Platinum-based Chemotherapy Resistance Research Articles

The Role of ADCY1 in Regulating the Sensitivity of Platinum-Based Chemotherapy in NSCLC.

Lung cancer has the highest fatality rate among malignant tumors in the world. Finding new biomarkers of drug resistance is of great importance in the prognosis of lung cancer patients. We found that the polymorphisms of Adenylate Cyclase 1 (ADCY1) are significantly associated with platinum-based chemotherapy resistance in lung cancer patients in our previous research. In this study, we wanted to identify the mechanism of ADCY1 affecting platinum resistance. We used an MTT assay to find if the expression of ADCY1 is associated with the sensitivity of cisplatin in A549, H1299, and A549-DDP cells. Then, we performed CCK-8 tests to detect the absorbance of these cells stimulated by ADCY1, which can discover the cell proliferation that is affected by ADCY1. We investigated cell apoptosis and cell cycles regulated by ADCY1 through the flow cytometry assay. RNA sequencing was used to find the downstream genes affected by ADCY1 which may be associated with drug resistance in lung cancer patients. ADCY1 has higher expression in lung cancer cells than in normal cells. ADCY1 can affect cisplatin resistance in lung cancer cells by regulating cell proliferation, cell apoptosis, and the cell cycle. It may control cell apoptosis by regulating the classical apoptosis biomarkers Bax and Bcl2. Our study showed that ADCY1 may be a new biomarker in the prognosis of lung cancer patients. Much work remains to be carried out to clarify the mechanism in this important emerging field.

Related Clinical Factors of Platinum-Based Chemotherapy Resistance in Patients with Epithelial Ovarian Cancer.

Ovarian cancer is the second most common malignancy in women, but it is a fatal gynecological tumor. Although it has a standard treatment regimen, resistance to chemotherapy makes patients more prone to early recurrence, leading to poor survival rates. Therefore, this study investigated factors related to platinum resistance through a complete analysis of clinical data. Clinical data of patients with ovarian cancer were collected, and the patients were categorized into platinum-sensitive and platinum-resistant groups. By comparing the differences in clinical data between the groups, the key factors affecting platinum resistance were analyzed. We collected the clinical data of patients with epithelial ovarian cancer (EOC) who were admitted to the Department of Oncology of the General Hospital of Ningxia Medical University between January 1, 2019, and December 31, 2020. We conducted univariate and multivariate analyses and evaluated overall survival and progression-free survival using the Kaplan-Meier method. We enrolled 161 patients with EOC, of whom 124 demonstrated platinum sensitivity and 37 demonstrated platinum resistance after the initial platinum-based chemotherapy. Univariate analyses revealed that the International Federation of Gynecology and Obstetrics (FIGO) stage, neoadjuvant chemotherapy, and Fagotti score were associated with an increased risk of platinum resistance for the first recurrence. In multivariate logistic regression analysis, only Fagotti score and neoadjuvant chemotherapy were associated with an increased risk of platinum resistance (odds ratio: 0.372 and 0.328, 95% confidence interval: 0.160-0.863 and 0.141-0.762, p = 0.021 and 0.010, respectively). The sample size of this study was relatively small because of nonstandard treatment of some patients, the absence of clinical data, and failure of follow-up. Patients with EOC exhibiting platinum resistance had a very poor prognosis. The Fagotti score and neoadjuvant chemotherapy appeared to increase the risk of platinum resistance at first recurrence.

