Co-treatment With Aripiprazole and Vincristine Sensitizes P-Glycoprotein-Overexpressing Drug-resistant MCF-7/ADR Breast Cancer Cells.

BACKGROUND/AIM: Evidence supports that use of aripiprazole sensitizes drug-resistant oral cancer cells. The aim of the study was to investigate whether aripiprazole can achieve sensitization of highly drug-resistant breast cancer cells, as well as identify its relevant mechanisms of action. MATERIALS AND METHODS: MCF-7/ADR, KB, and KBV20C breast cancer cells were treated with aripiprazole, vincristine (VIC), vinorelbine, vinblastine and their combination. Cell viability assay, annexin V analyses, cellular morphology and density observation with a microscope, western-blotting, fluorescence-activated cell sorting (FACS), and analysis for P-gp inhibitory activity were performed to investigate the drugs' mechanism of action. RESULTS: We found that high drug resistance in MCF-7/ADR cells results from high P-gp inhibitory activity via overexpression of P-gp. Aripiprazole reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. Furthermore, we demonstrated that co-treatment with vinorelbine and vinblastine increased the sensitization of MCF-7/ADR breast cancer cells to aripiprazole. We confirmed that VIC-aripiprazole combination has much higher sensitization effects than either VIC-thioridazine or VIC-trifluoperazine co-treatment in MCF-7/ADR cells, since the previously known bipolar drugs (thioridazine and trifluoperazine) has lower P-gp inhibitory activity. However, aripiprazole-induced sensitization was not observed in VIC-treated MDA-MB-231 breast cancer cells suggesting that combination therapy with aripiprazole is specific for P-gp-overexpressing drug-resistant breast cancer cells. CONCLUSION: Co-treatment with low doses of aripiprazole sensitized MCF-7/ADR cells to VIC. Combination therapy with aripiprazole may be a valuable tool for delaying or reducing cancer recurrence by targeting P-gp-overexpressing drug-resistant breast cancer cells.

Dendropanoxide Alleviates Thioacetamide-induced Hepatic Fibrosis via Inhibition of ROS Production and Inflammation in BALB/C Mice.

Hepatic fibrosis results from overproduction and excessive accumulation of extracellular matrix (ECM) proteins in hepatocytes. Although the beneficial effects of dendropanoxide (DPx) isolated from Dendropanax morbifera have been studied, its role as an anti-fibrotic agent remains elucidated. We investigated the protective effect of DPx in BALB/C mice that received thioacetamide (TAA) intraperitoneally for 6 weeks. Later DPx (20 mg/kg/day) or silymarin (50 mg/kg/day) was administered daily for 6 weeks, followed by biochemical and histological analyses of each group. Hematoxylin and eosin staining of the livers showed TAA-induced hepatic fibrosis, which was significantly reduced in the DPx group. DPx treatment significantly decreased TAA-induced hyperlipidemia as evidenced by the decreased AST, ALT, ALP, γ-GTP and serum TG concentrations and reduced the activities of catalase (CAT) and superoxide dismutase (SOD) activity. ELISA revealed reduced levels of total glutathione (GSH), malondialdehyde (MDA) and Inflammatory factors (IL-6, IL-1ß, and TNF-α). Immunostaining showed reduced in collagen-1, α-SMA, and TGF-ß1 expression and western blotting showed reduced levels of the apoptotic proteins, TGF-ß1, p-Smad2/3, and Smad4. RT-qPCR and Western blotting revealed modifications in SIRT1, SIRT3 and SIRT4. Thus, DPx exerted a protective effect against TAA-induced hepatic fibrosis in the male BALB/C mouse model by inhibiting oxidative stress, inflammation, and apoptosis via TGF-ß1/Smads signaling.

First-Line Combination Treatment with Low-Dose Bipolar Drugs for ABCB1-Overexpressing Drug-Resistant Cancer Populations.

