的任何关联。然而，CRC 中 HSP27 的表达与野生型 KRAS 和激活的 PI3K/AKT 的共存密切相关（p=0.004），这表明 HSP27 在克服肿瘤中 PI3K/AKT 诱导的 OIS 中可能发挥作用。我们的研究表明，使用存档组织在验证基于细胞培养的研究产生的假设方面具有作用。
