Relationship between Expression of Anaphase-promoting Complex and Prognostic Factors in Invasive Ductal Carcinoma of Breast

Abstract

Background: The role of the anaphase-promoting complex (APC) is to promote the degradation of mitotic cyclins and other substrates involved in sister chromatid adhesions. The APC appears to be responsible for the degradation of cyclin B and may have a potential role in the loss of control concerning cell proliferation in mammalian cells. However, a direct link between the defects in the APC components and oncogenesis has not been estabilished. This study investigates the relationship between APC expression and variable prognostic factors in invasive ductal carcinoma of the breast.

Methods: We evaluated 108 cases of invasive ductal carcinoma surgically resected from January, 1996 to May, 2000 at Wonju Christian Hospital, Wonju College of Medicine, Yonsei University. Immunohistochemical stains for APC, estrogen receptor, and Ki-67 were done in paraffin sections using the avidin-biotin complex method. The results were compared with clinical and pathologic parameters and flow cytometric DNA analysis factors.

Results: Forty cases (37.0%) showed immunopositive reactions for APC. The APC positivity in histologic grades 1, 2, and 3 were 28 cases (84.4%), 33 cases (60.0%), and 7 cases (35.0%), respectively (p=0.0011). The APC expressions in cases with the number of mitosis of less than 10, 10-19, and more than 20 per 10 high power fields, were noted in 37 cases (75.5%), 26 cases (63.4%), and 5 cases (27.8%), respectively (p=0.0016). The mean value of the Ki-67 labeling index was 221.7 in the APC-positive group and 317.9 in the APC-negative group (p= 0.0091). DNA flow cytometric analysis revealed higher APC expressions in cases with diploid patterns (p=0.0095). The APC expression rate increased significantly with decreasing histologic grade, with decreasing mitotic activity, in cases with a low Ki-67 labeling index, and those in the diploid group (p<0.05). The APC expression was not statistically correlated with clinical stage, tumor size, and estrogen receptor status.

Conclusion: These findings suggest that positive APC expression may be considered as a good prognostic factor of invasive ductal carcinoma, and loss of APC expression may be related with the progression of breast cancer.