Tumors include a heterogeneous population, of which a small proportion includes drug-resistant cancer (stem) cells. In drug-sensitive cancer populations, first-line chemotherapy reduces tumor volume via apoptosis. However, it stimulates drug-resistant cancer populations and finally results in tumor recurrence. Recurrent tumors are unresponsive to chemotherapeutic drugs and are primarily drug-resistant cancers. Therefore, increased apoptosis in drug-resistant cancer cells in heterogeneous populations is important in first-line chemotherapeutic treatments. The overexpression of ABCB1 (or P-gp) on cell membranes is an important characteristic of drug-resistant cancer cells; therefore, first-line combination treatments with P-gp inhibitors could delay tumor recurrence. Low doses of bipolar drugs showed P-gp inhibitory activity, and their use as a combined therapy sensitized drug-resistant cancer cells. FDA-approved bipolar drugs have been used in clinics for a long period of time, and their toxicities are well reported. They can be easily applied as first-line combination treatments for targeting resistant cancer populations. To apply bipolar drugs faster in first-line combination treatments, knowledge of their complete information is crucial. This review discusses the use of low-dose bipolar drugs in sensitizing ABCB1-overexpressing, drug-resistant cancers. We believe that this review will contribute to facilitating first-line combination treatments with low-dose bipolar drugs for targeting drug-resistant cancer populations. In addition, our findings may aid further investigations into targeting drug-resistant cancer populations with low-dose bipolar drugs.

Low-dose Pimecrolimus, an FDA-approved Calcineurin Inhibitor, Sensitizes Drug-resistant Cancer Cells via Strong P-gp Inhibition.

BACKGROUND/AIM: Co-treatment with calcineurin inhibitors, such as tacrolimus and cyclosporin A, can sensitize chemotherapy-resistant cancer cells with P-glycoprotein (P-gp)-over-expression. Pimecrolimus (PIME) is a clinically available calcineurin inhibitor with a structure similar to that of tacrolimus. Whether PIME can sensitize P-gp-over-expressing resistant cancer cells remains unclear. MATERIALS AND METHODS: Cell viability assay, annexin V analyses, cellular morphology and density observation with a microscope, western-blotting, fluorescence-activated cell sorting (FACS), and analysis for P-gp inhibitory activity were performed to investigate the mechanism of action. RESULTS: PIME exhibited strong cytotoxicity to vincristine (VIC)-treated drug-resistant cell lines (KBV20C and MCF-7/ADR) over-expressing P-gp. Co-treatment with VIC and PIME increased apoptosis and down-regulated the ERK signaling pathway, resulting in G2 arrest. PIME could be co-administered with vinorelbine or eribulin to sensitize resistant KBV20C or MCF-7/ADR cancer cells. Moreover, PIME strongly inhibited the efflux of both rhodamine 123 and calcein-AM substrates through P-gp after 4 h of treatment, indicating that VIC+PIME sensitized cancer cells by inhibiting VIC efflux via direct PIME binding to P-gp. Low doses of PIME, tacrolimus, and cyclosporin A showed similar sensitizing efficiencies in resistant KBV20C cells. These drugs showed similar P-gp inhibitory activities using both rhodamine 123 and calcein-AM substrates, suggesting that calcineurin inhibitors generally have strong P-gp inhibitory activities that sensitize drug-resistant cancer cells with P-gp over-expression. CONCLUSION: PIME, currently used in clinics, can be repositioned for treating patients with P-gp-over-expressing resistant cancer (stem) cells.

Terconazole, an Azole Antifungal Drug, Increases Cytotoxicity in Antimitotic Drug-Treated Resistant Cancer Cells with Substrate-Specific P-gp Inhibitory Activity.

