# CTSG may inhibit disease progression in HIV-related lung cancer patients by affecting immunosuppression

## TL;DR

This study shows that lower CTSG levels in HIV-related lung cancer are linked to worse outcomes and immune suppression, suggesting it could be a new treatment target.

## Contribution

The study identifies CTSG as a novel potential immunotherapeutic target in HIV-related lung cancer.

## Key findings

- CTSG expression is lower in non-small cell lung cancer tissues compared to normal tissues.
- HIV-related lung cancer tissues show significantly lower CTSG expression than non-HIV lung cancer tissues.
- CTSG levels correlate with immune markers like CD4+ T cell count and disease progression in HIV-related lung cancer.

## Abstract

Lung cancer is an independent risk factor for pulmonary complications following HIV infection. This study aimed to examine the expression and clinical significance of Cathepsin G (CTSG) protein in both non-HIV and HIV-related lung cancers.

The data related to lung adenocarcinoma (LUAD) and lung squamous carcinoma (LUSC) in the TCGA dataset and the data related to healthy individuals in the GTEx dataset, the GEPIA2 database was used to excavate the distinction in the expression of CTSG protein in non-small cell lung cancer (NSCLC) tissues versus normal non-cancerous tissues. The Ualcan database was used to compare the differences in CTSG expression at different stages of LUAD and LUSC. Immunohistochemistry (IHC) was used to detect the expression of CTSG proteins in the pathological tissues of patients with HIV-related lung cancer and patients with lung cancer without co-infection, the Kaplan-Meier method was used for survival analysis.

We observed that CTSG expression in NSCLC is lower compared to adjacent non-tumor tissues and correlates with NSCLC clinical stage. CTSG protein expression in HIV-related lung cancer tissues was lower than in adjacent tissues and lower than in lung cancer tissues without HIV infection, with a statistically significant difference (P < 0.05). It correlated with CD4 + T cell count and CD4+/CD8 + T cell ratio, as well as with the pathological type, distant metastasis, and clinical stage of HIV-related lung cancer, all with statistical significance (P < 0.05).

CTSG could potentially mitigate disease advancement in HIV-related lung cancer patients by inhibiting immune depletion, serving as a prospective immunotherapeutic target for both non-HIV and HIV-associated lung cancers.