HOXB8 expression in ovarian serous carcinoma effusions is associated with shorter survival

HOX proteins are key transcription factors in embryogenesis. HOXB5 and HOXB8 were previously shown to be overexpressed in ovarian/primary peritoneal serous carcinoma compared to breast carcinoma using gene expression arrays. The present study investigated the clinical role of HOXB5 and HOXB8 in advanced-stage (FIGO III-IV) ovarian serous carcinoma.

HOXB5 and HOXB8 protein expression was analyzed in 286 effusions and 76 patient-matched solid lesions (27 primary carcinomas, 49 metastases) using immunohistochemistry. Expression was analyzed for association with clinicopathologic parameters, including survival.

Cytoplasmic HOXB5 protein was detected in 268/286 (94%) effusions. HOXB8 was expressed at both the cytoplasm (252/286; 88%) and nucleus (131/286; 46%) of carcinoma cells. Cytoplasmic HOXB5, cytoplasmic HOXB8 and nuclear HOXB8 were found in 56/76 (74%), 76/76 (100%) and 30/76 (39%) solid lesions, respectively, with significantly higher HOXB5 expression in effusions (p=0.002) and higher cytoplasmic HOXB8 in solid lesions (p<0.001). HOXB5 expression was higher in post-chemotherapy disease recurrence effusions compared to pre-chemotherapy effusions tapped at diagnosis (p=0.04). In univariate survival analysis of the effusion cohort, higher expression of cytoplasmic HOXB8 was associated with significantly shorter progression-free survival (p=0.033), whereas higher nuclear HOXB8 expression was associated with significantly shorter overall survival in analysis limited to patients with post-chemotherapy effusions (p=0.036). Neither finding was independent prognostic factor in Cox multivariate analysis.

HOXB5 and HOXB8 are frequently expressed in ovarian serous carcinoma, with anatomic site-related differences for cytoplasmic staining. HOXB5 may be affected by chemotherapy in effusions. HOXB8 expression is associated with shorter survival in metastatic serous carcinoma.