Comparison of Photodynamic Priming Efficacy, with BPD or ALA-PpIX, to Overcome PFAS-Induced Platinum Resistance in Ovarian Cancer

Ovarian cancer is the most lethal gynecologic cancer, largely due to the development of platinum-based chemotherapy resistance. Understanding sources of chemoresistance and the development of mechanism-based treatments are critical. In a recent study, we reported that perfluoroalkyl substances (PFAS), endocrine disruptors that pollute drinking water supplies worldwide, induce carboplatin resistance in ovarian cancer cells, potentially by enhancing mitochondrial function. The ability of photodynamic priming (PDP) to overcome PFAS-induced resistance using photosensitizers that, in part, localize to mitochondria, specifically benzoporphyrin derivative (BPD) or aminolevulinic acid-induced protoporphyrin IX (ALA-PpIX)), will be presented. Ovarian cancer cells were exposed to PFAS, then treated with either BPD- or ALA-PpIX-PDP followed by carboplatin. Under PFAS exposure conditions that previously induced chemoresistance, both BPD- and ALA-PpIX-PDP sensitized ovarian cancer cells to carboplatin. A concomitant decrease in mitochondrial membrane potential was observed.

Potential tools for predicting response to chemotherapy in OC: Assessment of immune dysbiosis, participant’s self-rated health and microbial dynamics

Epithelial ovarian cancer (OC) is the deadliest female reproductive cancer; an estimated 13,270 women will die from OC in 2023. Platinum-based chemotherapy resistance mechanisms contribute to poor OC 5-year survival rates. Peripheral inflammation is linked to various disease states and we previously identified unique peritoneal microbial features predictive of OC. We hypothesized that unique peripheral immune profiles and peritoneal microbial features may be predictive of disease-free interval (time to recurrence) and response to chemotherapy in participants with OC. We also investigated self-rated health (SRH) scores in the context of peripheral inflammation as a potential screening tool for OC. Blood and peritoneal fluid were collected from participants with OC or a benign adnexal mass (BPM). Lymphocyte populations were analyzed using Fluorescence Activated Cell Sorting, serum cytokine levels were analyzed using the Human Th17 Magnetic Bead Panel assay and peritoneal fluid microbial features were analyzed using Next Generation Sequencing (NGS). Participants completed a standardized questionnaire on self-rated physical and emotional health. Participants were classified into three chemotherapy response categories: platinum-refractory, platinum-resistant or platinum-sensitive. A significant positive correlation was found between elevated inflammatory status on the day of surgery and longer disease-free interval. SRH measures did not correlate with immune status in participants with OC or a BPM. We identified a correlation between peritoneal microbial features and chemotherapy response. We conclude that immune dysbiosis may be useful in predicting OC recurrence. The immune findings reported here set the framework for additional studies utilizing immune profiles to predict platinum-based chemotherapy responsiveness in OC.

HIPK3 maintains sensitivity to platinum drugs and prevents disease progression in gastric cancer

In the realm of cancer therapeutics and resistance, kinases play a crucial role, particularly in gastric cancer (GC). Our study focused on platinum-based chemotherapy resistance in GC, revealing a significant reduction in homeodomain-interacting protein kinase 3 (HIPK3) expression in platinum-resistant tumors through meticulous analysis of transcriptome datasets. In vitro and in vivo experiments demonstrated that HIPK3 knockdown enhanced tumor proliferation and metastasis, while upregulation had the opposite effect. We identified the myocyte enhancer factor 2C (MEF2C) as a transcriptional regulator of HIPK3 and uncovered HIPK3's role in downregulating the morphogenesis regulator microtubule-associated protein (MAP7) through ubiquitination. Phosphoproteome profiling revealed HIPK3's inhibitory effects on mTOR and Wnt pathways crucial in cell proliferation and movement. A combined treatment strategy involving oxaliplatin, rapamycin, and IWR1-1-endo effectively overcame platinum resistance induced by reduced HIPK3 expression. Monitoring HIPK3 levels could serve as a GC malignancy and platinum resistance indicator, with our proposed treatment strategy offering novel avenues for reversing resistance in gastric cancer.

Reversal of Platinum-based Chemotherapy Resistance in Ovarian Cancer by Naringin Through Modulation of The Gut Microbiota in a Humanized Nude Mouse Model.

