# miR-195-5p Suppresses KRT80 Expression Inducing Cell Cycle Arrest in Colon Cancer

## TL;DR

This study shows that miR-195-5p reduces KRT80 levels in colon cancer, leading to slower tumor growth and cell cycle arrest.

## Contribution

The novel finding is that miR-195-5p directly suppresses KRT80, offering a potential new therapeutic strategy for colorectal cancer.

## Key findings

- miR-195-5p significantly downregulates KRT80 expression in CRC cell lines and mouse models.
- KRT80 silencing by miR-195-5p induces G1-phase cell cycle arrest and reduces tumor growth.
- Overexpression of KRT80 is confirmed in CRC tissues compared to normal mucosa.

## Abstract

Cytokeratin 80 (KRT80) is a protein type belonging to the keratin family, which has been correlated with more aggressive tumor phenotypes, higher rates of proliferation, enhanced migratory and invasive capabilities, and poorer clinical outcomes in different cancers. Although KRT80 may act as a mediator of oncogenic signaling, the molecular mechanisms in colorectal cancer (CRC) development still need to be evaluated. Here, we aimed to investigate the miR-195-5p molecular mechanism related to the modulation of KRT80 that underlies its role in CRC, emphasizing the potential properties of this miRNA for therapy. In summary, this study provides evidence that KRT80 is significantly overexpressed in CRC patients. Moreover, miR-195-5p effectively restores the KRT80 expression level in CRC cell lines and azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated mice, highlighting its regulatory role. Additionally, the critical oncogenic properties of KRT80 were demonstrated that, once silenced, suppressed tumor growth. These findings further reinforce the clinical potential of miR-195-5p in regard to affecting keratin expression and influencing CRC progression.

Background/Objectives: Keratins form a crucial component of the epithelial cytoskeleton, playing an essential role in maintaining tissue architecture and coordinating key cellular functions. KRT80 is a type II keratin that has emerged as an oncogenic driver in several malignancies, yet its involvement in colorectal cancer (CRC) remains unclear. Here, we investigated the molecular interaction between miR-195-5p, KRT80 expression, and CRC growth. Methods: Potential miR-195-5p binding sites in the KRT80 3′-UTR were identified through the use of integrated bioinformatic analyses, while publicly available datasets confirmed a significant overexpression of KRT80 in CRC tissues compared to normal mucosa. This finding was further validated through the use of mRNA and protein analysis in paired tumor and adjacent normal samples from CRC patients. Results: Functional assays involving CRC cell lines showed that transfection with miR-195-5p mimics led to a significant downregulation of KRT80 expression, reflecting the effects of direct KRT80 silencing by siRNA. Both molecular approaches induced G1-phase cell cycle arrest, concomitantly with reductions in G2/M populations. Furthermore, the in vivo delivery of miR-195-5p mimics in a mouse model of colitis-associated CRC resulted in a significant reduction in Krt80 expression in the colon. Conclusions: Collectively, our results reveal that miR-195-5p negatively regulates KRT80 expression, contributing to its tumor-suppressive activity in colorectal cancer and highlighting a molecular mechanism with potential therapeutic relevance.