Apoptosis In Cisplatin-resistant Cells Research Articles

Supramolecular nanodrug targeting CDK4/6 overcomes BAG1 mediated cisplatin resistance in oral squamous cell carcinoma

Chemoresistance to cisplatin remains a significant challenge affecting the prognosis of advanced oral squamous cell carcinoma (OSCC). However, the specific biomarkers and underlying mechanisms responsible for cisplatin resistance remain elusive. Through comprehensive bioinformatic analyses, we identified a potential biomarker, BCL2 associated athanogene-1 (BAG1), showing elevated expression in head and neck squamous cell carcinoma (HNSCC). Since OSCC represents the primary pathological type of HNSCC, we investigated BAG1 expression in human tumor tissues and cisplatin resistant OSCC cell lines, revealing that silencing BAG1 induced apoptosis in cisplatin-resistant cells both in vitro and in vivo. This effect led to impaired cell viability of cisplatin resistant OSCC cells and indicated a positive correlation between BAG1 expression and the G1/S transition during cell proliferation. Based on these insights, the administration of a CDK4/6 inhibitor in combination with cisplatin effectively overcame cisplatin resistance in OSCC through the CDK4/6-BAG1 axis. Additionally, to enable simultaneous drug delivery and enhance synergistic antitumor efficacy, we developed a novel supramolecular nanodrug LEE011-FFERGD/CDDP, which was validated in an OSCC orthotopic mouse model. In summary, our study highlights the potential of a combined administration of CDK4/6 inhibitor and cisplatin as a promising therapeutic regimen for treating advanced or cisplatin resistant OSCC.

Inhibition of Ceramide Kinase Is Effective against Cisplatin-Resistant Ovarian Cancer Cells by Regulating Ceramide and C1P Levels

Objective: Chemoresistance in ovarian cancer results in treatment failure, yet underlying mechanisms that regulate chemoresistance remain largely unclear. There is emerging evidence relating ovarian cancer drug resistance with bioactive sphingolipids and regulation of sphingolipid metabolism. This work investigated the expression and function of ceramide kinase (CerK), a lipid kinase that regulates central bioactive sphingolipids, in ovarian cancer, as well as the therapeutic potential of targeting CERK. Design: The levels of ceramide, ceramide 1-phosphate (C1P), and Cerk in ovarian cancer and normal counterparts were measured. Functions of Cerk in ovarian cancer were examined. Materials, Setting, Methods: Immunohistochemistry, ELISA, and mass spectrometry methods were used to measure the level of ceramides, C1P, and CerK in primary tissues. Proliferation and apoptosis assays were performed in ovarian cancer cells after CERK depletion, CERK overexpression, and NVP-231 treatment in the absence or presence of cisplatin. Results: Compared to normal ovarian cells, CerK and its mediating bioactive sphingolipids ceramide and C1P were decreased in ovarian cancer tissues. Interestingly, cisplatin-resistant ovarian cancer cells displayed increased CerK, decreased ceramide, and increased C1P, and furthermore, that CerK level was closely associated with ceramide and C1P levels in ovarian cancer cells. Functional analysis demonstrated that CerK overexpression was sufficient to promote growth and confer chemoresistance in ovarian cancer cells. CerK inhibition via both genetic and pharmacological approaches suppressed growth and induced apoptosis in cisplatin-resistant cells, and furthermore, this significantly augmented cisplatin’s efficacy. Limitations: The functional analysis of C1P was performed on in vitro ovarian cancer cells. In vivo studies were needed to further confirm the effects of CERK inhibition. Conclusions: Our work is the first to show the critical role of CerK as the underlying mechanism of ovarian cancer chemoresistance, through regulating ceramide and C1P.

