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Ovarian cancer is considered as one of the most lethal gynecological cancers, and cisplatin-based therapy has an important role as the first-line option for chemotherapy. Resistance to chemotherapy is the main obstacle against successful cancer chemotherapy with cisplatin. Therefore, identifying potent compositions and molecules with fewer side-effects is a big challenge to overcome cisplatin resistance. In this study, we investigated the possible mechanism and potency of sanguinarine, a plant-derived alkaloid, in human cisplatin-resistant ovarian cancer (A2780/R) cells. The effect of sanguinarine on cytotoxicity of cisplatin was determined by MTT assay. Apoptosis-inducing effect of sanguinarine alone and in combination with cisplatin was evaluated by annexin V/PI assay and DAPI staining. Intracellular glutathione (GSH) content was quantitated using GSH assay kit after treatment with sanguinarine. Results indicated that sanguinarine enhances the sensitivity of A2780/R cells to cisplatin. Apoptosis-inducing effect of cisplatin was also enhanced when combined with sanguinarine. Furthermore, sanguinarine reduced intracellular GSH content in a dose-dependent but not time-dependent manner. These findings suggest that sanguinarine could reverse cisplatin resistance in A2780/R cells through GSH reduction. Therefore, sanguinarine can be used as one of the potent adjuvants for ovarian cancer chemotherapy., (© 2019 John Wiley & Sons A/S.)

Multidrug resistance in tumor cells is still a big challenge in cancer treatment. Therefore, identification ofsafe and effective multidrug resistance-reversing compounds with minimal side effects is an important approach in cancer treatment. Here, we investigated the role and potential mechanisms of peroxisome proliferator-activated receptor γ in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. The effect of doxorubicin on cell viability following treatment with balaglitazone, a peroxisome proliferator-activated receptor γ agonist, was evaluated using trypan blue and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Rhodamine123 assay was used to determine the activity of two common drug efflux membrane transporters P-glycoprotein and multidrug resistance protein-1. P-glycoprotein, multidrug resistance protein-1, and phosphatase and tensin homolog deleted on chromosome 10 messenger RNA/protein expression levels were measured by quantitative reverse transcription polymerase chain reaction and western blot analyses. Annexin V/fluorescein isothiocyanate assay was also employed to investigate apoptosis. We showed that balaglitazone considerably enhanced the cytotoxicity of doxorubicin. Balaglitazone also significantly downregulated P-glycoprotein expression and activity in K562/DOX cells and reduced multidrug resistance through elevation of intracellular doxorubicin in cells. Furthermore, upon balaglitazone treatment, phosphatase and tensin homolog deleted on chromosome 10 expression could be restored in K562/DOX cells in a peroxisome proliferator-activated receptor γ-dependent manner. We concluded that peroxisome proliferator-activated receptor γ agonist, balaglitazone, could reverse multidrug resistance by inducing phosphatase and tensin homolog deleted on chromosome 10 and peroxisome proliferator-activated receptor/ phosphatase and tensin homolog deleted on chromosome 10 signaling pathway. These findings suggest that targeting peroxisome proliferator-activated receptor γ might serve as an effective approach for circumventing multidrug resistance in chemotherapy of cancerous patients.

Peroxisome proliferator-activated receptor gamma (PPARγ) plays key roles in regulating cellular differentiation, proliferation and apoptosis pathways. As such, they are considered promising targets for anticancer drug development, especially for breast cancer, multiple myeloma and hematologic malignancies. Chronic myeloid leukemia (CML) is a myeloproliferative disorder arising from an oncogenic Bcr-Abl tyrosine kinase. Inhibitors of this oncogene by small molecules such as imatinib are effective only in 75% of the patient's population. One of the potential strategies to overcome this resistance is to devise combination therapy protocols with other therapeutic agents including PPAR ligands. Since PPAR ligands are potentially interesting in different hematologic malignancies, this article will review the potential of PPAR ligands for use in CML treatment.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Therefore, identification of safe and effective MDR reversing compounds with minimal adverse side effects is an important approach in the cancer treatment. Studies show that peroxisome proliferator-activated receptor (PPARs) ligands can inhibit cell growth in many cancers. Here, we investigated the effect of different PPAR agonists include fenofibrate, troglitazone and aleglitazar on doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. The effects of doxorubicin (DOX) following treatment with PPAR agonists on cell viability were evaluated using MTT assay and the reversal fold (RF) values. Rhodamine123 (Rh123) assays were used to determine P-gp functioning. P-gp mRNA/protein expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis after incubation with troglitazone and aleglitazar. Our results showed that troglitazone and aleglitazar significantly enhanced the cytotoxicity of DOX and decreased the RF values in K562/DOX cells, however, no such results were found for fenofibrate. Troglitazone and aleglitazar significantly down regulated P-gp expression in K562/DOX cells; in addition, the present study revealed that aleglitazar elevated intracellular accumulation of Rh123in K562/DOX cells as short-term effects, which also contribute to the reversal of MDR. These findings show that troglitazone and especially aleglitazar exhibited potent effects in the reversal of P-gp-mediated MDR, suggesting that these compounds may be effective for combination therapy strategies and circumventing MDR in K562/DOX cells to other conventional chemotherapeutic drugs.