Azole antifungal drugs have been shown to enhance the cytotoxicity of antimitotic drugs in P-glycoprotein (P-gp)-overexpressing-resistant cancer cells. Herein, we examined two azole antifungal drugs, terconazole (TCZ) and butoconazole (BTZ), previously unexplored in resistant cancers. We found that both TCZ and BTZ increased cytotoxicity in vincristine (VIC)-treated P-gp-overexpressing drug-resistant KBV20C cancer cells. Following detailed analysis, low-dose VIC + TCZ exerted higher cytotoxicity than co-treatment with VIC + BTZ. Furthermore, we found that VIC + TCZ could increase apoptosis and induce G2 arrest. Additionally, low-dose TCZ could be combined with various antimitotic drugs to increase their cytotoxicity in P-gp-overexpressing antimitotic drug-resistant cancer cells. Moreover, TCZ exhibited P-gp inhibitory activity, suggesting that the inhibitory activity of P-gp plays a role in sensitization afforded by VIC + TCZ co-treatment. We also evaluated the cytotoxicity of 12 azole antifungal drugs at low doses in drug-resistant cancer cells. VIC + TCZ, VIC + itraconazole, and VIC + posaconazole exhibited the strongest cytotoxicity in P-gp-overexpressing KBV20C and MCF-7/ADR-resistant cancer cells. These drugs exerted robust P-gp inhibitory activity, accompanied by calcein-AM substrate efflux. Given that azole antifungal drugs have long been used in clinics, our results, which reposition azole antifungal drugs for treating P-gp-overexpressing-resistant cancer, could be employed to treat patients with drug-resistant cancer rapidly.

Glycolytic Metabolic Remodeling by the Truncate of Glioma-Associated Oncogene Homolog 1 in Triple-Negative Breast Cancer Cells.

Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. In particular, terminal effectors of the Hh signaling pathway are associated with the regulation of glioma-associated oncogene homolog 1 (GLI1) transcription factors. Overexpression of GLI1 is closely associated with poor prognosis in breast cancer. The Hh-GLI1 signaling pathway is activated and participates in the tumorigenesis and progression of breast cancer, especially in the aggressive subtype of triple-negative breast cancer (TNBC). However, the role of GLI1 in regulating TNBC metabolism remains unclear. This study aimed to explore the functional role of GLI1 in glycolytic metabolism in TNBC. Immunohistochemical analysis of GLI1 expression in a tissue microarray revealed significant correlations between GLI1 expression and advanced tumor stage and grade. GLI1 expression levels were drastically increased in MDA-MB-231 cells compared to those in other cell lines. Inhibition of GLI1 expression using GLI1 small interfering RNA (siRNA) in MDA-MB-231 cells resulted in a significant reduction in cell proliferation and induced cell cycle arrest at the G1 phase. Furthermore, GLI1 downregulation significantly reduced the expression of glycolysis-regulated proteins. GLI1 knockdown resulted in reduced glycolytic rates and extracellular lactate levels. Moreover, metabolic stress after GLI1 knockdown activated the energy sensor, adenosine monophosphate-activated protein kinase, which subsequently resulted in autophagy induction. In conclusion, this study indicates that targeting GLI1 reprograms the tumor glucose metabolism to suppress breast cancer cell growth and proliferation.

Combination Treatment Using Pyruvate Kinase M2 Inhibitors for the Sensitization of High Density Triple-negative Breast Cancer Cells.

BACKGROUND/AIM: Few studies have examined the correlation between pyruvate kinase M2 (PKM2) overexpression and triple-negative breast cancer (TNBC). TNBC is considered incurable with the currently available treatments, highlighting the need for alternative therapeutic targets. MATERIALS AND METHODS: PKM2 expression was examined immunohistochemically in human breast tumor samples. Furthermore, we studied the effect of three PKM2 inhibitors (gliotoxin, shikonin, and compound 3K) in the MDA-MB-231 TNBC cell line. RESULTS: PKM2 overexpression correlates with TNBC. Interestingly, most TNBC tissues showed increased levels of PKM2 compared to those of receptor-positive breast cancer tissues. This suggests that PKM2 overexpression is an important factor in the development of TNBC. MDA-MB-231 TNBC cells are resistant to anticancer drugs, such as vincristine (VIC) compared to other cancer cells. We found that the recently developed PKM2 inhibitor gliotoxin sensitized MDA-MB-231 cells at a relatively low dose to the same extent as the known PKM2 inhibitor shikonin, suggesting that PKM2 inhibitors could be an effective treatment for TNBC. Detailed sensitization mechanisms were also analyzed. Both gliotoxin and shikonin highly increased late apoptosis in MDA-MB-231 cells, as revealed by annexin V staining. However, MDA-MB-231 cells with high cellular density inhibited the sensitizing effect of PKM2 inhibitors; therefore, we investigated ways to overcome this inhibitory effect. We found that gliotoxin+shikonin co-treatment highly increased toxicity in MDA-MB-231 cells with high density, whereas either VIC+gliotoxin or VIC+shikonin were not effective. Thus, combination therapy with various PKM2 inhibitors may be more effective than combination therapy with anticancer drugs. Gliotoxin+shikonin co-treatment did not increase S or G2 arrest in cells, suggesting that the co-treatment showed a high increase in apoptosis without S or G2 arrest. We confirmed that another recently developed PKM2 inhibitor compound 3K had similar mechanisms of sensitizing MDA-MB-231 cells, suggesting that PKM2 inhibitors have similar sensitization mechanisms in TNBC. CONCLUSION: PKM2 is a regulator of the oncogenic function of TNBC, and combination therapy with various PKM2 inhibitors may be effective for high-density TNBC. Targeting PKM2 in TNBC lays the foundation for the development of PKM2 inhibitors as promising anti-TNBC agents.

