Modulation of drug and radiation resistance in small cell lung cancer cells by paclitaxel

Isoliensinine augments the therapeutic potential of paclitaxel in multidrug-resistant colon cancer stem cells and induced mitochondria-mediated cell death

Previously we have reported the isoliensinine (ISO) potentates the therapeutic potential of cisplatin in cisplatin resistant colorectal cancer stem cells. The present study evaluates the chemo-sensitizing potential of the combinatorial regimen of ISO and Paclitaxcel (PTX) on multidrug-resistant (MDR)-HCT-15 cells to reduce the dose requirement of both ISO and PTX. The results of the present study suggest that treatment with the combinatorial regimen of ISO and PTX enhanced the cytotoxic effect with resultant increase in apoptosis in MDR-HCT-15 cells as evident from the altered cellular morphology, G2/M cell cycle arrest, propidium iodide uptake, Annexin V, increased intracellular Ca2+ accumulation, decreased mitochondrial membrane potential, diminished ATP production, PARP-1 cleavage, altered expression of ERK1/2, and apoptotic proteins. Treatment with combinatorial regimen of ISO and PTX also modulated the expression of the transcription factors SOX2, OCT4 which determine the stemness of cancer cells. Thus, results of the present study suggest that ISO and PTX combination regimen induces apoptosis in MDR-HCT-15 in a synergistic manner.

Salvage Chemotherapy with Cisplatin, Ifosfamide, and Paclitaxel in Aggressive Variant of Metastatic Castration-Resistant Prostate Cancer

Significant progress has been achieved in the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, results in patients with aggressive variant prostate cancer (AVPC) have been disappointing. Here, we report retrospectively collected data from intensively pretreated AVPC patients (n = 17; 88.2% visceral metastases; 82% elevation of neuroendocrine markers) treated with salvage chemotherapy consisting of cisplatin, ifosfamide, and paclitaxel (TIP). At the interim analysis, 60% of patients showed radiographic response or stable disease (PFS = 2.5 months; OS = 6 months). In men who responded to chemotherapy, an OS > 15 months was observed. Preclinical analyses confirmed the high activity of the TIP regimen, especially in docetaxel-resistant prostate cancer cells. This effect was primarily mediated by increased cisplatin sensitivity in the emergence of taxane resistance. Proteomic and functional analyses identified a lower DNA repair capacity and cell cycle machinery deficiency to be causative. In contrast, paclitaxel showed inconsistent effects, partially antagonizing cisplatin and ifosfamide in some AVPC models. Consequently, paclitaxel has been excluded from the TIP combination for future patients. In summary, we report for the first time the promising efficacy of TIP as salvage therapy in AVPC. Our preclinical data indicate a pivotal role for cisplatin in overcoming docetaxel resistance.

Chemotherapy in metastatic castration-resistant prostate cancer: Current scenario and future perspectives

Taxanes - docetaxel and cabazitaxel - are the most active chemotherapy drugs currently used for the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, despite a good initial response and survival benefit, nearly all patients eventually develop resistance, which is an important barrier to long-term survival. Resistance to taxanes is also associated with cross-resistance to androgen receptor signaling inhibitors (ARSIs). Unfortunately, other than platinum-based treatments, which have demonstrated some benefit in a subset of patients with Aggressive Variant Prostate Cancer (AVPC), few therapeutic options are available to patients progressing to taxanes. Hence, more research is required to determine whether platinum-based chemotherapy will confer a survival benefit in mCRPC, and the identification of predictive biomarkers and the clinical evaluation of platinum compounds in molecularly selected patients is an urgent but unmet clinical need. The present review focuses on the current status of chemotherapy treatments in mCRPC, interactions with androgen deprivation therapy (ADT) and novel ARSIs, and the main mechanisms of resistance. We will examine the impact of platinum-based treatments in mCRPC and summarize the known predictive biomarkers of platinum response. Finally, future approaches and avenues will be discussed.

Taxane-induced Attenuation of the CXCR2/BCL-2 Axis Sensitizes Prostate Cancer to Platinum-based Treatment

BACKGROUND

Taxanes are the most active chemotherapy agents in metastatic castration-resistant prostate cancer (mCRPC) patients; yet, resistance occurs almost invariably, representing an important clinical challenge. Taxane-platinum combinations have shown clinical benefit in a subset of patients, but the mechanistic basis and biomarkers remain elusive.

