Correlation between protein and gene expression of HER-2 and topoisomerase 2a in infiltrative ductal breast carcinoma

Abstract

Introduction: Breast cancer is a heterogeneous disease and the most common malignancy in women with increasing incidence in recent years. According to immunohistochemical expression of estrogen receptor (ER-R), progesterone receptor (PR-R) and HER-2 four different molecular subtypes of breast cancer were identified: luminal A (ER-R+ and / or PR-R+, HER-2-), luminal B (ER-R+ and / or PR-R+, HER- 2+), HER-2 positive (ER-R- and / or PR-R-, HER-2+) and triple negative (ER-R- and / or PR-R-, HER-2-) breast cancer subtypes. HER-2 and TOP2A genes are amplified in 20– 30 % of breast cancers. Amplification of HER-2 and TOP2A genes are associated with a poor prognosis and predictive response to treatment by Herceptin and anthracycline. Co-amplification of HER-2 and TOP2A has been seen in approximately 12–38 % of patients with breast cancers. A few retrospective studies have reported that TOP2A gene amplification occurs almost exclusively in conjunction with HER-2 gene amplification. Aim: The aim of our study is to investigate HER-2 and TOP2A gene aberrations and their correlation with apoptotic and proliferative indexes, Bcl-2, p53, ER-R, PR-R, HER-2, TOP2A, BRCA1, clinicopathological parameters and overall survival in four molecular subtypes of breast cancer. Material and methods: Sixty paraffin-embedded breast cancer tissue samples were studied immunohistochemically for the expression of ER-R, PR-R, HER-2, p53, Bcl-2, ssDNA, Ki67, BRCA1, TOP2A and FISH for HER-2 and TOP2A gene aberrations. HER-2 and TOP2A gene copy number were analyzed by HER-2 FISH pharmDxTM kit and TOP2A FISH pharmDxTM kit (DakoCytomation), respectively. Results: Clinicopathological parameters - The ages of patients ranged from 38 to 87 years (64.79 ± 21). The tumor size ranged between 0.4 and 5.5 cm, and the histological grades were G1, G2 and G3 in 6 (10 %), 25 (41.7 %), and 17 (28.3 %) patients, respectively. In 26 patients (43.4 %) lymph node status was negative; while in 22 patients (36.6 %) was detected positive lymph node status...

Uvod: Karcinom dojke predstavlja jako heterogeno oboljenje kao i jedno od najzastupljenijih malignih bolesti u opštoj ženskoj populaciji. Na osnovu prisustva i nivoa ekspresije ER-R, PR-R i HER-2 receptora ostvarena je podela na četiri molekularna tipa karcinoma dojke: luminalni A (ER-R+ i / ili PR-R+, HER-2-), luminalni B (ER-R+ i / ili PR-R+, HER-2+), HER-2 pozitivni (ER-R- i / ili PR-R-, HER-2+) i trostruko negativni (ER-R- i / ili PR-R-, HER-2-) tip karcinoma dojke. U oko 20 do 30% karcinoma dojke javlja se amplifikacija HER-2 i TOP2A gena. Amplifikacija HER-2 i TOP2A gena je povezana sa lošijim ishodom bolesti, agresivnijim tokom i dobrim odgovorom pacijentkinja na terapiju Herceptinom i antraciklinima. Koamplifikacija HER-2 i TOP2A gena je prisutna u 12 do 38% karcinoma dojke. Na osnovu rezultata nekoliko studija postavljena je hipoteza po kojoj se amplifikacija TOP2A gena javlja isključivo sa amplifikacijom HER-2 gena, mada postoje i drugačija, suprotna mišljenja. Cilj: Cilj naše studije bio je da se odrede genski statusi HER-2 i TOP2A kao i njihova korelacija sa apoptotskim i proliferativnim indeksom, nivoom ekspresije ER-R, PR-R i HER-2 receptora, TOP2A, BRCA1, Bcl-2 i p53 proteina, osnovnim kliničko-patološkim parametrima kod tumora dojke 60 pacijentkinja podeljenih u četiri molekularna tipa. Materijal i metode: Šezdeset tkivnih uzoraka karcinoma dojke ispitivano je imunohistohemijskom metodom na prisustvo i stepen ekspresije ER-R, PR-R, HER-2, p53, Bcl-2, TOP2A, BRCA1, ssDNA, Ki67, kao i FISH metodom na stepen genske modifikacije HER-2 i TOP2A. Stepen modifikacije HER-2 i TOP2A gena analiziran je primenom HER-2 FISH pharmDxTM kit i TOP2A FISH pharmDxTM kit (DakoCytomation). Rezultati: Kliničko-patološki podaci - Starost ispitanica se kretala u rasponu izmeñu 38 i 87 godina (64.79 ± 21). Veličina tumora se kretala u opsegu izmeñu 0.4 i 5.5 cm, dok je histološki gradus G1 bio zastupljen kod 6 (10%) karcinoma, histološki gradus G2 kod 25 (41.7%) i histološki gradus G3 kod 17 (28.3%) karcinoma dojke...