Combination Treatment Of Paclitaxel Research Articles

Auranofin sensitizes breast cancer cells to paclitaxel mediated cell death via regulating FOXO3/Nrf2/Keap1 signaling pathway.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcriptional factor which acts as a regulator for cellular oxidative stress, and tightly regulated by Kelch-like ECH-associated protein 1 (Keap1). In this study, we found that auranofin and paclitaxel combination treatment increased TUNEL positive apoptotic cells and enhanced the DNA damage marker γ-H2AX in MCF-7 and MDA-MB-231 breast cancer cells. The immunoblotting analysis revealed the combination of auranofin and paclitaxel significantly increased the FOXO3 expression in a concentration dependent manner. Further we observed that auranofin and paclitaxel treatment prevents the translocation of Nrf2 in a concentration dependent manner. The increased FOXO3 expression might be involved in the cytoplasmic degradation of Nrf1-Keap1 complex. Further, the molecular docking results confirm auranofin act as the agonist for Foxo3. Therefore, the present results suggest that auranofin sensitize the breast cancer cells to paclitaxel via regulating FOXO3/Nrf2/Keap1signaling pathway.

Exploratory Analysis of Patients With Gastric/Gastroesophageal Junction Adenocarcinoma With or Without Liver Metastasis From the Phase 3 RAINBOW Study.

Liver metastasis (LM) is reported in approximately 40% of patients with advanced/metastatic gastric/gastroesophageal junction adenocarcinoma (metastatic esophagogastric adenocarcinoma; mGEA) and is associated with a worse prognosis. This post-hoc analysis from the RAINBOW trial reported the efficacy, safety, and biomarker outcomes of ramucirumab and paclitaxel combination treatment (RAM+PAC) in patients with (LM+) and without (LM-) LM at baseline. Patients (n=665) were randomly assigned on a 1:1 basis to receive either RAM+PAC (LM+: 150, LM-: 180) or placebo and paclitaxel (PL+PAC) (LM+: 138, LM-: 197). The overall survival (OS) and progression-free survival (PFS) were evaluated using stratified Kaplan-Meier and Cox regression models. The correlation of dichotomized biomarkers (VEGF-C, D; VEGFR-1,2) with efficacy in the LM+ versus LM- subgroups was analyzed using the Cox regression model with reported interaction P-values. The presence of LM was associated with earlier progression than those without LM, particularly in patients receiving PL+PAC (hazard ratio [HR], 1.68). RAM+PAC treatment improved OS and PFS irrespective of LM status but showed greater improvement in LM+ than that in LM- (OS HR, 0.71 [LM+] vs. 0.88 [LM-]; PFS HR, 0.47 [LM+] vs. 0.76 [LM-]). Treatment-emergent adverse events were similar between patients with and without LM. No predictive relationship was observed between biomarker levels (VEGF-C, D; VEGFR-1,2) and efficacy outcome (OS, PFS) (all interaction P-values >0.05). RAM provided a significant benefit, irrespective of LM status; however, its effect was numerically stronger in patients with LM. Therefore, RAM+PAC is a clinically meaningful therapeutic option for patients with mGEA and LM. ClinicalTrials.gov Identifier: NCT01170663.

Ceritinib is a novel triple negative breast cancer therapeutic agent

BackgroundTriple-negative breast cancers (TNBCs) are clinically aggressive subtypes of breast cancer. TNBC is difficult to treat with targeted agents due to the lack of commonly targeted therapies within this subtype. Androgen receptor (AR) has been detected in 12–55% of TNBCs. AR stimulates breast tumor growth in the absence of estrogen receptor (ER), and it has become an emerging molecular target in TNBC treatment.MethodsCeritinib is a small molecule inhibitor of tyrosine kinase and it is used in the therapy of non-small lung cancer patients. Enzalutamide is a small molecule compound targeting the androgen receptor and it is used to treat prostate cancer. Combination therapy of these drugs were investigated using AR positive breast cancer mouse xenograft models. Also, combination treatment of ceritinib and paclitaxel investigated using AR− and AR low mouse xenograft and patient derived xenograft models.ResultsWe screened 133 FDA approved drugs that have a therapeutic effect of AR+ TNBC cells. From the screen, we identified two drugs, ceritinib and crizotinib. Since ceritinib has a well- defined role in androgen independent AR signaling pathways, we further investigated the effect of ceritinib. Ceritinib treatment inhibited RTK/ACK/AR pathway and other downstream pathways in AR+ TNBC cells. The combination of ceritinib and enzalutamide showed a robust inhibitory effect on cell growth of AR+ TNBC cells in vitro and in vivo. Interestingly Ceritinib inhibits FAK-YB-1 signaling pathway that leads to paclitaxel resistance in all types of TNBC cells. The combination of paclitaxel and ceritinib showed drastic inhibition of tumor growth compared to a single drug alone.ConclusionsTo improve the response of AR antagonist in AR positive TNBC, we designed a novel combinational strategy comprised of enzalutamide and ceritinib to treat AR+ TNBC tumors through the dual blockade of androgen-dependent and androgen-independent AR signaling pathways. Furthermore, we introduced a novel therapeutic combination of ceritinib and paclitaxel for AR negative or AR-low TNBCs and this combination inhibited tumor growth to a great extent. All agents used in our study are FDA-approved, and thus the proposed combination therapy will likely be useful in the clinic.

