Increased glyceraldehyde-3-phosphate dehydrogenase expression in renal cell carcinoma identified by RNA-based, arbitrarily primed polymerase chain reaction.

Background: Renal cell carcinoma (RCC) comprises 85% of renal tumors and displays a great capacity to metastasize. The lack of diagnostic and prognostic markers complicates its early detection and in the majority of cases metastases are present at the time of diagnosis.

Methods: The current study reports on the identification of differentially expressed genes in RCC using random arbitrarily primed polymerase chain reaction (RAP-PCR).

Results: Four genes were identified, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase A (LDH A), human leukocyte antigen A (HLA A), and ferritin. GAPDH and HLA A were found to be overexpressed in 100% of the tumors and LDH A was increased in > 85% of the tumors analyzed compared with normal kidney counterparts. For GAPDH and LDH A higher protein levels in the tumors also were determined by Western blot analysis. Differential expression did not appear to correlate with gene amplification events as demonstrated by Southern blot analysis, indicating that regulatory mechanisms controlling the expression of these genes were altered. Finally, ferritin was judged to have a variable expression because it was decreased in approximately 50% of the tumors and augmented in 20%. The implications in proliferation and differentiation of all these genes were analyzed in RCC cell lines grown at different stages of confluency and additional information was obtained regarding expression of the GAPDH gene in proliferating primary cultures of normal and tumor cells derived from the same kidney samples.

Conclusions: The authors conclude that RAP-PCR is a useful technique with which to identify rapidly differentially expressed genes in a given system. In addition, they also conclude that GAPDH is a potent marker of cell proliferation in kidney tumor cells whose overexpression appears to be a late event in the development of RCC.