KRAS mutation and NF-κB activation indicates tolerance of chemotherapy and poor prognosis in colorectal cancer.

BACKGROUND: Evidence shows a strong relationship between KRAS mutations and the NF-κB signaling pathway. In colorectal cancer, however, the study of this subject has been very limited and results are inconsistent. AIMS: To examine the relationship between KRAS mutations and NF-κB activation and their effect on chemotherapy response and survival of colorectal cancer patients. MATERIALS AND METHODS: NF-κB activation was analyzed by immunohistochemistry in 167 primary colorectal cancer specimens in which the KRAS mutation status was confirmed. Clinical and pathologic data were extracted from the medical records and reviewed. RESULTS: Of 167 tumors screened, 63 (37.7 %) had NF-κB activation, 59 (35.3 %) had KRAS mutations, and 30 (18.0 %) had both NF-κB activation and KRAS mutations. The frequency of NF-κB activation in tumors with KRAS mutations was significantly higher than in tumors with wild type KRAS; 50.8 versus 30.6 %, P = 0.012. Patients with both KRAS mutations and NF-κB activation had a lower objective response to first-line chemotherapy than patients with other tumors, 23.8 versus 49.4 % (P = 0.035). Compared to patients with both KRAS mutations and NF-κB activation, overall survival of patients in other groups was significantly higher; median overall survival was 28.4 months (95 % CI 21.0-35.8) versus 46.3 months (95 % CI 39.4-53.2), hazard ratio 0.259 (95 % CI 0.125-0.538), P = 0.005. CONCLUSIONS: NF-κB activation was associated with KRAS mutation, and both KRAS mutation and NF-κB activation were indicative of high tolerance of chemotherapy and poor prognosis for colorectal cancer patients. Tumors with KRAS mutations and NF-κB activation may be a unique subtype of colorectal cancer.