Highly Halaven-Resistant KBV20C Cancer Cells Can Be Sensitized by Co-Treatment with Fluphenazine JI HYUN CHEON, BYUNG MU LEE, HYUNG SIK KIM and SUNGPIL YOON
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ANTICANCER RESEARCH 36 : 5867-5874 (2016) doi:10.21873/anticanres.11172 Highly Halaven-resistant KBV20C Cancer Cells Can Be Sensitized by Co-treatment with Fluphenazine JI HYUN CHEON, BYUNG MU LEE, HYUNG SIK KIM and SUNGPIL YOON School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea Abstract. Aim: To identify conditions that induce an increase developed and used in the clinic to treat resistant or metastatic in the sensitivity of highly Halaven (HAL)-resistant cancer cells cancer. HAL has been developed to overcome the resistance compared to sensitive cells. Materials and Methods: We of cancer cells to routinely used antimitotic drugs. HAL observed that drug-resistant KBV20C cells are highly resistant targets the depolymerization of microtubules (5, 6). HAL is to HAL compared to other antimitotic drugs. The concentration considered a promising drug for triple-negative breast cancer required to treat KBV20C cells was almost 500-fold higher than or certain resistant cancers (7, 8). Since patients are expected that used to treat sensitive parent KB cells. In order to increase to develop resistance to HAL, identifying the mechanism(s) sensitization, HAL-treated KBV20C cells were co-treated with that underlie cell sensitization to HAL would be an important the repositioned drug, fluphenazine (FLU). Results: HAL and step in the development of more effective treatments by FLU co-treatment inhibited the growth and increased apoptosis designing approaches to increase HAL-associated apoptosis. via G 2 arrest in HAL-treated KBV20C cancer cells. In the present study, we determined that P-glycoprotein Sensitization by HAL-FLU affected retinoblastoma protein (P-gp)-overexpressing KBV20C cells are highly resistant to (pRB), pHistone H3 and pH2AX protein levels. FLU could also HAL compared to their resistance to other antimitotic drugs. inhibit p-glycoprotein (P-gp) activity in HA-resistant KBV20C Fluphenazine (FLU) was used as a neuroleptic or anti-emetic cells. These observations suggest that the mechanisms agent (9, 10). However, FLU has been recently shown to underlying FLU-HAL sensitization in resistant KBV20C cells inhibit P-gp and is considered an anti-cancer involve both apoptosis and P-gp inhibition. Furthermore, both chemopreventive agent (11, 12). We then tested whether co- thioridazine (THIO) and mefloquine (MEF), but not treatment using HAL and FLU increases the sensitivity of azathioprine (AZA), sensitized HAL-treated KBV20C cells. highly HAL-resistant KBV20C cells. We further investigated Conclusion: These findings provide important information the mechanism underlying HAL-FLU sensitization using regarding the sensitization of HAL-resistant cells and indicate various apoptotic assays and molecular signatures to that FLU, THIO and MEF may have similar sensitization effects determine the factors involved in the effects observed in in highly HAL-resistant cells. HAL-resistant cancer cells co-treated with HAL and FLU. Additionally, we tested whether co-treatment with Antimitotic drugs, which target different binding sites on thioridazine (THIO), azathioprine (AZA) or mefloquine tubulin, are widely used for treating different cancers (1, 2). (MEF) sensitized HAL-treated KBV20C cells. Since these These compounds inhibit mitosis by targeting microtubules drugs have already been approved for the treatment of and preventing their polymerization or depolymerization (1- humans (13), they, as repositioned drugs, could be readily 4). Halaven (HAL), also called eribulin, was recently available for clinical use once their anti-cancer activities are better understood. These results will contribute to the development of FLU-, THIO- and MEF-based therapy for Τhis article is freely accessible online. co-treatment of cancer in highly HAL-resistant patients. Correspondence to: Hyung Sik Kim, Ph.D. and Sungpil Yoon, Materials and Methods Ph.D., School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Reagents. FLU, THIO, MEF and verapamil (VER) were purchased Korea. Tel: +82 312907789, Fax: +82 312928800, e-mail: from Sigma-Aldrich (St.Louis, MO, USA). AZA was purchased [email protected], [email protected] from Selleckchem (Houston, TX, USA). Vinblastine (VIB) was purchased from Enzo Life Sciences (Farmingdale, NY, USA). Key Words: Halaven, fluphenazine, mefloquine, thioridazine, P-gp, Aqueous solutions of HAL (Eisai Korea, Seoul, South Korea) were drug-resistance. obtained from the National Cancer Center in South Korea. 