Abstract 3696: GS-9716: A potent, selective and orally bioavailable small molecule inhibitor of MCL1 for the treatment of cancer

Abstract MCL1 is an anti-apoptotic member of the BCL2 family of proteins. These anti-apoptotic proteins prevent caspase-mediated cell apoptosis by binding to the pro-apoptotic proteins BIM, BAK and BAX, thereby inhibiting the formation of pores on the outer mitochondrial membrane. In cancer, MCL1 is upregulated to overcome such stress-induced effects, promoting cell survival, therapy resistance, and tumor progression. Here, we describe the in vitro and in vivo activity of GS-9716, a potent and selective MCL1 small molecule inhibitor that binds directly to MCL1 and induces rapid apoptosis in cancer cells by activating the mitochondrial apoptotic pathway. GS-9716 displayed potent and selective disruption of human MCL1-BIM protein dimer in vitro. In hematological and solid tumor cell line models, GS-9716 led to dose dependent reduction of MCL1-BIM and MCL1-BAK protein dimers. MCL1 protein dimer (BAK and BIM) reduction correlated with dose-dependent increases in cleaved caspase (apoptosis marker). GS-9716 potently reduced cellular viability across panels of hematological (Median GI50 = 30 nM) and breast cancer cell lines (Median GI50 = 470 nM). GS-9716 exhibits favorable pharmacokinetics properties with good oral bioavailability across species. GS-9716 dosed daily, once per week, or 7-day cycles of 2 days on/5 days off, resulted in significant tumor growth inhibition against models of multiple myeloma (H929), several TNBC cell line xenografts (HCC1187 and HCC70) and patient-derived xenografts. Also, in these models, GS-9716 demonstrated dose-dependent MCL1 protein dimer (BIM and BAK) reduction and activation of apoptosis in tumors. In addition to single agent activity, GS-9716 showed strong synergy with multiple anti-cancer therapies; robust in vitro synergy was observed with venetoclax in the AML models and as well as with paclitaxel in the TNBC models. The combination treatment of paclitaxel (dosed IV, QW) with GS-9716 (dosed orally, 2 days on/5 days off) in the TNBC HCC1187 xenograft model achieved complete tumor regression. Similar responses were also observed when GS-9716 was dosed with paclitaxel in the TNBC PDX models. GS-9716 is currently in Phase 1 clinical trial evaluating safety, tolerability and pharmacokinetics as monotherapy and in combination with anticancer therapies in adults with advanced solid tumors (NCT05006794). Citation Format: Clinton K. Matson, Thomas Kenney, Bart H. Steiner, Chloe R. Deodato, Anella Yahiaoui, Claudia A. Rubio, Julie T. Chan, Nevena Mollova, Kathleen S. Keegan, Chandrasekar Venkataramani. GS-9716: A potent, selective and orally bioavailable small molecule inhibitor of MCL1 for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3696.

Toll Like Receptor 4 Inhibition Improves Antitumor Responses to MBQ‐167 in Triple Negative Breast Cancer Cells in vitro

