Immunohistochemical Staining for Ras-Related Protein 25 (RAB25) Associates with Luminal B Breast Cancer Subtype.

INTRODUCTION: Luminal B breast cancer is associated with a poor prognosis and resistance to hormone therapy. Studies have suggested that Ras-related protein 25 (RAB25), a member of Rab small GTPase family, is involved in breast cancer pathogenesis. Our aim in the present study is to analyze the association between RAB25 protein expression and clinical and pathological characteristics, and to investigate whether the expression of RAB25 was associated with a specific molecular subtype of breast cancer. MATERIALS AND METHODS: A retrospective study was conducted regarding female patients diagnosed with breast cancer; clinicopathologic data was obtained from medical reports. RAB25 expression was evaluated by immunohistochemistry in 57 primary breast cancer samples. The results were correlated with clinicopathologic variables and different breast cancer molecular subtypes. RESULTS: RAB25 expression was significantly associated with tumors expressing oestrogen receptor (P=0.03). A high significant difference was observed by analyzing RAB25 expression in various breast cancer subtypes (P=0.01). RAB25 expression was found in 66.7% of Luminal B breast tumors, considered as the most aggressive hormone dependent mammary tumors and was strongly associated with luminal breast cancer subtypes (p=0.004) but not with age, tumor size, SBR grade, axillary lymph node, or tumor stage. CONCLUSION: RAB25 deregulated expression is most common in luminal B breast cancer tumors suggesting that RAB25 could be a potential therapeutic target for this molecular subtype.