As a chemotherapy agent, cisplatin (DDP) is often associated with drug resistance and gastrointestinal toxicity, factors that severely limit therapeutic efficacy in patients with ovarian cancer (OC). Naringin has been shown to increase sensitivity to cisplatin, but whether the intestinal microbiota is associated with this effect has not been reported so far. In this study, we applied a humanized mouse model for the first time to evaluate the reversal of cisplatin resistance by naringin, as well as naringin combined with the microbiota in ovarian cancer. The results showed that naringin combined with Bifidobacterium animalis subsp. lactis NCU-01 had an inhibitory effect on the tumor, significantly reducing tumor size (p<0.05), as well as the concentrations of serum tumor markers CA125 and HE4, increased the relative abundance of Bifidobacterium and Bacteroides, inhibit Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB)-induced intestinal inflammation and increase the expression of intestinal permeability-associated proteins ZO-1 (p<0.001) and occludin (p<0.01). In conclusion, the above data demonstrate how naringin combined with Bifidobacterium animalis subsp. lactis NCU-01 reverses cisplatin resistance in ovarian cancer by modulating the intestinal microbiota, inhibiting the TLR4/NF-κB signaling pathway and modulating the p38MAPK signaling pathway.

Concurrent silencing of TBCE and drug delivery to overcome platinum-based resistance in liver cancer.

Platinum-based chemotherapy resistance is a key factor of poor prognosis and recurrence in hepatocellular carcinoma (HCC). Herein, RNAseq analysis revealed that elevated tubulin folding cofactor E (TBCE) expression is associated with platinum-based chemotherapy resistance. High expression of TBCE contributes to worse prognoses and earlier recurrence among liver cancer patients. Mechanistically, TBCE silencing significantly affects cytoskeleton rearrangement, which in turn increases cisplatin-induced cycle arrest and apoptosis. To develop these findings into potential therapeutic drugs, endosomal pH-responsive nanoparticles (NPs) were developed to simultaneously encapsulate TBCE siRNA and cisplatin (DDP) to reverse this phenomena. NPs (siTBCE+DDP) concurrently silenced TBCE expression, increased cell sensitivity to platinum treatment, and subsequently resulted in superior anti-tumor effects both invitro and invivo in orthotopic and patient-derived xenograft (PDX) models. Taken together, NP-mediated delivery and the co-treatment of siTBCE+DDP proved to be effective in reversing chemotherapy resistance of DDP in multiple tumor models.

RUNX2 Reverses p53-Induced Chemotherapy Resistance in Gastric Cancer.

Gastric cancer is one of the most common malignancies worldwide; however, its overall mortality has not improved significantly over the last decade. Chemoresistance plays a critical role in this issue. This study aimed to clarify the role and mechanism of runt-related transcription factor 2 (RUNX2) in platinum-based chemotherapy resistance. First, a drug-resistant model of gastric cancer cells was established to evaluate the relative expression level of the RUNX2 as a potential biomarker of chemotherapy resistance. Next, exogenous silencing was conducted to study whether RUNX2 could reverse drug resistance and understand the underlying mechanisms. Simultaneously, the correlation between the clinical outcomes of 40 patients after chemotherapy and the RUNX2 expression levels in tumor samples was analyzed. We discovered that RUNX2 was significantly expressed in drug-resistant gastric cancer cells and tissues; it was also reversibly resistant to transformation treatment by exogenous RUNX2 silencing. It is confirmed that RUNX2 negatively regulates the apoptosis pathway of the p53 to reduce the chemotherapeutic effects of gastric cancer. RUNX2 is a possible target for platinum-based chemotherapy resistance.

