ING4 is negatively correlated with microvessel density in colon cancer

ING4 is a novel tumor suppressor which is downregulated in a number of cancers. In this study, we investigated the role of ING4 in tumor angiogenesis in colorectal carcinoma (CRC) patients. Semi-quantitative RT-PCR, western blots, and immunohistochemistry were used to determine ING4 mRNA and protein expression in CRC and normal tissue from 60 CRC specimens and 30 colonic adenoma specimens. The correlation between ING4 expression and clinical stage, histological grade as well as lymph node metastasis was evaluated. Immunohistochemistry was performed to explore the correlation between ING4 expression and microvessel density (MVD) in CRC. CRC tissue had significantly lower levels of ING4 mRNA and protein compared to colonic adenoma and normal intestinal tissue. Immunostaining showed ING4 expression in 38 (63.3 %), 30 (100 %), and 60 (100 %) cases of normal colonic mucosa, adenoma, and normal intestinal mucosal tissue, respectively. Lower ING4 levels correlated with higher clinical stage and histological grade. ING4 mRNA and protein levels were significantly lower in CRC patients with lymph node metastasis compared to patients without lymph node metastasis (0.41 +/- 0.30 vs. 0.91 +/- 0.29 and 0.60 +/- 0.21 vs. 0.87 +/- 0.27, respectively; p < 0.001). Importantly, ING4 mRNA and protein levels were negatively correlated with MVD in CRC patients (p < 0.001). Our data suggest that ING4 levels are a potential biomarker of CRC progression and that ING4 may inhibit tumor growth by modulating angiogenesis in CRC.