Abstract 107P
Background
In humans, cystathionine-β-synthase (CBS), cystathionine gamma-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST) biosynthesize Hydrogen Sulphide (H2S). The expression of these enzymes was found to be significantly upregulated in breast cancer (BC). H2S causes various alterations in cellular metabolism and plays a major role in metabolic reprogramming in several malignant tumors. At low concentrations H2S stimulates cellular bioenergetics and increases ATP production. It induces persulfidation of different transcription factors such as PGC1α and thus, promotes the mitochondrial biogenesis. Yet, the effect of endogenous H2S on other mitochondrial biogenesis signaling players such as PGC1α, Nrf1/2, TFAM and ND-1 is not well studied in BC. Thus, the main aim of this work was to unravel the expression profile of the mitochondrial biogenesis pathway in BC patients and the impact of knocking down of H2S synthesizing enzymes on the mitochondrial bioenergetic profile in BC cell lines.
Methods
Breast tissues were collected from 25 female BC patients. Aggressive BC cell line, MDA-MB-231 cells were transfected with CBS, CSE and 3MST siRNAs using lipofection technique. RNA extraction was done from BC tissues and cell lines followed by reverse transcription into cDNA. PGC1-α, Nrf1, NRF-2, TFAM and ND-1 expression was quantified using q-RT-PCR. Mitochondrial membrane potential was measured using Rhodamine 123.
Results
CBS, CSE, 3-MST and ND-1 were upregulated in BC tissues. However PGC1α, NRF1/2 and TFAM did not show a significant alteration in BC tissues compared to its normal counterparts. On the molecular level, knocking down of CBS and/or CSE in MDA-MB-231 cells resulted in a noticeable increase in the expression of PGC1α, NRF1/2 and ND-1. However, a significant increase in TFAM levels was observed only upon CBS silncing but not upon CSE silenecing. On the other hand, knocking down of 3-MST did not affect PGC1α, NRF1/2, TFAM and ND-1 levels in MDA-MB-231 cells. On the functional levels, Effecient knocking down of either CBS or CSE caused a reduction in the mitochondrial membrane potential of BC cells.
Conclusions
This study highlights a tangible influence of CBS and CSE-induced H2S production on mitochondrial biogenesis mediators in BC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
German University in Cairo.
Funding
Swiss National Science Foundation.
Disclosure
All authors have declared no conflicts of interest.