BACKGROUND Colorectal cancer(CRC) is one of the main causes of cancer-related deaths in China and around the world. Advanced CRC(ACRC) patients suffer from a low cure rate though treated with targeted therapies. The r...BACKGROUND Colorectal cancer(CRC) is one of the main causes of cancer-related deaths in China and around the world. Advanced CRC(ACRC) patients suffer from a low cure rate though treated with targeted therapies. The response rate is about 50% to chemotherapy and cetuximab, a monoclonal antibody targeting epidermal growth factor receptor(EGFR) and used for ACRC with wild-type KRAS. It is important to identify more predictors of cetuximab efficacy to further improve precise treatment. Autophagy, showing a key role in the cancer progression, is influenced by the EGFR pathway. Whether autophagy can predict cetuximab efficacy in ACRC is an interesting topic.AIM To investigate the effect of autophagy on the efficacy of cetuximab in colon cancer cells and ACRC patients with wild-type KRAS.METHODS ACRC patients treated with cetuximab plus chemotherapy, with detailed data and tumor tissue, at Sun Yat-sen University Cancer Center from January 1, 2005,to October 1, 2015, were studied. Expression of autophagy-related proteins[Beclin1, microtubule-associated protein 1 A/B-light chain 3(LC3), and 4 Ebinding protein 1(4 E-BP1)] was examined by Western blot in CRC cells and by immunohistochemistry in cancerous and normal tissues. The effect of autophagy on cetuximab-treated cancer cells was confirmed by MTT assay. The associations between Beclin1, LC3, and 4 E-BP1 expression in tumor tissue and the efficacy of cetuximab-based therapy were analyzed.RESULTS In CACO-2 cells exposed to cetuximab, LC3 and 4 E-BP1 were upregulated, and P62 was downregulated. Autophagosome formation was observed, and autophagy increased the efficacy of cetuximab. In 68 ACRC patients,immunohistochemistry showed that Beclin1 levels were significantly correlated with those of LC3(0.657, P < 0.001) and 4 E-BP1(0.211, P = 0.042) in ACRC tissues.LC3 was significantly overexpressed in tumor tissues compared to normal tissues(P < 0.001). In 45 patients with wild-type KRAS, the expression levels of these three proteins were not related to progression-free survival; however, the expression levels of Beclin1(P = 0.010) and 4 E-BP1(P = 0.005), pathological grade(P = 0.002), and T stage(P = 0.004) were independent prognostic factors for overall survival(OS).CONCLUSION The effect of cetuximab on colon cancer cells might be improved by autophagy.LC3 is overexpressed in tumor tissues, and Beclin1 and 4 E-BP1 could be significant predictors of OS in ACRC patients treated with cetuximab.展开更多
文摘BACKGROUND Colorectal cancer(CRC) is one of the main causes of cancer-related deaths in China and around the world. Advanced CRC(ACRC) patients suffer from a low cure rate though treated with targeted therapies. The response rate is about 50% to chemotherapy and cetuximab, a monoclonal antibody targeting epidermal growth factor receptor(EGFR) and used for ACRC with wild-type KRAS. It is important to identify more predictors of cetuximab efficacy to further improve precise treatment. Autophagy, showing a key role in the cancer progression, is influenced by the EGFR pathway. Whether autophagy can predict cetuximab efficacy in ACRC is an interesting topic.AIM To investigate the effect of autophagy on the efficacy of cetuximab in colon cancer cells and ACRC patients with wild-type KRAS.METHODS ACRC patients treated with cetuximab plus chemotherapy, with detailed data and tumor tissue, at Sun Yat-sen University Cancer Center from January 1, 2005,to October 1, 2015, were studied. Expression of autophagy-related proteins[Beclin1, microtubule-associated protein 1 A/B-light chain 3(LC3), and 4 Ebinding protein 1(4 E-BP1)] was examined by Western blot in CRC cells and by immunohistochemistry in cancerous and normal tissues. The effect of autophagy on cetuximab-treated cancer cells was confirmed by MTT assay. The associations between Beclin1, LC3, and 4 E-BP1 expression in tumor tissue and the efficacy of cetuximab-based therapy were analyzed.RESULTS In CACO-2 cells exposed to cetuximab, LC3 and 4 E-BP1 were upregulated, and P62 was downregulated. Autophagosome formation was observed, and autophagy increased the efficacy of cetuximab. In 68 ACRC patients,immunohistochemistry showed that Beclin1 levels were significantly correlated with those of LC3(0.657, P < 0.001) and 4 E-BP1(0.211, P = 0.042) in ACRC tissues.LC3 was significantly overexpressed in tumor tissues compared to normal tissues(P < 0.001). In 45 patients with wild-type KRAS, the expression levels of these three proteins were not related to progression-free survival; however, the expression levels of Beclin1(P = 0.010) and 4 E-BP1(P = 0.005), pathological grade(P = 0.002), and T stage(P = 0.004) were independent prognostic factors for overall survival(OS).CONCLUSION The effect of cetuximab on colon cancer cells might be improved by autophagy.LC3 is overexpressed in tumor tissues, and Beclin1 and 4 E-BP1 could be significant predictors of OS in ACRC patients treated with cetuximab.