Low-Dose Rifabutin Increases Cytotoxicity in Antimitotic-Drug-Treated Resistant Cancer Cells by Exhibiting Strong P-gp-Inhibitory Activity.

The cytotoxicity of various antibiotics at low doses in drug-resistant cancer cells was evaluated. Low doses of rifabutin were found to markedly increase the cytotoxicity of various antimitotic drugs, such as vincristine (VIC), to P-glycoprotein (P-gp)-overexpressing antimitotic-drug-resistant KBV20C cells. Rifabutin was also found to exert high levels of P-gp-inhibitory activity at 4 and 24 h posttreatment, suggesting that the cytotoxicity of VIC + rifabutin was mainly due to the direct binding of rifabutin to P-gp and the reduction of VIC efflux by P-gp. The combination of VIC + rifabutin also increased early apoptosis, G2 arrest, and the DNA damaging marker, pH2AX protein. Interestingly, only the combination of VIC + rifabutin induced remarkable levels of cytotoxicity in resistant KBV20C cells, whereas other combinations (VIC + rifampin, VIC + rifapentine, and VIC + rifaximin) induced less cytotoxicity. Such finding suggests that rifabutin specifically increases the cytotoxicity of VIC in KBV20C cells, independent of the toxic effect of the ansamycin antibiotic. Only rifabutin had high P-gp-inhibitory activity, which suggests that its high P-gp-inhibitory activity led to the increased cytotoxicity of VIC + rifabutin. As rifabutin has long been used in the clinic, repositioning this drug for P-gp-overexpressing resistant cancer could increase the availability of treatments for patients with drug-resistant cancer.

Contribution of Cancer-Targeting Drugs toward Faster Clinical Application.

With advances in cancer-targeting therapeutic strategies, cancer cells have developed drug resistance [...].

JAK2 Inhibitor, Fedratinib, Inhibits P-gp Activity and Co-Treatment Induces Cytotoxicity in Antimitotic Drug-Treated P-gp Overexpressing Resistant KBV20C Cancer Cells.

P-glycoprotein (P-gp) overexpression is one of the major mechanisms of multidrug resistance (MDR). Previously, co-treatment with Janus kinase 2 (JAK2) inhibitors sensitized P-gp-overexpressing drug-resistant cancer cells. In this study, we assessed the cytotoxic effects of JAK2 inhibitor, fedratinib, on drug-resistant KBV20C cancer cells. We found that co-treatment with fedratinib at low doses induced cytotoxicity in KBV20C cells treated with vincristine (VIC). However, fedratinib-induced cytotoxicity was little effect on VIC-treated sensitive KB parent cells, suggesting that these effects are specific to resistant cancer cells. Fluorescence-activated cell sorting (FACS), Western blotting, and annexin V analyses were used to further investigate fedratinib's mechanism of action in VIC-treated KBV20C cells. We found that fedratinib reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. G2 phase arrest and apoptosis in VIC-fedratinib-co-treated cells resulted from the upregulation of p21 and the DNA damaging marker pH2AX. Compared with dimethyl sulfoxide (DMSO)-treated cells, fedratinib-treated KBV20C cells showed two-fold higher P-gp-inhibitory activity, indicating that VIC-fedratinib sensitization is dependent on the activity of fedratinib. Similar to VIC, fedratinib co-treatment with other antimitotic drugs (i.e., eribulin, vinorelbine, and vinblastine) showed increased cytotoxicity in KBV20C cells. Furthermore, VIC-fedratinib had similar cytotoxic effects to co-treatment with other JAK2 inhibitors (i.e., VIC-CEP-33779 or VIC-NVP-BSK805) at the same dose; similar cytotoxic mechanisms (i.e., early apoptosis) were observed between treatments, suggesting that co-treatment with JAK2 inhibitors is generally cytotoxic to P-gp-overexpressing resistant cancer cells. Given that fedratinib is FDA-approved, our findings support its application in the co-treatment of P-gp-overexpressing cancer patients showing MDR.

