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.