Differential expression of the BCAT isoforms between breast cancer subtypes

Area of Science:

• Biochemistry
• Oncology
• Metabolic pathways

Background:

• Altered cellular metabolism is a hallmark of cancer, supporting rapid proliferation.
• Branched-chain amino acid (BCAA) metabolism, via human branched-chain aminotransferase (hBCAT) proteins, influences tumor growth.
• The role of the mitochondrial hBCAT isoform (hBCATm) in breast cancer is less understood compared to the cytosolic isoform (hBCATc).

Purpose of the Study:

• To investigate the expression profiles of hBCAT isoforms and IDH1 in different breast cancer subtypes.
• To correlate protein expression with clinical parameters and patient survival.
• To elucidate the differential metabolic roles of hBCAT isoforms in breast cancer.

Main Methods:

• Immunohistochemistry was used to assess protein expression of hBCAT and IDH1.
• Expression levels were analyzed across breast cancer subtypes: HER2+, luminal A, luminal B, and triple-negative breast cancer (TNBC).
• Correlations between protein expression, co-expression, and clinical parameters (hormone receptor status, tumor stage, lymph node metastasis, survival) were determined.

Main Results:

• hBCATc expression was significantly associated with aggressive HER2+ and luminal B subtypes.
• hBCATm and IDH1 expression were associated with the luminal A subtype, correlating with better prognosis.
• Enhanced IDH1 expression may support cells with increased hBCATm by replenishing the α-ketoglutarate pool.

Conclusions:

• hBCAT isoforms exhibit distinct expression patterns in breast cancer subtypes, suggesting differential regulation.
• hBCATc is linked to HER2+ tumors, while hBCATm is prevalent in ER+ tumors.
• These findings may reveal novel therapeutic targets for modulating cancer metabolism.