[The role of the heat shock protein in human breast cancer].
OBJECTIVE
To study the role of heat shock proteins (HSP) in the cell cycle and various processes of carcinogenesis.


METHODS
Immunohistochemical SP methods, electron microscopy, in situ hybridization and RT-PCR were used to evaluate the expression of HSP, mainly HSP90, ubiquitin and HSP70 in breast cancer tissues.


RESULTS
HSP90 mRNA was expressed at much higher levels in cancerous tissue than in non-cancerous tissues. In addition, a close relation between HSP90 mRNA expression and proliferating cell nuclear antigen labelling index (PCNA L. I.) was observed in cancerous tissue. These findings suggest that increased expression of HPS90 isoform may play a role in cell proliferation. On the other hand, HSP90 mRNA was expressed in the more poorly differentiated carcinomas of the breast. The intracellular localization of HSP70 was consistent with that of ubiquitin. The PCNA L. I. was significantly higher in specimens showing HSP70 in nucleus. HSP73 mRNA, a member of HSP70 family, was also expressed at higher levels in cancerous tissues associated with a high PCNA L. I. than in non-cancerous tissues.


CONCLUSIONS
These results suggest that HSP90 may play a role in cancer cell proliferation and that HSP90 may contribute to cell differentiation and structural constitution. In addition, HSP70, especially HSP73, is related to ubiquetin and seems to be a marker for cancer proliferation.
Naito
Z
Z
Department of Pathology, Nippon Mecical School, Tokyo, Japan 113.
Takashi
E
E
Asano
G
G
D001943:Breast Neoplasms / Q000378:metabolism*; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism*; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014452:Ubiquitins / Q000096:biosynthesis* / Q000235:genetics
D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D014452:Ubiquitins