Adseverin: A novel cisplatin-resistant marker in the human bladder cancer cell line HT1376 identified by quantitative proteomic analysis

Cisplatin is currently the most effective antitumor agent available against bladder cancer. However, a majority of patients eventually relapse with cisplatin-resistant disease. Chemoresistance thus remains a major obstacle in bladder cancer therapy. To clarify the molecular mechanisms underlying cisplatin resistance in bladder cancer, we established a cisplatin-resistant subline from the human bladder cancer cell line HT1376 (HT1376-CisR), and conducted large-scale analyses of the expressed proteins using two-dimensional (2D) gel electrophoresis coupled with mass spectrometry (MS). Comparative proteomic analysis of HT1376 and HT1376-CisR cells revealed 36 differentially expressed proteins, wherein 21 proteins were upregulated and 15 were downregulated in HT1376-CisR cells. Among the differentially regulated proteins, adseverin (SCIN), a calcium-dependent actin-binding protein, was overexpressed (4-fold upregulation) in HT1376-CisR, with the increase being more prominent in the mitochondrial fraction than in the cytosol fraction. SCIN mRNA knockdown significantly reduced cell proliferation with mitochondria-mediated apoptosis in HT1376-CisR cells. Immunoprecipitation analysis revealed voltage-dependent anion channels (VDACs) to be bound to SCIN in the mitochondrial fraction. Our results suggest that the VDAC-SCIN interaction may inhibit mitochondria-mediated apoptosis in cisplatin-resistant cells. Targeting the VDAC-SCIN interaction may offer a new therapeutic strategy for cisplatin-resistant bladder cancer.

Trichostatin A sensitizes cisplatin-resistant A549 cells to apoptosis by up-regulating death-associated protein kinase

To investigate the apoptosis-inducing effect of trichostatin A (TSA) in the human lung adenocarcinoma cisplatin-resistant cell line (A549/CDDP) and to examine whether TSA can enhance sensitivity to cisplatin treatment and the underlying molecular mechanisms of such an enhancement. Cell viability was evaluated using the Neutral Red assay. Apoptosis was assessed using Hoechst 33258 staining and flow cytometry analysis. Protein expression was detected by Western blotting. To determine the role of Death-associated protein kinase (DAPK) in TSA-induced apoptosis in the A549/CDDP cell line, cells were transfected with pcDNA3.1(+)-DAPK, which has a higher expression level of DAPK compared to endogenous expression, and DAPK activity was inhibited by both over-expression C-terminal fragment of DAPK which may competitive binding DAPK substrates to inhibit the function of DAPK and RNA interference. TSA induced apoptosis in both A549 cells and A549/CDDP cells. TSA enhanced the sensitivity of A549/CDDP cells to cisplatin, along with concomitant DAPK up-regulation. When DAPK was over-expressed, A549/CDDP cells became sensitive to cisplatin and the cytotoxicity of TSA could be increased. Moreover, the cytotoxicity of TSA could be alleviated by inhibition of DAPK activity by the expression of a recombinant C-terminal fragment of DAPK or RNA interference. TSA induced sensitivity to cisplatin treatment in cisplatin-resistant A549 cells. The up-regulation of DAPK is one of the mechanisms mediating sensitization to TSA-induced apoptosis in cisplatin-resistant cells.

EF24 Induces G2/M Arrest and Apoptosis in Cisplatin-resistant Human Ovarian Cancer Cells by Increasing PTEN Expression

We report that EF24, a synthetic compound 3,5-bis(2-flurobenzylidene)piperidin-4-one, greatly inhibits cisplatin-resistant (CR) human ovarian cancer cell proliferation. The inhibitory effect of EF24 on cell proliferation is associated with G(2)/M phase cell cycle arrest and increased G(2)/M checkpoint protein (pp53, p53, and p21) levels. Within 24 h following treatment, EF24 induced apoptosis in CR cells. The apoptosis was partially blocked by the general caspase inhibitor z-VAD. Within 12 h, EF24 induced a membranous FasL expression, consistent with a substantial decrease in the Ser(473) and Thr(308) phosphorylation of Akt, a known negative regulator of FasL transcription. Also, EF24 activated the phosphorylated PTEN and marginally up-regulated total PTEN expression through the inhibition of ubiquitin-mediated PTEN degradation. Suppression of PTEN expression with siRNA significantly reduced the p53 and p21 levels and activated Akt phosphorylation at Ser(473) and Thr(308), resulting in decreased apoptosis and increased cell survival. On the other hand, overexpression of PTEN markedly induced apoptosis. Our results clearly suggested that EF24 induced significant increase in PTEN expression. The up-regulation of PTEN inhibited Akt and MDM2, which enhanced the level of p53, thereby inducing G(2)/M arrest and apoptosis. Therefore, EF24 appears to have a potential therapeutic role in human ovarian cancer through the activation of PTEN.

