Lower plasma adiponectin levels are associated with larger tumor size and metastasis in clear-cell carcinoma of the kidney.
OBJECTIVE
To examine a possible relationship between plasma adiponectin levels and renal cell carcinoma (RCC). Adiponectin, a cytokine secreted by adipocytes, is a potent antiangiogenic factor. Plasma levels of adiponectin in patients with RCC and tumor adiponectin receptors R1 and R2 (AdipoR1&2) expression levels were measured and correlated with disease characteristics.


METHODS
Preoperative plasma samples from 42 patients were analyzed in triplicate for adiponectin levels with a specific ELISA assay. All patients had clear-cell RCC, including 15 with metastatic disease. Diabetic patients were excluded; all had normal renal function. The RCC and surrounding normal renal tissue were comparatively analyzed for AdipoR1&2 expressions (immunoblotting) in 15 patients.


RESULTS
Mean, median, and range of plasma adiponectin levels were 6.33, 5.84, and 1-25.2 microg/ml, respectively. A strong inverse correlation was found between plasma adiponectin levels and tumor size with significantly lower levels of adiponectin in tumors > or =4 cm (p<0.01). The median adiponectin levels in metastatic and nonmetastatic patients were 4.08 and 7.4 microg/ml, respectively (p=0.029). A trend toward significant lower adiponectin levels in high versus low Fuhrman grade (3 and 4 vs. 1 and 2) was noted (p=0.057). Expression of AdipoR1&R2 was found to be lower in tumor tissue compared with the patient's normal surrounding kidney tissues in 40% of the cases. Metastatic tumors expressed lower levels of AdipoR2. Body mass index was not inversely correlated with adiponectin levels.


CONCLUSIONS
Lower blood levels of adiponectin are positively associated with clear-cell RCC aggressiveness and could potentially be used as a biomarker.
Pinthus
Jehonathan H
JH
Department of Surgery/Urology, McMaster University, Hamilton, Ontario, Canada. jehonathan.pinthus@hrcc.on.ca
Kleinmann
Nir
N
Tisdale
Britton
B
Chatterjee
Suman
S
Lu
Jian-Ping
JP
Gillis
Aubrey
A
Hamlet
Tamika
T
Singh
Gurmit
G
Farrokhyar
Forough
F
Kapoor
Anil
A
D052242:Adiponectin / Q000097:blood*; D002292:Carcinoma, Renal Cell / Q000097:blood* / Q000473:pathology* / Q000556:secondary; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000097:blood* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009929:Organ Size
D052242:Adiponectin