Cisplatin-resistant Patients Research Articles

ZFAS1 Promotes Cisplatin Resistance via Suppressing miR-421 Expression in Oral Squamous Cell Carcinoma.

PurposeOral squamous cell carcinoma (OSCC), with high incidence and mortality, represents one of the main reasons for head and neck malignant tumors. We want to investigate the effect of ZFAS1 on DDP resistance in oral squamous cell carcinoma.MethodsThe proliferation and migration of cells was detected by CCK-8 and Transwell assay. The apoptosis was measured by flow cytometry and Western blot. The interaction of ZFAS1, miR-421, and MEIS2 was verified by luciferase reporter assay. The role of ZFAS1 in DDP resistance in vivo was tested by the nude mice model. The expression of ZFAS1 in exosomes from cisplatin-resistant patients was also determined.ResultsZFAS1 overexpression improved OSCC cell growth and inhibited OSCC cell susceptibility to DDP. In addition, the silencing of ZFAS1 promoted DDP-induced apoptosis. ZFAS1 directly bound to miR-421, which was verified by luciferase reporter assay. Inhibition of miR-421 reversed the effect of si-ZFAS1, which promoted the cell viability and decreased the sensitivity of DDP in DDP-resistant cells. The in vivo experiment showed the role of ZFAS1 in increasing the DDP resistance in OSCC tumor. Importantly, this study also showed upregulated ZFAS1 in serum exosomes derived from cisplatin-resistant patients.ConclusionZFAS1 promotes chemoresistance of oral squamous cell carcinoma to cisplatin and might become a latent therapeutic target for treating OSCC.

NEAT1 Knockdown Suppresses the Cisplatin Resistance in Ovarian Cancer by Regulating miR-770-5p/PARP1 Axis.

BackgroundLong noncoding RNAs play essential roles in regulating drug resistance in cancers. However, how and whether lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) could mediate cisplatin resistance in ovarian cancer remain poorly understood.Patients and MethodsEighteen cisplatin-sensitive and 19 cisplatin-resistant patients with ovarian cancer were recruited. Cisplatin-resistant ovarian cancer cells were used for this study. The expression levels of NEAT1, microRNA (miR)-770-5p and poly adenosine diphosphate-ribose polymerase 1 (PARP1) were detected by quantitative real-time polymerase chain reaction or Western blot. Cisplatin resistance was assessed by the half-maximal inhibitory concentration (IC50) of cisplatin, cell viability and apoptosis using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, flow cytometry and Western blot, respectively. The target association between miR-770-5p and NEAT1 or PARP1 was investigated by dual-luciferase reporter assay. The xenograft model was used to investigate cisplatin resistance in vivo.ResultsNEAT1 expression is elevated in cisplatin-resistant ovarian cancer tissues and cells. Knockdown of NEAT1 repressed cisplatin resistance by decreasing the IC50 of cisplatin, cell viability and increasing apoptosis. MiR-770-5p was bound to NEAT1 and PARP1 was confirmed as a target of miR-770-5p. MiR-770-5p inhibition or PARP1 restoration could abate the effect of NEAT1 silencing on cisplatin resistance in cisplatin-resistant ovarian cancer cells. Moreover, NEAT1 knockdown reduced PARP1 expression by increasing miR-770-5p. Interference of NEAT1 decreased xenograft tumor growth by regulating miR-770-5p and PARP1.ConclusionKnockdown of NEAT1 inhibited cisplatin resistance in ovarian cancer cells by up-regulating miR-770-5p and down-regulating PARP1, providing a new target for improving the efficacy of cisplatin-based therapy in ovarian cancer.

