MCT4-Mediated Metabolic Reprogramming in Tumor-Associated Macrophages Promotes Hepatocellular Carcinoma Progression

Area of Science:

• Oncology
• Immunology
• Metabolism

Background:

• Monocarboxylate transporter protein 4 (MCT4) facilitates lactate efflux, crucial for cellular metabolism.
• Tumor-associated macrophages (TAMs) play a significant role in cancer progression, particularly in hepatocellular carcinoma (HCC).
• MCT4's role in TAMs within the HCC microenvironment requires detailed investigation.

Purpose of the Study:

• To characterize MCT4 overexpression in TAMs at the single-cell level in HCC.
• To investigate MCT4's role in HCC progression via metabolic reprogramming of TAMs.
• To explore the association between MCT4 expression, TAM polarization, and patient prognosis.

Main Methods:

• Bioinformatic analysis of public databases (UALCAN, TIMER2.0, TISCH2) for SLC16A3 expression in HCC immune cells.
• In vitro experiments involving SLC16A3 knockdown using shRNAs.
• Evaluation of TAM polarization via Western blot, qRT-PCR, and flow cytometry.
• Protein-protein interaction network analysis to identify key glycolysis genes associated with SLC16A3.

Main Results:

• MCT4 expression was significantly higher in HCC TAMs compared to other immune cells.
• SLC16A3 knockdown reduced M2 TAM marker CD163 and shifted TAM populations from CD163+ to CD86+.
• High SLC16A3 expression and increased M2 TAM infiltration were associated with poorer HCC patient prognosis (P=0.008).

Conclusions:

• MCT4 overexpression in TAMs may drive metabolic reprogramming towards glycolysis.
• MCT4 promotes M2 polarization of TAMs, contributing to HCC progression.
• Targeting MCT4 in TAMs could represent a therapeutic strategy for improving HCC outcomes.