Hydralazine inhibits cysteamine dioxygenase to treat preeclampsia and senesce glioblastoma

The vasodilator hydralazine (HYZ) has been used clinically for ~ 70 years and remains on the World Health Organization's List of Essential Medicines as a therapy for preeclampsia. Despite its longstanding use and the concomitant progress toward a general understanding of vasodilation, the target and mechanism of HYZ have remained unknown. We show that HYZ selectively targets 2-aminoethanethiol dioxygenase (ADO) by chelating its metal cofactor and alkylating one of its ligands. This covalent inactivation slows entry of proteins into the Cys/N-degron pathway that ADO initiates. HYZ's capacity to stabilize regulators of G-protein signaling (RGS4/5) normally marked for degradation by ADO explains its effect on blood vessel tension and comports with prior associations of insufficient RGS levels with human preeclampsia and analogous symptoms in mice. The established importance of ADO in glioblastoma led us to test HYZ in these cell types. Indeed, a single treatment induced senescence, suggesting a potential new HYZ-based therapy for this deadly brain cancer.

Proton pump inhibitors can reverse the YAP mediated paclitaxel resistance in epithelial ovarian cancer

Background

Several reports indicated that the expression of Yes-associated protein (YAP) was associated with multi-drug resistance. Acidic microenvironment increased by the overexpression of vacuolar-ATPase (V-ATPase) was also observed in tumor growth and drug resistance. We hypothesize that proton pump inhibitors (PPIs), currently used in the anti-acid treatment of peptic disease, could inhibit the acidification of the tumor microenvironment and increase the sensitivity of tumor cells to cytotoxic agents. Thus, our objective is to explore the reversal of drug resistance by the inhibition of YAP through specific PPIs in the epithelial ovarian carcinoma (EOC) cells. .

Results

We found that V-ATPase D1 was a positive regulator of YAP. Sub-lethal doses of the proton pump inhibitor esomeprazole (EMSO) in combination with paclitaxel (PTX) increased the PTX sensitivity in PTX-resistant EOC cells, as compared to PTX single treatments by inhibiting YAP and reserving pH gradient created by the V-ATPase D1. Moreover, sub-lethal doses of EMSO combined with PTX decreased autophagy and improved caspases independent apoptosis of PTX-resistant EOC cells.

Conclusions

These results suggested that sub-lethal doses of esomeprazole reverse YAP-mediated PTX resistance through the inhibiting of both YAP expression and acidic tumor microenvironment created by the V-ATPase D1. Therefore, we think the use of PPIs represents a promising strategy to improve the effectiveness of anti-EOC.

The Evaluation of Potential Cytotoxic Effect of Different Proton Pump Inhibitors on Different Human Cancer Cell Lines

OBJECTIVE

To assess the differential cytotoxic activity of PPIs on different human cancer cell lines; namely A549 lung cancer, CACO-2 colorectal cancer, MCF-7 breast cancer, and PANC-1 pancreatic cancer, A375 skin melanoma.

METHODS

In this study, the five human cancer cell lines and human non-cancerous fibroblasts were treated with increasing concentration of PPIs Omeprazole (OMP), Esomeprazole (ESOM), and Lansoprazole (LANSO) (50-300μM), over 24h, 48h, and 72h. Cell viability was determined using 3-(4,5- Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and the IC50 values of PPIs were measured. The most sensitive cell line A375 was used for further investigation. The cytotoxic effects of LANSO on these cells were assessed using Annexin-V Propidium Iodide (AV-PI) flow cytometry. As of action mechanism; anti-inflammatory effects of each PPIs and PPIs-DOXO combination therapy on LPS-stimulated RAW 264.7 mouse macrophages were assessed.

RESULTS

Dose and time dependence cytotoxic activity of PPIs on human cancer cell lines was founded. Unlike DOXO; All PPIs had a selective cytotoxic effect in the normal fibroblasts. Unlike the equipotent OMP and ESOM; LANSO was the most potent drug with IC50 values at 72h of 99, 217, 272, 208, 181μM against A375, A549, CACO-2, MCF-7, and PANC-1, respectively. AV-PI flow cytometry revealed dose-dependent apoptotic effects of LANSO alone and substantially enhanced in DOXO-co-treatments. Interestingly unlike ESOM and OMP, LANSO proved more effective than indomethacin in LPS-stimulated RAW 264.7 macrophages. None of the tested compounds, as well as indomethacin, exerted any cytotoxicity against RAW 264.7 macrophages. PPIs-DOXO lacked potential synergistic combination antiinflammation therapies.

CONCLUSION

This study provides the evidence that PPIs induce a direct and differential cytotoxic activity against human cancer cell line by the induction of the apoptosis. Moreover, PPIs increase cancer cell lines sensitivity to doxorubicin via apoptosis augmentation. Nevertheless, PPIs-DOXO lacked potential synergistic combination therapies in either antiproliferation or anti-inflammation.