Identification of ferroptosis-related subtypes, characteristics of TME infiltration and development of prognostic models in gastric cancer

Abstract

Background: Ferroptosis is a distinct form of cell death characterized by unique morphology, biochemistry, and genetics, playing a crucial role in the initiation, progression, prognosis, and therapeutic strategies of tumors. However, the impact of ferroptosis-related genes (FRGs) on the tumor microenvironment (TME) remains unclear. This study may advance the existing knowledge of FRGs in gastric cancer, and push ahead with more effective prognostic assessment and the development of more effective immunotherapy approaches.

Methods: FRGs were acquired from the FerrDb database and a consensus clustering technique was adopted to categorize patients with GC into groups in line with the expression profiles of 44 FRGs in order to further investigate the expression properties of these proteins. Assessment of the immune status, microsatellite instability (MSI) and cancer stem cell (CSC) index between the high- and low- risk groups to assess the proportion of TIICs in the TME, ssGSVA was adopted to detect the abundance of infiltrating immune cells from the low-risk and high-risk groups. Expression levels of eight ferroptosis-related genes of prognostic signature in GC tissues and adjacent normal tissues was detected by RT-PCR.

Results: In the GC cohort, TP53 has the highest mutation frequency (44 %), and was shown to be highly linked with the expression levels of 11 FRGs. In accordance with the Kaplan-Meier curve, the overall survival time of patients with subtype A (Low FRG-score) discernibly exceeded that of patients with subtype B (High FRG-score).In addition, there is a significant difference in the infiltration of most immune cells between subtype A and subtype B, and some important immune checkpoints (CTLA4, PDCD1, CD274, LAG3, PDCD1LG2, and HAVCR2) have higher expression in cluster A. Finally, low FRG-scores were significantly associated with MSI-H status, while high FRG-scores were significantly associated with microsatellite stable status (MSS). FRG-score is negatively related to the cancer stem cell (CSC).

Conclusion: Low FRG-score, due to its high microsatellite instability (MSI-H), high mutational load and immune activation, indicates the possible advantage of OS. In addition, the FRG-score was closely related to the cancer stem cell (CSC) index and the sensitive degree of chemotherapeutic drug.

Keywords: Cancer stem cell; Ferroptosis; Gastric cancer; Microsatellite instability; Overall survival; Tumor microenvironment.