The detoxification enzyme, Glyoxalase 1 (Glo 1) has been found to be over-expressed in breast and prostate tumor biopsies relative to adjacent non-tumor tissue. The glutathione-dependent Glo 1/2 enzyme system efficiently detoxifies reactive carbonyl species such as methylglyoxal and glyoxal. The α-oxoaldehyde, methylglyoxal results from the breakdown of glucose and the triose-phosphates and glyoxal is generated primarily via lipid peroxidation. These reactive species form adducts with nucleic acids, amino acids and lipids, leading to diminished cellular function and cell death. The primary aim of our study is to investigate the metabolic and biological effects of Glyoxalase 1 (Glo 1) inhibition by S-p-bromobenzylglutathione cyclopentyl diester (pBrBzGSH(Cp)2) and knockdown by siRNA. We used a panel of breast, prostate and ovarian cancer cell lines for these studies. Using the glutathione analogue, pBrBzGSH(Cp)2, we have determined the IC50 values in our cancer cell lines using the MTT assay. They are as follows: 14.6 μM for MCF-7, 19.5 μM for MBA-MB-231, and 11.7 μM for MDA-MB-468. For the prostate cancer cells, 11.3 μM for LNCaP, 9.0 μM for DU 145, 14.5 μM for 22Rv1. For the ovarian cancer cells, 12.7 μM for UWB1.289 and 29.2 μM for UWB1.289+BRCA1. We quantified reduced and oxidized glutathione (GSH and GSSG) in during Glo I inhibition. Treatment with pBrBzGSH(Cp)2 at the IC50 concentration elevated intracellular GSH by 10-50% for 5 of the 7 cell lines tested. We quantified the DNA adduct, (R)-/(S)-N2-(1-carboxyethyl)-2’-deoxyguanosine ((R)-/(S)-CEdG) in both pBrBzGSH(Cp)2 treated and untreated cells. Preliminary results indicate the MDA-MB-231 breast cancer cells have elevated CEdG levels in pBrBzGSH(Cp)2 treated cells versus untreated cells. We are also quantifying carboxyethyl lysine (CEL) and carboxymethyl lysine (CML) to probe intracellular accumulation of methylglyoxal and glyoxal. Finally, putative compensatory responses to Glo 1 knockdown was probed by qRT-PCR. In preliminary studies, we observed a 2 to 6 fold increase in AKR1B10 in our Glo 1 knockdowns. Taken together, Glo 1 inhibition may be part of a viable therapeutic strategy in Glo 1 over-expressing tumors that are not responsive to conventional therapies.

Investigating the metabolic and biological effects of glyoxalase 1 inhibition and knockdown in cancer cell lines

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.