Epidermal growth factor can induce apoptosis in neuroblastoma

Background/Purpose In previous studies, incubation of doxorubicin-resistant neuroblastoma SK-N-SH (Dox-R) cells with epidermal growth factor (EGF) decreased extracellular signal–regulated kinase activation. Because extracellular signal–regulated kinase activation is associated with cell proliferation, we hypothesized that EGF could induce apoptosis and decrease the rate of cell growth in these cells. Methods The growth of wild-type (WT) SK-N-SH and Dox-R cells after incubation with EGF concentrations ranging from 1 to 100 ng/mL was determined by a colorimetric assay. Apoptosis was assessed by Hoechst staining and DNA laddering in WT, Dox-R, and cisplatin-resistant cells treated with EGF (100 ng/mL). Cleaved caspase-3 and EGF receptor (human epidermal growth factor receptor [HER1-HER4]) expression were verified by Western blot and reverse transcriptase–polymerase chain reaction. Results Epidermal growth factor decreased WT cell growth at concentrations between 50 and 100 ng/mL; Dox-R cell growth was attenuated at all EGF concentrations. Apoptosis was observed in WT and Dox-R cells incubated with EGF. Maximal cleaved caspase-3 expression occurred in WT cells treated with EGF 100 ng/mL and in Dox-R treated with EGF 5 to 10 ng/mL. Epidermal growth factor did not induce apoptosis in cisplatin-resistant cells. HER2 and HER3 transcription was maximal in WT and Dox-R cells, respectively. Conclusions Wild-type and Dox-R cells exhibited decreased cell growth after EGF treatment because of apoptosis. This involved caspase-3 activation and could work through HER2 and HER3 receptors.

The novel trinuclear platinum complex BBR3464 induces a cellular response different from cisplatin

BBR3464 is a new platinum-based drug non cross-resistant with cisplatin. To characterise the cellular basis of BBR3464 cytotoxicity as opposed to cisplatin, we performed a comparative study of the two drugs in cisplatin-resistant neuroblastoma and astrocytoma cells. In both model systems, BBR3464 proved to be more potent than cisplatin and was able to overcome cisplatin resistance. The higher potency exhibited by BBR3464 correlated with an increased cellular platinum accumulation and DNA–adduct formation. At equitoxic doses, BBR3464 induced apoptosis to a lesser extent than cisplatin and failed to overcome the decreased susceptibility to cisplatin-induced apoptosis in cisplatin-resistant cells. Cell cycle analysis showed a dose-dependent G2/M arrest by BBR3464. In astrocytoma cells, cisplatin treatment resulted in the upregulation of p53, p21 and bax, while only p21 induction was observed after BBR3464 treatment. In cisplatin-resistant cells, the reduced sensitivity to cisplatin paralleled a resistance to the induction of p53/p21 pathway by cisplatin, while the same doses of BBR3464 induced p21 to a similar extent in the resistant cells as in the parental cells. In conclusion, BBR3464 induces a cellular response that is different from cisplatin, supporting the view that the two drugs act through different mechanisms. Our data indicate that BBR3464 may be a promising agent in the treatment of tumours unresponsive to cisplatin and with a non-functional p53.

Cytotoxicity, Apoptosis, and in Vitro DNA Damage Induced by Potassium Chromate

Cr6+ is a known human cytotoxic and carcinogenic agent that requires intracellular reduction for activation. We have analyzed the cytotoxic and DNA binding properties of K2CrO4 (Cr6+) in comparison with those of Cl3Cr (Cr3+). The results indicate that K2CrO4 exhibits higher cytotoxicity than Cl3Cr in several human and murine cell lines. The cytotoxic activity of K2CrO4 is also indicated by the fact that is able to produce cell killing through apoptosis in cisplatin-resistant cells transformed by H-ras oncogene. Moreover, in vitro DNA binding experiments show that, in the presence of ascorbate (the major intracellular reductant of Cr6+), K2CrO4 induces both interstrand cross-links and strand breaks. Because the chromate anion is by itself unreactive toward DNA, these data suggest that the cytotoxicity of K2CrO4 may be associated with the DNA binding of reactive intermediate chromium species resulting from reduction of Cr6+.