Cellular Transcriptomics of Carboplatin Resistance in a Metastatic Canine Osteosarcoma Cell Line

Osteosarcoma prognosis has remained unchanged for the past three decades. In both humans and canines, treatment is limited to excision, radiation, and chemotherapy. Chemoresistance is the primary cause of treatment failure, and the trajectory of tumor evolution while under selective pressure from treatment is thought to be the major contributing factor in both species. We sought to understand the nature of platinum-based chemotherapy resistance by investigating cells that were subjected to repeated treatment and recovery cycles with increased carboplatin concentrations. Three HMPOS-derived cell lines, two resistant and one naïve, underwent single-cell RNA sequencing to examine transcriptomic perturbation and identify pathways leading to resistance and phenotypic changes. We identified the mechanisms of acquired chemoresistance and inferred the induced cellular trajectory that evolved with repeated exposure. The gene expression patterns indicated that acquired chemoresistance was strongly associated with a process similar to epithelial-mesenchymal transition (EMT), a phenomenon associated with the acquisition of migratory and invasive properties associated with metastatic disease. We conclude that the observed trajectory of tumor adaptability is directly correlated with chemoresistance and the phase of the EMT-like phenotype is directly affected by the level of chemoresistance. We infer that the EMT-like phenotype is a critical component of tumor evolution under treatment pressure and is vital to understanding the mechanisms of chemoresistance and to improving osteosarcoma prognosis.

Metabolic reprogramming of three major nutrients in platinum-resistant ovarian cancer.

Metabolic reprogramming is a phenomenon in which cancer cells alter their metabolic pathways to support their uncontrolled growth and survival. Platinum-based chemotherapy resistance is associated with changes in glucose metabolism, amino acid metabolism, fatty acid metabolism, and tricarboxylic acid cycle. These changes lead to the creation of metabolic intermediates that can provide precursors for the biosynthesis of cellular components and help maintain cellular energy homeostasis. This article reviews the research progress of the metabolic reprogramming mechanism of platinumbased chemotherapy resistance caused by three major nutrients in ovarian cancer.

RNA sequencing and bioinformatics analysis revealed PACSIN3 as a potential novel biomarker for platinum resistance in epithelial ovarian cancer

Failure to respond to treatment in epithelial ovarian cancer can often be attributed to platinum-based chemotherapy resistance. However, the possible mechanisms or candidate biomarkers associated with platinum resistance are yet to be elucidated, even though many researchers have performed related studies. We performed RNA sequencing of clinical specimens obtained from patients with platinum-sensitive or resistant epithelial ovarian cancer (EOC). Furthermore, various bioinformatics approaches, including spatial analysis of functional enrichment, were used to identify key regulators and associated underlying mechanisms of platinum resistance in EOC. Through RNA-sequencing, we identified 263 differentially expressed genes (98 upregulated and 165 downregulated) and subjected them to Gene Oncology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses, which were characterized to the traditional platinum-resistant characteristics. Subsequently, the gene interaction network and module analysis by spatial analysis of functional enrichment software demonstrated protein kinase C and casein kinase substrate in neurons 3 (PACSIN3) as the only upregulated hub gene, and neurotensin (NTS) and KIAA0319 as downregulated hub genes in platinum-resistant EOC. We selected PACSIN3 for further analysis because it has not been studied in relation to response to platinum-based chemotherapy. PACSIN3 was significantly upregulated in ovarian cancer cells compared to immortalized human ovarian surface epithelial cells. In addition, cisplatin-induced apoptosis was measured in PACSIN3 knockout OVCA433 and BRCA-mutated EOC cell line, SNU251, by a fluorescence-activated cell sorting-based Annexin-V/propium iodide double staining assay, which revealed a significant increase in apoptosis. Taken together, the present study presents PACSIN3 as a promising predictive biomarker associated with platinum resistance, especially in BRCA-mutated epithelial ovarian cancers.

DNA Methylation Biomarkers for Prediction of Response to Platinum-Based Chemotherapy: Where Do We Stand?

