Copy Number Variation and mRNA Expression of ERBB2 (HER2) Gene in Breast Cancer Samples from the North Bengal Region of Bangladesh
Authors: Mahmudul Hasan1, Nelofar Yasmin2, Md Abdul Auwal1, Rabeya Khatun2, Tasnima Kamal1, Md Rashel Mollah1, Al-Amin Hossain1, Azadur Rahman Bhuiyan1, Md Ashraful Islam1, Zinnat Ara Moni1, Asma Ul Husna Biswas1, Md Asadur Rahman3, Md Farhadul Islam1,4*
Institution: 1Rajshahi University, Rajshahi; 2Institute of Biological Science, Rajshahi University, Rajshahi; 3Rajshahi Medical College; 4Griffith University, Australia
Introduction
Breast cancer development and progression are influenced by genetic and molecular alterations, including changes in the ERBB2 (HER2) gene, which encodes a receptor tyrosine kinase involved in cell growth and survival. Increased HER2 copy number and mRNA expression may contribute to tumour progression. However, regional data on HER2 copy-number variation (CNV) and mRNA expression in breast cancer samples from North Bengal, Bangladesh, remain limited. This study aimed to investigate HER2 CNV and mRNA expression patterns and evaluate their associations with clinicopathological characteristics, providing baseline regional molecular data for future research into breast cancer biology, diagnostic approaches, prognosis, and treatment response.
Methods
Formalin-fixed breast cancer tissues from 88 patients and 10 noncancerous breast tissues were collected from Rajshahi Medical College Hospital (RMCH). DNA and RNA were extracted using the TRIzol method, and RNA was reverse-transcribed into cDNA. HER2 DNA-CNV and mRNA expression were assessed using SYBR Green-based quantitative PCR (qPCR), with GAPDH as the internal reference. Clinicopathological associations were evaluated using SPSS version 26.0. A p-value below 0.05 was considered statistically significant.
Results
Among the 88 patients, ages ranged from 33 to 70 years, with a mean of 44.73 ± 7.67 years. High HER2 CNV was observed in 86.36% (76/88) of cancer samples, while low and unchanged CNV occurred in 7.95% (7/88) and 5.68% (5/88), respectively. High HER2 mRNA expression was detected in 51.13% (45/88), compared with low expression in 35.22% (31/88) and normal expression in 13.63% (12/88). Both HER2 CNV and mRNA expression were significantly higher in cancer than in noncancerous tissues (p = 0.008 and p < 0.001, respectively). HER2 CNV was associated with tumour size (p = 0.04), while mRNA expression was associated with tumour size and histological grade (p = 0.02 for both). A weak but statistically significant positive correlation was observed between HER2 CNV and mRNA expression (r = 0.28, p = 0.01).
Conclusion
HER2 CNV and mRNA expression showed distinct patterns and significant associations with selected clinicopathological characteristics in this North Bengal cohort. These findings provide baseline regional molecular data and support further investigation of HER2 alterations in breast cancer. Larger studies incorporating clinical outcomes and established HER2 protein or gene-amplification assessments are needed to determine their diagnostic and prognostic relevance.