In contrast, the percentage of LDH5, the most efficient isoform in catalyzing conversion of kinase inhibitor U0126 pyruvate to lactate, did not correlate with log transformed serum LDH levels. To further determine a possible correlation between high serum LDH and high serum lactate, we subsequently measured lactate levels in the patients sera. As shown in Figure 1, panel vi, serum lactate levels show a weak insignificant association with the log transformed serum LDH levels. We further categorized each of the LDH isoenzymes, total LDH Inhibitors,Modulators,Libraries level, and serum lactate level into low, normal, and high levels using the clinical cutoffs. Abnormally low levels of LDH 1 and 2 are asso ciated with abnormally high serum LDH level and abnormally high levels of LDH 3 and 4 are associated with abnormally high serum LDH level.

Again, no association was detected between the high LDH5 and high serum LDH levels. To assess whether any of the serum LDH isoenzymes or serum lactate correlated with OS we performed a survival analysis. At a median follow up of 5. 8 months 31 out of Inhibitors,Modulators,Libraries 49 patients had died. As previously shown, patients with a more than 1. 2 fold increase in total serum LDH levels had shortened OS compared with patients with an equal or less than 1. 2 fold increase in total serum LDH. Furthermore, patients with low serum LDH1 or high serum LDH4 had a worse OS compared with patients with normal serum LDH1 and 4. Expression of LDHA and HIF 1 in the nevus melanoma progression pathway The detected changes in the LDH isoenzymes, and, in par ticular, the increase of the more glycolytic LDH isoen zymes along with the corresponding decrease of the non glycolytic LDH isoenzymes, may be attributable to changes in expression of the LDHA and LDHB subunits in melanoma cells.

To investigate whether melanoma Inhibitors,Modulators,Libraries cells express LDHA that mediates conversion of pyruvate to lactate, we performed immunohistochemistry studies of a nevus melanoma pro gression TMA. As shown in Additional file 3 LDHA is expressed in nevic melanocytes, and in primary and meta static melanomas, but its levels are higher in primary thick melanomas. Depicted in Figure 2, panel a, are boxplots of the TMA LDHA data, which document increased expres sion of LDHA with progression from nevi to advanced melanoma .

Pairwise comparison between different stages of the nevus mela noma progression pathway showed that the most signifi Inhibitors,Modulators,Libraries cant increase was between primary thick primary melanomas and nevi, with the mean LDHA expression increased approximately three fold. In addition, the data also indicate trend towards reduction between thick primary melanomas and meta static melanomas. Since it has been reported that HIF Inhibitors,Modulators,Libraries 1 increases LDHA expression, we also determined HIF 1 expression in the nevus melanoma maybe TMA. In agreement with the data of a previous report, HIF 1 was expressed in primary melanoma tissues.