OBJECTIVE

To identify mechanisms and response indicators for the antitumor efficacy of taxane-platinum combinations in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS

Transcriptomic data from a publicly available mCRPC dataset of taxane-exposed and taxane-naïve patients were analyzed to identify response indicators and emerging vulnerabilities. Functional and preclinical validation was performed in taxane-resistant mCRPC cell lines and genetically engineered mouse models (GEMMs).

INTERVENTION

Metastatic CRPC cells were treated with docetaxel, cisplatin, carboplatin, the CXCR2 antagonist SB265610, and the BCL-2 inhibitor venetoclax. Gain and loss of function in culture of CXCR2 and BCL-2 were achieved by overexpression or siRNA silencing. Preclinical assays in GEMM mice tested the antitumor efficacy of taxane-platinum combinations.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Proliferation, apoptosis, and colony assays measured drug activity in vitro. Preclinical endpoints in mice included growth, survival, and histopathology. Changes in CXCR2, BCL-2, and chemokines were analyzed by reverse transcriptase quantitative polymerase chain reaction and Western blot. Human expression data were analyzed using Gene Set Enrichment Analysis, hierarchical clustering, and correlation studies. GraphPad Prism software and R-studio were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Transcriptomic data from taxane-exposed human mCRPC tumors correlate with a marked negative enrichment of apoptosis and inflammatory response pathways accompanied by a marked downregulation of CXCR2 and BCL-2. Mechanistically, we show that docetaxel inhibits CXCR2 and that BCL-2 downregulation occurs as a downstream effect. Further, we demonstrated in experimental models that the sensitivity to cisplatin is dependent on CXCR2 and BCL-2, and that targeting them sensitizes prostate cancer (PC) cells to cisplatin. In vivo taxane-platinum combinations are highly synergistic, and previous exposure to taxanes sensitizes mCRPC tumors to second-line cisplatin treatment.

CONCLUSIONS

The hitherto unappreciated attenuation of the CXCR2/BCL-2 axis in taxane-treated mCRPC patients is an acquired vulnerability with potential predictive activity for platinum-based treatments.

PATIENT SUMMARY

A subset of patients with aggressive and therapy-resistant prostate cancer benefits from taxane-platinum combination chemotherapy; however, we lack the mechanistic understanding of how that synergistic effect occurs. Here, using patient data and preclinical models, we found that taxanes reduce cancer cell escape mechanisms to chemotherapy-induced cell death, hence making these cells more vulnerable to additional platinum treatment.

The Novel Triazolonaphthalimide Derivative LSS-11 Synergizes the Anti-Proliferative Effect of Paclitaxel via STAT3-Dependent MDR1 and MRP1 Downregulation in Chemoresistant Lung Cancer Cells

Multidrug resistance (MDR) is a major cause of the inefficacy and poor response to paclitaxel-based chemotherapy. The combination of conventional cytotoxic drugs has been a plausible strategy for overcoming paclitaxel resistance. Herein, we investigated the cytotoxic effects and underlying mechanism of LSS-11, a novel naphthalimide derivative-based topoisomerase inhibitor, in paclitaxel-resistant A549 (A549/T) lung cancer cells. LSS-11 enhanced cell death in A549/T cells by inducing apoptosis through increasing the DR5 protein level and PARP1 cleavage. Importantly, LSS-11 dose-dependently reduced STAT3 phosphorylation and downregulated its target genes MDR1 and MRP1, without affecting P-gp transport function. Chromatin coimmunoprecipitation (ChIP) assay further revealed that LSS-11 hindered the binding of STAT3 to the MDR1 and MRP1 promoters. Additionally, pharmacological inhibition of p-STAT3 by sulforaphane downregulated MDR1 and MRP1, resulting in A549/T cell death by triggering apoptosis. Collectively, our data show that LSS-11 is a potent naphthalimide-based chemosensitizer that could enhance cell death in paclitaxel-resistant lung cancer cells through the DR5/PARP1 pathway and STAT3/MDR1/MRP1 STAT3 inhibition.

