Expression of two isozymes of acyl-coenzyme A: cholesterol acyltransferase-1 and -2 in clear cell type renal cell carcinoma.
OBJECTIVE
The present study investigated the expression of acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) and -2 in clear cell type renal cell carcinoma (RCC).


METHODS
Clear cell type RCC and corresponding normal kidney tissue samples were obtained from 19 surgical cases (28-85 years of age). Tissue extracts were assayed for ACAT activity and protein expression by immunoblotting with anti-ACAT-1 and anti-ACAT-2 antibodies. Frozen sections were subjected to Oil red O staining for lipids, and were immunostained with ACAT-specific antibodies.


RESULTS
Acyl-coenzyme A cholesterol acyltransferase activity was 5.7-fold higher (P < 0.01) in clear cell carcinoma (23.52 +/- 4.90 pmol/mg protein/min) than in normal kidney (4.12 +/- 0.36). Consistent with this, immunoblotting and immunohistochemical staining revealed strong expression of ACAT-1 in clear cell type RCC. Densitometric analysis showed that ACAT-1 expression was 2.9-fold higher in clear cell type RCC than in normal kidney. In contrast, ACAT-2 expression was negative in clear cell type RCC and normal kidney. Oil red O staining showed massive deposits of lipid in RCC cells.


CONCLUSIONS
We identified strong expression of ACAT-1 in clear cell type RCC. Upregulation of ACAT-1 leads to high ACAT enzymatic activity, which accelerates the accumulation of cholesterol ester in clear cell type RCC.
Matsumoto
Kenshi
K
Department of Urology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Honjo, Kumamoto, Japan. kenshilund@hotmail.com
Fujiwara
Yukio
Y
Nagai
Ryoji
R
Yoshida
Masaki
M
Ueda
Shoichi
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002292:Carcinoma, Renal Cell / Q000201:enzymology*; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D007680:Kidney Neoplasms / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D002785:Sterol O-Acyltransferase / Q000276:immunology / Q000378:metabolism*
D000906:Antibodies; D014408:Biomarkers, Tumor; D007527:Isoenzymes; D002785:Sterol O-Acyltransferase