Oxaliplatin In Colorectal Cancer Research Articles

AKR1C1 interacts with STAT3 to increase intracellular glutathione and confers resistance to oxaliplatin in colorectal cancer

Oxaliplatin (OXA), a platinum-based chemotherapeutic agent, remains a mainstay in first-line treatments for advanced colorectal cancer (CRC). However, the eventual development of OXA resistance represents a significant clinical challenge. In the present study, we demonstrate that the aldo-keto reductase 1C1 (AKR1C1) is overexpressed in CRC cells upon acquisition of OXA resistance, evident in OXA-resistant CRC cell lines. We employed genetic silencing and pharmacological inhibition strategies to establish that suppression of AKR1C1 restores OXA sensitivity. Mechanistically, AKR1C1 interacts with and activates the transcription factor STAT3, which upregulates the glutamate transporter EAAT3, thereby elevating intracellular glutathione levels and conferring OXA resistance. Alantolactone, a potent natural product inhibitor of AKR1C1, effectively reverses this chemoresistance, restricting the growth of OXA-resistant CRC cells both in vitro and in vivo. Our findings uncover a critical AKR1C1-dependent mechanism behind OXA resistance and propose a promising combinatorial therapeutic strategy to overcome this resistance in CRC.

Liensinine sensitizes colorectal cancer cells to oxaliplatin by targeting HIF-1α to inhibit autophagy

BackgroundOxaliplatin is the most common chemotherapeutic agent for patients with colorectal cancer. However, its anti-cancer efficacy is restricted by drug resistance occurring through several mechanisms, including autophagy. Liensinine exerts a considerable anti-tumor effect and can regulate autophagy. Inhibition of autophagy is a strategy to reverse resistance to oxaliplatin. The aim of this study was to check if liensinine can enhance the therapeutic efficacy of oxaliplatin in colorectal cancer and if so, elucidate its mechanism. MethodsTwo colorectal cancer cell lines, HCT116 and LoVo, and one normal intestinal epithelial cell, NCM-460 were used for in vitro experiments. Cell Counting Kit-8 (CCK-8), colony formation, and flow cytometry assays were used to evaluate the cytotoxicity of liensinine and oxaliplatin. Network pharmacology analysis and Human XL Oncology Array were used to screen targets of liensinine. Transfections and autophagy regulators were used to confirm these targets. The relationship between the target and clinical effect of oxaliplatin was analyzed. Patient-derived xenograft (PDX) models were used to validate the effects of liensinine and oxaliplatin. ResultsCCK-8 and colony formation assays both showed that the combination treatment of liensinine and oxaliplatin exerted synergistic effects. Results of the network pharmacology analysis and Human XL Oncology Array suggested that liensinine can inhibit autophagy by targeting HIF-1α/eNOS. HIF-1α was identified as the key factor modulated by liensinine in autophagy and induces resistance to oxaliplatin. HIF-1α levels in tumor cells and prognosis for FOLFOX were negatively correlated in clinical data. The results from three PDX models with different HIF-1α levels showed their association with intrinsic and acquired resistance to oxaliplatin in these models, which could be reversed by liensinine. ConclusionsResearch on the relationship between HIF-1α levels and the clinical effect of oxaliplatin is lacking, and whether liensinine regulates HIF-1α is unknown. Our findings suggest that liensinine overcomes the resistance of colorectal cancer cells to oxaliplatin by suppressing HIF-1α levels to inhibit autophagy. Our findings can contribute to improving prognosis following colorectal cancer therapy.

Regorafenib activates oxidative stress by inhibiting SELENOS and potentiates oxaliplatin-induced cell death in colon cancer cells

Colorectal cancer (CRC) is the third most common cancer, and is one of the leading causes of cancer-related death worldwide. At the time of diagnosis, about 20% of patients with CRC present metastatic disease. Regorafenib, an oral multi-kinase inhibitor, has been demonstrated the efficacy and tolerability in patients with metastatic CRC. Oxaliplatin is a frontline treatment regimen for CRC, and combination treatments with oxaliplatin and other chemotherapeutic agents exert superior therapeutic effects. However, side effects and drug resistance limited their further clinical application. Here, we found that combined treatment with regorafenib and oxaliplatin synergistically enhanced anti-tumor activities in CRC by activating reactive oxygen species (ROS) mediated endoplasmic reticulum (ER) stress, C-Jun-amino-terminal kinase (JNK) and p38 signaling pathways. Regorafenib promoted ROS production by suppressing the expression of selenoprotein S (SELENOS). Knocking down SELENOS sensitized ROS-mediated anti-tumor effects of regorafenib in CRC cells. Furthermore, mouse xenograft models demonstrated that synergistic anti-tumor effects of combined treatment with regorafenib and oxaliplatin. This study provided solid experimental evidences for the combined treatment with regorafenib and oxaliplatin in CRC.

