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ABL regulation by AXL promotes cisplatin resistance in esophageal cancer.

ABSTRACT: Esophageal adenocarcinoma (EAC) is characterized by resistance to chemotherapy and poor outcome. Although cisplatin (CDDP) has been used as a first-line therapy in patients with EAC, resistance remains a major clinical problem. The AXL receptor tyrosine kinase, originally isolated as a transforming gene from leukemia, is overexpressed in several solid tumors. Herein, we assessed AXL protein expression in human EACs and examined its role in CDDP resistance in human EAC cells. AXL overexpression was detected in more than 50% of tumors examined. Elevating AXL in nonoverexpressing cells doubled the CDDP IC(50) and increased cell survival three-fold, while attenuating AXL in overexpressing cells reduced survival two-fold. The effects of AXL modulation on cell survival were associated with changes in cellular and molecular markers of apoptosis. Mechanistic investigations revealed that AXL blocked CDDP-induced activation of endogenous p73? (TP73), reducing its protein half-life, and inhibited CDDP-induced levels of p-c-ABL(Y412) and p-p73?(Y99). These changes were associated with a disruption of c-ABL/p73? protein interactions due to association with c-ABL in the cytoplasm, thereby blocking nuclear accumulation of c-ABL and phosphorylation of p73? in response to DNA damage. Together, our results establish that AXL promotes CDDP resistance in esophageal adenocarcinoma and argue that therapeutic targeting of AXL may sensitize these cancers to DNA-damaging drugs.

SUBMITTER: Hong J

PROVIDER: S-EPMC5907497 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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ABL regulation by AXL promotes cisplatin resistance in esophageal cancer.

Hong Jun J Peng Dunfa D Chen Zheng Z Sehdev Vikas V Belkhiri Abbes A

Cancer research 20121101 1

Esophageal adenocarcinoma (EAC) is characterized by resistance to chemotherapy and poor outcome. Although cisplatin (CDDP) has been used as a first-line therapy in patients with EAC, resistance remains a major clinical problem. The AXL receptor tyrosine kinase, originally isolated as a transforming gene from leukemia, is overexpressed in several solid tumors. Herein, we assessed AXL protein expression in human EACs and examined its role in CDDP resistance in human EAC cells. AXL overexpression w ...[more]

PMID: 23117882

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Project description:Background: Chemotherapy resistance is a barrier to effective cancer prognoses. Cisplatin (CDDP) resistance is a major challenge for esophageal cancer (EC) therapy. A deeper understanding of the fundamental mechanisms of cisplatin resistance and improved targeting strategies are required in clinical settings. This study was performed to identify and characterize a marker of cisplatin resistance in EC cells. Method: KYSE140 and Eca-109 cells were subjected to escalating concentrations of cisplatin, resulting in the development of cisplatin-resistant KYSE140/CDDP and Eca-109/CDDP cell lines, respectively. RNA Sequencing (RNA-seq) was utilized to screen for the genes exhibiting differential expression between cisplatin-resistant and parental cells. Reverse transcription quantitative PCR was conducted to assess gene expression, and western blotting was employed to analyze protein levels. A sphere-formation assay was performed to validate tumor cell stemness. Cell counting kit-8 (CCK-8) experiments were conducted to confirm the sensitivity of cells to cisplatin. We examined the relationship between target genes and the clinicopathological features of patients with EC. Furthermore, the expression of target genes in EC tissues was evaluated via western blotting and fluorescence probe in situ hybridization (FISH). Results: KYNU was upregulated in cisplatin-resistant EC cells (KYSE140/CDDP and Eca-109/CDDP cells) and in EC tissues compared to that in the respective parental cell lines (KYSE140 and Eca-109 cells) and non-carcinoma tissues. Downregulation of KYNU increased cell sensitivity to cisplatin and suppressed tumor stemness, whereas abnormal KYNU expression had the opposite effect. KYNU expression was correlated with the expression of tumor stemness-associated factors (SOX2, Nanog, and OCT4) and the tumor size. Conclusions: KYNU may promote drug resistance in EC by regulating cancer stemness, and could serve as a biomarker and therapeutic target for EC.

