Treatment resistance of rectal cancers: identification and functional validation of novel therapeutic targets

我们最近证实，基因表达谱可能有助于预测直肠癌对术前放化疗(CT/RT)的反应。根据T水平的缩小，54个基因在应答者和无应答者之间的表达水平有显著差异。虽然子项目1的主要目标是在更大的患者群中前瞻性地验证该基因集，但本子项目的目标是通过改变这些基因在癌细胞系中的表达水平来从功能上验证这些基因。因此，我们将筛选已建立的CRC(结直肠癌)细胞系，以识别那些在耐药原发肿瘤中上调基因表达水平高的细胞系。功能验证将通过RNA干扰介导的基因敲除和评估这种基因敲除相对于CT/RT暴露的后果进行。这些实验将通过建立反应性和耐受性直肠腺癌的细胞系来支持。我们预计，这一功能验证过程将揭示CT/RT耐药的相关途径。这将是朝着识别修改这些途径的小分子迈出的第一步，从而使先天耐药细胞系，最终原发肿瘤，可以在体外对CT/RT敏感。

We recently demonstrated that gene expression profiling might be useful for predicting the response of rectal carcinomas to preoperative chemoradiotherapy (CT/RT). Based on T-level downsizing, 54 genes showed significantly different expression levels between responders and nonresponders. While a major objective of subproject 1 is to prospectively validate this gene set in a much larger cohort of patients, the present subproject aims to functionally validate these genes by modifying their expression levels in cancer cell lines. We will therefore screen established CRC (colorectal cancer) cell lines to identify those cell lines with high expression levels for genes which were upregulated in resistant primary tumors. The functional validation will be pursued by RNA interference-mediated knockdown and assessment of the consequences of this knockdown relative to exposure to CT/RT. These experiments will be supported by establishing cell lines from responsive and resistant rectal adenocarcinomas. We anticipate that this process of functional validation will unveil relevant pathways for resistance to CT/RT. This would be a first step toward identifying small molecules that modify these pathways such that a priori resistant cell lines, and eventually primary tumors, could be sensitized to CT/RT in vitro.