Simple SummaryPlatinum-based agents are one of the most widely used chemotherapy drugs for various types of cancer. However, one of the main challenges in the application of platinum drugs is resistance, which is currently being widely investigated. Epigenetic DNA methylation-based biomarkers are promising to aid in the selection of patients, helping to foresee their platinum therapy response in advance. These biomarkers enable minimally invasive patient sample collection, short analysis, and good sensitivity. Hence, improved methodologies for the detection and quantification of DNA methylation biomarkers will facilitate their use in the choice of an optimal treatment strategy.Platinum-based chemotherapy is routinely used for the treatment of several cancers. Despite all the advances made in cancer research regarding this therapy and its mechanisms of action, tumor resistance remains a major concern, limiting its effectiveness. DNA methylation-based biomarkers may assist in the selection of patients that may benefit (or not) from this type of treatment and provide new targets to circumvent platinum chemoresistance, namely, through demethylating agents. We performed a systematic search of studies on biomarkers that might be predictive of platinum-based chemotherapy resistance, including in vitro and in vivo pre-clinical models and clinical studies using patient samples. DNA methylation biomarkers predictive of response to platinum remain mostly unexplored but seem promising in assisting clinicians in the generation of more personalized follow-up and treatment strategies. Improved methodologies for their detection and quantification, including non-invasively in liquid biopsies, are additional attractive features that can bring these biomarkers into clinical practice, fostering precision medicine.

Role of APOA1 in the resistance to platinum-based chemotherapy in squamous cervical cancer

BackgroundTo investigate the mechanism by which apolipoprotein A1 (APOA1) enhances the resistance of cervical squamous carcinoma to platinum-based chemotherapy.MethodsTwo cervical squamous carcinoma cell lines (SiHa and Caski) overexpressing APOA1 were constructed, treated with carboplatin, and compared to normal control cells.ResultsIn both SiHa and Caski cell lines, the clone-forming ability of CBP-treated cells was lower than that of untreated cells, and the change in the number of clones of overexpressing cells was lower than that of normal control cells (p < 0.05), indicating that APOA1 overexpression enhanced chemoresistance. A screen for APOA1 downstream proteins affecting platinum-based chemoresistance using Tandem Mass Tag revealed 64 differentially expressed proteins in SiHa cells, which were subjected to Gene Ontology (annotation, Kyoto Encyclopedia of Genes and Genomes enrichment, subcellular localization, structural domain annotation and enrichment, clustering, and interaction network analyses. Sixty-four differentially expressed proteins matching cancer-relavent association terms were screened and parallel response monitoring identified 29 proteins as possibly involved in the mechanism of platinum-based chemoresistance.ConclusionsOur analysis suggested that the mechanism may involve numerous regulatory pathways, including promoting tumor growth via the p38 MAPK signaling pathway through STAT1, promoting tumor progression via the PI3K signaling pathway through CD81 and C3, and promoting resistance to platinum-based chemotherapy resistance through TOP2A. The present study aimed to preliminarily explore the function and mechanism of APOA1 in platinum-based chemoresistance in cervical cancer, and the detailed mechanism needs to be further studied.

Molecular mechanisms of platinum‑based chemotherapy resistance in ovarian cancer (Review).

Cisplatin is one of the most effective chemotherapy drugs for ovarian cancer, but resistance is common. The initial response to platinum-based chemotherapy is as high as 80%, but in most advanced patients, final relapse and death are caused by acquired drug resistance. The development of resistance to therapy in ovarian cancer is a significant hindrance to therapeutic efficacy. The resistance of ovarian cancer cells to chemotherapeutic mechanisms is rather complex and includes multidrug resistance, DNA damage repair, cell metabolism, oxidative stress, cell cycle regulation, cancer stem cells, immunity, apoptotic pathways, autophagy and abnormal signaling pathways. The present review provided an update of recent developments in our understanding of the mechanisms of ovarian cancer platinum-based chemotherapy resistance, discussed current and emerging approaches for targeting these patients and presented challenges associated with these approaches, with a focus on development and overcoming resistance.