0250-7005/2016 $2.00+.40 5867 ANTICANCER RESEARCH 36 : 5867-5874 (2016) Antibodies. Antibodies against pGSK3 β, pHistone H3, proliferating Briefly, cells grown in 60-mm dishes were washed three times with cell nuclear antigen (PCNA) and cleaved-poly(ADP-ribose) 5 ml PBS. Next, 500 μl of 20% trichloroacetic acid (TCA) was polymerase (C-PARP) were from Cell Signaling Technology added to each plate. The cells were then dislodged by scraping and (Danvers, MA, USA). Antibodies against glyceraldehyde 3- transferred to Eppendorf tubes. Proteins were pelleted by phosphate dehydrogenase (GAPDH), survivin and retinoblastoma centrifugation for 5 min at 3,000 rpm and re-suspended in 1M Tris- protein (pRb) were from Santa Cruz Biotechnology (Santa Cruz, CA, HCl (pH 8.0) buffer. The total protein concentrations were USA). Antibody against pH2AX was from Abcam (Cambridge, UK). estimated. The proteins were resolved by sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and subjected to Cell culturing. Human oral squamous carcinoma cell lines, KB and its Western blot analysis as previously described (17-19). multidrug-resistant subline, KBV20C, were obtained from Dr. Yong Kee Kim (College of Pharmacy, Sookmyung Women’s University, Results Seoul, Republic of Korea) and have been previously described (14- 16). All cell lines were cultured in RPMI 1640 containing 10% fetal bovine serum, 100 U/ml penicillin and 100 μg/ml streptomycin KBV20C cells, highly resistant to HAL, are sensitized by FLU (WelGENE, Daegu, South Korea). co-treatment. KBV20C cells present an antimitotic drug- resistant phenotype via P-gp overexpression (14-16). When Microscopic observation. Cells grown in 6-well plates were treated testing the degree of resistance of KBV20C cells to HAL, we with the indicated drugs for the indicated times. The medium was determined that KBV20C cells are highly resistance to HAL. removed and PBS was added in each dish. Cells were examined in In fact, in KBV20C cells, the necessary concentration of two independent experiments immediately using an Axio observer.Z1 HAL required to observe a similar phenotype was fluorescence inverted microscope (Carl Zeiss, Oberkochen, Germany) approximately 500-fold higher than that used in parent drug- with a 5× or 10× objective lens (Carl Zeiss EC Plan-Neofluar). sensitive KB cells (Figure 1A). These data suggest a 500-fold Fluorescence-activated cell sorting (FACS) analysis. FACS analysis difference in HAL half-maximal inhibitory concentration was performed as previously described (17-19). Cells were grown (IC 50 ) between sensitive KB and resistant KBV20C cells. in 60-mm diameter dishes and treated with the indicated drugs for Compared to previous studies assessing the IC 50 of KB and the prescribed times. The cells were then dislodged by trypsin and KBV20C cells using other antimitotic drugs, such as pelleted by centrifugation. The pelleted cells were washed vinblastine, vincristine, paclitaxcel, docetaxcel and thoroughly with PBS, suspended in 75% ethanol for at least 1 h at colchicines (1-4), KBV20C cells are highly resistant to HAL. 4˚C, washed with PBS and re-suspended in a cold propidium iodide (PI) staining solution (100 μg/ml RNase A and 50 μg/ml PI in PBS) Verapamil co-treatment with HAL overcame KBV20C for 30 min at 37˚C. The stained cells were analyzed in two resistance (data not shown or see Figure 3C and D) independent experiments for relative DNA content using a confirming that HAL-resistance in KBV20C cells involves FACSCalibur flow cytometry system (BD Bioscience, Franklin the pumping-out ability of the cells associated with P-gp Lakes, NJ, USA). overexpression. It also suggests that HAL is a highly selective substrate pumped-out by P-gp in KBV20C cells. Therefore, Annexin V analysis. Annexin V analysis was conducted using the we assumed that identifying the sensitization mechanisms of annexin V-fluorescein isothiocyanate (FITC) staining kit (BD KBV20C cells can provide important information to Bioscience) as previously described (17-19). Cells were grown in 60-mm diameter dishes and treated with the indicated drugs for the overcome HAL-resistant phenotypes in the clinic. prescribed times. The cells were then dislodged by trypsin and FLU is a potential anti-cancer drug and a potential inhibitor pelleted by centrifugation. The pelleted cells were washed with of cancer-related Akt pathways (20). First, we tested whether PBS. Cells in 100 μl of binding buffer received 5 μl of Annexin V- FLU was a substrate for P-gp in drug-resistant KBV20C cells. FITC and 5 μl of PI and were, then, incubated for 15 min at room As shown in Figure 1B, using various concentrations of FLU, temperature. The stained cells were analyzed using a FACSCalibur we determined that KB and KBV20C presented a similar flow cytometry system (BD Bioscience). Two independent sensitization level, suggesting that FLU is not a substrate of experiments were performed. P-gp in drug-resistant KBV20C cells. It also suggests that Rhodamine and calcein-AM uptake tests. These tests were used for FLU can be used as an anti-cancer drug in resistant cells, determination of ability for inhibition of P-gp using a previously including HAL-resistant cancer cells. Furthermore, we tested described method (17-19). Briefly, cells grown in 6-well plates were whether co-treatment with FLU could sensitize HAL-treated treated with indicated drugs and incubated for 24 h at 37˚C. Cells KBV20C cells. As shown in Figure 1C and D, HAL-FLU co- were then incubated with and 1 μg/ml rhodamine or 0.1 μg/ml treatment reduced cellular proliferation and increased G 2 arrest calcein-AM for 1 h 30 min at 37˚C.