# Differential effects of minocycline on human breast epithelial cells, human breast cancer cells and their tumor hybrids

## TL;DR

Minocycline affects breast cancer and normal cells differently, which may lead to side effects in cancer therapy.

## Contribution

The study reveals differential effects of minocycline on breast cancer cells, normal cells, and tumor hybrids.

## Key findings

- Minocycline inhibited proliferation and migration in a dose-dependent manner in some cell lines.
- MMP-2 and MMP-9 were downregulated in normal cells but not in cancer or hybrid cells.
- EMT and stemness markers were unaffected by minocycline in all tested cell lines.

## Abstract

The antibiotic minocycline has been suggested as a potential agent in cancer therapy due to its anti-inflammatory properties and effectiveness as an NF-κB inhibitor. In previous studies, we showed that minocycline could effectively block the fusion of breast epithelial cells and cancer cells. However, its influence on breast cancer cell characteristics, including proliferation, migration, and gene expression has not yet been investigated.

M13SV1-EGFP-Neo breast epithelial cells, HS578T-Hyg breast cancer cells and M13HS-2 and M13HS-8 tumor hybrids were used as breast (cancer) model cell lines in this study. Cells were treated with up to 50 µg/ml minocycline. An XTT assay and a colony formation assay were used to study cell proliferation. Western blot analysis and Zymography were used to examine the expression of MMP-2 and MMP-9, EMT, and stemness marker. Cell migration was measured by Scratch assay. Using a two-way ANOVA and the Tukey post-hoc test, statistical significance was determined.

Minocycline inhibited proliferation and colony formation capacity in a dose-dependent manner, whereas EMT and stemness marker expression remained unchanged in all cell lines. Zymography data showed that MMP-2 and MMP-9 expression was down-regulated M13SV1-EGFP-Neo treated with minocycline, but not in HS578T-Hyg cells or M13HS-2 and M13HS-8 tumor hybrids. Minocycline inhibited the migration of M13SV1-EGFP-Neo cells in a dose-dependent manner, while the migration of HS578T-Hyg, M13HS-2 and M13HS-8 tumor hybrid cells necessitated a minimum of 25 µg/ml minocycline,

The results showed that non-malignant cells and neoplastic cells reacted differently to minocycline. This could mean that minocycline will have unwanted side effects if it is used in cancer therapy.

The online version contains supplementary material available at 10.1007/s11033-025-10666-1.