Triple negative breast cancer (TNBC) is an aggressive variant of breast cancer that lacks the expression of estrogen, progesterone, and human epithelial growth factor receptors. Due to the scarce availability of receptor‐targeted or hormonal treatments, TNBC patients are submitted to taxane‐based chemotherapies like paclitaxel. Patients initially respond to paclitaxel, but 4 out of 10 patients may develop tumor recurrence along with high metastasis and mortality rates. Several studies demonstrate that paclitaxel may induce chemoresistance and metastasis through the activation of Toll‐Like Receptor 4 (TLR4)/NFKB signaling pathway, a known cancer prognostic marker in breast cancer. Hence, new treatments are needed to improve TNBC prognosis in patients. Recently, our laboratory and collaborators developed MBQ‐167, a potent Rac and Cdc42 inhibitor that decreases tumor burden, cell proliferation, and metastasis in TNBC mouse models. In preliminary studies with TNBC mice, we observed that MBQ‐167/Paclitaxel combination treatment prevented metastasis progression compared to paclitaxel treatment alone. This led us to hypothesize that MBQ‐167 chemosensitizes aggressive breast cancer cells and reduces metastasis by blocking Rac/Cdc4, hence decreasing their downstream target NfkB activity. This research project aims to evaluate cellular and molecular events that explain how MBQ‐167 prevents paclitaxel‐induced metastasis. Here, we generated TLR4‐knockdowns (TLR4‐KD) in MDA‐MB‐231 TNBC cell lines using lentiviral particles with shRNAs against the TLR4 mRNA. After knockdown validation with western blot analysis (WB), Wildtype (MDA‐MB‐231), Scramble control knockdowns (Sc‐KD), and TLR4‐KD cells were treated with different concentrations of MBQ‐167, paclitaxel, doxorubicin, or combinations. After treatments, we evaluated the effect on cell viability from MTT assays at 96 and 120 hours, cell apoptosis through Caspase‐Glo 3/7 Assays at 48 hours, and cellular migration through scratch wound healing assays. Our results demonstrate that partial inhibition of TLR4 decreases the cell viability of cells, increases apoptosis, and decreases cell migration after treatment with MBQ‐167 (250 nM and 500 nM), Paclitaxel (5 nM and 10 nM), or Doxorubicin (250 nM and 500 nM). We also observed an additive response upon combinatorial treatments with MBQ‐167/Paclitaxel and MBQ‐167/Doxorubicin when TLR4‐KD cells were compared to wild‐type and Sc‐KD cells. Altogether, these results suggest that TLR4‐KD chemosensitizes cells to Paclitaxel and Doxorubicin chemotherapies. In addition, TLR4 inhibition improves cellular response to Rac/Cdc42 inhibitor, MBQ‐167. Therefore, TLR4‐KD may reduce Rac and NfkB signaling, improving treatment response to MBQ‐167, MBQ‐167/Paclitaxel, and MBQ‐167/Doxorubicin. Other cellular studies, including Rac and NfkB activation assays, are being evaluated in our laboratory.

A novel multifunctional nanoparticles formed by molecular recognition between AS1411 aptamer and redox-responsive paclitaxel-nucleoside analogue prodrug for combination treatment of β-lapachone and paclitaxel

Despite its high antitumor activity, the clinical application of chemotherapy is greatly impeded by lacking of specific accumulation and poor solubility. To address the above challenges, we designed a AS1411 aptamer modified nanoparticles based on molecular recognition of nucleobases. Firstly, a redox sensitive Paclitaxel-SS-Zidovudine (PZ) prodrug was synthesized. Then PZ/β-lapachone/AS1411/DSPE-PEG nanoparticles were prepared and AS1411 aptamer was connected through molecular recognition between the nucleoside analogue Zidovudine (ZDV) and the thymine on aptamer. DSPE-PEG (DP) was incorporated into nanoparticles to prolong the residence time of nanoparticles in the blood circulation. Furthermore, to realize the combination treatment, β-lapachone (LAP) has been incorporated into nanoparticles with high drug loading efficiency through the interaction of π-π stacking force and H-bonding between LAP and Paclitaxel (PTX). LAP can generate abundant exogenous reactive oxygen species (ROS) via the bioactivation of NAD(P)H: quinone oxidoreductase-1 (NQO1). Moreover, the connection of Zidovudine (ZDV) and AS1411 through molecular recognition of nucleobases further optimized the nanoparticles with high affinity to nucleolin which overexpressed on tumor cell membrane, thereby inducing the specific accumulation of nanoparticles in tumor sites. In vivo and in vitro studies showed that the obtained nanoparticles of PZ/LAP/AS1411/DP exhibited better tumor growth inhibition and lower systemic side effects. Herein, we have rationally conducted a novel self-codelivery system for effectively synergistic antitumor treatment.

Response Surface Methodology to Optimize the Combination Treatment of Paclitaxel, Bufalin and Cinobufagin for Hepatoma Therapy.