TOPBP1 regulates resistance of gastric cancer to oxaliplatin by promoting transcription of PARP1

Gastric cancer (GC) is the third leading cause of cancer-associated mortality worldwide. The platinum derivative oxaliplatin is widely applied in standard GC chemotherapy but recurrence and metastasis are common in advanced GC cases due to intrinsic or induced chemoresistance. Poly(ADP-Ribose) polymerase 1 (PARP1) is an enzyme crucial for repairing DNA damage induced by platinum compounds, which undermines the effectiveness of platinum-based chemotherapy. Data from the current study showed that topoisomerase IIβ binding protein 1 (TOPBP1), an interacting partner of topoisomerase IIβ, is highly expressed in oxaliplatin-resistant GC (OR-GC) cells and promotes PARP1 transcription through direct binding to its proximal promoter region. Furthermore, AKT-mediated phosphorylation of TOPBP1 at Ser1159 was indispensable for inducing PARP1 expression in OR-GC cells. Disruption of the TOPBP1/PARP1 regulatory pathway decreased cell viability and augmented apoptosis of OR-GC cells. The positive correlation between TOPBP1 and PARP1 was confirmed using both the TCGA database and immunohistochemical analysis of GC tissues. In GC patients receiving oxaliplatin treatment, high expression of TOPBP1 or PARP1 was associated with poor prognosis. Our finding that the TOPBP1/PARP1 pathway facilitates acquisition of oxaliplatin resistance uncovers a novel mechanism underlying platinum-based chemotherapy resistance in gastric cancer that may be utilized for developing effective therapeutic strategies.

Role of ubiquitin-specific peptidase 22 in multidrug resistance of colorectal cancer and its correlation with multidrug resistance gene P-gp

Objective: To investigate the role of ubiquitin-specific peptidase 22 (USP22) in colorectal cancer multidrug resistance and its correlation with multidrug resistance genes P-gp and MRP1, and to preliminarily explore the mechanism of USP22 affecting colorectal cancer resistance. Methods: USP22 over-expression plasmid was transfected into colorectal cancer cells (RKO, SW480)with low expression of USP22. Cell counting kit (CCK-8) assay was used to detect the effect of USP22 on oxaliplatin resistance in colorectal cancer cells. The cells were treated with oxaliplatin of the same concentration. Western blot method was used to detect the expression of apoptosis-related proteins cleaved-caspase3, Bcl-2, and drug resistance proteins MRP1, P-gp in the cells. The cell efflux test was used to detect the effect of up-regulated USP22 on Calcein-AM and rhodamine123. Immunohistochemical methods were used to detect the expressions of USP22 and P-gp in the oxaliplatin chemotherapy-sensitive group and the drug-resistant group and to analyze the correlation between USP22 and MRP1, P-gp. Results: CCK-8 assay showed that the IC50 values of SW480-USP22 (SW480 cells overexpressing USP22) treated with oxaliplatin for 24 h and 48 h was (4.62±0.05)μmol/L and (2.32±0.04)μmol/L respectively; which was 2.7 times and 3.0 times higher than that in control cells, respectively. After treating with 1.25 μmol/L oxaliplatin for 48 h, USP22 overexpression can inhibit SW480 cells apoptosis. The fluorescence intensity of calcein-AM and rhodamine123 in the SW480-USP22 group were significantly increased when compared with that in the control cells (both P<0.01). The protein expression levels of MRP1 and P-gp in SW480-USP22 cells were significantly increased when compared with that in the control cells(both P<0.01). Immunohistochemistry showed that the positive expression rates of USP22, MRP1, and P-gp in the oxaliplatin chemotherapy-sensitive group were significantly lower than those in the chemotherapy-resistant group, the difference was statistically significant (all P<0.05), and USP22 was positively correlated with the expressions of MRP1 and P-gp in colorectal cancer tissues (r1=0.377, r2=0.423, both P<0.05). Conclusions: The up-regulation of USP22 is related to the acquired resistance of colorectal cancer cells to oxaliplatin. USP22 may be involved in the process of platinum-based chemotherapy resistance of colorectal cancer by regulating the expressions of P-gp and MRP1.

