Differential expression of aldose reductase in TNF-α responsive rat hepatoma cell lines

We analyzed the differential expression pattern of intracellular proteins in tumor necrosis factor-α (TNF-α)-sensitive KDH-8/YK and TNF-α-resistant cKDH-8/11 rat hepatoma cell lines by means of two-dimensional electrophoresis (2-DE). The 2-DE protein patterns of KDH-8/YK cells demonstrated an increase in the protein spot of relative molecular mass (Mr) 36,000 and isoelectric point (pI) 4.9, which was determined by mass spectrometry (MS). Peptide mass fingerprinting (PMF) suggested that aldose reductase (AR), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and tropomyosin were the candidate components of the spot. By immunoblot using specific antibodies, the spot was identified to be AR with a pI that was lower than the theoretical value.