Hepatoma is a common malignancy in the world with high morbidity and mortality. The treatment of hepatoma is limited by its poor response to many chemotherapeutic agents. Although paclitaxel (PTX) is widely used in clinical chemotherapy, the low sensitivity to hepatoma restricts its application. Combination therapy is a promising approach to resolve this dilemma. To evaluate the interaction between paclitaxel, bufalin (BFL) and cinobufagin (CBF), and explore the optimum combination efficiently. HepG2 cells were treated with PTX, BFL and CBF individually or in combination. Their interactions were evaluated by two classical models (Chou-Talalay model and Bliss independence). Response surface methodology (RSM) was used to explore the optimum combination. Furthermore, the optimum drug combination was verified by the morphological experiment. Synergistic effects were observed when cells were exposed to binary mixtures of PTX+CBF and BFL+CBF. Although the interaction of PTX and BFL was summative, a strong synergistic effect was observed when cells were exposed to ternary mixtures of PTX+BFL+CBF. The interaction results of RSM were consistent with classical models, but more efficient. Moreover, the optimum combination dose was given by RSM without the combinatorial explosion of exhaustive testing. The combination of BFL and CBF synergistically enhanced the potency of PTX against HepG2 cells. RSM could give an accurate evaluation for drug interactions and efficient prediction of optimum combination.

High-throughput screening and genome-wide analyses of 44 anticancer drugs in the 1000 Genomes cell lines reveals an association of the NQO1 gene with the response of multiple anticancer drugs.

Cancer patients exhibit a broad range of inter-individual variability in response and toxicity to widely used anticancer drugs, and genetic variation is a major contributor to this variability. To identify new genes that influence the response of 44 FDA-approved anticancer drug treatments widely used to treat various types of cancer, we conducted high-throughput screening and genome-wide association mapping using 680 lymphoblastoid cell lines from the 1000 Genomes Project. The drug treatments considered in this study represent nine drug classes widely used in the treatment of cancer in addition to the paclitaxel + epirubicin combination therapy commonly used for breast cancer patients. Our genome-wide association study (GWAS) found several significant and suggestive associations. We prioritized consistent associations for functional follow-up using gene-expression analyses. The NAD(P)H quinone dehydrogenase 1 (NQO1) gene was found to be associated with the dose-response of arsenic trioxide, erlotinib, trametinib, and a combination treatment of paclitaxel + epirubicin. NQO1 has previously been shown as a biomarker of epirubicin response, but our results reveal novel associations with these additional treatments. Baseline gene expression of NQO1 was positively correlated with response for 43 of the 44 treatments surveyed. By interrogating the functional mechanisms of this association, the results demonstrate differences in both baseline and drug-exposed induction.

Doxorubicin-paclitaxel sequential treatment: insights of DNA methylation and gene expression changes of luminal A and triple negative breast cancer cell lines.

Breast cancer is one of the significant causes of death among women diagnosed with cancer worldwide. Even though several chemotherapy combinations are still the primary treatment of breast cancer, unsuccessful treatments, and poor prognostic outcomes are still being reported. DNA methylation and gene expression changes among two breast cancer cell lines representing luminal A (MCF-7) and triple-negative (MDA-MB-231) cancers were determined after sequential combination treatment of doxorubicin and paclitaxel and analyzed using Ingenuity Pathway Analysis. Promoter methylation changes were seen in different treated MCF-7 cells and accompanied by changes in the gene expression of CCNA1 and PTGS2. In MDA-MB-231 cells, the hypomethylation of ESR1 was not accompanied by an increase in its gene expression in any treated cells. The hypomethylation of GSTP1 and MGMT was accompanied by an increase in gene expression levels in the group treated with doxorubicin only. Also, significant downregulation of several genes like MUC1 and MKI67 in MCF-7 cells treated with doxorubicin showed much lower gene expression (- 37.63, - 10.88 folds) when compared with cells treated with paclitaxel (- 2.47, - 2.05 folds) or the combination treatment (- 18.99, - 2.81 folds), respectively. On the other hand, a synergistic effect on MMP9 gene expression was significantly seen in MDA-MB-231 cells treated with the combination (- 9.99 folds) in comparison with the cells treated with doxorubicin (- 3.62 folds) or paclitaxel (1.75 folds) alone. Chemotherapy combinations do not always augment the molecular changes seen in each drug alone, and these changes could be utilized as treatment response markers.

The impacts of race and regimens on the efficacy and safety of paclitaxel and platinum combination treatment for patients with advanced non-small cell lung cancer

Paclitaxel-platinum chemotherapy is the first-line treatment for advanced non-small cell lung cancer (NSCLC) patients. This study quantitatively evaluated the factors influencing the efficacy and safety of the paclitaxel-platinum regimen to provide the necessary reference for the development of clinical practice and clinical trials. A literature search was performed using public databases. The parametric survival function was used to analyze the overall survival (OS) time course of patients treated with the paclitaxel-platinum regimen. The random effects model in the single-arm meta-analysis was used to analyze the objective response rate (ORR) and the incidence of grade 3-4 adverse events (AEs) under the predefined subgroups according to race and the regimen. A total of 31 studies consisting of 3365 participants were included in the analysis. Race was the most important determinant of efficacy and safety in the paclitaxel-platinum regimen, with the median survival time and ORR in East Asians and non-East Asians being 12.2 months (95% CI: 10.5-14.4 months) and 37% (95% CI: 32-41%) and 8.4 months (95% CI: 6.5-11.0 months) and 28% (95% CI: 25-32%), respectively. The incidence of grade 3-4 AEs such as leukopenia and neutropenia was about three times higher in East Asians compared to non-East Asians. The efficacy and safety of the paclitaxel-platinum regimen can vary between East Asian and non-East Asian populations and between different treatment schedules. The results of this study can provide a reliable and precise external control for the future evaluation of new treatment options for advanced NSCLC.

