Bif-1 and Bax expression in cutaneous Merkel cell carcinoma.
BACKGROUND
Bax-interacting factor-1 (Bif-1) binds to Bax, which in turn activates this proapoptotic protein. In the absence of Bif-1, the ability to induce apoptosis through the intrinsic pathway is greatly reduced. Merkel cell carcinoma (MCC) classically shows an aggressive behavior and lack of response to chemotherapy, which remains unexplained. Previous studies have documented the presence of Bax in MCC, but Bif-1 expression has not been evaluated. Herein, the expression of Bif-1 and Bax in cutaneous MCC is examined.


METHODS
The immunohistochemical expression of Bif-1 and Bax protein was examined in nine cases of MCC. Both positive and negative controls were conducted. All the cases were reviewed by a single dermatopathologist.


RESULTS
Bif-1 was detected in nine cases (100%), and Bax was expressed in six cases (66%). The percent positive cells for Bif-1 in MCC ranged from 85% to 98% positive (mean 93.9%). At the same time, decreased Bax expression was shown with 0-8% positive cells (mean 3.45%).


CONCLUSIONS
The increased expression of Bif-1 in MCC is associated with low levels of Bax staining. These findings suggest that the upregulation of Bif-1 could in part be responsible for tumorigenesis in cutaneous MCC. As shown, Bax and Bif-1 expression are not exclusively antithetical; therefore, future studies evaluating the expression of both proteins should be conducted.
Schlauder
Scott M
SM
Department of Pathology, University of South Florida, College of Medicine, Tampa, FL 33612, USA.
Calder
Kenneth B
KB
Khalil
Farah K
FK
Passmore
Leslie
L
Mathew
Rahel A
RA
Morgan
Michael B
MB
D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis* / Q000235:genetics; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000502:physiology; D015266:Carcinoma, Merkel Cell / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis* / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; C429293:SH3GLB1 protein, human; D051028:bcl-2-Associated X Protein