Abstract B08: High-resolution positron emission microscopy of patient-derived tumor organoids

Abstract Tumor organoids are self-organizing three-dimensional tumor models grown in vitro from patient-derived tumor tissue. They closely recapitulate the structural and functional microenvironment of solid tumors. Rapid translation of biomedical information from preclinical models to patients requires imaging biomarkers that span the full scale of tumor models. However, a key limitation is that, unlike human patients or preclinical mouse models, the tiny organoids are incompatible with the suite of radiologic tools used in oncology clinics. Here, we present 18F-fluorodeoxyglucose positron-emission microscopy (FDG-PEM), a radioluminescence-based technique for imaging glucose metabolism in patient-derived tumor organoids with spatial resolution 100-fold better than that of clinical positron emission tomography (PET). Tumor organoids derived from head-and-neck cancer patients were imaged to reveal metabolic maps that, in combination with brightfield imaging, functionally mirror the PET/CT images from the clinic. Tumor organoids were fed with FDG and mounted on a thin CdWO4 scintillator plate. Scintillator flashes were directly imaged by a single-photon-sensitivity electron-multiplying charge-coupled devices (EMCCD) camera. The EMCCD signal was calibrated with known radioactivity of FDG for accurate quantification of PEM images. Dual-modality PEM/fluorescence imaging found that FDG uptake occurred mainly in the viable region of tumor organoids and was more specific than staining by 2-NBDG, a fluorescent glucose mimetic. The influx rate constant (Ki) of FDG into the tumor organoids was calculated and found to be similar to the patient tumor from which the organoids were grown. This positive correlation of FDG influx between patient and organoid tumor suggests that PEM can be a preclinical tool to bridge the gap between laboratory and clinical cancer imaging. Finally, organoids treated with cisplatin displayed a dose-dependent decrease in the metabolic activity, while organoids derived from cisplatin-resistant patients retained high metabolic activity despite cisplatin treatment. Our results suggest that PEM imaging of patient-derived organoids could be used to predict individual patient response to different treatments to provide a more personalized approach to cancer care. Citation Format: Syamantak Khan, June Ho Shin, Ning Cheng, Calvin Kuo, John Sunwoo, Guillem Pratx. High-resolution positron emission microscopy of patient-derived tumor organoids [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr B08.

Long non-coding RNA LINC00346 contributes to cisplatin resistance in nasopharyngeal carcinoma by repressing miR-342-5p.

Cisplatin has been used as the first-line chemotherapy to treat advanced nasopharyngeal carcinoma (NPC), while acquired cisplatin resistance resulting from epigenetic regulation is not well understood. The relative expression of LINC00346 was detected in healthy persons, cisplatin-sensitive (CS) patients and cisplatin-resistant (CR) patients. The regulatory effect of LINC00346 on the proliferation was detected by cell-counting kit-8. Apoptosis was assayed by histone/DNA ELISA and Caspase-3 activity. Clonal formation and cisplatin resistance were also deciphered. Luciferase reporter and RNA immunoprecipitation assay were adopted to study the interaction between LINC00346 and miR-342-5p. LINC00346 was highly expressed in NPC patients, especially in CR patients, which was associated with cisplatin resistance and poor prognosis. Inhibition of LINC00346 expression promoted cisplatin sensitivity of NPC cells, while LINC00346 over-expression promoted cisplatin resistance of NPC cells. miR-342-5p expression was negatively correlated with cisplatin resistance, and microRNA-342-5p siRNAs treatment could rescue the cisplatin resistance diminished by LINC00346 inhibition. It was further found that miR-342-5p was negatively regulated by LINC00346. In conclusion, LINC00346 regulates the cisplatin resistance of NPC cells by inhibiting miR-342-5p, which could provide a potential target for chemotherapy resistance.

Inhibition of HMGB1 Overcomes Resistance to Radiation and Chemotherapy in Nasopharyngeal Carcinoma.

