Decreased expression of ING2 gene and its clinicopathological significance in Chinese NSCLC patients.

The inhibitor of growth 2 (ING2) is a member of ING family, involved in cell cycle regulation, DNA repair, apoptosis and senescence, and participating in chromatin remodeling and transcriptional regulation by histone modification. Recent researches suggest ING2 plays roles in carcinogenesis both as tumor suppressor gene and ongocene depending on tumor types and cell status. Here, we investigated the status of ING2 in a series of 64 Chinese non-small cell lung cancer (NSCLC) patients using immunohistochemistry (IHC) and confirmed the results with Western blotting. RT-PCR results revealed the expression level of ING2 was consistent with mRNA level. The IHC results showed that ING2 protein expression was significantly decreased in NSCLC samples compared with normal lung tissues (P<0.05). ING2 expression was lost in 32.8% (21/64) NSCLC tissues, which was more frequently in adenocarcinoma (ADK) than in squamous cell carcinoma (SCC), 45.8% (11/24) and 26.3% (10/38), respectively. We also found ING2 translocation from the nucleus to the cytoplasm, which may be a critical event for carcinogenesis. And the status of ING2 in SCC was significantly associated with lymph node metastasis status and TNM stage. After sequencing ING2 gene, we found no heterozygosity or mutation. Taken together, these results indicated that the aberrantly expression of ING2 may contribute to NSCLC tumorigenesis.