The advance anticancer role of polymeric core-shell ZnO nanoparticles containing oxaliplatin in colorectal cancer.

We evaluated the activity of core-shell ZnO nanoparticles (ZnO-NPs@polymer shell) containing Oxaliplatin via polymerization through in vitro studies and in vivo mouse models of colorectal cancer. ZnO NPs were synthesized in situ when the polymerization step was completed by co-precipitation. Gadolinium coordinated-ZnONPs@polymer shell (ZnO-Gd NPs@polymer shell) was synthesized by exploiting Gd's oxophilicity (III). The biophysical properties of the NPs were studied using powder X-ray diffraction (PXRD), Fourier transforms infrared spectroscopy, Ultraviolet-visible spectroscopy (UV-Vis), field emission electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy, dynamic light scattering, and z-potential. (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) was used to determine the antiproliferative activity of ZnO-Gd-OXA. Moreover, a xenograft mouse model of colon cancer was exerted to survey its antitumor activity and effect on tumor growth. In the following, the model was also evaluated by histological staining (H-E; Hematoxylin & Eosin and trichrome staining) and gene expression analyses through the application of RT-PCR/ELISA, which included biochemical evaluation (MDA, thiols, SOD, CAT). The formation of ZnO NPs, which contained a crystallite size of 16.8 nm, was confirmed by the outcomes of the PXRD analysis. The Plate-like morphology and presence of Pt were obtained in EDX outcomes. TEM analysis displayed the attained ZnO NPs in a spherical shape and a diameter of 33 ± 8.5 nm, while the hydrodynamic sizes indicated that the particles were highly aggregated. The biological results demonstrated that ZnO-Gd-OXA inhibited tumor growth by inducing reactive oxygen species and inhibiting fibrosis, warranting further research on this novel colorectalcancer treatment agent.

Enhanced De Novo Lipid Synthesis Mediated by FASN Induces Chemoresistance in Colorectal Cancer.

Oxaliplatin is one of the most widely used chemotherapy drugs for colorectal cancer (CRC). Resistance to oxaliplatin threatens the prognosis of CRC. Since previous studies have aroused interest in fatty acid metabolism in cancer, in this study, we determined whether fatty acid biosynthesis and the related regulating mechanism contribute to oxaliplatin resistance in CRC. The effect of the fatty acid synthase (FASN) and its inhibitor Orlistat was characterized in Gene Expression Omnibus (GEO) databases, oxaliplatin-resistant cell lines, and xenografts. MRNA-seq and analysis identified related pathway changes after the application of Orlistat, which was verified by Western blotting. By leveraging the GEO databases, FASN and closely related gene signatures were identified as being correlated with the response to oxaliplatin-based chemotherapy and poor prognosis. Additionally, FASN-upregulated expression promoted oxaliplatin resistance in CRC cell lines. We then applied Orlistat, a typical FASN inhibitor, in cell culture and xenograft models of oxaliplatin-resistant CRC, which attenuated the resistance to oxaliplatin. Additionally, the combination of the FASN inhibitor and oxaliplatin significantly increased cell cycle arrest and facilitated apoptosis, partly due to the diminished phosphorylation of the MAPK/ERK and PI3K/AKT pathways. In vivo studies showed that inhibiting fatty acid biosynthesis with Orlistat restrained the growth of xenograft tumors and increased the responsiveness to oxaliplatin. Our study revealed that FASN enhanced resistance to oxaliplatin in CRC. The inhibition of FASN could rescue the response to oxaliplatin by regulating MAPK/ERK and PI3K/AKT pathways.

The SLC22A2 gene is a determinant of hematological toxicity of oxaliplatin in patients with colorectal cancer.

To investigate the association between polymorphisms in the SLC22A2 gene and the hematological toxicity of oxaliplatin in colorectal cancer (CRC) patients receiving chemotherapy. A total of 81 patients with colon or rectal cancer were included in the study. The single nucleotide polymorphisms (SNPs) rs3127573, rs316019, and rs1869641 of the SLC22A2 gene were selected for genotyping using the polymerase chain reaction (PCR) and sequence analysis. Oxaliplatin-associated hematological toxicities were evaluated using the Common Toxicity Criteria for Adverse Events (CTCAE, Version 5.0). The rs1869641 genotype was significantly associated with the occurrence of thrombocytopenia (p = 0.047), whereas the rs316019 genotype was significantly associated with severity of leucopenia and neutropenia (p = 0.004 and 0.001, respectively). The rs3127573 genotype was not associated with hematological toxicities arising during chemotherapy with oxaliplatin. It is shown here, for the first time, that the rs316019 gene variant of the SLC22A2 gene may be associated with the hematological toxicity of oxaliplatin. Patients with genotype CA/AA of rs316019 are more likely to develop serious hematological adverse effects.