ObjectiveThis study aimed to investigate the effect of high mobility group protein B1 (HMGB1) on chemoresistance and radioresistance in nasopharyngeal carcinoma (NPC).Materials and MethodsHMGB1-knockout HK1 cell lines were generated using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system. Western blotting was used to evaluate the protein expression level of HMGB1. DNA repair efficiency of non-homologous end joining (NHEJ) and homologous recombination (HR) was monitored through NHEJ and HR reporter assay. Cellular protein–protein interaction between HMGB1 and NHEJ apparatus was determined by immunoprecipitation. Direct protein–protein interaction was examined by affinity capture assay with purified protein. Protein-DNA binding was evaluated by chromatin fractionation assay. Cell viability assay was employed to measure cell sensitivity to ionizing radiation (IR) or cisplatin.ResultsHMGB1-knockout NPC cells showed significant decrease in NHEJ efficiency. HMGB1 immunoprecipitated NHEJ key factors in NPC cells and promoted DNA-binding activity of Ku70. Mutational analysis revealed that serine 155 of Ku70 was required for its direct interaction with HMGB1. HMGB1 was highly expressed in radio- and chemoresistant NPC cells. Deficiency of HMGB1 sensitized wild-type (WT) and resistant NPC cells to IR and cisplatin. Glycyrrhizin, which is HMGB1 inhibitor, impaired DNA binding of HMGB1 and exhibited excellent synergy with IR and cisplatin.ConclusionHMGB1 promotes NHEJ via interaction with Ku70 resulting in resistance to IR and cisplatin. Inhibition of HMGB1 by glycyrrhizin is a potential therapeutic regimen to treat cisplatin and IR resistant NPC patients.

Hypermethylation of CSF3R is a novel cisplatin resistance marker and predictor of response to postoperative chemotherapy in hepatoblastoma.

Most hepatoblastoma patients undergo pre/postoperative cisplatin treatment. Approximately 20% patients are cisplatin resistant, and show poor prognosis and high recurrence rates. However, some cisplatin-sensitive patients show early recurrence. We consider that a small population of cisplatin-resistant cells may remain after preoperative chemotherapy. Previous studies showed a correlation between DNA hypermethylation and hepatoblastoma progression. Here, we examined whether DNA hypermethylation was related to cisplatin resistance and could be a potential indicator for cisplatin as postoperative chemotherapy. We extracted DNA from 43 resected hepatoblastoma tumors. Methylation array analyses were performed in 11 samples, including six cisplatin-sensitive and five cisplatin-resistant samples. We also performed cDNA microarray analysis in parental and cisplatin-resistant HuH6 cells. Through comparison of the datasets, we selected the strongest correlated cisplatin-resistant candidate gene. Using bisulfite pyrosequencing, the candidate gene methylation level was assessed in 38 cisplatin-sensitive patients after checking its usefulness as a substitute modality of methylation array. Correlations between the methylation status and clinical data were analyzed. CSF3R was the strongest correlated variable. Bisulfite pyrosequencing analysis also confirmed CSF3R was significantly hypermethylated in cisplatin-resistant patients. Among the 38 cisplatin-sensitive patients, recurrence curves showed that the CSF3R high methylation patients had significantly higher recurrence than CSF3R low methylation patients. The recurrence curve of methylation high patients was similar to that of cisplatin-resistant patients. Our findings suggested that CSF3R hypermethylation was related to cisplatin resistance in HB patients and could be a predictor of postoperative chemotherapy, and indicate that CSF3R high methylation patients should be treated with non-CDDP regimens.

RETRACTED: Circular RNA Cdr1as Upregulates SCAI to Suppress Cisplatin Resistance in Ovarian Cancer via miR-1270 Suppression

The aim of this study is to explore the roles of circular RNA (circRNA) Cdr1as on cisplatin resistance in ovarian cancer and explore the underlying mechanisms. We investigated the expression of circRNAs in five paired cisplatin-sensitive and cisplatin-resistant tissues of ovarian cancer by microarray analysis. The quantitative real-time PCR analysis was to investigate the expression pattern of Cdr1as in cisplatin-resistant ovarian cancer patient tissues and cell lines. Then, the effects of Cdr1as on cisplatin resistance, cell proliferation, and apoptosis were assessed in ovarian cancer cells. In this study, Cdr1as was observed to be downregulated in cisplatin-resistant patient tissues and cell lines. Overexpression of Cdr1as inhibited cell proliferation and promoted the cisplatin-induced cell apoptosis in ovarian cancer cells. Then we demonstrated that repressed Cdr1as promoted the miR-1270 expression, and miR-1270 could bind to the predicted binding site of Cdr1as. Furthermore, we found that miR-1270 displayed its role via modulating the Suppressor of Cancer Cell Invasion (SCAI) expression. Importantly, we demonstrated that Cdr1as was downregulated in serum exosomes from cisplatin-resistant patients. In summary, our study demonstrated that Cdr1as sensitizes ovarian cancer to cisplatin by regulating the miR-1270/SCAI signaling pathway.