Involvement of DDX6 gene in radio- and chemoresistance in glioblastoma

CCRT (concomitant chemotherapy and radiation therapy) is often used for glioblastoma multiforme (GBM) treatment after surgical therapy, however, patients treated with CCRT undergo poor prognosis due to development of treatment resistant recurrence. Many studies have been performed to overcome these problems and to discover genes influencing treatment resistance. To discover potential genes inducing CCRT resistance in GBM, we used whole genome screening by infecting shRNA pool in patient-derived cell. The cells infected ~8,000 shRNAs were implanted in mouse brain and treated RT/TMZ as in CCRT treated patients. We found DDX6 as the candidate gene for treatment resistance after screening and establishing DDX6 knock down cells for functional validation. Using these cells, we confirmed tumor associated ability of DDX6 in vitro and in vivo. Although proliferation improvement was not found, decreased DDX6 influenced upregulated clonogenic ability and resistant response against radiation treatment in vivo and in vitro. Taken together, we suggest that DDX6 discovered by using whole genome screening was responsible for radio- and chemoresistance in GBM.

In vitro Development of Chemotherapy and Targeted Therapy Drug-Resistant Cancer Cell Lines: A Practical Guide with Case Studies

The development of a drug-resistant cell line can take from 3 to 18 months. However, little is published on the methodology of this development process. This article will discuss key decisions to be made prior to starting resistant cell line development; the choice of parent cell line, dose of selecting agent, treatment interval, and optimizing the dose of drug for the parent cell line. Clinically relevant drug-resistant cell lines are developed by mimicking the conditions cancer patients experience during chemotherapy and cell lines display between two- and eight-fold resistance compared to their parental cell line. Doses of drug administered are low, and a pulsed treatment strategy is often used where the cells recover in drug-free media. High-level laboratory models are developed with the aim of understanding potential mechanisms of resistance to chemotherapy agents. Doses of drug are higher and escalated over time. It is common to have difficulty developing stable clinically relevant drug-resistant cell lines. A comparative selection strategy of multiple cell lines or multiple chemotherapeutic agents mitigates this risk and gives insight into which agents or type of cell line develops resistance easily. Successful selection strategies from our research are presented. Pulsed-selection produced platinum or taxane-resistant large cell lung cancer (H1299 and H460) and temozolomide-resistant melanoma (Malme-3M and HT144) cell lines. Continuous selection produced a lapatinib-resistant breast cancer cell line (HCC1954). Techniques for maintaining drug-resistant cell lines are outlined including; maintaining cells with chemotherapy, pulse treating with chemotherapy, or returning to master drug-resistant stocks. The heterogeneity of drug-resistant models produced from the same parent cell line with the same chemotherapy agent is explored with reference to P-glycoprotein. Heterogeneity in drug-resistant cell lines reflects the heterogeneity that can occur in clinical drug resistance.

Same-single-cell analysis for the study of drug efflux modulation of multidrug resistant cells using a microfluidic chip

Since multidrug resistance (MDR) is a major cause of failure in cancer chemotherapy, we report a microfluidic approach combined with the same-single-cell analysis to investigate the modulation of MDR, manifested as the inhibition of drug efflux. A microfluidic chip that was capable of selecting and retaining a single multidrug-resistant cancer cell was used to investigate drug efflux inhibition in leukemia cell lines. Three advantages of the microfluidic-based same-single-cell analysis (dubbed as SASCA) method have been revealed. First, it readily detects the modulation of drug efflux of anticancer compounds (e.g., daunorubicin) by MDR modulators (e.g., verapamil) among cellular variations. Second, SASCA is able to compare the different cellular abilities in response to drug efflux modulation based on the drug transport kinetics of single cells. Third, SASCA requires only a small number of cells, which may be beneficial for investigating drug resistance in minor cell subpopulations (e.g., cancer "stem" cells).

