Association between the apoptotic effect of Cabazitaxel and its pro-oxidant efficacy on the redox adaptation mechanisms in prostate cancer cells with different resistance phenotypes

ABSTRACTRedox adaptation causes poor prognosis by adapting cancer cells to excessive oxidative stress. Previously, we introduced an oxidative stress-resistant metastatic prostate cancer (mPC) model (LNCaP-HPR) that redox adaptation reduced the effect of Cabazitaxel (Cab), the last taxane-derivative for metastatic castration-resistant PC (mCRPC). Whereas, we investigated for the first time whether there is an association between the altered apoptotic effect and pro-oxidant efficacy of Cab on the redox adaptation in PC cells with different phenotypes, including LNCaP mPC, LNCaP-HPR, C4–2 mCRPC, and RWPE-1 cells. Cab was shown pro-oxidant efficacy proportionally with the apoptotic effect, more prominent in the less aggressive LNCaP cells, by increasing the endogenous ROS, mitochondrial damage, and inhibiting nuclear ROS scavengers, p-Nrf2 and HIF-1α. However, the pro-oxidant and apoptotic effect was lower in the LNCaP-HPR and C4–2 cells, indicating that the drug sensitivity of the cells adapted to survive with more ROS was reduced via altered regulation of redox adaptation. Additionally, unlike LNCaP, Cab caused an increase in the p-NF-κB activation, suggesting that the p-NF-κB might accompany maintaining survival with the increased ROS in the aggressive PC cells. Moreover, the cytotoxic and apoptotic effects of Cab were less on RWPE-1 cells compared to LNCaP but were closer to those on the more aggressive LNCaP-HPR and C4–2 cells, except for the changing pro-oxidant effect of Cab. Consequently, this study indicates the variable pro-oxidant effects of Cab on redox-sensitive proteins, which could be a target for improving Cab’s apoptotic effect more in aggressive PC cells

Synthetically Lethal BMN 673 (Talazoparib) Loaded Solid Lipid Nanoparticles for BRCA1 Mutant Triple Negative Breast Cancer

PurposeThe purpose of the study was to produce BMN 673 loaded solid lipid nanoparticles (SLNs) to improve its therapeutic index, to minimize toxicity and to overcome homologous recombination (HR)-mediated resistance.MethodsFirstly, BMN 673-SLNs were characterized using Nano Zeta Sizer. After treatment with different concentrations of BMN 673 and BMN 673-SLNs, cell viability of HCC1937((BRCA1-/-)), HCC1937-R (BMN 673-resistant) TNBC and MCF-10A normal human mammary breast epithelial cell line was analyzed by WST-1 assay. In an attempt to assess the therapeutic synthetic lethality efficacy of SLNs formulation, cell cycle arrest, DNA damage, mRNA expression levels of PARP1, H2AFX, RAD51 and BRCA1 gene were investigated. Then, PARP, ?H2AX, RAD51 and BRCA1 protein expression and nuclear localization were analyzed by western blot and immunofluorescence analysis.ResultsWhen compared with BMN 673, BMN 673-SLNs showed remarkably a decrease in HCC1937 and HCC1937-R cells with less damage to MCF-10A cells. BMN 673-SLNs significantly induced toxicity through double-stranded DNA breaks, G2/M cell cycle arrest and PARP cleavage in TNBC cells. Additionally, BMN 673-resistance was mediated by miR-107, miR-193b and miR-1255b targeting BRCA1 and RAD51 in HCC1937 and HCC1937-R cells. However, BMN 673-SLNs treatment could overcome HR-mediated resistance in TNBC cells.ConclusionsAs a result, our findings suggest that SLNs formulation strongly provides a synthetic lethal therapeutic potential in BRCA1 mutated sensitive and resistant TNBC cells

An in vitro model for the development of acquired tamoxifen resistance

The development of resistance to tamoxifen (Tam) remains a challenging clinical problem for ER+ breast cancer patients. To understand the mechanisms underlying of resistance, previous studies have driven the acquisition of Tam resistance by exposing cells to varying concentration of drug for varying lengths of time. However, a detailed protocol for the establishment of Tam-resistant cells remains to be clarified. In the present study, we aimed to determine and compare the effect of different in vitro protocols on the degree of resistance to 4-hydroxytamoxifen (4-OH Tam) for MCF7 cells. For this purpose, MCF7-Tam resistance (MCF7-TamR) cells were developed by treated with different concentrations (100, 200, 400, 600, 800 and 1000 nM) of 4-OH Tam over 3 months. The relative resistance was measured by WST-1 analysis. Studies characterizing of the 4-OH Tam resistance of MCF7-TamR cells were performed by 17 beta-oestradiol (E2) and Annexin V/PI analysis. In addition, the expression levels of ABCC1, ABCG2 and ABCG1 were detected by RT-PCR, any changes in morphological of each resistance group were observed at the end of each month and compared with parental MCF7 cells. Consequently, exposure time and concentration can affect the degree of resistance to 4-OH Tam; thus, dose and treatment duration should be chosen according to the desired degree of resistance. This work presents a novel procedure for the generation of MCF7-TamR cells, thus enabling the identification and characterization of MCF7-TamR cells

