# Clinical impact of the methylation status of SMAD4 and AKR1B1 genes in a liquid biopsy sample as a prognostic marker for breast cancer

## TL;DR

This study shows that methylation of SMAD4 and AKR1B1 genes in liquid biopsies can predict breast cancer prognosis and treatment outcomes.

## Contribution

The study introduces SMAD4 and AKR1B1 methylation as novel noninvasive prognostic biomarkers for breast cancer.

## Key findings

- SMAD4 and AKR1B1 methylation levels were significantly higher in cancer patients compared to benign and healthy groups.
- SMAD4 and AKR1B1 methylation showed higher diagnostic accuracy than traditional biomarkers like CA 15-3 and CEA.
- Hypermethylation of these genes was linked to aggressive cancer features and worse survival outcomes.

## Abstract

The role of DNA methylation in the prognosis of breast cancer, particularly concerning small mothers against decapentaplegic 4 (SMAD4) and aldo-keto reductase family 1 member B1 (AKR1B1), remains largely unexplored. This study aimed to investigate the clinical role of SMAD4 and AKR1B1 methylation as noninvasive prognostic biomarkers in breast cancer. The study included 140 individuals. The patients were stratified into two groups based on their diagnostic investigation: women diagnosed with cancer in breast (N = 80) and cases with benign lesions in breast (N = 30). Additionally, a group of subjects considered as healthy served as the control group (N = 30). Methylation levels of SMAD4 and AKR1B1 were quantified using the Methyl II quantitative PCR system. The methylation specificity and sensitivity were examined through performing a receiver operating characteristic (ROC) curve analysis. The association of the methylation of investigated patterns with breast cancer clinical features and response to treatment was also examined. Survival patterns were assesed using Kaplan-Meier analyses. The outcomes revealed that hypermethylation of SMAD4 and AKR1B1 was upregulated in cancerous patients relative to the benign group and healthy subjects. Based on the values of the area under the curve (AUC) (0.945 and 0.935, respectively) for SMAD4 and AKR1B1, both markers demonstrated superior diagnostic accuracy, surpassing conventional biomarkers for instance cancer antigen 15 − 3 (CA 15 − 3; AUC = 0.698) as well as carcinoembryonic antigen (CEA; AUC = 0.537). Remarkably, SMAD4 and AKR1B1 hypermethylation exhibited a significant association with invasive duct carcinoma (IDC), particularly in early stages, high grades, and cases with lymph node metastasis. A significant difference was observed in methylation status concerning both items and treatment response. Additionally, survival outcomes indicated that hypermethylation of SMAD4 and AKR1B1 was associated with worse DFS and OS. In conclusion, SMAD4 and AKR1B1 methylation may serve as significant epigenetic markers affecting breast cancer prognosis, potentially indicating more aggressive disease and poorer outcomes in these patients.