Purpose: Topoisomerase Ⅱ-α is a key enzyme in DNA replication and a molecular target for many anti-cancer drugs. The C-erbB-2 oncogene (HER-2/neu) is the most frequently amplified oncogene in breast cancer. Because of the physical
proximity of
c-erbB-2 and topoisomerase Ⅱ-α, co-amplification of the c-erbB-2 and topoisomerase Ⅱ-α may occur. To investigate the clinical significance of the topoisomerase Ⅱ-α and c-erbB-2, the correlation between topoisomerase Ⅱ-α and c-erbB-2 was
examined
by immunohistochemical staining in 43 invasive ductal breast carcinomas and its relationship with other prognostic factors.
Methods: Topoisomerase Ⅱ-α and c-erbB-2 expression was studied immunohistochemically using sections of formalin fixed, paraffin-embedded tumor specimens from 43 invasive ductal breast carcinomas. The correlation between topoisomerase
Ⅱ-α
and
c-erbB-2 expression, and its relationship with the clinicopathological factors such as the tumor size, lymph node metastasis, TNM stage, histological grade, nuclear grade, estrogen receptors and progesteron receptors was investigated.
Results: C-erbB-2 was expressed in 9 (20.9%) out of the 43 infiltrating ductal carcinoma cases. Among the prognostic factors, the tumor size, lymph node metastasis, tumor stage, nuclear grade, status of progesteron receptors and estrogen
receptors did not significantly correlated with c-erbB-2 expression. The tumor size, lymph node metastasis, tumor stage, histological grade, and the absence of estrogen receptors displayed a significant relationship with the increase in the
topoisomerase-α index. However, the topoisomerase Ⅱ-α index did not correlate with the nuclear grade and the status of progesterone receptors. The topoisomerase Ⅱ-α index was slightly higher in the c-erbB-2 positive expression cases compared
to
c-erbB-2 negative expression cases but this increase was not significant (P=0.503).
Conclusion: These results suggest that topoisomerase Ⅱ-α may play some role as a prognostic factor, but further investigation is needed.
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