# Senescence-associated and immune-related 9p21.3 locus genes in colorectal cancer: epigenetic architecture, molecular landscape and therapeutic possibilities

## TL;DR

The study explores how genes at the 9p21.3 locus affect colorectal cancer progression and treatment, suggesting personalized therapies based on epigenetic changes.

## Contribution

The paper introduces a novel analysis of the 9p21.3 locus's role in CRC, linking epigenetic changes to treatment outcomes and personalized therapy strategies.

## Key findings

- The 9p21.3 locus integrates cell cycle, immune signaling, and metabolic regulation in CRC.
- Epigenetic changes at 9p21.3 can influence CRC therapy outcomes and immunogenicity.
- Demethylating agents and immunotherapy may improve treatment by targeting this locus.

## Abstract

Colorectal cancer (CRC) progression is influenced by genetic and epigenetic aberrations. Oncogenesis of CRC involves the accumulation of mutations in proteins involved in the regulation of cell proliferation, growth and death (Graphical abstract A). DNA methylation has been demonstrated to contribute to tumor initiation, progression, and modulation of therapeutic responses. In this particular landscape, the 9p21.3 locus has been observed to integrate various cellular processes, including cell cycle control (CDKN2A/CDKN2B and ANRIL), immune signaling (cluster of type I interferons), and metabolic regulation (MTAP, MLLT3). This creates relationships that may affect tumor intrinsic and extrinsic features, immunogenicity, and therapeutic sensitivity. The objective of our analysis is to provide a comprehensive overview of the role of the 9p21.3 locus in CRC, focusing on its potential implications for treatment decisions and prediction of treatment responses. Analyzing the 9p21.3 status would help stratify CRC patients into different groups and guide the choice of personalized therapy for CRC. It could also enhance current CRC treatment by pretreating patients with demethylating agents and using an immunotherapeutic approach in combination with senolytic drugs (Graphical abstract B).

Graphical abstract. (A) Stages of CRC oncogenesis. The gradual accumulation of mutations in intestinal cells leads to disruptions in signaling pathways (WNT, MAPK, PI3K, TGFb, p53) and leads to malignancy (B) Epigenetic changes in the 9p21.3 locus can impact the outcome of CRC therapy. Demethylating may restore gene expression at the 9p21.3 locus and enhance the effects of chemotherapy and immunotherapy. Illustration created with BioRender.com.Figure illustrating molecular mechanisms in colon cancer. Panel A shows progression from a healthy colon to invasive colon cancer, highlighting key signaling pathways at each stage and increase in chromosomal instability and CpG island hypermethylation. Panel B depicts epigenetic regulation at locus 9p21.3 affecting therapy outcome, with arrows linking demethylating drugs, gene transcription, immunotherapy, and chemotherapy. Illustration created with BioRender.com.

Graphical abstract. (A) Stages of CRC oncogenesis. The gradual accumulation of mutations in intestinal cells leads to disruptions in signaling pathways (WNT, MAPK, PI3K, TGFb, p53) and leads to malignancy (B) Epigenetic changes in the 9p21.3 locus can impact the outcome of CRC therapy. Demethylating may restore gene expression at the 9p21.3 locus and enhance the effects of chemotherapy and immunotherapy. Illustration created with BioRender.com.