Co-treatment of Low Dose Pacritinib, a Phase III Jak2 Inhibitor, Greatly Increases Apoptosis of P-gp Over-expressing Cancer Cells With Multidrug Resistance.

BACKGROUND/AIM: The over-expression of P-glycoprotein (P-gp) is a major mechanism underlying multidrug resistance (MDR). Co-treatment with Janus kinase 2 (Jak2) inhibitors sensitizes P-gp-over-expressing drug-resistant cancer cells. In this study, we evaluated pacritinib, a Jak2 inhibitor currently in phase III clinical trials. MATERIALS AND METHODS: Microscopic observation, cell viability assay, colony forming assay, rhodamine uptake tests, annexin V analyses, fluorescence-activated cell sorting (FACS), and western-blot analysis were performed to further investigate the mechanism of action. RESULTS: We found that pacritinib reduced cell viability, induced G2 arrest, and upregulated early apoptosis when administered to P-gp-over-expressing resistant KBV20C cells with vincristine (VIC). Moreover, apoptosis and G2 arrest in VIC-pacritinib-treated cells were involved in the upregulation of pH2AX expression. Pacritinib had an approximately 2-fold higher P-gp-inhibitory activity than the dimethyl sulfoxide (DMSO)-treated control, indicating that VIC-pacritinib sensitization involves the P-gp-inhibitory effects of pacritinib. Similar to VIC, other antimitotic drugs (vinorelbine, vinblastine, and eribulin) could also sensitize against KBV20C cells by co-treatment with pacritinib. Furthermore, comparison of pacritinib with previously characterized Jak2 inhibitors revealed that the VIC-pacritinib combination had sensitization effects similar to those of VIC- CEP-33779 or VIC-NVP-BSK805 combinations at lower doses in KBV20C cells. Generally, Jak2 inhibitor and VIC co-treatment sensitized P-gp-over-expressing resistant cancer cells by inducing early apoptosis. CONCLUSION: Collectively, pacritinib, induced G2 arrest, reduced cell viability, had high P-gp inhibitory activity, and upregulated the expression of pH2AX when used in combination with VIC. As pacritinib is a Jak2 inhibitor currently in phase III clinical trials, our findings may facilitate the application of this co-treatment in patients with MDR cancer.

PKM2 Is Overexpressed in Glioma Tissues, and Its Inhibition Highly Increases Late Apoptosis in U87MG Cells With Low-density Specificity.

BACKGROUND/AIM: Pyruvate kinase M2 (PKM2) functions as an important rate-limiting enzyme in aerobic glycolysis and is involved in tumor initiation and progression. However, there are few studies on the correlation between PKM2 expression and its role in glioma. MATERIALS AND METHODS: PKM2 expression was immunohistochemically examined in human brain tumor samples. Furthermore, we studied the effects of two PKM2 inhibitors (shikonin and compound 3K) on the U87MG glioma cell line. RESULTS: PKM2 was overexpressed in most glioma tissues when compared to controls. Interestingly, glioma-adjacent tissues from showed slight PKM2 overexpression. This suggests that PKM2 overexpression maybe an important trigger factor for glioma tumorigenesis. We found that the PKM2 inhibitor shikonin was effective against U87MG cells at a relatively low dose and was largely dependent on low cellular density compared to the effects of the anticancer drug vincristine. Shikonin highly increased late-apoptosis of U87MG cells. We also demonstrated that autophagy was involved in the increase in late-apoptosis levels caused by shikonin. Although vincristine treatment led to a high level of G2-phase arrest in U87MG cells, shikonin did not increase G2 arrest. Co-treatment with two PKM2 inhibitors, shikonin and compound 3K, increased the inhibitory effects. CONCLUSION: Combination therapy with PKM2 inhibitors together might be more effective than combination therapy with anticancer drugs. Our findings encourage the application of PKM2-targeting in gliomas, and lay the foundation for the development of PKM2 inhibitors as promising antitumor agents for glioma.

