Axitinib targeted cancer stemlike cells to enhance efficacy of chemotherapeutic drugs via inhibiting the drug transport function of ABCG2.

Stemlike cells have been isolated by their ability to efflux Hoechst 33342 dye and are called the side population (SP). We evaluated the effect of axitinib on targeting cancer stemlike cells and enhancing the efficacy of chemotherapeutical agents. We found that axitinib enhanced the cytotoxicity of topotecan and mitoxantrone in SP cells sorted from human lung cancer A549 cells and increased cell apoptosis induced by chemotherapeutical agents. Moreover, axitinib particularly inhibited the function of adenosine triphosphate (ATP)-binding cassette subfamily G member 2 (ABCG2) and reversed ABCG2-mediated multidrug resistance (MDR) in vitro. However, no significant reversal effect was observed in ABCB1-, ABCC1- or lung resistance-related protein (LRP)-mediated MDR. Furthermore, in both sensitive and MDR cancer cells axitinib neither altered the expression of ABCG2 at the mRNA or protein levels nor blocked the phosphorylation of AKT and extracellular signal-regulated kinase (ERK)1/2. In nude mice bearing ABCG2-overexpressing S1-M1-80 xenografts, axitinib significantly enhanced the antitumor activity of topotecan without causing additional toxicity. Taken together, these data suggest that axitinib particularly targets cancer stemlike cells and reverses ABCG2-mediated drug resistance by inhibiting the transporter activity of ABCG2.

ABCG2-overexpressing S1-M1-80 cell xenografts in nude mice keep original biochemistry and cell biological properties.

S1-M1-80 cells, derived from human colon carcinoma S1 cells, are mitoxantrone-selected ABCG2-overexpressing cells and are widely used in in vitro studies of multidrug resistance(MDR). In this study, S1-M1-80 cell xenografts were established to investigate whether the MDR phenotype and cell biological properties were maintained in vivo. Our results showed that the proliferation, cell cycle, and ABCG2 expression level in S1-M1-80 cells were similar to those in cells isolated from S1-M1-80 cell xenografts (named xS1-M1-80 cells). Consistently, xS1-M1-80 cells exhibited high levels of resistance to ABCG2 substrates such as mitoxantrone and topotecan, but remained sensitive to the non-ABCG2 substrate cisplatin. Furthermore, the specific ABCG2 inhibitor Ko143 potently sensitized xS1-M1-80 cells to mitoxantrone and topotecan. These results suggest that S1-M1-80 cell xenografts in nude mice retain their original cytological characteristics at 9 weeks. Thus, this model could serve as a good system for further investigation of ABCG2-mediated MDR.

Loss of MED12 Induces Tumor Dormancy in Human Epithelial Ovarian Cancer via Downregulation of EGFR.

A high rate of disease relapse makes epithelial ovarian cancer (EOC) the leading cause of death among all gynecologic malignancies. These relapses are often due to tumor dormancy. Here we identify the RNA polymerase II transcriptional mediator subunit 12 (MED12) as an important molecular regulator of tumor dormancy. MED12 knockout (KO) induced dormancy of EOC cells in vitro and in vivo, and microarray analysis showed that MED12 KO decreased expression of EGFR. Restoration of EGFR expression in MED12 KO cells restored proliferation. Additionally, MED12 bound to the promoter of EGFR, and correlation studies showed that MED12 expression positively correlated with EGFR expression in EOC patient samples. Clinical data demonstrated that chemotherapy-resistant patients expressed lower levels of MED12 compared with responsive patients. Overall, our data show that MED12 plays an important role in regulating dormancy of EOC through regulation of EGFR.Significance: MED12 is identified as a novel, important regulator of tumor dormancy in human ovarian cancer. Cancer Res; 78(13); 3532-43. ©2018 AACR.

P-glycoprotein is not involved in pathway of anti-Fas/Fas-induced apoptosis in KBv200 cells.