ZNF76 predicts prognosis and response to platinum chemotherapy in human ovarian cancer.

Ovarian cancer (OV) is the most lethal gynecologic malignancy. One major reason of the high mortality of the disease is due to platinum-based chemotherapy resistance. Increasing evidence reveal the important biological functions and clinical significance of zinc finger proteins (ZNFs) in OV. In the present study, the relationship between the zinc finger protein 76 (ZNF76) and clinical outcome and platinum resistance in patients with OV was explored. We further analyzed ZNF76 expression via multiple gene expression databases and identified its functional networks using cBioPortal. RT-qPCR and IHC assay shown that the ZNF76 mRNA and protein expression were significantly lower in OV tumor than that in normal ovary tissues. A strong relationship between ZNF76 expression and platinum resistance was determined in patients with OV. The low expression of ZNF76 was associated with worse survival in OV. Multivariable analysis showed that the low expression of ZNF76 was an independent factor predicting poor outcome in OV. The prognosis value of ZNF76 in pan-cancer was validated from multiple cohorts using the PrognoScan database and GEPIA 2. A gene-clinical nomogram was constructed by multivariate cox regression analysis, combined with clinical characterization and ZNF76 expression in TCGA. Functional network analysis suggested that ZNF76 was involved in several biology progressions which associated with OV. Ten hub genes (CDC5L, DHX16, SNRPC, LSM2, CUL7, PFDN6, VARS, HSD17B8, PPIL1, and RGL2) were identified as positively associated with the expression of ZNF76 in OV. In conclusion, ZNF76 may serve as a promising prognostic-related biomarker and predict the response to platinum in OV patients.

Whole-Exome Sequencing on Circulating Tumor Cells Explores Platinum-Drug Resistance Mutations in Advanced Non-small Cell Lung Cancer

Circulating tumor cells (CTCs) have important applications in clinical practice on early tumor diagnosis, prognostic prediction, and treatment evaluation. Platinum-based chemotherapy is a fundamental treatment for non-small cell lung cancer (NSCLC) patients who are not suitable for targeted drug therapies. However, most patients progressed after a period of treatment. Therefore, revealing the genetic information contributing to drug resistance and tumor metastasis in CTCs is valuable for treatment adjustment. In this study, we enrolled nine NSCLC patients with platinum-based chemotherapy resistance. For each patient, 10 CTCs were isolated when progression occurred to perform single cell–level whole-exome sequencing (WES). Meanwhile the patients’ paired primary-diagnosed formalin-fixed and paraffin-embedded samples and progressive biopsy specimens were also selected to perform WES. Comparisons of distinct mutation profiles between primary and progressive specimens as well as CTCs reflected different evolutionary mechanisms between CTC and lymph node metastasis, embodied in a higher proportion of mutations in CTCs shared with paired progressive lung tumor and hydrothorax specimens (4.4–33.3%) than with progressive lymphatic node samples (0.6–11.8%). Functional annotation showed that CTCs not only harbored cancer-driver gene mutations, including frequent mutations of EGFR and TP53 shared with primary and/or progressive tumors, but also particularly harbored cell cycle–regulated or stem cell–related gene mutations, including SHKBP1, NUMA1, ZNF143, MUC16, ORC1, PON1, PELP1, etc., most of which derived from primary tumor samples and played crucial roles in chemo-drug resistance and metastasis for NSCLCs. Thus, detection of genetic information in CTCs is a feasible strategy for studying drug resistance and discovering new drug targets when progressive tumor specimens were unavailable.

