Lactate Dehydrogenase Isoenzymes in Mammalian Cells Exposed to Isophenphos

The cytotoalcity of isophenphos, an organophosphorus insecticide that has the potential to cause delayed polyneuropathy, was evaluated in GBK and V79 ce1ls. A 72 h time course following isophenphos exposure indicated a dose-dependent growth inhibition as dctermined by cell counts. The administration of isophenphos (20g/ml) to GBK cells cultured at high densities indicated a decrease in the activities of LDH isocnzymes. Analysis of V79 cells revealed a decrease of LDH3, the only LDH isocnzyme detected in these cells.

Testicular germ cell tumors type 2 have high RNA expression of LDHB,the gene for lactate dehydrogenase subunit B

This study analyzed RNA expression of genes for three serum tumor markers,alpha fetoprotein(AFP),human chorionic gonadotropin(hCG),and lactate dehydrogenase(LDH),in patients with testicular germ cell tumors(TGCT)type 2.The gene AFP encodes AFP,the gene for chorionic gonadotropin beta polypeptide 5(CGB5)encodes a major part of the specific beta subunit of hCG,and the genes for LDH subunit A(LDHA),LDH subunit B(LDHB),and LDH subunit C(LDHC)encode three different subunits of LDH.LDHB encodes the LDHB subunit present as a tetramer in LDH isoenzyme 1(LDH-1).We examined three datasets with 203 samples of normal testis tissue(NT)and TGCT type 2.Yolk sac tumor(YST)expressed RNA of AFP fourteen thousand times higher than seminoma(SE),embryonal carcinoma(EC),and teratoma(TER)combined(P=0.00015).In the second microarray,choriocarcinoma(CC)expressed RNA of CGB5 ten times higher than other histologic types of TGCT combined.EC expressed RNA of LDHB twice higher than SE,YST and TER combined(P=0.000041).EC expressed RNA of LDHB higher than that YST expressed RNA of AFP and that CC expressed RNA of CGB5.In conclusion,TGCT type 2 expressed RNA of LDHB markedly higher than the RNA of 23 other candidate genes for TGCT type 2.