AIM: To verify whether P-glycoprotein (P-gp) could induce cell resistance to apoptosis by inhibiting caspase-8 and caspase-3. METHODS: Human KB cells, either drug-sensitive or with multidrug resistance (MDR) phenotype caused by overexpression of P-gp (KBv200 cells), were treated with anti-Fas (CH-11 monoclonal antibody) to induce apoptosis. Cytotoxicity was detected by MTT assay. Symptoms of cell death were assessed by morphological observation after Hoechst33258 staining, activation of caspase-8 and caspase-3 was measured by Western blotting. RESULTS: Compared with KB cells, the resistance of KBv200 cells to VCR (vincristine) was about 51-fold higher. Anti-Fas (CH-11) induced cytotoxicity and apoptosis in both sensitive KB cells and MDR phenotype KBv200 cells. The IC50 of CH-11 in KB cells was similar to that in KBv200 cells. CH-11 induced similar apoptotic rates in both KB cells and KBv200 cells, which could be classified as caspase-dependent apoptotic pathway. Verapamil (VRP) did not affect CH-11-mediated apoptosis in KBv200 cells. CONCLUSION: Expression of P-glycoprotein does not induce resistance to caspase-8 and -3 activation or anti-Fas-induced cell apoptosis.

Screening novel, potent multidrug-resistant modulators from imidazole derivatives.

The overexpression of P-glycoprotein (P-gp) by tumor cells results in multidrug resistance (MDR) to structurally unrelated anticancer drugs. Combined therapy with MDR-related cytotoxins and MDR modulators is a promising strategy to overcome clinical MDR. This study was designed to screen potent MDR modulators from imidazole derivatives. Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The intracellular accumulation of doxorubicin (Dox) was detected by fluorescence spectrophotometry. The function of P-gp was examined by Rhodamine 123 accumulation detected with flow cytometry (FCM). Among imidazole derivatives, FG020326, FG020327, and FG020318 were found to possess three- to fourfold stronger reversal MDR activity than verapamil, a well-known positive MDR modulator. Imidazole derivatives significantly increased the Dox accumulation and inhibited P-gp function exhibited by the increase of Rhodamine accumulation in MDR cells. The fold reversal of MDR was relative with the increase of Rhodamine accumulation. FG020326, FG020327, and FG020318 showed potent MDR reversal activity in vitro. Their mechanism of MDR reversal is associated with the inhibition of P-gp function and the increase of anticancer accumulation. These results suggest FG020326, FG020327, and FG020318 are promising to further study and develop.

[The discordant results in serum through reverse syphilis screening algorithm].

OBJECTIVE: The emerging reverse sequence on syphilis screening program generates special discordant results, characterized with the appearance of both positive treponemal test and negative nontreponemal test at the same time. The aim of this study was to analyze the characteristics of the discordant results among low syphilis prevalence population in China, to provide evidence for improving the process of reverse sequence syphilis screening program. METHODS: Laboratory data was retrospectively analyzed, under reverse sequence screening algorithm selecting ELISA as the initial screening test for syphilis. All the screening reactive samples were tested by TPPA for confirmation and by quantitative TRUST for the reactivity of syphilis. RESULTS: 666 out of a total of 21 049 serum samples were reactive under the screening program. Among the 666 reactive samples, 169 were reactive to TRUST. One in the 169 samples was confirmed negative on TPPA, and the faulse positive rate on ELISA was 0.6% (1/169). In those 666 reactive samples, 497 were nonreactive to TRUST. 74 in the 497 samples were confirmed negative to TPPA, with faulse positive rate of ELISA as 14.9% (74/497). In the group of 591 TPPA confirmed positive samples, the TRUST negative rate was found 71.6% (423/591), significantly higher than the TRUST positive rate(chi-square test, χ(2) = 110.025, P = 0.000). CONCLUSION: Among the results from reverse sequence syphilis screening program, majority of the samples which showed positive treponemal antibody, would have negative nontreponemal antibody. We therefore recommended a more reasonable reverse sequence syphilis algorithm to be used. Faulse positivity could be eliminated if TPPA was performed on all screening reactive samples by ELISA a first and then followed by quantitative TRUST on samples that were TPPA confirmed as positive.

