The relationship between MSI status and vessel density in colorectal carcinoma.

The development of new blood vessels is a prerequisite for progression of malignant neoplasms. Factors that induce neoangiogenesis include VEGF, VEGF-C, VEGF-D, PD-ECG, ANG-2, TSP-1, HIF-1 and HIF-2. From the etiopathogenetic viewpoint, colorectal carcinoma is heterogenic. It may develop via a sequence of mutations leading to chromosome instability or else result from DNA repair defects, which are manifested as microsatellite instability. The objective of the present investigations was the comparison of neoangiogenesis in microsatellite-stable colorectal carcinomas, as well as in tumors with low and high instability levels. The material included 71 surgical cases of colorectal carcinoma. Vessel density was assessed by immunohistochemical reactions to CD34 and vWf, calculating the number of vessel sections within the invasion margin, in visual fields selected at random, and within hot spots. Microsatellite instability was evaluated in frozen materials employing the PCR reaction with gel and capillary electrophoresis. In all the cases, the authors detected CD34+ and less numerous vWf+ vessels within the tumor and in its vicinity. In 45 cases, no microsatellite instability was found, in 13 cases, low level instability (MSI-L) was observed, and in another 13 - high microsatellite instability (MSI-H). Some differences in vessel density were noted between the above groups, yet they were not statistically significant. On the other hand, the authors observed more numerous CD34+ vessels in cases with metastases to the regional lymph nodes. In conclusion, it is suggested that neoangiogenesis in sporadic colorectal carcinoma is directly related to metastatic potential, but not to MSI status.