MiR-708-5p enhances erlotinib/paclitaxel efficacy and overcomes chemoresistance in lung cancer cells.

Lung cancer is a collection of aggressive tumors generally not diagnosed until late-stage, resulting in high mortality rates. The vast majority of non-small cell lung cancer (NSCLC) patients undergo combinatory chemotherapeutic treatment, which initially reduces tumor growth, but frequently becomes ineffective due to toxicity and resistance. Researchers have identified multiple signaling pathways involved in lung cancer chemoresistance, including cyclooxygenase-2 (COX-2)/microsomal prostaglandin E synthase-1 (mPGES-1) derived prostaglandin E2 (PGE2). While COX-2 inhibitors have shown promise in the clinic, their use is limited due to severe side effects. One novel approach to effectively suppress COX-2 signaling is through microRNA (miRNA). MiRNAs are small-noncoding RNAs commonly misexpressed in cancer. One tumor suppressive miRNA, miR-708-5p, has been shown to repress pro-resistant signaling pathways, including COX-2 and mPGES-1. Here, we demonstrate that chemotherapies reduce COX-2 expression, possibly through induction of miR-708-5p. Moreover, combination treatment of erlotinib (ERL) or paclitaxel (PAC) with miR-708-5p enhances COX-2 and mPGES-1 protein suppression. We also show that combination chemotherapeutic and miR-708-5p treatment intensifies the anti-proliferative and pro-apoptotic effects of ERL and PAC. We also created ERL and PAC resistant lung cancer cell lines, which have increased COX-2 expression and diminished miR-708-5p levels compared to naïve lung cancer cells. While ERL and PAC treatments do not alter resistant cell phenotype alone, combination treatment with miR-708-5p partially restores the chemotherapies’ anti-proliferative effects and fully restores their pro-apoptotic qualities. These data suggest miR-708-5p may have potential combinatory therapeutic value to more efficaciously treat lung tumors while overcoming chemoresistance.

Transcriptome analysis of iBET-151, a BET inhibitor alone and in combination with paclitaxel in gastric cancer cells.

BET inhibitor, as an epigenetic regulator inhibitor, reduces the expression of oncogenes such as Myc and Bcl-2, which affects cancer growth and development. However, it has modest activity because of the narrow therapeutic index. Therefore, combination therapy is necessary to increase the anti-tumor effect. Paclitaxel, an anti-mitotic inhibitor, is used as second-line therapy for gastric cancer (GC) as a monotherapy or combination. In this study, we performed RNA sequencing of GC cells treated with iBET-151 and/or paclitaxel to identify the differentially expressed genes associated with possible mechanisms of synergistic effect. We also performed Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses to determine the most enriched terms and pathways of upregulated and downregulated genes. We found 460 genes in which iBET-151 and paclitaxel combination treatment changed more than single-treatment or no-treatment. Thus, additional functional studies are needed, but our results provide the first evidence of the synergistic effect between iBET-151 and paclitaxel in regulating the transcriptome of GC cells.

Anti-tumor Synergistic Effect of a Dual Cancer-Specific Recombinant Adenovirus and Paclitaxel on Breast Cancer.

This study aimed at investigating the anticancer potential of the recombinant adenovirus Ad-apoptin-hTERTp-E1a (Ad-VT) and its synergistic combination with paclitaxel (PTX) in breast cancer treatment. First, we used the Calcusyn software to analyze the synergy between the Ad-VT and paclitaxel, and to determine the final drug concentration. Second, we used crystal violet staining and WST-1 assays to analyze the inhibitory effect of Ad-VT and paclitaxel combination treatment on MCF-7, MDA-MB-231, and MCF-10A cells. Subsequently, we used Hoechst, Annexin V, JC-1 staining to analyze the inhibition pathway of drugs on breast cancer cells. We also used Transwell assays to analyze the cell migration and invasion of MCF-7 and MDA-MB-231 cells. The pGL4.51 plasmid was used to transfect and to generate MDA-MB-231 cells, that stably express luciferase (MDA-MB-231-LUC). The in vivo tumor inhibition effect of Ad-VT and paclitaxel combination treatment was subsequently confirmed using a tumor-bearing nude mouse model. This combination treatment can increase the inhibition of breast cancer cells and reduce paclitaxel toxicity. Ad-VT had a strong apoptosis-inducing effect on MCF-7 and MDA-MB-231 cells, that was mainly mediated through the mitochondrial apoptotic pathway. The combination of Ad-VT and paclitaxel could significantly increase the inhibition of breast cancer cell migration and invasion. Combination of Ad-VT and paclitaxel can inhibit tumor growth and reduce toxicity in vivo. Ad-VT can also inhibit the growth of breast cancer cells and promote their apoptosis. Meanwhile, when it is combined with paclitaxel, Ad-VT could play a significant role in a synergistic tumor inhibition.

