MATERIALS AND METHODS: Caco-2 and LS174T cells lines treated with omeprazole and esomeprazole were used in this study to assess the bacterial attachment of H. pylori within certain incubation periods.

RESULTS: The presence of proton pump inhibitors increased the H. pylori adherence in a time-dependent manner in both Caco-2 and LS174T cell lines. The double inhibition of P-glycoprotein using proton pump inhibitor and P-glycoprotein inhibitor caused low P-glycoprotein expression in the cell lines, resulting in higher H. pylori adherence compared to the control cell lines.

OBJECTIVE: The purpose of this study was to investigate the influence of P-gp modulation on the efficacy of treatment regimen.

METHOD: P-gp modulation in rats was performed by using P-gp inducer (150 mg/kg rifampicin) and P-gp inhibitor (10 mg/kg cyclosporine A) for 14 days prior to be infected with Helicobacter pylori (H. pylori). The rats were further divided into groups, which were normal control, vehicle control, antibiotics and omeprazole, antibiotics only and omeprazole only for another 2 weeks of treatment. The ulcer formation and P-gp expression were determined by using macroscopic evaluation and western blot analysis, respectively.

RESULTS: The highest P-gp expression was shown in the induced P-gp rats (2.00 ± 0.68) while the lowest P-gp expression was shown in the inhibited P-gp rats (0.45 ± 0.36) compared to the normal P-gp rats. In all groups, the rats which were infected with H. pylori, had a significant increase (p P-gp expression level and a more severe ulcer formation compared to the healthy rats. The ulcer developed at different levels in the rats with inhibited, induced, or normal P-gp expression. After receiving the standard therapy for H. pylori, it was observed that the healing rate for ulcer was increased to 91% (rats with inhibited P-gp expression), 82% (rats with induced P-gp expression) and 75% in rats with normal P-gp. The use of rifampicin to induce P-gp level was also shown to be effective in eradicating the H. pylori infection.

PURPOSE: This study outlines CuE's cytotoxic activity against drug-resistant tumor cell lines. Three members of ABC transporters superfamily, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and ABCB5 were investigated, whose overexpression in tumors is tightly linked to multidrug resistance. Further factors of drug resistance studied were the tumor suppressor TP53 and the epidermal growth factor receptor (EGFR).

METHODS: Cytotoxicity assays (resazurin assays) were used to investigate the activity of Citrullus colocynthis and CuE towards multidrug resistant cancer cells. Molecular docking (In silico) has been carried out to explore the CuE's mode of binding to ABC transporters (P-gp, BCRP and ABCB5). The visualization of doxorubicin uptake was done by a Spinning Disc Confocal Microscope. The assessment of proteins expression was done by western blotting analysis. COMPARE and hierarchical cluster analyses were applied to identify, which genes correlate with sensitivity or resistance to cucurbitacins (CuA, CuB, CuE, CuD, CuI, and CuK).

RESULTS: Multidrug-resistant cells overexpressing P-gp or BCRP were cross-resistant to CuE. By contrast, TP53 knock-out cells were sensitive to CuE. Remarkably, resistant cells transfected with oncogenic ΔEGFR or ABCB5 were hypersensitive (collateral sensitive) to CuE. In silico analyses demonstrated that CuE is a substrate for P-gp and BCRP. Immunoblot analyses highlighted that CuE targeted EGFR and silenced its downstream signaling cascades. The most striking result that emerged from the doxorubicin uptake by ABCB5 overexpressing cells is that CuE is an effective inhibitor for ABCB5 transporter when compared with verapamil. The COMPARE analyses of transcriptome-wide expression profiles of tumor cell lines of the NCI identified common genes involved in cell cycle regulation, cellular adhesion and intracellular communication for different cucurbitacins.