LncRNA UCA1 Mediates Resistance to Cisplatin by Regulating the miR-143/FOSL2-Signaling Pathway in Ovarian Cancer

The aim of this study was to explore the roles of the long noncoding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) on cisplatin resistance in ovarian cancer and the underlying mechanisms. We investigated the expression of lncRNAs in 3 paired cisplatin-sensitive and cisplatin-resistant tissues of ovarian cancer by microarray analysis. The qRT-PCR analysis was to investigate the expression pattern of UCA1 in cisplatin-resistant ovarian cancer patient tissues and cell lines. Then we examined the effects of UCA1 on cisplatin resistance in vitro and in vivo. In this study, UCA1 was observed to be upregulated in cisplatin-resistant patient tissues and cell lines. Knockdown of UCA1 inhibited cell proliferation and promoted the cisplatin-induced cell apoptosis in ovarian cancer cells. Then we demonstrated that repressed UCA1 promoted the miR-143 expression and miR-143 could bind to the predicted binding site of UCA1. Furthermore, we found that miR-143 displayed its role via modulating the FOSL2 expression. Importantly, we demonstrated that UCA1 was upregulated in serum exosomes from cisplatin-resistant patients. In summary, our study demonstrated that UCA1 modulates cisplatin resistance through the miR-143/FOSL2 pathway in ovarian cancer.

Relationship between p-cofilin and cisplatin resistance in patients with ovarian cancer and the role of p-cofilin in prognosis.

This study aims to determine the correlation between p-cofilin expression and cisplatin resistance in patients with ovarian cancer, and also to investigate the role of p-cofilin in prognosis. The ovarian cancer cell line A2780/DDP resistant to cisplatin was prepared. The cell resistance to cisplatin was measured via MTT assay. The cell invasion capacity was identified via Transwell assay. The mRNA expression and protein level was evaluated via semi-quantitative PCR and Western blot, respectively. The tumor tissues of patients with cisplatin-resistant ovarian cancer were collected. The relationship between prognosis and p-cofilin expression was analyzed. The growth rate of A2780 was similar to that of A2780/DDP. The sensitivity of A2780 to cisplatin was significantly higher than that of A2780/DDP (p< 0.01). The migration capacity of A2780/DDP was significantly increased compared to that of A2780 (p< 0.01), indicating that the cisplatin-resistant cell lines were successfully constructed. Both CFL1 mRNA level and p-cofilin level in A2780/DDP was significantly higher than that in A2780 (p< 0.01). The p-cofilin level in cancer tissues in patients with cisplatin-resistant ovarian cancer was significantly higher than that in patients with cisplatin-sensitive ovarian cancer (p< 0.01). The cisplatin resistance was positively correlated with the p-cofilin expression level (r= 0.802, p= 0.023). The survival time of patients with normal or low level of p-cofilin was significantly longer than that of patients with high expression. The cisplatin resistance of ovarian cancer is closely related to the expression level of p-cofilin, which affects the prognosis of patients with ovarian cancer.

MicroRNA-504 modulates osteosarcoma cell chemoresistance to cisplatin by targeting p53.

Chemoresistance implicates the therapeutic value of cisplatin and remains a primary obstacle to its clinical use. MicroRNAs (miRs) negatively modulate the expression of their target genes and are associated with the occurrence and progression of various types of tumor. The abnormal expression of miR-504 has been reported in certain types of human tumor and has been associated with tumor prognosis. However, the association between miR-504 and cisplatin in human osteosarcoma remains unclear. The present study therefore aimed to assess the in vitro effects and possible mechanism of miR-504 in cell proliferation, apoptosis and cisplatin resistance in MG63 osteosarcoma cells. The results demonstrated that miR-504 was overexpressed in osteosarcoma tissues and cells. This overexpression also induced cell proliferation, as determined by MTT and EdU staining assays. Furthermore, miR-504 suppressed cisplatin-induced apoptosis, which was demonstrated via MTT, cell morphology analysis and flow cytometry. Cisplatin-induced G1 arrest was also suppressed, which was determined by flow cytometry. The potential target genes of miR-504 were predicted using bioinformatics. p53 was confirmed to be a direct target of miR-504 using a luciferase reporter assay and western blot analysis revealed that miR-504 negatively regulated p53 expression at a molecular level. These results indicate that miR-504 contributes to cisplatin resistance in MG63 osteosarcoma cells by suppressing p53. miR-504 may therefore be a potential biomarker for cisplatin resistance in patients with osteosarcoma.