Low Dose of Paclitaxel Combined with XAV939 Attenuates Metastasis, Angiogenesis and Growth in Breast Cancer by Suppressing Wnt Signaling.

Triple-negative breast cancer (TNBC) accounts for 15% of overall breast cancer. A lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2 receptor) makes TNBC more aggressive and metastatic. Wnt signaling is one of the important pathways in the cellular process; in TNBC it is aberrantly regulated, which leads to the progression and metastasis. In this study, we designed a therapeutic strategy using a combination of a low dose of paclitaxel and a Wnt signaling inhibitor (XAV939), and examined the effect of the paclitaxel-combined XAV939 treatment on diverse breast cancer lines including TNBC cell lines (MDA-MB-231, MDA-MB-468, and BT549) and ER+ve cell lines (MCF-7 and T-47D). The combination treatment of paclitaxel (20 nM) and XAV939 (10 µM) exerted a comparable therapeutic effect on MDA-MB-231, MDA-MB-468, BT549, MCF-7, and T-47D cell lines, relative to paclitaxel with a high dose (200 nM). The paclitaxel-combined XAV939 treatment induced apoptosis by suppressing Bcl-2 and by increasing the cleavage of caspases-3 and PARP. In addition, the in vivo results of the paclitaxel-combined XAV939 treatment in a mice model with the MDA-MB-231 xenograft further confirmed its therapeutic effect. Furthermore, the paclitaxel-combined XAV939 treatment reduced the expression of β-catenin, a key molecule in the Wnt pathway, which led to suppression of the expression of epithelial-mesenchymal transition (EMT) markers and angiogenic proteins both at mRNA and protein levels. The expression level of E-cadherin was raised, which potentially indicates the inhibition of EMT. Importantly, the breast tumor induced by pristane was significantly reduced by the paclitaxel-combined XAV939 treatment. Overall, the paclitaxel-combined XAV939 regimen was found to induce apoptosis and to inhibit Wnt signaling, resulting in the suppression of EMT and angiogenesis. For the first time, we report that our combination approach using a low dose of paclitaxel and XAV939 could be conducive to treating TNBC and an external carcinogen-induced breast cancer.

Orlistat Displays Antitumor Activity and Enhances the Efficacy of Paclitaxel in Human Hepatoma Hep3B Cells.

Orlistat has been proved to be an effective fatty acid synthase inhibitor that is able to inhibit the proliferation and induce apoptosis in many cancer cell types. However, the anticancer effects of orlistat on hepatocellular carcinoma are undefined. We found that orlistat inhibited cell growth and induced G0/G1 cell cycle arrest with increased cyclin D, cyclin E, and p21 expression in human hepatoma Hep3B cells. Furthermore, protein expression of cyclin A, cyclin B, Cdk1, Cdk2, and Cdk4 was reduced by orlistat. This study investigated the role of lipid metabolism on orlistat-induced human hepatoma Hep3B cell death. The decrease in the expression of key enzymes in fatty acid metabolism, including FASN, ACOT8, PPT1, FABP1, CPT1 and CPT2, was observed after orlistat treatment. We also demonstrated that peroxisomal activity was involved in the orlistat-induced Hep3B cell death. In this study, we established an in vitro model to investigate the effect of orlistat on lipid accumulation. We found that orlistat significantly inhibited the cellular lipid content when administered in fatty acid overload conditions in Hep3B cells. Combination treatment of orlistat and paclitaxel was able to induce a synergistic effect on growth inhibition and cell apoptosis in Hep3B cells. Our data suggested that orlistat displays antitumor activity and enhances the efficacy of paclitaxel in Hep3B cells.

Targeting HER2 in patient-derived xenograft ovarian cancer models sensitizes tumors to chemotherapy.

