title: Inhibin/activin subunits (inhibin-alpha, -betaA and -betaB) are differentially expressed in human breast cancer and their metastasis.
abstract: Inhibins (INH) are dimeric glycoproteins, composed of an alpha-subunit (INH-alpha) and one of two possible beta-subunits (INH-betaA or -betaB). Aims of this study were to determine the frequency and tissue distribution of INH-alpha, -betaA and -betaB in breast cancer tissue. Paraffin-fixed ductal carcinoma in situ (DCIS; n=7), invasive ductal carcinomas without lymph node metastases (IDC; n=8), infiltrating ductal carcinomas with their lymph node metastases (IDC/LN; n=8), primary ductal carcinomas with their subsequent recurrence (n=7) were analyzed by immunohistochemical means with monoclonal antibodies against inhibin-alpha, -betaA and -betaB subunits. INH-alpha was observed in DCIS (5/7), while its expression was significantly higher in DCIS than IDC (1/7; p<0.05) and IDC/LN (0/8; p<0.005) and recurrent breast cancer tissue (0/7; p<0.005). The INH-betaA subunit was also demonstrated in all DCIS cases with a significantly higher intensity compared to IDC (p<0.05), IDC/LN (p<0.01) and primary carcinoma with subsequent recurrence (p<0.05). INH-betaA expression was significant higher in primary tumors with subsequent recurrence compared to IDC/LN (p<0.05). The metastatic lymph nodes expressed the lowest inhibin-betaA compared to all other groups (p<0.01). INH-betaB was also demonstrated in all mammary carcinoma tissues, but without any statistical differences. The differential expression of INH-alpha in DCIS might suggest a function as a tumor suppressor in breast tissue, suggesting a useful marker for recognizing patients with subsequent risk of developing invasive ductal cancer. The higher INH-betaA expression in DCIS than invasive cancer suggests an important role in mammary carcinogenesis. Interestingly, primary breast tumor with a subsequent recurrence expressed a higher intensity of the inhibin-betaA subunit, suggesting an important role in metastatic pathogenesis, and utilization as a tumor marker. The immunoreactivity of inhibin-betaA was significantly higher in DCIS than invasive ductal carcinomas, suggesting an important role in mammary carcinogenesis. The metastatic lymph nodes expressed lower INH-betaA and -betaB than the primary tumor, which might be the cause of less differentiated and aggressive tumor cells within the primary tumor. Therefore, inhibin/activin subunits might be useful prognostic markers for breast cancer.
authors.affiliation: First Department of Obstetrics and Gynecology, Ludwig-Maximilians-University Munich, 80337 Munich, Germany.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Mylonas
authors.forename: Udo
authors.initials: U
authors.lastname: Jeschke
authors.forename: Naim
authors.initials: N
authors.lastname: Shabani
authors.forename: Christina
authors.initials: C
authors.lastname: Kuhn
authors.forename: Klaus
authors.initials: K
authors.lastname: Friese
authors.forename: Bernd
authors.initials: B
authors.lastname: Gerber
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D028322:Inhibin-beta Subunits / Q000032:analysis / Q000378:metabolism*; D007265:Inhibins / Q000032:analysis / Q000378:metabolism*; D008207:Lymphatic Metastasis; D011379:Prognosis; D012008:Recurrence
chemical_list: D014408:Biomarkers, Tumor; C422402:INHBB protein, human; C103008:inhibin beta A subunit; C094377:inhibin-alpha subunit; D007265:Inhibins; D028322:Inhibin-beta Subunits