# Differential Oxidative Stress Profiles in Circulating and Peritumoral Adipose Tissue Across Stages of Colorectal Cancer

## TL;DR

This study found that colorectal cancer patients have higher oxidative stress in blood and tumor-adjacent fat compared to healthy people, with changes worsening as cancer progresses.

## Contribution

The study reveals a systemic and peritumoral oxidative imbalance in CRC patients, linked to Nrf2/HO-1 downregulation and disease progression.

## Key findings

- CRC patients showed elevated MDA and protein carbonyl levels, with reduced SOD and catalase activities in plasma.
- Superoxide production in peritumoral adipose tissue was significantly higher in CRC patients compared to controls.
- Nrf2/HO-1 protein expression in PAT was reduced in CRC patients and correlated with cancer stages.

## Abstract

This study intends to assess oxidative stress markers and endogenous enzymes in plasma and peritumoral adipose tissues (PATs) obtained from normal subjects and patients with stages I-IV colorectal cancer (CRC). 63 participants were recruited, including 23 patients with colorectal cancer and 40 healthy subjects. CRC patients had increased circulating malondialdehyde (MDA) and protein carbonyl concentrations, as well as reduced superoxide dismutase (SOD) and catalase activities, compared to normal volunteers. (p < 0.05). The findings aligned with the oxidative parameters assessed in peritumoral adipose tissue. Superoxide production in PAT was dramatically higher in the CRC group compared to the control group (p < 0.05). Moreover, oxidative stress markers were progressively altered in relation to CRC stages. Nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) protein expression was reduced in PAT isolated from CRC compared to normal subjects and associated with CRC stages. CRC patients showed a systemic and peritumoral oxidative imbalance, along with elevated superoxide production in the PAT. The oxidative modifications worsened with the progression of CRC stage and were associated with the downregulation of the Nrf2/HO-1 antioxidant cascade in peritumoral adipose tissue.