Pan-inhibition of the three H2S synthesizing enzymes restrains tumor progression and immunosuppression in breast cancer.

BACKGROUND: Hydrogen sulfide (H2S) is a significant endogenous mediator that has been implicated in the progression of various forms of cancer including breast cancer (BC). Cystathionine-ß-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST) are the three principal mammalian enzymes responsible for H2S production. Overexpression of CBS, CSE and 3MST was found to be associated with poor prognosis of BC patients. Moreover, H2S was linked to an immune-suppressive tumor microenvironment in BC. Recently it was observed that BC cells, in response to single or dual inhibition of H2S synthesizing enzymes, develop an escape mechanism by overexpressing alternative sources of H2S generation. Thus, the aim of this work is to escape the H2S compensatory mechanism by pan repressing the three enzymes using microRNAs (miRNAs) and to investigate their impact on the oncogenic and immunogenic profile of BC cells. METHODS: BC female patients (n = 25) were recruited. In-silico analysis was used to identify miRNAs targeting CBS, CSE, and 3MST. MDA-MB-231 cells were cultured and transfected using oligonucleotides. Total RNA was extracted using Biazol, reverse transcribed and quantified using qRT-PCR. H2S levels were measured using AzMc assay. BC hallmarks were assessed using trans-well migration, wound healing, MTT, and colony forming assays. RESULTS: miR-193a and miR-548c were validated by eight different bioinformatics software to simultaneously target CBS, CSE and 3MST. MiR-193a and miR-548c were significantly downregulated in BC tissues compared to their non-cancerous counterparts. Ectopic expression of miR-193a and miR-548c in MDA-MB-231 TNBC cells resulted in a marked repression of CBS, CSE, and 3MST transcript and protein levels, a significant decrease in H2S levels, reduction in cellular viability, inhibition of migration and colony forming ability, repression of immune-suppressor proteins GAL3 GAL9, and CD155 and upregulation of the immunostimulatory MICA and MICB proteins. CONCLUSION: This study sheds the light onto miR-193a and miR-548c as potential pan-repressors of the H2S synthesizing enzymes. and identifies them as novel tumor suppressor and immunomodulatory miRNAs in TNBC.

Role of Hydrogen Sulfide in Oncological and Non-Oncological Disorders and Its Regulation by Non-Coding RNAs: A Comprehensive Review.

Recently, myriad studies have defined the versatile abilities of gasotransmitters and their synthesizing enzymes to play a "Maestro" role in orchestrating several oncological and non-oncological circuits and, thus, nominated them as possible therapeutic targets. Although a significant amount of work has been conducted on the role of nitric oxide (NO) and carbon monoxide (CO) and their inter-relationship in the field of oncology, research about hydrogen sulfide (H2S) remains in its infancy. Recently, non-coding RNAs (ncRNAs) have been reported to play a dominating role in the regulation of the endogenous machinery system of H2S in several pathological contexts. A growing list of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are leading the way as upstream regulators for H2S biosynthesis in different mammalian cells during the development and progression of human diseases; therefore, their targeting can be of great therapeutic benefit. In the current review, the authors shed the light onto the biosynthetic pathways of H2S and their regulation by miRNAs and lncRNAs in various oncological and non-oncological disorders.

Origanum majorana L. protects against neuroinflammation-mediated cognitive impairment: a phyto-pharmacological study.

BACKGROUND: Neuroinflammation and oxidative stress are critical players in the pathogenesis of numerous neurodegenerative diseases, such as Alzheimer's disease (AD) which is responsible for most cases of dementia in the elderly. With the lack of curative treatments, natural phenolics are potential candidates to delay the onset and progression of such age-related disorders due to their potent antioxidant and anti-inflammatory effects. This study aims at assessing the phytochemical characteristics of Origanum majorana L. (OM) hydroalcohol extract and its neuroprotective activities in a murine neuroinflammatory model. METHODS: OM phytochemical analysis was done by HPLC/PDA/ESI-MSn. Oxidative stress was induced in vitro by hydrogen peroxide and cell viability was measured using WST-1 assay. Swiss albino mice were injected intraperitoneally with OM extract at a dose of 100 mg/kg for 12 days and with 250 µg/kg LPS daily starting from day 6 to induce neuroinflammation. Cognitive functions were assessed by novel object recognition and Y-maze behavioral tests. Hematoxylin and eosin staining was used to assess the degree of neurodegeneration in the brain. Reactive astrogliosis and inflammation were assessed by immunohistochemistry using GFAP and COX-2 antibodies, respectively. RESULTS: OM is rich in phenolics, with rosmarinic acid and its derivatives being major constituents. OM extract and rosmarinic acid significantly protected microglial cells against oxidative stress-induced cell death (p < 0.001). OM protected against the LPS-induced alteration of recognition and spatial memory in mice (p < 0.001) and (p < 0.05), respectively. Mice that received OM extract prior to the induction of neuroinflammation showed comparable histology to control brains, with no overt neurodegeneration. Furthermore, OM pre-treatment decreased the immunohistochemistry profiler score of GFAP from positive to low positive and COX-2 from low positive to negative in the brain tissue, compared to the LPS group. CONCLUSION: These findings highlight the potential preventive effects of OM phenolics against neuroinflammation and pave the way toward drug discovery and development for neurodegenerative disorders.

Mitochondrial dysfunction--a pharmacological target in Alzheimer's disease.

Increasing evidences suggest that mitochondrial dysfunction plays an important role in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD). Alterations of mitochondrial efficiency and function are mainly related to alterations in mitochondrial content, amount of respiratory enzymes, or changes in enzyme activities leading to oxidative stress, mitochondrial permeability transition pore opening, and enhanced apoptosis. More recently, structural changes of the network are related to bioenergetic function, and its consequences are a matter of intensive research. Several mitochondria-targeting compounds with potential efficacy in AD including dimebon, methylene blue, piracetam, simvastatin, Ginkgo biloba, curcumin, and omega-3 polyunsaturated fatty acids have been identified. The majority of preclinical data indicate beneficial effects, whereas most controlled clinical trials did not meet the expectations. Since mitochondrial dysfunction represents an early event in disease progression, one reason for the disappointing clinical results could be that pharmacological interventions might came too late. Thus, more studies are needed that focus on therapeutic strategies starting before severe disease progress.