Comparison of KRAS mutation status between primary tumor and metastasis in Chinese colorectal cancer patients.

Detection of KRAS mutation status is a routine clinical procedure for predicting response to anti-EGFR therapy in colorectal cancer (CRC) patients. Previous studies showed high concordance of KRAS mutation status in primary lesion and corresponding metastatic sites in CRC. However, the data were mostly from Caucasians. The aim of this study is to compare KRAS mutation and other molecules mutation status between primary tumor and corresponding metastatic lesion in Chinese patients with CRC. In this retrospective study, Chinese CRC patients with paired samples of primary tumor and metastatic site were detected for KRAS codon 12 and 13 with quantitative real-time PCR, or detected for OncoCarta™ panel of 19 genes with MassARRAY(®) technique, including KRAS, BRAF, NRAS and PIK3CA et al. Forty-eight paired CRC samples were analyzed for KRAS codon 12 and 13 using quantitative real-time PCR. Ten paired samples were analyzed by 19 genes OncoCarta™ Panel with MassARRAY(®) technique. KRAS mutation was found in 15 (25.9 %) primary tumors and 18 (31.0 %) metastases. The discordance of KRAS was observed in 11 (19.0 %) patients. Alteration of mutation points in primary site with mutant KRAS was not observed. In the 10 patients with multiple gene detection, PIK3CA mutation showed concordant mutation status in primary tumor and metastatic site, whereas discordance in BRAF, NRAS and AKT1 was detected. A concordance rate of 81.0 % was detected in KRAS mutation between primary tumor and metastatic lesion in Chinese patients with CRC. Discordance of BRAF, NRAS and AKT1 mutation status in primary tumor and metastases was observed.

Melatonin overcomes gemcitabine resistance in pancreatic ductal adenocarcinoma by abrogating nuclear factor-κB activation.

Constitutive activation and gemcitabine induction of nuclear factor-κB (NF-κB) contribute to the aggressive behavior and chemotherapeutic resistance of pancreatic ductal adenocarcinoma (PDAC). Thus, targeting the NF-κB pathway has proven an insurmountable challenge for PDAC therapy. In this study, we investigated whether the inhibition of NF-κB signaling pathway by melatonin might lead to tumor suppression and overcome gemcitabine resistance in pancreatic tumors. Our results showed that melatonin inhibited activities of NF-κB by suppressing IκBα phosphorylation and decreased the expression of NF-κB response genes in MiaPaCa-2, AsPc-1, Panc-28 cells and gemcitabine resistance MiaPaCa-2/GR cells. Moreover, melatonin not only inhibited cell proliferation and invasion in a receptor-independent manner, but also enhanced gemcitabine cytotoxicity at pharmacologic concentrations in these PDAC cells. In vivo, the mice treated with both agents experienced a larger reduction in tumor burden than the single drug-treated groups in an orthotopic xenograft mouse model. Taken together, these results indicate that melatonin inhibits proliferation and invasion of PDAC cells and overcomes gemcitabine resistance of pancreatic tumors through NF-κB inhibition. Our findings therefore provide novel preclinical knowledge about melatonin inhibition of NF-κB in PDAC and suggest that melatonin should be investigated clinically, alone or in combination with gemcitabine for PDAC treatment.