Overexpression of NDUFA4L2 is associated with poor prognosis in patients with colorectal cancer

Background NDUFA4L2 (NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 4-like 2, also called NADH-ubiquinone oxidoreductase MLRQ subunit homologue) was clearly enriched in the mitochondrial fraction under hypoxic conditions, and immunofluorescence showed a clear colocalization of NDUFA4L2 and cytochrome c in some tumour cells. However, little study has investigated its prognostic value in colorectal cancer (CRC). MethodsIn our study, mRNA-NDUFA4L2 and protein expression were analysed in 150 cases of CRC and adjacent normal tissues using immunohistochemistry, semi-quantitative reverse transcriptase-polymerase chain reaction. The correlation between NDUFA4L2 expression and clinicopathological factors was evaluated by the Chi-square test. Overall survival of patients was analysed by the Kaplan-Meier method. Results NDUFA4L2 overexpression was observed in 84% (126/150) of CRC tissues, but only in 24.7% (37/150) of adjacent normal tissues (P<0.05). Semi-quantitative reverse transcriptase-polymerase chain reaction showed average mRNA expression levels to be 23.341.356 and 4.34 +/- 1.132 for CRC tissue and adjacent normal tissue (P<0.05). Statistical analysis showed a significant correlation of NDUFA4L2 expression with histological grade, Dukes' stages, lymph node metastasis and liver metastasis. More importantly, multivariate analysis indicated that overexpression of NDUFA4L2 was an independent prognostic factor for CRC patients (P=0.002). NDUFA4L2-negative patients had a higher tumour-free/overall survival rate than patients with high NDUFA4L2 expression (P=0.001 and 0.002, respectively). Conclusions Our data suggest that NDUFA4L2 overexpression is associated with tumour progression and a poor prognosis in CRC patients.