Succinate dehydrogenase expression in breast cancer

Area of Science:

• Oncology
• Biochemistry
• Molecular Biology

Background:

• Succinate dehydrogenase (SDH) is a key enzyme in cellular respiration.
• SDH dysfunction has been implicated in various cancers.
• Understanding SDH expression in breast cancer subtypes is crucial for potential therapeutic strategies.

Purpose of the Study:

• To investigate succinate dehydrogenase (SDH) expression in breast cancer molecular subtypes.
• To assess the clinical implications of SDH expression, including SDHA and SDHB, in relation to patient age, tumor grade, and proliferation markers.

Main Methods:

• Immunohistochemistry was performed on 721 breast cancer tissue microarrays.
• Staining included markers for ER, PR, HER-2, Ki-67, HIF-1α, SDHA, and SDHB.
• Breast cancer molecular subtypes (luminal A, luminal B, HER-2, TNBC) were classified using IHC and FISH data.

Main Results:

• HER-2 subtype breast cancers exhibited the highest SDHA expression in tumor cells, while luminal A subtypes showed low/negative SDHA expression.
• Stromal SDHB expression was most frequent in HER-2 subtype and least frequent in triple-negative breast cancer (TNBC).
• SDHA-negative breast cancers were linked to younger age at diagnosis, and SDHB-negative cancers to lower histologic grade and Ki-67 labeling index.

Conclusions:

• Loss of SDHA or SDHB expression was observed in approximately 3% of the studied breast cancers.
• Low SDH expression in breast tumor cells is associated with younger patient age and less aggressive tumor histology (low grade).
• SDH expression patterns differ significantly across breast cancer molecular subtypes, suggesting subtype-specific roles.