Using intracellular metabolic profiling to identify novel biomarkers of cisplatin-induced acute kidney injury in NRK-52E cells.

The aim of this study was to investigate changes in the intracellular metabolism resulting from cisplatin (CDDP)-induced nephrotoxicity in normal kidney tubular epithelial NRK-52E cells. Cytotoxicity, cell cycle analysis, and apoptotic cell death were all evaluated in NRK-52E cells treated with CDDP. Subsequently, proton nuclear magnetic resonance (1H-NMR) spectroscopy was used to investigate cellular metabolic profiles. CDDP-induced nephrotoxicity was determined in vivo model. Cytotoxicity in the NRK-52E cells significantly rose following treatment with CDDP and these increases were found to be concentration-dependent. Both p53 and Bax protein expression was increased in CDDP-treated NRK-52E cells, correlating with enhanced cellular apoptosis. In addition, a number of metabolites were altered in both media and cell lysates in these cells. In cell lysates, citrate, creatinine, and acetate levels were dramatically reduced following treatment with 20 µM CDDP concentrations, while glutamate level was elevated. Lactate and acetate levels were significantly increased in culture media but citrate concentrations were reduced following high 20 µM CDDP concentrations incubation. In addition, excretion of clusterin, calbindin, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), selenium binding protein 1 (SBP1), and pyruvate kinase M2 (PKM2) into the culture media was significantly increased in CDDP-treated cells while expression of acetyl CoA synthetase 1 (AceCS1) was markedly reduced in these cells. These findings suggest that acetate-dependent metabolic pathway may be a reliable and useful biomarker for detecting CDDP-induced nephrotoxicity. Taken together, data demonstrate that the discovery of novel biomarkers by metabolite profiling in target cells may contribute to the detection of nephrotoxicity and new drug development.

Sensitization Effects of Repurposed Blood Pressure-regulating Drugs on Drug-resistant Cancer Cells.

BACKGROUND/AIM: We investigated drugs that could sensitize KBV20C cancer cells resistant to eribulin or vincristine (VIC) treatment and assessed their associated mechanisms of action. MATERIALS AND METHODS: Such cancer cells were known to overexpress P-glycoprotein (P-gp). Considering that reserpine (P-gp inhibitor) plays a regulatory role in patients with high blood pressure, we investigated the effect of low doses of 27 blood pressure-regulating drugs on VIC-resistant KBV20C cells. This was done to identify drugs that could be repurposed for sensitizing antimitotic drug-resistant KBV20C cells at relatively low doses. Fluorescence-activated cell sorting (FACS), annexin V analyses, rhodamine uptake tests and western-blot analysis were performed to further investigate the mechanism of action of such drugs. RESULTS: We found that co-treatment with amiodarone, nicardipine, carvedilol, or vardenafil at low doses could highly sensitize KBV20C cells treated with eribulin or VIC. These drugs reduced cellular viability, increased G2 arrest and up-regulated apoptosis when co-administered with eribulin or VIC. Considering that they sensitize with either co-treatment of eribulin or VIC, we assumed that they can be combined with other antimitotic drugs to sensitize the resistant cancer cells. Through detailed quantitative analysis, we found that eribulin with amiodarone had a higher sensitization effect than eribulin with nicardipine or eribulin with carvedilol. We found that reserpine had the highest P-gp-inhibitory activity, indicating that eribulin- or VIC-reserpine sensitization involves the P-gp inhibitory effects of reserpine. However, we found that amiodarone, nicardipine, carvedilol and vardenafil had very low P-gp inhibitory activity. Moreover, we found that cells co-treated with VIC-carvedilol down-regulated expression of pERK. CONCLUSION: Highly antimitotic drug-resistant KBV20C cells can be sensitized by co-treatment with the repurposed blood pressure-regulating drugs amiodarone, nicardipine, carvedilol or vardenafil. These findings indicate that the repurposed blood pressure-regulating drugs may potentially be used in drug-resistant cancer patients without any toxic effects due to P-gp inhibition.

