Predictive and prognostic implications of 4E-BP1, Beclin-1, and LC3for cetuximab treatment combined with chemotherapy in advanced colorectal cancer with wild-type KRAS: Analysis from real-world data

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.

Activation of mammalian target of rapamycin contributes to pain nociception induced in rats by BmK I, a sodium channel-specific modulator

The mammalian target of rapamycin （mTOR） pathway is essential for maintenance of the sensitivity of certain adult sensory neurons. Here, we investigated whether the mTOR cascade is involved in scorpion envenomation-induced pain hypersensitivity in rats. The results showed that intraplantar injection of a neurotoxin from Buthus martensii Karsch, BmK I （10 pg）, induced the activation of mTOR, as well as its downstream molecules p70 ribosomal S6 protein kinase （p70 S6K） and eukaryotic initiation factor 4E-binding protein 1 （4E-BP1）, in lumbar 5-6 dorsal root ganglia neurons on both sides in rats. The activation peaked at 2 h and recovered 1 day after injection. Compared with the control group, the ratios of p-mTOR/p-p70 S6K/p-4E- BP1 in three types of neurons changed significantly. The cell typology of p-mTOR/p-p70 S6K/p-4E-BP1 immuno-reactive neurons also changed. Intrathecal administration of deforolimus, a specific inhibitor of mTOR, attenuated BmK I-induced pain responses （spontaneous flinching, paroxysmal pain-like behavior, and mechanical hypersensitivity）. Together, these results imply that the mTOR signaling pathway is mobilized by and contributes to experimental scorpion sting-induced pain.