Tyrosine kinase receptor TIE-1 mediates platinum resistance by promoting nucleotide excision repair in ovarian cancer

Platinum resistance is one of the most challenging problems in ovarian cancer treatment. High-throughput functional siRNA screening identified tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE-1) as a gene that confers cells resistant to cisplatin. Conversely enforced over-expression of TIE-1 was validated to decrease cisplatin sensitivity in multiple ovarian cancer cell lines and up-regulation of TIE-1 was correlated with poor prognosis and cisplatin resistance in patients with ovarian cancer. Mechanistically, TIE-1 up-regulates the nucleotide excision repair (NER) system mediated by xeroderma pigmentosum complementation group C (XPC), thereby leading to decreased susceptibility to cisplatin-induced cell death without affecting cisplatin uptake and excretion. Importantly potentiation of therapeutic efficacy by TIE-1 inhibition was selective to DNA-adduct-type chemotherapeutic platinum reagents. Therefore, TIE-1 is suggested to promote XPC-dependent NER, rendering ovarian cancer cells resistant to platinum. Accompanied with novel findings, TIE-1 could represent as a novel therapeutic target for platinum-resistant ovarian cancer.

Osteopontin promotes cancer cell drug resistance, invasion, and lactate production and is associated with poor outcome of patients with advanced non-small-cell lung cancer.

BackgroundOsteopontin (OPN), a member of the small integrin binding ligand N-linked glycoprotein family, has been analyzed in numerous types of human malignancy.PurposeThe present study detected the expression levels of OPN and evaluated its role in tumor progression in patients with non-small cell lung cancer (NSCLC).Patients and methodsOPN expression levels were detected using immunohistochemistry in 101 NSCLC tumors. The mRNA and protein levels have significant difference between advanced NSCLC and stage I/II NSCLC. The drug resistance, invasive ability and lactate production of NSCLC cancer cell lines (A549 and SK-MES-1) were detected in cancer cells with the disturbance of OPN.ResultsImmunostaining indicated that OPN was primarily expressed in the cytoplasm of NSCLC cells. Moreover, OPN correlates with NSCLC clinical traits. The results demonstrated that OPN expression levels significantly correlated with cancer differentiation, distant metastasis and the efficacy of platinum-based treatment. Notably, the results identified OPN expression levels as a potential factor for predicting the response of cells to first-line platinum-based chemotherapy using multivariate analysis, as well as predicting cancer differentiation and distant metastasis. Additionally, the abrogation of OPN levels reduced lactate production in NSCLC cells and occurred along side with the downregulation of lactate dehydrogenase A (LDHA).ConclusionThe results of the current study suggest that OPN may be able to predict poor prognosis and cisplatin resistance in patients.

Abstract A65: Combination of a thioxodihydroquinazolinone compound with cisplatin eliminates ovarian cancer stem cell-like cells (CSC-LCs) and shows preclinical potential

