Role of IGFBP4 and IGF-I expression in esophageal squamous cell carcinoma

The purpose of this research is to determine the correlation between IGFBP-4/IGF-I expression and the clinical status of esophageal squamous cell carcinoma (ESCC). Immunohistochemical staining for IGFBP-4 and IGF-I was performed in 61 clinical samples. The correlation between IGFBP-4/IGF-I staining and clinicopathological features was examined statistically. In addition, we compared the mRNA expression levels of IGFBP-4 and IGF-I between ESCC cancer tissues and the normal esophageal epithelium using a quantitative real-time RT-PCR. According to the results of immunohistochemical staining, IGFBP-4 expression in the region of normal epithelial cells showed an increase of 52.5 % compared to expression in the tumor cells. There was no statistically significant correlation between IGFBP-4/IGF-I and clinicopathological features. The correlation between IGF-I and IGFBP-4 was not significant either. RT-PCR assay showed IGF-I expression in ESCC tissue has a tendency to be higher than that of normal esophageal epithelium. On the other hand, IGFBP-4 expression levels in cancer tissue were lower in comparison with normal epithelium. These results were not significant. There were the differences of IGFBP-4 expression between the region of ESCC and the region of normal epithelium cells. One suggested possibility is that IGF-independent action of IGFBP-4 might have taken part in these results. We need further exploratory experiments to elucidate the details of the actual function of IGFBP-4 expression in ESCC.