c-myc in Kaposi's Sarcoma – Incidental or Causative?
Kyle Feller, Shi Yang, Navpreet Tung, Jung Lee, Meera Mahalingam. Boston University School of Medicine, Boston, MA
Background: The c-myc proto-oncogene, which plays a central role in the regulation of cellular transcription, differentiation and apoptosis, can also promote angiogenesis. This gives c-myc a dual, direct and indirect, oncogenic function as tumor growth requires both cell proliferation and uncontrolled angiogenesis. The correlation between the expression of the c-Myc protein and presence of Kaposi's sarcoma-associated viral DNA in Kaposi's sarcoma, an angioproliferative disorder, has not been previously examined.
Design: Formalin-fixed paraffin-embedded archival tissue samples of Kaposi's sarcoma (n=24) were obtained. Immunohistochemical staining for the c-Myc protein was performed using the monoclonal anti-c-myc antibody 9E10.The control group included tissue samples of hemangiomas (n=11) and non-radiation induced angiosarcomas (n=6). Cases were marked as positive if they exhibited either nuclear or cytoplasmic staining. DNA extraction and PCR amplification were performed on all of the cases of Kaposi's sarcoma for presence of Kaposi's sarcoma-associated herpesvirus DNA. Statistical analyses were conducted to ascertain if there was a correlation between the results of immunohistochemical and PCR-based virus DNA detection.
Results: Immunohistochemical analyses revealed positive staining in 13/24 Kaposi's sarcoma cases (54%; nuclear=4; cytoplasmic=4; both=5) with negative staining in the control group. DNA PCR analyses revealed that 20/24 Kaposi's sarcoma cases (83%) were positive for Kaposi's sarcoma-associated herpesvirus DNA. Ten of 24 Kaposi's sarcoma cases (42%) were positive for both, one case (4%) was negative for both. No statistical correlation between c-Myc levels and the presence of viral DNA was observed.
Conclusions: Our findings indicate that the presence of the c-Myc protein, as determined by immunohistochemistry, does not correlate with the existence of Kaposi's sarcoma-associated herpesvirus DNA. Amplification of c-myc using more sensitive techniques, such as in situ hybridization, is required to ascertain whether it plays a definitive role in the etiopathogenesis of Kaposi's sarcoma.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 92, Tuesday Morning