Drug Repositioning With an Anticancer Effect: Contributions to Reduced Cancer Incidence in Susceptible Individuals.

Certain diseases and age groups are associated with a higher incidence of cancer. Cancer prevention can be achieved using repositioned drugs that have anticancer ability, thereby reducing the incidence of cancer in susceptible individuals. This implies that the selection of repositioned drugs can have dual benefits: controlling pre-existing diseases and facilitating cancer prevention. This report outlines the rationale underlying drug repositioning for medications with an anticancer effect and discusses its advantages. We discuss repositioned drugs with anticancer effects that may contribute to cancer prevention in susceptible individuals and the general population with temporary, treatable conditions. The discussion of drug repositioning in this review should facilitate the initiation of clinical trials and lead to therapeutic application of such drugs to reduce the incidence of cancer in susceptible individuals.

A Low Dose of Aripiprazole Has the Strongest Sensitization Effect Among 19 Repositioned Bipolar Drugs in P-gp-overexpressing Drug-resistant Cancer Cells.

BACKGROUND/AIM: We investigated drugs that could sensitize P-glycoprotein (P-gp)-overexpressing drug-resistant cancer cells to vincristine (VIC) or eribulin treatment and assessed their associated mechanisms of action. MATERIALS AND METHODS: We investigated 15 bipolar drugs (quetiapine, risperidone, clozapine, asenapine, iloperidone, paliperidone, ziprasidone, trifluoperazine, loxapine succinate, pilocarpine, valproic acid, carbamazepine, levetiracetam, topiramate, and felbamate) to identify drugs with a sensitizing effect on VIC-resistant KBV20C cells at relatively low doses. Fluorescence-activated cell sorting (FACS), annexin V analyses, and rhodamine uptake tests were performed to further investigate the mechanism of action. RESULTS: We found that co-treatment with half the tested drugs (quetiapine, iloperidone, trifluoperazine, loxapine, risperidone, ziprasidone, or felbamate) at low doses could highly sensitize VIC-resistant KBV20C cells. With lower amounts of the bipolar drugs or VIC, we found that among the 15 bipolar drugs tested, 2 combinations (VIC-quetiapine and VIC-trifluoperazine) had much higher sensitization effects, suggesting that lower effective doses were sufficient for sensitizing P-gp-overexpressing resistant cells compared to those required with the other drugs. Furthermore, when we compared quetiapine and trifluoperazine to previously known bipolar drugs (fluphenazine, thioridazine, pimozide, or aripiprazole), we found that aripiprazole, administered at lower doses, had a much higher sensitization effect. We also demonstrated that co-treatment with another anti-mitotic drug (eribulin) increased the sensitization of KBV20C cells similar to VIC. We also found that aripiprazole had higher P-gp-inhibitory activity than the other bipolar drugs, indicating that this activity was involved in the higher level of VIC-aripiprazole sensitization. CONCLUSION: Co-treatment of anti-mitotic drug-resistant cancer cells with a low dose of aripiprazole had the strongest sensitization effect and is highly dependent on P-gp-inhibitory activity.

Biological Evaluation of Oxindole Derivative as a Novel Anticancer Agent against Human Kidney Carcinoma Cells.

