Research

Microsatellite instability at a tetranucleotide repeat in type I endometrial carcinoma

Yoo Duk Choi¹ , Jin Choi² , Jo Heon Kim¹ , Ji Shin Lee¹ , Jae Hyuk Lee^1,3 , Chan Choi^1,3 , Ho Sun Choi² , Min Cheol Lee^1,3 , Chang Soo Park^1,3 , Sang Woo Juhng¹ and Jong Hee Nam^1,3

¹  Department of Pathology, Chonnam National University Medical School, Gwangju, Republic of Korea

²  Department of Obstetric and Gynecology, Chonnam National University Medical School, Gwangju, Republic of Korea

³  Brain Korea 21 Project, Center for Biomedical Human Resources at Chonnam National University, Gwangju, Republic of Korea

author email corresponding author email

Journal of Experimental & Clinical Cancer Research 2008, 27:88doi:10.1186/1756-9966-27-88

Published:	31 December 2008

Abstract

Background

Microsatellite instability (MSI) at tri- or tetranucleotide repeat markers (elevated microsatellite alterations at selected tetranucleotide repeat, EMAST) has been recently described. But, the underlying genetic mechanism of EMAST is unclear. This study was to investigate the prevalence of EMAST, in type I endometrial carcinoma, and to determine the correlation between the MSI status and mismatch repair genes (MMR) or p53.

Methods

We examined the 3 mono-, 3 di-, and 6 tetranucleotide repeat markers by PCR in 39 cases of type I endometrial carcinoma and performed the immunohistochemistry of hMSH2, hMLH1, and p53 protein.

Results

More than two MSI at mono- and dinucleotide repeat markers was noted in 8 cases (MSI-H, 20.5%). MSI, at a tetranucleotide repeat, was detected in 15 cases (EMAST, 38.5%). In remaining 16 cases, any MSI was not observed. (MSS, 42.1%), MSI status was not associated with FIGO stage, grade or depth of invasion. The absence of expression of either one of both hMSH2 or hMLH1 was noted in seven (87.5%) of eight MSI-H tumors, one (6.3%) of 16 MSS tumors, and five (33.3%) of 15 EMAST tumors. (p = 0.010) The expression of p53 protein was found in one (12.5%) of eight MSI-H tumors, five (31.3%) of 16 MSS tumors, and seven of 15 EMAST tumors. (p = 0.247)

Conclusion

Our results showed that about 38.5% of type I endometrial carcinomas exhibited EMAST, and that EMAST was rarely associated with alteration of hMSH2 or hMLH1.