 Corresponding author: Shalmoli Bhattacharyya Department of Biophysics, PGIMER, Chandigarh, India-160012. Copyright © 2021 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Biochemical and histopathological evaluation of an in vivo model of breast cancer Neha Sharma 1 , Anila Negi 1 , Dharambir Kashyap 2 , Amanjit Bal 2 and Shalmoli Bhattacharyya 1, * 1 Department of Biophysics, PGIMER, Chandigarh, India-160012. 2 Department of Histopathology, PGIMER, Chandigarh, India-160012. GSC Biological and Pharmaceutical Sciences, 2021, 16(01), 202–210 Publication history: Received on 01 June 2021; revised on 26 July 2021; accepted on 28 July 2021 Article DOI: https://doi.org/10.30574/gscbps.2021.16.1.0193 Abstract Though, the clinical management of breast cancer has improved significantly over the past 30 years, it still remains the leading cause of cancer-related female death worldwide. Prevention is the fundamental issue in breast cancer control, for which identification markers in terms of initiation and promotion are necessary. To understand this, an animal model which can recapitulate the early symptoms of breast cancer development and progression is required. Present study is an attempt to develop a convenient and economical in-vivo animal model of breast cancer suitable to conduct such study. Female Wistar and SD rats were injected with different doses and routes of administration of 7, 12- Dihydroxymethylbenz (a) anthracene (DMBA). Animals were observed for the presence of visible/palpable tumours in mammary glands. Various parameters (Tumor morphology, oxidative stress and histopathological studies were studied in different tissues (mammary, lungs, kidney, liver) after the appearance of mammary tumours in rats. After 14 weeks all the animals developed breast carcinomas. The results of this study revealed a significant difference in oxidative stress parameters between DMBA treated and control groups and these alterations were strain dependent. The H&E staining of mice mammary tissue showed development of metaplastic triple negative breast cancer. Immunohistochemistry observation confirmed the triple negative nature of mammary tumours developed in the mice. Data confirmed that DMBA can be used as breast cancer initiator and present model can be further exploited to screen potential anti-breast cancer compounds in vivo. Keywords: Animal model; Breast cancer; DMBA; Oxidative stress; Triple negative breast cancer 1. Introduction Breast cancer (BC) is one of the most frequent malignancy and second leading cause of cancer death among women worldwide. Recently more attention has been directed towards its prevention. Despite development of new treating strategies and advances in identifying novel targeted therapies the affected number is on rise [1]. It can be defined as an uncontrolled growth of breast cells originating from breast tissue. It could be as a result of mutations in the genes responsible for regulating the growth of cells [1]. Numerous factors, including molecular and cellular pathways could be involved in the initiation and progression of breast cancer. Classification of clinical subtypes (ER+, PR+, HER2+, and TNBC (Triple-negative) increases the complexity of breast cancers, which thus necessitates further investigation [2]. Diagnosis of breast cancer at an early stage by available screening methods is based on analyzing anatomical changes of the breast. Hence, it may take years for the tumour to grow to a sufficient size to be detectable [3]. Therefore, an experimental system is needed that closely mimics the human disease, and elucidate the influence of host factors on the initiation of the neoplastic process and to discover whether it can be manipulated by treatment of the host. For translation of anticancer therapies and imaging agents that have shown promising results in invitro studies, the development of an invivo model that can recapitulate the hallmark clinical symptoms of breast cancer is necessary.