THE EFFECT OF SOLID LIPID NANOPARTICLES ON TAMOXIFEN-RESISTANT BREAST CANCER CELLS

To overcome the acquired Tamoxifen (Tam) resistance in Tam-resistant breast cancer cells without damaging normal cells, we have examined the therapeutic efficacy of Tam-loaded solid lipid nanoparticles (SLNs). Tam-loaded SLNs were produced by hot homogenization method. After characterization, in vitro cytotoxic and apoptotic activity of Tam-SLNs were evaluated in MCF7, MCF7-TamR (Tam-resistant breast cancer cells) and MCF10A cells. Tam-SLNs had an average size nearly 300 nm and a zeta potential of approximately-40 mV. In vitro cytotoxicity results showed that Tam-SLNs indicated the cytotoxic and apoptotic activity on MCF7 and MCF7-TamR cells. We found that MCF7-TamR cell viability was also suppressed significantly by Tam-SLNs and thus, Tam-SLNs could delay and overcome Tam-resistance (p<0.05). Furthermore, the Tam-SLNs did not induce apoptosis on MCF10A control cells. The lowest MCF10A cell viability was 83.0% whereas MCF7 and MCF7-TamR (R↔ and R↑) cells viability are reduced to 21.98%, 27.5% and 29.4% at 10 µM of Tam-SLNs, respectively (p<0.05). The obtained results were supported by apoptosis assays. SLNs-delivery system provided therapeutic efficacy to overcome Tam-resistance thanks to unique features of SLNs including small size, drug accumulation in the tumor site and controlled drug release. Therefore, Tam-SLNs may have therapeutic potential for the treatment of TAM-resistant breast cancer

E-Health and Bioengineering Conference

The anti-estrogen tamoxifen (Tam) is the most preferred option for patients with estrogen-receptor (ER)-positive breast cancer. However, multi-drug resistance (MDR) is a considerable clinical problem in the successful chemotherapeutic treatment. Members of the ATP-binding cassette (ABC) transporter family proteins play an important role in acquired drug resistance. Many studies have focused primarily on the clinical significance of P-gp (MDR1), BCRP and MRP1 members belong to ABC transporter superfamily on anticancer-drug resistance. Consequently, several strategies have been improved to overcome drug resistance. Nanoparticle drug delivery systems provide an increase in the intracellular concentration of the drugs as well as a reduction in toxicity of free-drug on healthy cells thanks to unique physical and biological properties. Solid lipid nanoparticles (SLNs) have been improved as an alternative colloidal drug delivery systems due to successful incorporation of both hydrophilic and hydrophobic compounds and their related benefits (controlled drug release, high entrapment efficiency and small size etc.) For this purpose, the aim of this study was to discuss the role of Tam-loaded solid lipid nanoparticles (SLNs) to overcome MDR and determine the ability of Tam-SLNs to induce apoptosis

BMN 673 (talazoparib): A potent PARP inhibitor for triple negative breast cancer with different genetic profile

The objective of the present study was to elucidate the effect of BMN 673 (talozoparib) on BRCA1 mutant (HCC1937) and wild-type (MDA-MB-231) triple negative breast cancer (TNBC). The in vitro cytotoxicity results indicated that BMN 673 had considerable inhibitory effects on HCC1937 and MDA-MB-231 cell lines by inducing apoptosis, multicaspase activity, G2/M arrest, and altering the expression levels of apoptosis-related genes (P < 0.01). Additionally, BMN 673 indicated no toxicity on MCF-10A control cells until a certain concentration and incubation time. However, BMN 673, a novel and selective poly ADP ribose polymerase inhibitor, was more potent in TNBC cells bearing BRCA1 mutant than those with wild-type BRCA1. In conclusion, our study, for the first time, demonstrated a molecular mechanism of the induction of apoptosis by BMN 673 in TNBC with different genetic profile. However, further investigations regarding the exact molecular mechanisms underlying BMN 673-inducing apoptotic death and gene-cell line associations are required

E-Health and Bioengineering Conference

We mentioned the importance of clinical sequence analysis in risk determination, diagnostic and therapeutic process of familial breast cancer and we also summarized next generation sequencing applications in this cancer type. In conclusion, BRCA1/2 genes mutations are associated with an increasing the risk of particularly familial breast cancer. However, sequencing of moderate penetrance genes and/or whole exome could also fill large knowledge gaps in explaining genetic predisposition of breast cancer