Expression of heat shock protein 70 and c-myc in cervical carcinoma

Abstract

Heat shock protein 70 (hsp70), is a molecular chaperone that binds to c-myc and regulates its accumulation and localisation. In an attempt to confirm this association and to find out its prognostic significance in cervical carcinoma, paraffin embedded sections from 15 chronic cervicitis, 31 squamous cell carcinomas (scc) and 7 adenocarcinomas of the uterine cervix were immunohistochemically (IHC) stained for hsp70 and c-myc. hsp70 was faintly expressed cytoplasmically in non neoplastic squamous and endocervical epithelium, while mainly nuclear staining with variable intensities was seen in all scc and in squamous intraepithelial lesions (SIL) overlying 8 tumors. Both cytoplasmic and nuclear staining was noted in adenocarcinoma. c-myc was moderately expressed in the cytoplasm of all non neoplastic endocervical glands, while very mild cytoplasmic staining was noted in squamous epithelium. In SIL and in scc the staining intensity increased and was mainly nuclear. For adenocarcinoma, nuclear and cytoplasmic staining with different intensities was noted. There were significant positive correlations between the IHC expression of hsp70 and c-myc (p = 0.0001). In conclusion, our results confirm the co-association of c-myc and hsp70. This co-association might be a mechanism of tumor escape by preventing hsp70 binding to one of its normal target, the MHC class I, and preventing its subsequent expression on the surface of the cancerous cells. Lastly, the nuclear expression of hsp70 might be considered as an indicator of malignant transformation.