Effect of dicycloplatin, a novel platinum chemotherapeutical drug, on inhibiting cell growth and inducing cell apoptosis.

Dicycloplatin, a new supramolecular platinum-based antitumor drug, has been approved by the State Food and Administration (SFDA) of China. In this study, we investigated the anticancer activity of dicycloplatin in cancer cells and signaling pathways involved in dicycloplatin-induced apoptosis. Dicycloplatin inhibited the proliferation of cancer cells and increased the percentage of apoptosis in a concentration-dependent manner. Besides, some apoptosis related events were observed after treatment with dicycloplatin, including increase of reactive oxygen species (ROS), collapse of mitochondrial membrane potential (Δψm), release of cytochrome c from the mitochondria to the cytosol, upregulation of p53, which were accompanied by activation of caspase-9, caspase-3, caspase-8, and poly (ADP-ribose) polymerase cleavage in a concentration-dependent manner. The role of apoptosis in dicycloplatin-mediated cell death was further confirmed by the concomitant treatment with caspase-8 or caspase-9 inhibitors, which inhibited apoptosis and PARP cleavage. Intracellular glutathione (GSH) was also found to inhibit the cytotoxic effect of dicycloplatin. In conclusion, these findings suggest that dicycloplatin induces apoptosis through ROS stress-mediated death receptor pathway and mitochondrial pathway which is similar to carboplatin.

Prognostic value of the multidrug resistance transporter ABCG2 gene polymorphisms in Chinese patients with de novo acute leukaemia.

BACKGROUND: Functional polymorphisms of the ABCG2 gene may contribute to individual variability in drug response and the prognosis of patients. METHODS: In the present study, the genetic polymorphisms and expression of ABCG2 were analysed in blasts cells obtained from 184 Chinese patients with de novo acute leukaemia to investigate their possible association with clinical outcomes. RESULTS: A novel synonymous ABCG2-single nucleotide polymorphism (SNP) at exon 16 (13561218 C/T) and five known SNPs at exon 2 (13608835 G/A), exon 5 (13600044 C/A), intron 10 (13576005 C/T), intron 13 (13564503 C/T) and intron 14 (13563578 A/G) were identified with occurrence rates of 1.1%, 64.1%, 30.4%, 21.2%, 39.7% and 28.8%, respectively. We found that patients with the ABCG2 34GG genotype displayed longer disease free survival (DFS) (P<0.001) and overall survival (OS) (P<0.001) than those with the 34GA/AA genotypes. Furthermore, the DFS and OS were significantly diminished in bone marrow transplantation (BMT) patients with the 34GA/AA genotypes relative to those with the 34GG genotype. CONCLUSIONS: These results suggest that these highly prevalent ABCG2 34GA/AA genotypes are associated with poor prognosis of Chinese patients with acute leukaemia and BMT patients.

[Pathogen spectrum and drug resistance of spit samples from cancer patients].

BACKGROUND & OBJECTIVE: Some cancer patients were not died of cancer, but died of infection after operation, chemotherapy, radiotherapy, or interventional treatment. This study was to investigate the pathogen spectrum and drug resistance of spit samples from cancer patients. METHODS: The pathogen spectrum and drug resistance of 955 positive spit samples from cancer patients were analyzed with WHONET-5 statistical software. RESULTS: The detection rates were 43.3% for fungus (mainly included C.albicans), 31.2% for Gram-positive coccus (mainly included coagulase-negative Staphylococcus), and 25.5% for Gram-negative bacillus (mainly included P.aeruginosa and K.pneumonia). Drug sensitivity test showed that fungus was sensitive to amphotericin B, but resistant against categorical azoles; Gram-positive coccus was highly sensitive to vancomycin, but highly resistant against oxacillin, penicillin and erythromycin; Gram-negative bacillus was highly sensitive to impanel, but highly resistant against the first and second generations of cephalosporin such as ampicillin and piperacillin. CONCLUSIONS: The pathogen spectrum of cancer patients with nosocomial infection mainly includes fungus, Gram-positive coccus, and Gram-negative coccus. Treating cancer patients with antibiotics should be based on drug sensitivity test.