# Differential BACH1 Expression in Basal-like Breast Tumors of Black Women Identified via Immunohistochemistry

## TL;DR

This study finds that BACH1 protein levels are higher in basal-like breast tumors from Black women compared to White women, suggesting a potential racial and subtype-specific role in breast cancer progression.

## Contribution

The study reveals a novel racial disparity in BACH1 expression and its correlation with MCT1 in basal-like breast cancer subtypes.

## Key findings

- BACH1 expression is significantly higher in tumors from Black women compared to White women.
- Higher BACH1 levels correlate with larger tumor size and the basal-like breast cancer subtype.
- BACH1 and MCT1 are positively correlated in tumors from Black women but only weakly in those from White women.

## Abstract

BACH1 mRNA has been known to promote breast cancer metastasis and predict the survival of breast cancer patients. We analyzed BACH1 protein levels in tumor tissues using immunohistochemistry assays. Expression levels of transcription factor BACH1 differ in tumors from Black women compared to those from White women. When we used a patient cohort of 130, higher levels of BACH1 were linked to tumors that were larger in size and a specific type of breast cancer called basal-like breast cancer. Another protein, MCT1, which is connected to BACH1, was also positively linked in tumors from Black women. These findings suggest that functional molecule BACH1 proteins are highly expressed in tumors from Black women, as well as in the basal-like subtype of breast tumors.

BACH1 has been identified as a functional regulator of cancer metastasis and metabolic signaling in breast cancer cells. However, the clinical relevance of BACH1 expression in breast tumors remains poorly understood. Using a tissue microarray from a cohort of 130 patients, we assessed the expression of BACH1 and its known target gene, MCT1 (encoded by SLC16A1), through immunohistochemistry (IHC). The expression data were then analyzed in relation to clinical variables, including breast cancer subtypes, tissue types, tumor size and grade, patient racial background, and age group. We found positive associations between BACH1 expression and tumor size, tumor grade, and the basal-like subtype. Importantly, BACH1 expression was significantly higher in tumors from Black women compared to those from White women, as well as in the basal-like subtype of breast tumors from Black women. Additionally, a positive correlation was observed between BACH1 and MCT1 IHC scores in tumors from Black women, while a weak association was noted in tumors from White women. Our study provides compelling evidence that BACH1 expression is evident based on the race and subtypes of breast cancer patients.