Malignancies of the uterine corpus and immunoreactivity score of the DNA "mismatch-repair" enzyme human Mut-S-homologon-2.
We analyzed human Mut-S-Homologon-2 expression in normal endometrial tissue (n = 15) and malignancies of the uterine corpus (n = 40). Human Mut-S-Homologon-2 protein was investigated immunohistochemically on frozen sections, using a highly sensitive streptavidin-peroxidase technique and a specific mouse monoclonal antibody (clone FE11). Human Mut-S-Homologon-2 labeling pattern was compared with the staining pattern of the proliferation marker Ki-67 in the same tumors. A human Mut-S-Homologon-2 immunoreactivity score (human Mut-S-Homologon-2-IRS: negative 0-1; weak 2-3; moderate 4-6; strong 8-12) for semiquantitative analysis of human Mut-S-Homologon-2 expression is presented. In normal endometrial tissue samples we found weak nuclear immunoreactivity for human Mut-S-Homologon-2 in 67%, whereas the remaining 33% were negative for human Mut-S-Homologon-2 (mean human Mut-S-Homologon-2-IRS 1.25 +/- 1.29). All malignancies of the uterine corpus analyzed revealed moderate to strong nuclear immunoreactivity (mean human Mut-S-Homologon-2-IRS 9.00, +/- 3.16). Human Mut-S-Homologon-2 staining was heterogeneous, with visual differences among individual tumor cells. Expression of human Mut-S-Homologon-2 protein was consistently and strongly upregulated in tumor cells of malignancies of the uterine corpus compared with normal endometrial tissue (human Mut-S-Homologon-2-PP p<0.001; human Mut-S-Homologon-2-IS p<0.001; human Mut-S-Homologon-2-IRS p<0.001). No statistically significant correlation in comparing the labeling patterns for human Mut-S-Homologon-2 with the labeling patterns for Ki-67 (mean percentage of Ki-67-positive tumor cells 22.00% +/- 17.20) was observed in malignancies of the uterine corpus (human Mut-S-Homologon-2-PP p=0.443; human Mut-S-Homologon-2-IS p=0.234; human Mut-S-Homologon-2-IRS p=0.173). Our findings indicate that human Mut-S-Homologon-2 is expressed in normal human endometrial tissue and that expression of human Mut-S-Homologon-2 may be of importance for the genetic stability of malignancies of the uterine corpus in vivo. (J Histochem Cytochem 47:113-118, 1999).
Friedrich
M
M
Departments of Obstetrics and Gynecology, Universität des Saarlandes, Homburg/Saar, Germany.
Villena-Heinsen
C
C
Reitnauer
K
K
Schmidt
W
W
Tilgen
W
W
Reichrath
J
J
D020137:Base Pair Mismatch; D004260:DNA Repair; D004268:DNA-Binding Proteins; D004717:Endometrium / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D051718:MutS Homolog 2 Protein; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D014594:Uterine Neoplasms / Q000378:metabolism*
D004268:DNA-Binding Proteins; D019394:Ki-67 Antigen; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein