Cisplatin-resistant Cancer Cell Line Research Articles

Exonuclease 1 (Exo1) Participates in Mammalian Non-Homologous End Joining and Contributes to Drug Resistance in Ovarian Cancer.

BackgroundExonuclease 1 (Exo1) participates in a variety of DNA damage repair, including mismatch repair, nucleotide excision repair, and homologous recombination. Genetic study in yeast indicates a role of Exo1 in non-homologous end joining (NHEJ), acting as a regulator for accuracy repairing DNA. This study aimed to investigate the effects of human Exo1 in NHEJ and drug resistance in ovarian cells.Material/MethodsEctopic expression of Exo1 was carried out using pcDNA3.1-EXO1 plasmid in SKOV3 cells. GST-tagged human Exo1 was purified using pTXB1-gst-EXO1 and the his-tagged-Ku was collected using pET15b.his.Ku. Exo1 and Ku70 proteins expressed in bacteria were harvested and purified. DNA-protein binding was examined using affinity capture assay. The cells were treated using drugs for 72 hours. Then, the viabilities of cells were evaluated with sulforhodamine B cell viability analysis. The protein expression was evaluated using western blot assay.ResultsAs expected, human cells that deficient of Exo1 were sensitive to ionizing radiation and DNA damaging drugs (cisplatin and doxorubicin). Cisplatin resistant ovarian cancer cell line and Exo1 deficient cell lines were successfully generated. Exo1 interacts with NHEJ required factor Ku70 and affects NHEJ efficiency. We observed that Exo1 expression level was upregulated in drug resistant cell line and knockdown of Exo1 in drug resistant cells sensitized cells to cisplatin and doxorubicin.ConclusionsExo1 participated in mammalian non-homologous end joining and contributed to drug resistance in ovarian cancer.

Heterobimetallic propargyl gold complexes with π-bound copper or silver with enhanced anticancer activity.

Several propargyl functionalised substrates with different heteroatoms (N, O or S) have been used for the preparation of propargyl gold(i) phosphine complexes. The complexes were prepared in high yields either by reaction of the substrate with [Au(acac)PPh3] or by reaction of [AuCl(PPh3)] with potassium hydroxide and the substrate in methanol. Several of the complexes have been characterised by X-ray diffraction showing the presence of secondary bonds such as π-stacking and aurophilic interactions. The reaction of the propargyl gold(i) phosphine complexes with [Cu(NO3)(PPh3)2] or [Ag(OTf)(PPh3)2] afforded heterobimetallic complexes with π-coordination of {Cu(PPh3)2} or {Ag(PPh3)2} to the alkyne bond. When the substituent of the propargyl unit contained more strongly coordinating pyridine moieties, [(PyCH2)2NCH2C[triple bond, length as m-dash]CAuPPh3], coordination of the heterometal to the pyridine units occurred, displacing the phosphine groups and giving rise to a dimeric structure. The antiproliferative activity of the complexes against cisplatin resistant lung cancer cell line A549 was determined by MTT assay. The mononuclear gold complexes showed excellent activities with IC50 values < 14 μM. Coordination of copper of silver to the alkynyl fragment resulted in a significant increase in activity suggesting a synergistic effect between the two metal centres.

SNHG15 Contributes To Cisplatin Resistance In Breast Cancer Through Sponging miR-381.

BackgroundIncreasing evidence implies the participation of long non-coding RNAs (lncRNAs) in chemoresistance to cancer treatment. Their role and molecular mechanisms in breast cancer chemoresistance, nevertheless, are yet not considerably elucidated. In this work, we research the function of small nucleolar RNA host gene 15 (SNHG15) in cisplatin (DDP) resistance of breast cancer and uncover the underlying molecular mechanism.MethodsSNHG15 and miR-381 expression levels were detected using Quantitative real-time PCR (qRT-PCR) analysis. The functional roles of SNHG15 and miR-381 in breast cancer were determined using MTT assay and flow cytometry analysis. The effect of SNHG15 on miR-381 expression was determined using Luciferase reporter assay, RNA immunoprecipitation (RIP) assay and qRT-PCR analysis.ResultsSNHG15 was found to be up-regulated in cisplatin resistant breast cancer tissues and cell lines. Breast cancer patients with high SNHG15 expression had a poor prognosis. SNHG15 silencing enhanced cisplatin sensitivity of MCF-7/DDP and MDA-MB-231/DDP cells. Additionally, SNHG15 could function as a miR-381 sponge. miR-381 overexpression could overcome cisplatin resistance. miR-381 knockdown countered SNHG15 knockdown-mediated enhancement of cisplatin sensitivity in MCF-7/DDP and MDA-MB-231/DDP cells. Besides, SNHG15 knockdown facilitated cisplatin sensitivity of cisplatin resistant breast cancer cells in vivo.ConclusionIn summary, SNHG15 knockdown overcame cisplatin resistance of breast cancer by sponging miR-381, providing a novel therapeutic target for breast cancer.

Arctigenin enhances the sensitivity of cisplatin resistant colorectal cancer cell by activating autophagy

Arctigenin is the active content of arctium lappa that present anti-cancer abilities in various carcinomas. However, its role and underlying mechanism in drug-resistant colorectal cancer cells has not been addressed. The present study used SW480 and SW620 to established cisplatin-resistant colorectal cancer cell lines, and explored the impact of arctigenin on these cells. Arctigenin at 100 μM significantly inhibited cell proliferation of cisplatin treated R–SW480 and R–SW620 cells as compared with cells treated with cisplatin alone. Arctigenin elevates cell apoptosis, up-regulated pro-apoptotic protein cleaved-caspase-3 and caspase-9 expression level in cisplatin treated R–SW480 and R–SW620 cells. Additionally, arctigenin triggered autophagy and promoted LC3-Ⅱ and p65 expression, while inhibited LC3-Ⅰexpression. Arctigenin impeded the IC50 of not only cisplatin but also oxaliplatin, doxorubicin and Paclitaxel of R–SW480 and R–SW620 cells. More importantly, the mRNA expression of multi drug resistance 1 (MDR1) and protein expression of pgp were significantly inhibited by arctigenin administration. Taken together, arctigenin has the potential in sensitize colorectal cancer cells by activating autophagy, which induced cell apoptosis and inhibited cell growth. Our study revealed that arctigenin has the potential for colorectal cancer treatment and may be useful in adjuvant chemotherapy.

Curcumin enhances cisplatin sensitivity by suppressing NADPH oxidase 5 expression in human epithelial cancer.

Cisplatin-based chemotherapy regimens serve a pivotal role in human cancer treatment. Nevertheless, treatment failure may occur if the cancer is inherently resistant to cisplatin or acquires a resistant phenotype during the course of treatment. Although cisplatin resistance can hinder the efficacy of cisplatin treatment for human cancer, the underlying mechanism remains poorly understood. The current study established a cisplatin-resistant human epithelial cancer cell line. Notably, differential upregulation of NADPH oxidase 5 (NOX5) was identified in this resistant cell line. Furthermore, cisplatin treatment induced cancer cells to express NOX5 and cells that overexpressed NOX5 exhibited greater resistance to cisplatin via the activation of Akt. Treatment with curcumin may suppress NOX5 expression in cancer cells and enhance sensitivity to cisplatin treatment. In a xenograft model, a combined regimen of cisplatin with low-dose curcumin significantly reduced malignant tumor growth. These data demonstrate that curcumin has a chemosensitizing effect on cisplatin-resistant epithelial cancer types. Therefore, the use of curcumin in addition to a cisplatin-based treatment regimen may improve treatment outcomes in human patients with epithelial cancer.

Surface Coordination of Black Phosphorus with Modified Cisplatin.

Black phosphorus (BP) is a two-dimensional (2D) nanomaterial with high charge-carrier mobility, a tunable direct bandgap, and a unique in-plane anisotropic structure; however, the easiness of BP oxidation into P xO y species in ambient conditions largely limits its applications. In this study, modified cisplatin-Pt-NO3 [Pt(NH3)2(NO3)2] is used for surface coordination with BP nanosheets to generate Pt@BP, which maintains the surface morphology and properties of BP nanosheets for more than 24 h in ambient conditions. In addition, Pt@BP interacts with DNA both in vitro and in cell. Pt@BP shows a good cellular uptake rate and significantly increases the drug sensitivity of cisplatin-resistant cancer cell lines (A2780 and HepG2) compared with unmodified cisplatin. Our study is the first attempt to stabilize bare BP with cationic cisplatin species, and the generated Pt@BP could be used for potential synergistic photothermal/chemotherapy of cisplatin-resistant cancer.

Atezolizumab and Bevacizumab Attenuate Cisplatin Resistant Ovarian Cancer Cells Progression Synergistically via Suppressing Epithelial-Mesenchymal Transition.

The AURELIA trial demonstrated that adding Bevacizumab to chemotherapy significantly improved progression-free survival (PFS) for platinum resistant recurrent ovarian cancer. Recently, immunotherapy also presented potential anti-tumor effects in several malignant solid tumors. This study aimed to investigate whether combining anti-PD-L1 Atezolizumab with BEV may have a synergistic effect and enhance the efficacy of both treatments in cisplatin resistant epithelial ovarian cancer (CREOC). We retrospectively analyzed 124 epithelial ovarian cancer (EOC) patients from Gynecologic Oncology Department of Tianjin Cancer Hospital between January 2013 and June 2018, who all were diagnosed with cisplatin resistance due to progressing <6 months after completing platinum-based therapy. Based on responding to at least 2 cycles of Bevacizumab-containing chemotherapy (BC), these Patients were divided into BC response group and BC non-response group. Immunohistochemistry was used to detect that PD-L1 expression and tumor angiogenesis-related proteins (VEGF and Semaphorin4D) in tissues from 124 patients with CREOC. The positive expressions of PD-L1, VEGF, and Semaphorin4D (SEMA4D) were found in 58.73, 50.79, and 71.43% of the 63 cases CREOC tissues with BC response, respectively, which were significantly higher than that in the 61 cases BC non-response group (P < 0.05). PD-L1 expression correlated with SEMA4D and VEGF positively (r = 0.344 and 0.363, P < 0.001). Over-expressions of PD-L1, VEGF and SEMA4D are associated with more malignant clinicopathologic characteristics of CREOC Patients. In survival analysis, patients' response to BC was the independent factor for evaluation of PFS and overall survival (OS). Cell functional assays showed that Atezolizumab in combination with Bevacizumab inhibited the proliferation, migration, and invasion of cisplatin resistant ovarian cancer cell line A2780cis in vitro synergistically, which maybe associate with Bevacizumab suppressing the epithelial-mesenchymal transition (EMT) and PD-L1 expression by targeting STAT3. Furthermore, Bevacizumab and Atezolizumab induced synergistic anti-tumor effect in vivo. These findings suggest a novel therapeutic strategy for cisplatin resistant recurrent EOC and its mechanism warrants further study.

Polymer “ruthenium-cyclopentadienyl” conjugates - New emerging anti-cancer drugs

In this work, we aimed to understand the biological activity and the mechanism of action of three polymer-‘ruthenium-cyclopentadienyl’ conjugates (RuPMC) and a low molecular weight parental compound (Ru1) in cancer cells. Several biological assays were performed in ovarian (A2780) and breast (MCF7, MDA-MB-231) human cancer derived cell lines as well as in A2780cis, a cisplatin resistant cancer cell line. Our results show that all compounds have high activity towards cancer cells with low IC50 values in the micromolar range. We observed that all Ru-PMC compounds are mainly found inside the cells, in contrast with the parental low molecular weight compound Ru1 that was mainly found at the membrane. All compounds induced mitochondrial alterations. PMC3 and Ru1 caused F-actin cytoskeleton morphology changes and reduced the clonogenic ability of the cells. The conjugate PMC3 induced apoptosis at low concentrations comparing to cisplatin and could overcame the platinum resistance of A2780cis cancer cells. A proteomic analysis showed that these compounds induce alterations in several cellular proteins which are related to the phenotypic disorders induced by them.Our results suggest that PMC3 is foreseen as a lead candidate to future studies and acting through a different mechanism of action than cisplatin. Here we established the potential of these Ru compounds as new metallodrugs for cancer chemotherapy.

Cervical cancer cell lines are sensitive to sub-erythemal UV exposure

High risk human papillomavirus (HPV) infections are the causative agent in virtually every cervical cancer as well as a host of other anogenital and oropharyngeal malignancies. These viruses must activate DNA repair pathways to facilitate their replication, while avoiding the cell cycle arrest and apoptosis that can accompany DNA damage. HPV oncoproteins facilitate each of these goals, but also reduce genome stability. Our data dissect the cytotoxic and cytoprotective characteristics of HPV oncogenes in cervical cancer cells. These data show that while the transformation of keratinocytes by HPV oncogene leaves these cells more sensitive to UV, the oncogenes also protect against UV-induced apoptosis. Cisplatin and UV resistant cervical cancer cell lines were generated and probed for their sensitivity to genotoxic agents. Cervical cancer cells can acquire resistance to one DNA crosslinking agent (UV or cisplatin) without gaining broad tolerance of crosslinked DNA. Further, cisplatin resistance may or may not result in sensitivity to PARP1 inhibition.

Seco-4-methyl-DCK derivatives as potent chemosensitizers

Twenty-five seco-4-methyl-DCK derivatives were designed, synthesized and evaluated for chemoreversal activity when combined with paclitaxel or vincristine in two drug-resistant cancer cell lines (A2780/T and KB-V) respectively. Most of the new compounds displayed moderate to significant MDR reversal activities in the P-gp overexpressing A2780/T and KB-V cells. Especially, compounds 7o and 7y showed the most potent chemosensitization activities with more than 496 and 735 reversal ratios at a concentration of 10 μM. Unexpectedly the newly synthesized compounds did not show chemosensitization activities observed in a non-P-gp overexpressing cisplatin resistant human ovarian cancer cell line (A2780/CDDP), implying that the MDR reversal effects might be associated with P-gp overexpression. Moreover, these compounds did not exhibit significant antiproliferative activities against nontumorigenic cell lines (HUVEC, HOSEC and T29) compared to the positive control verapamil at the tested concentration, which suggested better safety than verapamil. The pharmacological actions of the compounds will be studied further to explore their merit for development as novel candidates to overcome P-gp mediated MDR cancer.

Apollon silencing enhanced the sensitivity to cisplatin-induced cytotoxicity of chemoresistant breast cancer cell line MCF-1/cisplatin

Objective To explore the effect of Apollon on cisplatin-induced chemoresistance of breast cancer cell line MCF-1/cisplatin (DDP). Methods Apollon silencing was performed by transient transfection of small interfering RNA (siRNA). The inhibitory effect of different concentrations of cisplatin (10, 20, 40, 80, and 100 μmol/L) on cell viability was measured by methyl thiazol tetrazolium (MTT) assays. The mRNA and protein expression levels were detected by real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting, respectively. Results As compared with MCF-7 cells, Apollon mRNA and protein levels were 1.70±0.21 folds and 2.23±0.33 folds enhanced in cisplatin-resistant breast cancer cell line MCF-1/DDP, respectively (P=0.007, 0.003). Knockdown of Apollon increased the sensitivity to cisplatin-induced cytotoxicity of MCF-1/DDP. As compared with non-transfected control group, the half maximal inhibitory concentration (IC50) value of cisplatin was significantly decreased from (81.39±3.67) μmol/L to (33.24±2.01) μmol/L (P=0.002). Meanwhile, the mRNA and protein expression levels of Apollon and β-catenin were remarkably declined to 0.43±0.16 (P=0.005), 0.54±0.10 (P=0.006) and 0.23±0.08 (P=0.003), 0.44±0.20 (P=0.005) after Apollon silencing, respectively. In addition, the mRNA and protein expression levels of β-catenin were significantly 1.91±0.23 folds (P=0.0044) and 2.21±0.31 (P=0.0023) folds enhanced with little influence on Apollon expression (P=0.890, 0.730) upon the treatment of WAY-262611 in siRNA-transfected cells. Conclusion Apollon silencing enhanced the sensitivity to cisplatin-induced cytotoxicity of chemoresistant breast cancer cell line MCF-1/DDP, which might be partially dependent on the reduced β-catenin expression. Key words: Breast cancer; Apollon; Cisplatin-resistant

Suppression of SESN1 reduces cisplatin and hyperthermia resistance through increasing reactive oxygen species (ROS) in human maxillary cancer cells

Introduction: Cisplatin is used as a standard chemotherapeutic agent for head and neck cancer treatment. However, some head and neck cancers have cisplatin resistance, leading to difficulty in treatment and poor prognosis. Overcoming cisplatin resistance remains an important strategy to improve prognoses for head and neck cancer patients.Objective: Elucidation of the mechanisms underlying cisplatin resistance can suggest novel targets to enhance the anticancer effects of cisplatin for treating head and neck cancers.Material and methods: We used a cisplatin-resistant human maxillary cancer cell line, IMC-3CR to analyse the cisplatin resistance mechanisms. Cisplatin-induced genes were analysed in IMC-3CR cells using PCR array. Among the genes with expression increased by cisplatin, we specifically examined SESN1. SESN family reportedly regenerates peroxiredoxin and suppresses oxidative DNA injury by reactive oxygen species (ROS), which can be induced by chemotherapeutic agents such as cisplatin, radiation, and hyperthermia. The function of SESN1 in cisplatin resistance and ROS generation were analysed using specific RNAi.Results: Results show that SESN1 was induced by cisplatin treatment in IMC-3CR cells. Suppression of SESN1 by RNAi induced apoptosis and reduced cell viability through enhancement of ROS after cisplatin treatment. Moreover, suppression of SESN1 enhanced the cell-killing effects of hyperthermia with increased ROS, but did not affect the cell-killing effects of radiation.Conclusions: This study demonstrated the participation of SESN1 in cisplatin and hyperthermia resistance of human head and neck cancers. SESN1 is a novel molecular target to overcome cisplatin resistance and hyperthermia resistance and improve head and neck cancer treatment.

Glutaryl Polyamidoamine Dendrimer for Overcoming Cisplatin-Resistance of Breast Cancer Cells

Cisplatin has limited clinical applications due to drug resistance. PAMAM dendrimer was chosen as a vehicle to counteract cisplatin-resistance and its mechanism was assessed. Generation 5 Polyamidoamine dendrimer (G5) was modified by glutaric anhydride (GA) and then conjugated with cisplatin. The cisplatin release of G5-GA-cisplatin was evaluated at pH 5.5 and pH 7.4. The cytotoxicity of G5-GA-cisplatin and free cisplatin was compared in cisplatin-resistant breast cancer cell line MCF-7R. The intracellular platinum content of MCF-7R was determined using ICP-MS. The expression of Ctr1 and ATP7B of MCF-7R cells was also evaluated. An average of 75 amino groups present in the G5 PAMAM surface were converted into glutaric acid (G5-GA75) and platinum loading was 350±21 μg per 1 mg of G5-GA75. G5-Ac75-cisplatin complex exhibited controlled release of cisplatin at different pH over a period of 96 h. After 96 h incubation with G5-Ac75-cisplatin, cell viability was 27.47±2.53%, 12.18±0.65% and 11.62±0.84% using platinum concentration of 1 μg/ml, 3 μg/ml and 5 μg/ml, respectively. Meanwhile, 46.33±5.06% cells survived even in the high platinum concentration of 5 μg/ml after 96 h incubation with free cisplatin. G5-GA75 led to 3-6 times higher cisplatin accumulation than free cisplatin in MCF-7R cells, because MCF-7R cells exhibited lower Ctr1 expression and higher ATP7B expression than MCF-7 cells. The G5-GA75-cisplatin complex displayed greater anticancer activity than free cisplatin in the cisplatin-resistant breast cancer cell line MCF-7R. The low levels of Ctr1 and high levels of ATP7B in MCF-7R caused G5-GA75 to allow the accumulation of cisplatin, which in turn increased the cytotoxicity. Results indicated that glutaryl G5 PAMAM may be a potential carrier for cisplatin targeting in breast cancer.

SiRNA interfering STAT3 enhances DDP sensitivity in cervical cancer cells.

Signal transducer and activator of transcription 3 (STAT3) is an important regulatory protein in the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, which regulates cell proliferation, apoptosis, and other biological processes. It is closely related to tumor occurrence, progress, and resistance. Cisplatin (DDP) resistant cervical cancer cell line was established by shock induction to investigate the role of STAT3 in cervical cancer cells drug resistance. The expression of STAT3 in different chemotherapy response cervical cancer tissues was compared. The cervical cancer was divided into two groups upon STAT3 median level. Cervical cancer cell inhibitory rate by DDP treatment was compared. Western blot was used to detect STAT3 and phosphorylated STAT3 (p-STAT3) expressions in CaSki and CaSki/DDP cells. Cell apoptosis rate was tested by flow cytometry. CaSki/DDP cells were divided into small interfere RNA-normal control (siRNA-NC) group and siRNA-STAT3 group. Cell proliferation was evaluated by EdU staining. The rate of STAT3 over-expression in cervical cancer patients with no significant chemotherapy response was markedly higher than that with a significant response. The inhibitory effect of DDP on tumor cells derived from patients with low STAT3 expression was significantly higher, while the apoptosis rate was apparently lower than that of CaSki/DDP cells from patients with high STAT3 expression. siRNA-STAT3 transfection significantly reduced the expressions of STAT3 and p-STAT3, decreased cell proliferation, and enhanced cell apoptosis in CaSki/DDP cells. STAT3 over-expression is associated with DDP resistance in cervical cancer. Decreasing STAT3 can significantly promote the apoptosis of cervical cancer CaSki cells and decrease the DDP resistance.

Abstract 1967: Synthesis, in vitro evaluation in ovarian cancer cells and molecular modeling analysis of novel 2-aminothiazole and 2-aminopyridine derivatives

Abstract Background: Resistance to chemotherapy remains a major hurdle in complete cure against ovarian cancer. Among 75 percent of respondents to chemotherapy, the majority would relapse within two years. Cancer cells can overcome therapy-induced damage by activation of back-up signaling pathways and flexible modulation of affected networks resulting in chemo-resistance. Platinum-based drugs are the most active agents in use against the ovarian cancer. Non platinum-based chemotherapy regimens are usually given in the ‘platinum-resistant' setting. Methods: A series of N-protected and N-deprotected amino acid derivatives of ethyl-2-aminothiazole-4-carboxylate (4a-d &amp; 6a-d) and 2-aminopyridine (5a-d &amp; 7a-d) have been synthesized and characterized by FT-IR, 1H NMR, 13C NMR, mass spectrometry and elemental analysis. The compounds were evaluated in silico for selected target inhibition. AutoDockVina virtual screening program was used to target multiple markers in cell signaling pathway (including p110a/PI3K, EGFR, VEGFR, PDGFR, BCR-ABL, RET, c-KIT, c-Raf, ALK, ,B-Raf, , CTLA-4). Anti-tumor activity was determined in parent (A2780) and cisplatin resistant (A2780CISR) ovarian cancer cell lines by MTT reduction assay.Binding affinity data of standard drugs and synthesized compounds 4c, 6b and 7c were compared. Binding mode and 2D interactions of the compounds with p110a isoform of PI3K, EGFR, VEGFR and PDGFR were determined. Results: Among selected targets, p110a isoform of PI3K is the main target involved in development of ovarian cancer; all three ligands were found to be active against this target. Compound 4c&amp;6b exhibited excellent inhibition of p110a isoform of PI3K with binding energy -8.3 Kcal/mol and -8 Kcal/mol that is comparable to the reference compound i.e. -9.8 Kcal/mol. Overall, compound 4c&amp;6b exhibited greatest inhibition with lowest binding energies against most of the targets.All the tested compounds exhibited dose dependent anti-proliferative effect against both cell lines. IC50 and RF values of cisplatin and tested compounds were determined. Compounds 4c, 6b and 7c showed interesting results as they were more active in cisplatin resistant cell line than in parent cells. The RF values of these compounds were 0.83, 0.46 and 0.53 respectively. Discussion: RF value of a compound provides an idea if the compound can induce more cell death than corresponding drug in resistant cell lines. RF value less than 1 for a compound/drug is an indication of ability of that compound to bring about more cell death than standard drug in resistant cells. These data warrant further investigations into the mechanism of reversal of resistance induced by potential compounds. Citation Format: Shagufta Naz, Humaira Nadeem, sadia sarwar, Rehan Z. Paracha, Jun Q. Yu, Fazlul Huq. Synthesis, in vitro evaluation in ovarian cancer cells and molecular modeling analysis of novel 2-aminothiazole and 2-aminopyridine derivatives [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1967.

Molecular targeting of glutaminase sensitizes ovarian cancer cells to chemotherapy.

Altered metabolism is a reemerging hallmark of tumorigenesis. Increased cell proliferation results in metabolic reprogramming to facilitate the needs of the rapidly dividing tumor cells. In addition to increased glucose uptake, tumors also take up increased levels of glutamine. Some cancers develop a reliance on glutamine, and are referred to as "glutamine addicted." These tumors over express the enzyme glutaminase which is involved in the first step of glutaminolysis. The goal of this study was to determine the effects of combined treatment of the glutaminase inhibitor bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl) ethyl sulfide (BPTES) with chemotherapy on drug resistant ovarian cancer cells. We found that ovarian cancer cells show different dependencies on exogenous glutamine. However, regardless of glutamine dependence status, treatment with BPTES sensitized both paclitaxel, and cisplatin resistant cancer cell lines to chemotherapy by inhibiting cell proliferation. Monotherapy with BPTES alone resulted in a significant reduction in the ability of glutamine dependent cancer cells to form colonies in a clonogenic assay. In addition, glutamine dependent, metastatic cancer cells expressed higher levels of glutaminase 1 (GLS1) isoforms, KGA and GAC, than untransformed cells. Moreover, dual targeting of both isoforms using siRNA was more effective at sensitizing the cancer cells to cisplatin than targeting either GAC or KGA alone. Our results suggest that both GLS1 isoforms are important for glutamine dependent ovarian cancer survival, hence, both GLS1 isoforms should be targeted for therapy in metastatic ovarian cancer therapy.

Upregulation of phosphatase and tensin homolog is essential for the effect of 4-aminopyridine on A549/CDDP cells

4-aminopyridine (4-AP), a voltage-gated potassium channel blocker, was revealed to possess pro‑apoptotic properties in various types of cancer cells. The present study aimed to explore the effect of 4‑AP on a cisplatin (DDP) resistant lung cancer cell line A549/CDDP and the underlying mechanism by which it had an effect. In the present study, an MTT assay and cell cycle analysis were used to determine that 4‑AP inhibited cell growth invitro and a tumorigenesis assay in nude mice determined that 4‑AP also inhibited cell growth invivo. 4‑AP induced cell apoptosis of A549/CDDP cells observed by electron microscopy and Annexin V‑APC/7‑ADD analysis. In addition, 4‑AP enhanced the sensitivity of A549/CDDP cells to DDP as revealed by an MTT assay. Mechanistically, 4‑AP upregulated the phosphatase and tensin homolog (PTEN) and modulated the phosphoinositide 3‑kinase/protein kinase B signaling pathway and its downstream cell cycle factors, including cyclin D1, cyclin‑dependent kinase 4 and p21, as well as apoptosis‑associated proteins B‑cell lymphoma 2, pro‑caspase 9, pro‑caspase 3, cleaved caspase 9 and cleaved caspase 3. The effects of 4‑AP on cell growth and apoptosis were reversed by PTEN silencing. In conclusion, the results indicated that 4‑AP inhibited cell growth, induced apoptosis and sensitized A549/CDDP cells to DDP via the upregulation of PTEN. 4‑AP may be a potential therapeutic agent for patients with DDP resistance.

Ovarian serous carcinomas acquire cisplatin resistance and increased invasion through downregulation of the high-temperature-required protein A2 (HtrA2), following repeated treatment with cisplatin.

High-temperature-required protein A2 (HtrA2) is one of the serine proteases related to apoptosis. HtrA2 protein expression has been associated with cisplatin resistance and poor prognosis in ovarian serous adenocarcinoma (SAC). The aim of this study was to understand the influence of HtrA2 on repeated treatment with cisplatin. The change in HtrA2 expression in 31 ovarian cancers was investigated by immunohistochemical analysis, before and after cisplatin-based chemotherapy, and the association between HtrA2 expression after chemotherapy and prognosis was analyzed. The association between the change in HtrA2 and proteins associated with LATS1 in ovarian serous cancer cell lines after repeated treatment with cisplatin was evaluated in vitro. In immunohistochemical analysis, repeated cisplatin treatment induced downregulation of HtrA2 protein expression, before and after cisplatin-based chemotherapy in SAC. Progression-free survival and overall survival of SAC with low expression of HtrA2 were worse than those with high expression. In vitro analysis using cisplatin-sensitive ovarian cancer cell lines, KF28, and cisplatin-resistant cancer cell lines, KFr13, obtained from KF28 by repeated cisplatin treatment, showed that HtrA2 protein expression was lower in KFr13 than in KF28. Furthermore, KFr13 had a higher invasive capacity than KF28. Next, downregulation of HtrA2 transfected with an HtrA2-specific siRNA in KF28 had not only cisplatin resistance, but also more invasive capacity than those with non-specific siRNA. Repeated treatment with cisplatin downregulated the HtrA2 protein, which led to cisplatin resistance and increased invasive capacity. Thus, HtrA2 might be a biomarker of response to cisplatin treatment and prognosis, after cisplatin-based chemotherapy.

Downregulation of Inhibition of Apoptosis-Stimulating Protein of p53 (iASPP) Suppresses Cisplatin-Resistant Gastric Carcinoma In Vitro.

BackgroundGastric cancer (GC) with cisplatin resistance is one of the leading causes of limitations to therapy. Inhibition of apoptosis-stimulating protein of p53 (iASPP) plays a key role in GC. However, the role of iASPP in GC with cisplatin resistance remains unclear. The aim of this study was to investigate iASPP expression in GC, and the functions of iASPP in cisplatin-resistant cell lines.Material/MethodsIn this study, the expression of iASPP was investigated in normal GC patients and patients with cisplatin resistance, along with GC cell lines and cell lines with cisplatin resistance. Furthermore, knockdown of iASPP was conducted in cell lines; and cell proliferation, apoptosis rate, cell cycle distribution, and cell migration and invasion were determined through CCK8, flow cytometry, Scratch test and Transwell assay, respectively.ResultsThe expression of iASPP in GC patients with cisplatin resistance was significant higher than in the health control group. Higher expression of iASPP was detected in cisplatin-resistant cancer cell lines. Cell proliferation of SGC-7901 and MGC-803 was inhibited by transfection with siRNA, along with evaluated apoptosis rate and G1 phase retardant. Furthermore, cells viability, including migration and invasion, was suppressed post-transfection with siRNA.ConclusionsiASPP induced cisplatin resistance in GC patients. Thus, knockdown of iASPP might be a novel therapeutic strategy for the treatment of GC cisplatin-resistant patients.

KuQuinones Equilibria Assessment for Biomedical Applications.

A small library of pentacyclic quinoid compounds, called KuQuinones (KuQs), has been prepared through a one-pot reaction. KuQuinones complex structure is made up by two naphthoquinone units connected by a five-membered ring. Due to KuQs structural features, keto-enol tautomerization in solution likely occurs, leading to the generation of four different species, i.e., the enol, the enolate, the external enol and the diquinoid species. The interchange among KuQ tautomers leads to substantial spectral variations of the dye depending on the experimental conditions used. The comprehension of tautomeric equilibria of this new class of quinoid compounds is strongly required in order to explain their behavior in solution and in biological environment. UV-vis, 1H NMR spectroscopies, and DFT calculations resulted appropriate tools to understand the nature of the prevalent KuQuinone species in solution. Moreover, due to the structural similarity of KuQuinones with camptothecin (CPT), a largely used anticancer agent, KuQs have been tested against Cisplatin-resistant SKOV3 and SW480 cancer cell lines. Results highlighted that KuQs are highly active toward the analyzed cell lines and almost nontoxic for healthy cell, indicating a high specific activity.