Abstract Cancer stem cell-like cells (CSC-LCs) contribute to drug resistance and recurrence of ovarian cancer. Strategies that can eradicate CSC-LCs are expected to substantially improve the outcome of ovarian cancer treatments. We have previously identified a class of thioxodihydroquinazolinone small molecules, which have strong synergistic antitumor activity with platinum drugs, the standard chemotherapeutic agents for ovarian cancer treatment. In the current study, using the activity of aldehyde dehydrogenase (ALDH) as a marker of CSC-LCs, we demonstrated that the combination of thioxodihydroquinazolinone compound 19 with cisplatin is able to deplete ALDH-high CSC-LC population in both established platinum-resistant ovarian cancer cell lines and primary ovarian cancer cells from metastatic ascites of a cisplatin-resistant patient. Compound 19 enhanced the accumulation of intracellular cisplatin in ALDH-high ovarian cancer cells. The combination of compound 19 with cisplatin was also able to reduce the sphere-forming capability of cisplatin-resistant ovarian cancer cells. Using a spheroid-based in vitro metastasis model of ovarian cancer, we demonstrated that the combination of compound 19 with cisplatin prevents spheroid ovarian cancer cells from attaching to substratum and spreading. In vivo, the treatment by the combination of compound 19 with cisplatin significantly reduced tumor burden in a cisplatin-resistant intraperitoneal ovarian cancer xenograft mouse model, as compared to cisplatin-alone treatment. Taken together, our study demonstrated that the thioxodihydroquinazolinone compounds are a new class of agents that in combination with cisplatin are capable of eliminating CSC-LCs in ovarian cancer. Further development of thioxodihydroquinazolinone small molecules may yield a more effective treatment for cisplatin-resistant metastatic ovarian cancer. Citation Format: Jing Ma, Joseph Salamoun, Peter Wipf, Robert Edwards, Bennett Van Houten, Wei Qian. Combination of a thioxodihydroquinazolinone compound with cisplatin eliminates ovarian cancer stem cell-like cells (CSC-LCs) and shows preclinical potential. [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 A65.

LINC00857 expression predicts and mediates the response to platinum-based chemotherapy in muscle-invasive bladder cancer.

Approximately 20% of patients with bladder cancer are diagnosed with muscle‐invasive disease (MIBC). The treatment involves radical cystectomy, but almost 50% of patients with MIBC eventually relapse and develop metastasis. The use of platinum‐based chemotherapy in the neoadjuvant setting or for metastatic patients has been shown to improve the overall survival in a subset of patients. Unfortunately, no biomarkers are available to select patients with MIBC who will benefit from chemotherapy or to monitor the efficacy of the treatment. Recently, long noncoding RNAs (lncRNAs) were shown to regulate a variety of processes involved in the development and progression of cancer, including bladder cancer. Moreover, several lncRNAs have been shown to play a role in chemotherapy resistance. Here, we analyzed lncRNA expression associated with response to platinum‐based chemotherapy in metastatic MIBC using data from the MiTranscriptome lncRNA expression database. Expression of the lncRNA,LINC00857, was found to be upregulated in tumors from patients that did not respond to platinum‐based chemotherapy. Moreover, high expression of LINC00857 is correlated with shorter recurrence‐free and overall survival of patients with MIBC. Knockdown of LINC00857 significantly decreased cell viability of bladder cancer cell lines through the induction of apoptosis. Furthermore, LINC00857 knockdown sensitized UM‐UC‐3 and T24 bladder cancer cells to cisplatin, via the negative regulation of the LMAN1 gene. Our data indicate that LINC00857 plays an important role in the regulation of response to platinum‐based chemotherapy. LINC00857 potentially could serve as a novel prognostic and predictive biomarker and might be a therapeutic target to overcome cisplatin resistance in patients with MIBC.

Combination of a thioxodihydroquinazolinone with cisplatin eliminates ovarian cancer stem cell-like cells (CSC-LCs) and shows preclinical potential.

Cancer stem cell-like cells (CSC-LCs) contribute to drug resistance and recurrence of ovarian cancer. Strategies that can eradicate CSC-LCs are expected to substantially improve the outcome of ovarian cancer treatment. We have previously identified a class of thioxodihydroquinazolinone small molecules, which have strong synergistic antitumor activity with platinum drugs, the standard chemotherapeutic agents for ovarian cancer treatment. In the current study, using the activity of aldehyde dehydrogenase (ALDH) as a marker of CSC-LCs, we demonstrated that the combination of thioxodihydroquinazolinone compound 19 with cisplatin is able to diminish ALDH-high CSC-LC populations in both platinum-resistant ovarian cancer cell lines and primary ovarian cancer cells from metastatic ascites of a cisplatin-resistant patient. Compound 19 enhanced the accumulation of intracellular cisplatin in ALDH-high ovarian CSC-LCs. The combination of compound 19 with cisplatin was also able to reduce the sphere-forming capability of cisplatin-resistant ovarian cancer cells. Using a spheroid-based in vitro metastasis model of ovarian cancer, we demonstrated that the co-administration of compound 19 with cisplatin prevents ovarian cancer spheroid cells from attaching to substratum and spreading. In a cisplatin-resistant in vivo intraperitoneal xenograft mouse model, the combination of compound 19 with cisplatin significantly reduced tumor burden, as compared to cisplatin alone. Taken together, our study demonstrated that thioxodihydroquinazolinones represent a new class of agents that in combination with cisplatin are capable of eliminating CSC-LCs in ovarian cancer. Further development of thioxodihydroquinazolinone small molecules may yield a more effective treatment for cisplatin-resistant metastatic ovarian cancer.