Ovarian cancer is the most lethal gynecologic malignancy. About 75% of ovarian cancer patients relapse and/or develop chemo‐resistant disease after initial response to standard‐of‐care treatment with platinum‐based therapies. HER2 amplifications and overexpression in ovarian cancer are reported to vary, and responses to HER2 inhibitors have been poor. Next generation sequencing technologies in conjunction with testing using patient‐derived xenografts (PDX) allow validation of personalized treatments. Using a whole‐genome mate‐pair next generation sequencing (MPseq) protocol, we identified several high grade serous ovarian cancers (HGS‐OC) with DNA alterations in genes encoding members of the ERBB2 pathway. The efficiency of anti‐HER2 therapy was tested in three different PDX lines with the identified alterations and high levels of HER2 protein expression. Treatment responses to pertuzumab or pertuzumab/trastuzumab were compared in each PDX line WITH standard carboplatin and paclitaxel combination treatment. In all three PDX models, HER2‐targeted therapy resulted in significant inhibition of tumor growth compared with untreated controls. However, the responses in each case were inferior to those to chemotherapy, even for chemo‐resistant lines. When chemotherapy and HER2‐targeted therapy were administered together, a significant regression of tumor was observed after 6 weeks of treatment compared with chemotherapy alone. Post‐treatment analysis of these tissues revealed that inhibition of the ERBB2 pathway occurred at the level of phosphorylation and expression of downstream targets. In conclusion, while targeting of presumably activated ERBB2 pathway alone in HGS‐OC results in a modest treatment benefit, a combination therapy including both chemotherapy drugs and HER2 inhibitors provides a far better response. Further studies are needed to address development of recurrence and sensitivity of recurrent disease to HER2‐targeted therapy.

Dasatinib sensitises triple negative breast cancer cells to chemotherapy by targeting breast cancer stem cells

BackgroundPatients with triple negative breast cancer (TNBC) exhibit poor prognosis and are at high risk of tumour relapse, due to the resistance to chemotherapy. These aggressive phenotypes are in part attributed to the presence of breast cancer stem cells (BCSCs). Therefore, targeting BCSCs is a priority to overcoming chemotherapy failure in TNBCs.MethodsWe generated paclitaxel (pac)-resistant TNBC cells which displayed higher sphere forming potential and percentage of BCSC subpopulations compared to the parental cells. A screen with various kinase inhibitors revealed dasatinib, a Src kinase family inhibitor, as a potent suppressor of BCSC expansion/sphere formation in pac-resistant TNBC cells.ResultsWe found dasatinib to block pac-induced BCSC enrichment and Src activation in both parental and pac-resistant TNBC cells. Interestingly, dasatinib induced an epithelial differentiation of the pac-resistant mesenchymal cells, resulting in their enhanced sensitivity to paclitaxel. The combination treatment of dasatinib and paclitaxel not only decreased the BCSCs numbers and their sphere forming capacity but also synergistically reduced cell viability of pac-resistant cells. Preclinical models of breast cancer further demonstrated the efficiency of the dasatinib/paclitaxel combination treatment in inhibiting tumour growth.ConclusionsDasatinib is a promising anti-BCSC drug that could be used in combination with paclitaxel to overcome chemoresistance in TNBC.

Sab concentrations indicate chemotherapeutic susceptibility in ovarian cancer cell lines.

The occurrence of chemotherapy-resistant tumors makes ovarian cancer (OC) the most lethal gynecological malignancy. While many factors may contribute to chemoresistance, the mechanisms responsible for regulating tumor vulnerability are under investigation. Our analysis of gene expression data revealed that Sab, a mitochondrial outer membrane (MOM) scaffold protein, was down-regulated in OC patients. Sab-mediated signaling induces cell death, suggesting that this apoptotic pathway is diminished in OC. We examined Sab expression in a panel of OC cell lines and found that the magnitude of Sab expression correlated to chemo-responsiveness; wherein, OC cells with low Sab levels were chemoresistant. The Sab levels were reflected by a corresponding amount of stress-induced c-Jun N-terminal kinase (JNK) on the MOM. BH3 profiling and examination of Bcl-2 and BH3-only protein concentrations revealed that cells with high Sab concentrations were primed for apoptosis, as determined by the decrease in pro-survival Bcl-2 proteins and an increase in pro-apoptotic BH3-only proteins on mitochondria. Furthermore, overexpression of Sab in chemoresistant cells enhanced apoptotic priming and restored cellular vulnerability to a combination treatment of cisplatin and paclitaxel. Contrariwise, inhibiting Sab-mediated signaling or silencing Sab expression in a chemosensitive cell line resulted in decreased apoptotic priming and increased resistance. The effects of silencing on Sab on the resistance to chemotherapeutic agents were emulated by the silencing or inhibition of JNK, which could be attributed to changes in Bcl-2 protein concentrations induced by sub-chronic JNK inhibition. We propose that Sab may be a prognostic biomarker to discern personalized treatments for OC patients.