A systematic review of platinum and taxane resistance from bench to clinic: An inverse relationship

We undertook a systematic review of the pre-clinical and clinical literature for studies investigating the relationship between platinum and taxane resistance. Medline was searched for (1) cell models of acquired drug resistance reporting platinum and taxane sensitivities and (2) clinical trials of platinum or taxane salvage therapy in ovarian cancer. One hundred and thirty-seven models of acquired drug resistance were identified. 68.1% of cisplatin-resistant cells were sensitive to paclitaxel and 66.7% of paclitaxel-resistant cells were sensitive to cisplatin. A similar inverse pattern was observed for cisplatin vs. docetaxel, carboplatin vs. paclitaxel and carboplatin vs. docetaxel. These associations were independent of cancer type, agents used to develop resistance and reported mechanisms of resistance. Sixty-five eligible clinical trials of paclitaxel-based salvage after platinum therapy were identified. Studies of single agent paclitaxel in platinum-resistant ovarian cancer where patients had previously recieved paclitaxel had a pooled response rate of 35.3%, n=232, compared to 22% in paclitaxel naïve patients n=1918 (p<0.01, Chi-squared). Suggesting that pre-treatment with paclitaxel may improve the response of salvage paclitaxel therapy. The response rate to paclitaxel/platinum combination regimens in platinum-sensitive ovarian cancer was 79.5%, n=88 compared to 49.4%, n=85 for paclitaxel combined with other agents (p<0.001, Chi-squared), suggesting a positive interaction between taxanes and platinum. Therefore, the inverse relationship between platinum and taxanes resistance seen in cell models is mirrored in the clinical response to these agents in ovarian cancer. An understanding of the cellular and molecular mechanisms responsible would be valuable in predicting response to salvage chemotherapy and may identify new therapeutic targets.

Therapeutic resistance in lung cancer

Despite considerable progress over the last 25 years in the systemic therapy of lung cancer, intrinsic and acquired resistance to chemotherapeutic agents and radiation remains a vexing problem. The number of mechanisms of therapeutic resistance in lung cancer has expanded considerably over the past three decades, and the crucial role of stress resistance pathways is increasingly recognised as a cause of intrinsic and acquired chemo- and radiotherapy resistance. This paper reviews recent evidence for stress defence proteins, particularly RALBP1/RLIP76, in mediating intrinsic and acquired chemotherapy and radiation resistance in human lung cancer.

Oxaliplatin induces drug resistance more rapidly than cisplatin in H69 small cell lung cancer cells

Cisplatin produces good responses in solid tumours including small cell lung cancer (SCLC) but this is limited by the development of resistance. Oxaliplatin is reported to show activity against some cisplatin-resistant cancers but there is little known about oxaliplatin in SCLC and there are no reports of oxaliplatin resistant SCLC cell lines. Studies of drug resistance mainly focus on the cellular resistance mechanisms rather than how the cells develop resistance. This study examines the development of cisplatin and oxaliplatin resistance in H69 human SCLC cells in response to repeated treatment with clinically relevant doses of cisplatin or oxaliplatin for either 4 days or 2 h. Treatments with 200 ng/ml cisplatin or 400 ng/ml oxaliplatin for 4 days produced sublines (H69CIS200 and H69OX400, respectively) that showed low level (approximately two-fold) resistance after eight treatments. Treatments with 1,000 ng/ml cisplatin or 2,000 ng/ml oxaliplatin for 2 h also produced sublines, however, these were not stably resistant suggesting shorter treatment pulses of drug may be more effective. Cells survived the first five treatments without any increase in resistance, by arresting their growth for a period and then regrowing. The period of growth arrest was reduced after the sixth treatment and the H69CIS200 and H69OX400 sublines showed a reduced growth arrest in response to cisplatin and oxaliplatin treatment suggesting that 'regrowth resistance' initially protected against drug treatment and this was further upregulated and became part of the resistance phenotype of these sublines. Oxaliplatin dose escalation produced more surviving sublines than cisplatin dose escalation but neither set of sublines were associated with increased resistance as determined by 5-day cytotoxicity assays, also suggesting the involvement of regrowth resistance. The resistant sublines showed no change in platinum accumulation or glutathione levels even though the H69OX400 subline was more sensitive to buthionine sulphoximine treatment. The H69CIS200 cells were cross-resistant to oxaliplatin demonstrating that oxaliplatin does not have activity against low level cisplatin resistance. Relative to the H69 cells, the H69CIS200 and H69OX400 sublines were more sensitive to paclitaxel and taxotere suggesting that the taxanes may be useful in the treatment of platinum-resistant SCLC. These novel cellular models of cisplatin and oxaliplatin resistant SCLC will be useful in developing strategies to treat platinum-resistant SCLC.