Entinostat reverses cisplatin resistance in esophageal squamous cell carcinoma via down-regulation of multidrug resistance gene 1

Cisplatin resistance frequently occurs in esophageal squamous cell carcinoma (ESCC). The underlying mechanism for cisplatin resistance in ESCC remains largely obscure. Here we report that entinostat reversed cisplatin resistance in ESCC both in vitro and in vivo by induction of apoptosis and inhibition of cell proliferation, accompanied by a decrease of multidrug resistance gene 1 (MDR1), P-Src, Mcl-1, Cyclin D1 and an increase of cleaved PARP. MDR1 expression was associated with worsen survival of ESCC patients with cisplatin-based chemotherapy. Dasatinib potentiated entinostat to overcome cisplatin resistance. By inhibiting Src, dasatinib reduced the expression of MDR1 and Mcl-1. Furthermore, Obatoclax, an inhibitor of Mcl-1, obviously decreased the expression of MDR1, suggesting that entinostat might surmount cisplatin resistance in ESCC via a Src-Mcl-1-MDR1 pathway. Interestingly, cisplatin also enhanced the effect of entinostat both in vitro and in vivo. Our data disclose a molecular basis that entinostat reverses cisplatin resistance, and provide a promising strategy with combinatorial drugs to treat cisplatin resistant ESCC patients.

Downregulation of Inhibition of Apoptosis-Stimulating Protein of p53 (iASPP) Suppresses Cisplatin-Resistant Gastric Carcinoma In Vitro.

BackgroundGastric cancer (GC) with cisplatin resistance is one of the leading causes of limitations to therapy. Inhibition of apoptosis-stimulating protein of p53 (iASPP) plays a key role in GC. However, the role of iASPP in GC with cisplatin resistance remains unclear. The aim of this study was to investigate iASPP expression in GC, and the functions of iASPP in cisplatin-resistant cell lines.Material/MethodsIn this study, the expression of iASPP was investigated in normal GC patients and patients with cisplatin resistance, along with GC cell lines and cell lines with cisplatin resistance. Furthermore, knockdown of iASPP was conducted in cell lines; and cell proliferation, apoptosis rate, cell cycle distribution, and cell migration and invasion were determined through CCK8, flow cytometry, Scratch test and Transwell assay, respectively.ResultsThe expression of iASPP in GC patients with cisplatin resistance was significant higher than in the health control group. Higher expression of iASPP was detected in cisplatin-resistant cancer cell lines. Cell proliferation of SGC-7901 and MGC-803 was inhibited by transfection with siRNA, along with evaluated apoptosis rate and G1 phase retardant. Furthermore, cells viability, including migration and invasion, was suppressed post-transfection with siRNA.ConclusionsiASPP induced cisplatin resistance in GC patients. Thus, knockdown of iASPP might be a novel therapeutic strategy for the treatment of GC cisplatin-resistant patients.

Over-expression of BAG-1 in head and neck squamous cell carcinomas (HNSCC) is associated with cisplatin-resistance