Whole-exome sequencing on circulating tumor cells explores platinum-based chemotherapy resistance in advanced non-small cell lung cancer.

e21021 Background: Circulating tumour cells (CTCs) have important applications in clinical practice on early tumour diagnosis, prognostic prediction and treatment evaluation. Platinum-based chemotherapy is the first-line treatment for non-small cell lung cancer (NSCLC) patients without targeted drugs. But most patients progressed after a period of treatment. Therefore, to dissect the genetic information contributing to drug resistance and tumour progression in CTCs is valuable for guidance of treatment adjustment. Methods: In this study, we enrolled 9 NSCLC patients treated with platinum-based chemotherapy. For each patient, 10 CTCs were isolated after progression to perform a single cell-level whole-exome sequencing (WES). Meanwhile the patients’ paired primary-diagnosed FFPE sample and progressive biopsy specimens were also performed WES. Results: Comparisons of WES data between primary and progressive specimens, as well as CTCs revealed that more than half patients’ tumour mutation burden (TMB) increased after progression. Dozes to hundreds of single-nucleotide variants (SNVs) and insertions or deletions (Indels) were detected in the CTCs. Slightly more proportion of SNVs/Indels in CTCs shared with paired primary tumours (1.2%-23.1%) than with progressive samples (0.6%-11.7%). Conclusions: Functional annotation on SNVs/Indels showed that CTCs not only harboured cancer driver gene mutations, such as EGFR and TP53, shared with primary and/or progressive tumours, but also harboured chemotherapy-resistance and stem cell-related gene mutations, including SHKBP1, NUMA1, ZNF143, MUC16, ORC1, PON1, PELP1, etc. which have crucial roles in drug resistance and poor prognosis for NSCLCs. Thus, detection of genetic information in CTCs was necessary for guidance of individual therapy and drug resistance study.

Combination of Niraparib, Cisplatin and Twist Knockdown in Cisplatin-Resistant Ovarian Cancer Cells Potentially Enhances Synthetic Lethality through ER-Stress Mediated Mitochondrial Apoptosis Pathway.

Poly (ADP-ribose) polymerase 1 inhibitors (PARPi) are used to treat recurrent ovarian cancer (OC) patients due to greater survival benefits and minimal side effects, especially in those patients with complete or partial response to platinum-based chemotherapy. However, acquired resistance of platinum-based chemotherapy leads to the limited efficacy of PARPi monotherapy in most patients. Twist is recognized as a possible oncogene and contributes to acquired cisplatin resistance in OC cells. In this study, we show how Twist knockdown cisplatin-resistant (CisR) OC cells blocked DNA damage response (DDR) to sensitize these cells to a concurrent treatment of cisplatin as a platinum-based chemotherapy agent and niraparib as a PARPi on in vitro two-dimensional (2D) and three-dimensional (3D) cell culture. To investigate the lethality of PARPi and cisplatin on Twist knockdown CisR OC cells, two CisR cell lines (OV90 and SKOV3) were established using step-wise dose escalation method. In addition, in vitro 3D spheroidal cell model was generated using modified hanging drop and hydrogel scaffolds techniques on poly-2-hydroxylethly methacrylate (poly-HEMA) coated plates. Twist expression was strongly correlated with the expression of DDR proteins, PARP1 and XRCC1 and overexpression of both proteins was associated with cisplatin resistance in OC cells. Moreover, combination of cisplatin (Cis) and niraparib (Nira) produced lethality on Twist-knockdown CisR OC cells, according to combination index (CI). We found that Cis alone, Nira alone, or a combination of Cis+Nira therapy increased cell death by suppressing DDR proteins in 2D monolayer cell culture. Notably, the combination of Nira and Cis was considerably effective against 3D-cultures of Twist knockdown CisR OC cells in which Endoplasmic reticulum (ER) stress is upregulated, leading to initiation of mitochondrial-mediated cell death. In addition, immunohistochemically, Cis alone, Nira alone or Cis+Nira showed lower ki-67 (cell proliferative marker) expression and higher cleaved caspase-3 (apoptotic marker) immuno-reactivity. Hence, lethality of PARPi with the combination of Cis on Twist knockdown CisR OC cells may provide an effective way to expand the therapeutic potential to overcome platinum-based chemotherapy resistance and PARPi cross resistance in OC.