Renal cell carcinoma has emerged as one of the leading causes of cancer-related deaths in the USA. Here, we examined the anticancer profile of oxindole derivatives (SH-859) in human renal cancer cells. Targeting 786-O cells by SH-859 inhibited cell growth and affected the protein kinase B/mechanistic target of rapamycin 1 pathway, which in turn downregulated the expression of glycolytic enzymes, including lactate dehydrogenase A and glucose transporter-1, as well as other signaling proteins. Treatment with SH-859 altered glycolysis, mitochondrial function, and levels of adenosine triphosphate and cellular metabolites. Flow cytometry revealed the induction of apoptosis and G0/G1 cell cycle arrest in renal cancer cells following SH-859 treatment. Induction of autophagy was also confirmed after SH-859 treatment by acridine orange and monodansylcadaverine staining, immunocytochemistry, and Western blot analyses. Finally, SH-859 also inhibited the tumor development in a xenograft model. Thus, SH-859 can serve as a potential molecule for the treatment of human renal carcinoma.

Low-Dose Crizotinib, a Tyrosine Kinase Inhibitor, Highly and Specifically Sensitizes P-Glycoprotein-Overexpressing Chemoresistant Cancer Cells Through Induction of Late Apoptosis in vivo and in vitro.

We investigated possible conditions or drugs that could target P-glycoprotein (P-gp)-overexpressing drug-resistant KBV20C cancer cells. Specifically, we focused on identifying a single treatment with a relatively low half maximal inhibitory concentration (IC50). Our approach utilized repurposing drugs, which are already used in clinical practice. We evaluated 13 TKIs (gefitinib, imatinib, erlotinib, nilotinib, pazopanib, masatinib, sunitinib, sorafenib, regorafenib, lapatinib, vandetanib, cediranib, and crizotinib) for their sensitizing effects on P-gp-overexpressing drug-resistant KBV20C cells. We found that crizotinib had a much greater sensitization effect than the other tested drugs at relatively low doses. In a detailed quantitative analysis using both lower doses and time-duration treatments, we demonstrated that crizotinib, which increased the levels of apoptosis and G2 arrest, was the best TKI to induce sensitization in P-gp-overexpressing KBV20C cells. Upon comparing resistant KBV20C cells and sensitive KB parent cells, crizotinib was found to markedly sensitize drug-resistant KBV20C cancer cells compared with other TKIs. This suggests that crizotinib is a resistant cancer cell-sensitizing drug that induces apoptosis. In mice bearing xenografted P-gp-overexpressing KBV20C cells, we confirmed that crizotinib significantly reduced tumor growth and weight, without apparent side effects. In addition, although lapatinib and crizotinib have a high P-gp inhibitory activity, we found that co-treatment with crizotinib and vincristine (VIC) did not have much of a sensitization effect on KBV20C cells, whereas lapatinib had a high sensitization effect on VIC-treated KBV20C cells. This suggests that crizotinib is a single-treatment specific drug for resistant cancer cells. These findings provide valuable information regarding the sensitization of drug-resistant cells and indicate that low-dose crizotinib monotherapy may be used in patients with specific P-gp-overexpressing chemoresistant cancer.

Risk assessment of unintentional phthalates contaminants in cosmetics.

A risk assessment was performed for three types of phthalates, benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), and di(2-ethylhexyl)phthalate (DEHP) unintentionally contaminated in cosmetics. A total of 100 products of 8 types of cosmetics were analyzed employing gas chromatography-mass spectrometry (GC-MS). By applying the maximum detected values of phthalates based on the worst exposure cases, their systemic exposure dosage (SED) was calculated. Accordingly, DEHP was identified as the main unintentional phthalates contaminants (0.10-600.00 ppm) in the cosmetics, with an SED of 3.37 × 10-9-3.75 × 10-4 mg/kg/day. In the non-cancer risk assessment, a margin of safety (MOS ≥ 100, safe) of 1.28 × 104-1.42 × 109 was estimated. In the cancer risk assessment, the lifetime cancer risk (LCR ≤ 10-5, safe) was determined to be 8.81 × 10-12-9.79 × 10-7. Based on the results of both risk assessments, the levels of unintentional phthalates contaminants in cosmetics were deemed safe. Some phthalates are widely used as plasticizers and are essential for daily life; however, various toxicities, including endocrine disruption, have been reported. Therefore, even under these "worst case" assumptions, an adequate margin of safety is shown such that this might be a low priority for further work although exposure to unintentional phthalates contaminants through cosmetics should be considered as part of cumulative exposure.