Project description:Background: Esophageal adenocarcinoma (EAC) is highly aggressive and characterized by poor prognosis. AXL expression has been linked to Barrett's tumorigenesis and resistance to chemotherapy, which is associated with c-ABL intracellular localization. However, the molecular and functional relationship between AXL and c-ABL and the clinical significance of the co-expression of these proteins in EAC remain unclear. Methods: We used immunohistochemical analysis (IHC) on tissue microarrays containing human EAC samples (n=53) and normal esophageal tissues (n=11) in combination with corresponding deidentified clinicopathological information to evaluate the expression and the prognostic significance of AXL and c-ABL in EAC. The data were statistically analyzed using Kruskal-Wallis, the chi-square, the Fisher's exact, and Pearson tests. The Kaplan-Meier method and Cox proportional hazards regression model were used to evaluate cancer patient survival. We used a serum deprivation EAC cell model to investigate the pro-survival function of AXL and c-ABL using cell viability, apoptosis, and lactate dehydrogenase activity assays. We performed in vitro assays, including Western blotting, quantitative real-time PCR, and translational chromatin immunoprecipitation (TrIP-Chip) to study the molecular relationship between AXL and c-ABL in EAC cells. Results: IHC analysis revealed that AXL and c-ABL were overexpressed in 55% and 66% of EAC samples, respectively, as compared to normal tissues. Co-overexpression of the two proteins was observed in 49% of EAC samples. The chi-square test indicated a significant association between AXL and c-ABL expression in the EAC samples (χ2 = 6.873, p = 0.032), and the expression of these proteins was significantly associated with EAC patient age (p < 0.001), tumor stage (p < 0.01), and lymph node status (p < 0.001). AXL and c-ABL protein expression data analysis exhibited an identical clinicopathological association profile. Additionally, we found a significant association between expression of AXL (χ2 = 16.7, p = 0.002) or c-ABL (χ2 = 13.4, p = 0.001) and survival of EAC patients. The Cox proportional hazards model and log rank test predicted a significant increase in mortality of patients with high expression of AXL [hazard ratio (HR): 2.86, 95% confidence interval (CI): 1.53 - 5.34, p = 0.003] or c-ABL [HR: 3.29, 95% CI: 1.35 - 8.03, p = 0.001] as compared to those patients with low expression of AXL or c-ABL proteins. Molecular investigations indicated that AXL positively regulates c-ABL protein expression through increased cap-dependent protein translation involving phosphorylation of EIF4E in EAC cells. Next, we investigated the functional relationship between AXL and c-ABL in EAC cells. We demonstrated that the pro-survival activity of AXL requires c-ABL expression in response to serum deprivation. Conclusion: This study highlights the importance of the co-overexpression of AXL and c-ABL proteins as a valuable prognostic biomarker and targeting these proteins could be an effective therapeutic approach in EAC or other solid tumors expressing high levels of AXL and c-ABL proteins.

Project description:PURPOSE:Chemotherapy resistance of esophageal cancer is a key factor affecting the postoperative treatment of esophageal cancer. Among the media that transmit signals between cells, the exosomes secreted by tumor cells mediate information transmission between tumor cells, which can make sensitive cells obtain resistance. Although some cellular exosomes play an important role in tumor's acquired drug resistance, the related action mechanism is still not explored specifically. METHODS:To elucidate this process, we constructed a cisplatin-resistant esophageal cancer cell line, and proved that exosomes conferring cellular resistance in esophageal cancer can promote cisplatin resistance in sensitive cells. Through high-throughput sequencing analysis of the exosome and of cells after stimulation by exosomes, we determined that the miRNA193 in exosomes conferring cellular resistance played a key role in sensitive cells acquiring resistance to cisplatin. In vitro experiments showed that miRNA193 can regulate the cell cycle of esophageal cancer cells and inhibit apoptosis, so that sensitive cells can acquire resistance to cisplatin. An in vivo experiment proved that miRNA193 can promote tumor proliferation through the exosomes, and provide sensitive cells with slight resistance to cisplatin. RESULTS:Small RNA sequencing of exosomes showed that exosomes in drug-resistant cells have 189 up-regulated and 304 down-regulated miRNAs; transcriptome results showed that drug-sensitive cells treated with drug-resistant cellular exosomes have 3446 high-expression and 1709 low-expression genes; correlation analysis showed that drug-resistant cellular exosomes mainly affect the drug resistance of sensitive cells through paths such as cytokine-cytokine receptor interaction, and the VEGF and Jak-STAT signaling pathways; miRNA193, one of the high-expression miRNAs in drug-resistant cellular exosomes, can promote drug resistance by removing cisplatin's inhibition of the cell cycle of sensitive cells. CONCLUSION:Sensitive cells can become resistant to cisplatin through acquired drug-resistant cellular exosomes, and miRNA193 can make tumor cells acquire cisplatin resistance by regulating the cell cycle.

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ABL regulation by AXL promotes cisplatin resistance in esophageal cancer.

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ABL regulation by AXL promotes cisplatin resistance in esophageal cancer.

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