Functional characterization of the nitrogen permease regulator-like-2 candidate tumor suppressor gene in colorectal cancer cell lines

The nitrogen permease regulator-like-2 (NPRL2) gene is a candidate tumor suppressor gene, which has been identified in the 3p21.3 human chromosome region. Decreased expression levels of NPRL2 have been observed in colorectal cancer (CRC) tissues, however, the function of NPRL2 in CRC progression remains to be fully elucidated. The present study investigated the biological characteristics of the HCT116 and HT29 CRC cell lines overexpressing exogenous NPRL2. NPRL2 recombinant lentiviral vectors were also constructed and transfected in the present study. Cell growth was determined using a Cell Counting Kit-8 assay and a colony formation assay. The cell cycle and rate of apoptosis were assessed using flow cytometric analysis. Transwell assays were used to evaluate cell invasion. The protein expression of phosphorylated (p)-AKT and caspase 3, B-cell lymphoma 2 (Bcl2) and Bcl-2-associated X protein apoptosis-associated genes, were detected using western blotting. The results revealed that NPRL2 overexpression inhibited cell growth, induced cell cycle G(1) phase arrest, promoted apoptosis and inhibited invasion in the two human CRC cell lines. Furthermore, the protein expression levels of p-AKT and Bcl2 were significantly reduced in the NPRL2-transfected HCT116 and HT29 cells, compared with the mock-transfected group and control group, while the protein expression of caspase-3 was increased. Therefore, NPRL2 acted as a functional tumor suppressor in the CRC cell lines.