BackgroundIn order to improve therapy for head and neck squamous cell carcinoma (HNSCC), biomarkers associated with local and/or distant tumor relapses and cancer drug resistance are urgently needed. This study identified a potential biomarker, Bcl-2 associated athanogene-1 (BAG-1), that is implicated in HNSCC insensitive to cisplatin and tumor progression.MethodsPrimary and advanced (relapsed from parental) University of Michigan squamous cell carcinoma cell lines were tested for sensitivity to cisplatin and gene expression profiles were compared between primary (cisplatin sensitive) and the relapsed (cisplatin resistant) cell lines by using Agilent microarrays. Additionally, differentially expressed genes phosphorylated AKT, and BAG-1, and BCL-xL were evaluated for expression using HNSCC tissue arrays.ResultsAdvanced HNSCC cells revealed resistant to cisplatin accompanied by increased expression of BAG-1 protein. siRNA knockdown of BAG-1 expression resulted in significant improvement of HNSCC sensitivity to cisplatin. BAG-1 expression enhanced stability of BCL-xL and conferred cisplatin resistant to the HNSCC cells. In addition, high levels of expression of phosphorylated AKT, BAG-1, and BCL-xL were observed in advanced HNSCC compared to in that of primary HNSCC.ConclusionIncreased expression of BAG-1 was associated with cisplatin resistance and tumor progression in HNSCC patients and warrants further validation in larger independent studies. Over expression of BAG-1 may be a biomarker for cisplatin resistance in patients with primary or recurrent HNSCCs and targeting BAG-1 could be helpful in overcoming cisplatin resistance.

Re: Genetic Determinants of Cisplatin Resistance in Patients with Advanced Germ Cell Tumors.

Re: Genetic Determinants of Cisplatin Resistance in Patients with Advanced Germ Cell Tumors.

Abstract 4404: Novel approach to circumvent cisplatin resistant lung cancer by targeting metabolism

Abstract For the past three decades, there are no drugs which could reverse cisplatin resistance or selectively kill these resistant cells. We have discovered that cisplatin resistant (CR) lung cancer shares one common factor which is increase in reactive oxygen species (ROS). Decreased intracellular thioredoxin-1(TRX1) due to excessive secretion was found in vitro and in vivo, as well as in patients’ serum which could be a primary contributory factor to higher mitochondria-ROS levels. Furthermore, CR cells possess significantly increased number of mitochondria and consume higher rates of oxygen. Key glycolytic enzymes (HKII and LDHA) and lactate production were decreased in CR cells which suggests rewiring of tumor metabolic pathways. NAD+, crucial co-factor of all redox systems, is significantly reduced in all CR cells. Importantly, treatment with riluzole (the FDA approved drug that interferes with cystine/glutamate pump and results in reduced intracellular glutathione (GSH) levels) led to further decrease in NAD+ and LDHA, as well as heightened oxidative stress in CR cells. ROS levels were increased (2-3X) more in resistant cells after riluzole treatment while no significant change occurred in parental cells. The ID50 dosage of parental cells were 3-4 fold more than theirs CR cell counterparts and no cytotoxicity were found in normal lung fibroblast (n=8; p&amp;lt;0.05). Addition of 200 µM NAD+ re-stabilized LDHA, reduced ROS, and reversed riluzole induced cell death. To further determine whether LDHA correlates with ROS levels and sensitivity to riluzole, we inhibited LDHA expressions in parental cell lines S and H460 using siRNA. Lactate productions were decreased in knockdown cells and further attenuated upon riluzole treatment when compared with scrambled control. Higher basal levels of ROS were obtained from S+siLDHA and H460+siLDHA and further increased in ROS levels were observed when treated with riluzole. We then evaluated the viability of these cells under riluzole treatment. Both siLDHA clones were sensitive to riluzole particularly in S+siLDHA which showed 4 fold more sensitivity. Importantly, treatment of riluzole also led to further decrease in LDHA expressions at both protein and mRNA levels. Using riluzole in 2 mouse xenograft models (H460CR (KRAS mutant) and SC (wt)) resulted in completely disappeared in wild type mice and were significant reduced in KRAS mutant mice (n=5 per treatment group; p&amp;lt;0.002). Repurpose of riluzole should be considered for future treatment of CR lung cancer patients. Supported by Department of Veterans Affairs, CDA2 award (1K2BX001289) and Woman Cancer Association Fund. Citation Format: Medhi Wangpaichitr, Chunjing Wu, Ying Ying Li, Lynn G. Feun, Macus T. Kuo, Niramol Savaraj. Novel approach to circumvent cisplatin resistant lung cancer by targeting metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4404. doi:10.1158/1538-7445.AM2017-4404