Combination of pristimerin and paclitaxel additively induces autophagy in human breast cancer cells via ERK1/2 regulation.

Pristimerin, a quinonemethide triterpenoid, has demonstrated anticancer activity against a number of types of cancer, including breast cancer. However, its mechanism of action remains unclear. The present study investigated the autophagy-induced anticancer efficacy of pristimerin on MDA-MB-231 human breast cancer cells. Pristimerin inhibited the growth of these cells in a concentration-dependent manner. Treatment with pristimerin dose-dependently induced an increase of light chain 3B (LC3-II), whereas autophagy inhibitor 3-methyladenine (3-MA) inhibited pristimerin-induced LC3-II accumulation and cytotoxic effects. Autophagy was also activated by paclitaxel as observed by an elevated LC3-II level. Although 24 µM paclitaxel induced autophagy without cytotoxicity, combined with pristimerin it additively induced cell growth inhibition and autophagy induction. Autophagy induction was measured with an autophagy detection kit and LC3-II levels were monitored by western blot analysis. Treatment with 3-MA inhibited LC3-II accumulation and cell death induced by a combination of paclitaxel and pristimerin. Pristimerin and paclitaxel inhibited extracellular signal-regulated kinase (ERK)1/2/p90RSK signaling, consistent with autophagy indicators, namely p62 degradation and beclin 1 expression. In addition, ERK activator ceramide C6 treatment suppressed the LC3-II levels induced by a combination of paclitaxel and pristimerin. These results suggested that exposure to pristimerin induced autophagic cell death, whereas a combination treatment of pristimerin and paclitaxel resulted in an additive effect on ERK-dependent autophagic cell death.

Abstract A57: Drug sensitivity and resistance testing (DSRT) of clinically important compounds on primary ovarian cancer cell lines

Abstract The heterogeneity of chemoresponses in high-grade serous ovarian cancer (HGS-OvCa) presents a major clinical challenge. The inherited or acquired nonresponsiveness to current therapies is likely to be one reason for relapse and treatment failure. Better models for predicting effective treatment options and drug combinations are needed. Although most tumors initially respond to standard platinum-taxane combination therapy, treatment resistance eventually evolves in 80-90% of the patients. Drug sensitivity and resistance testing (DSRT) was performed by using high-throughput screening (HTS) of 306 small-drug molecules on six primary cell lines from patients with disseminated HGS-OvCa. Commonly available ovarian cancer cell line OVCAR8 was used as a control. The drug effect was investigated with help of a quantitative scoring approach, drug sensitivity score (DSS). Sixteen drugs of clinical interest were investigated in more detail. Drug sensitivity varied greatly within primary cell lines. Out of 306 compounds, 29 were effective on the most resistant cell line, whereas 102 compounds showed effect on the most sensitive line. We found that 9 out of the 16 clinically important compounds gave no response on the tested cell lines. Seven compounds provided response on the screened cell lines: four HSP90 inhibitors, an HSP70 inhibitor, a Wee1 inhibitor, and a proteasome inhibitor. Of these seven compounds, the most effective drug compounds (the Wee1 inhibitor and two HSP90 inhibitors) were chosen for validation on primary HGS-OvCa cell lines to verify the HTS result. The effectiveness of currently used clinical treatment-line drugs, cisplatin and paclitaxel, was compared to the putative novel drug compounds on the primary cell lines and the control cell line. One primary cell line was completely resistant to the validated drug compounds as well as to cisplatin and paclitaxel combination treatment. Five cell lines were sensitive to cisplatin-paclitaxel treatment, but the sensitivity to the three most effective compounds varied greatly. The commonly available cell line OVCAR8 was the most sensitive of all tested cell lines. In conclusion, we found three potential drug compounds of clinical interest effective for disseminated HGS-OvCa. The analyses demonstrate that patient-derived primary HGS-OvCa cell lines have unique heterogeneous characteristics that are likely to have an effect on the choice of best drug candidates for each individual cell line, and furthermore for each patient. Consequently, more combinatorial drug treatment strategies should be validated to find new specific personalized drug treatment strategies. Citation Format: Pia Roering, Piia Mikkonen, Swapnil Potdar, Krister Wennerberg, Johanna Hynninen, Seija Grénman, Annika Auranen, Olli Carpén, Katja Kaipio. Drug sensitivity and resistance testing (DSRT) of clinically important compounds on primary ovarian cancer cell lines. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A57.