Exploring assessment of balance using virtual reality in patients at risk of chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting toxicity for people treated for cancer. Impaired balance and falls are functional consequences of CIPN. Virtual reality (VR) technology may be able to assess balance and identify patients at risk of falls. To assess the impact of potentially neurotoxic chemotherapy on balance using VR, and explore associations between VR balance assessment, falls and CIPN. This prospective, repeated measures longitudinal study was conducted at two Australian cancer centres. Eligible participants were commencing adjuvant chemotherapy containing a taxane for breast cancer, or oxaliplatin for colorectal cancer (CRC), per institutional guidelines. Balance assessments using VR were conducted at baseline, end of chemotherapy and 3 and 6 months after completion of chemotherapy. Participants also completed a comprehensive CIPN assessment comprising clinical and patient-reported outcomes, and recorded falls or near falls. Out of 34 participants consented, 24 (71%) had breast cancer and 10 (29%) had CRC. Compared to baseline, balance threshold was reduced in 10/28 (36%) evaluable participants assessed at the end of chemotherapy, and persistent in 7/22 (32%) at 6months. CIPN was identified in 86% at end of chemotherapy and persisted to 6months after chemotherapy completion in 73%. Falls or near falls were reported by 12/34 (35%) participants, and were associated with impaired VR balance threshold (P=0.002). While VR balance assessment was no better at identifying CIPN than existing measures, it is a potential surrogate method to assess patients at risk of falls from CIPN.

Low-dose orlistat promotes the therapeutic effect of oxaliplatin in colorectal cancer

The failure of and resistance to oxaliplatin (OXA)-based chemotherapies may lead to poor prognosis in colorectal cancer (CRC) patients. It has been reported that orlistat (Orli) exhibits potent antitumor effects in several malignant tumors. Here, we identified that OXA in combination with low-dose Orli could sensitize CRC cells to OXA and induce marked synergistic apoptosis in vitro and in vivo. The potential synergistic effects were confirmed and quantified by in silico analysis. Furthermore, we validated the synergistic anti-tumor effects in CRC PDX mice model. A qPCR array was performed to evaluate the changes in 85 apoptosis-related genes to elucidate the possible molecular mechanisms in combination-induced cytotoxicity. To conclude, the antitumor synergistic effects of OXA and Orli make them effective and promising candidates for cancer treatment.

Health Care Utilization and Anti-Cancer Drug Expenditure for Six Solid Cancers in Korea From 2007 to 2019.

BackgroundThe burden of care continues to rise considerably worldwide and the challenge of diversity in cancer research has become important. We aimed to examine trends of cancer care utilization and anti-cancer medication among patients with six solid cancers (gastric, colorectal, liver, lung, breast, and prostate cancer) in South Korea.MethodsThis study analyzed patients diagnosed with six types of solid cancer from 2007 to 2019 using data from the National Health Insurance claims database. We analyzed the total number of cancer cases, each patient’s length of stay (LOS) in a hospital, the number of outpatient physician visits, total medical care costs, total out-of-pocket (OOP) costs, and expenditures on anti-cancer drugs.ResultsUtilization of healthcare services and spending on cancer care including anti-cancer drugs both increased in the 13-year study period. The average LOS was the highest for colorectal cancer patients at 43.5 days, and breast cancer patients had the highest average number of physician visits at 11.8. Breast cancer patients had the highest total medical costs (USD 923 million), anti-cancer drug spending (USD 156 million), and the largest increase (5 times) over the 13-year period. The anti-cancer drugs with the largest market shares were ramucirumab for gastric cancer; oxaliplatin for colorectal cancer; sorafenib for liver cancer; pembrolizumab, nivolumab, for lung cancer; trastuzumab for breast cancer; and bicalutamide for prostate cancer.ConclusionThis study was a large-scale analysis from a nationally representative database of the total population. The study also shows the pattern of cancer care in an Asian country and can provide implications for future cancer research.

Network Pharmacology and Molecular Docking Analyses of the Synergistic Mechanism of Babao Dan and Oxaliplatin in Colorectal Cancer

<bold>Objective</bold> To further explore the mechanism of Babao Dan (BBD) combined with oxaliplatin (L-OHP) in treating colorectal cancer (CRC) through a network pharmacology analysis. <bold>Methods</bold> The analysis involved the following steps: screen the chemical components of BBD through literature review of Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), Chemistry Database, PubChem, and other databases; obtain L-OHP-related targets through GeneCards database; and search CRC-related targets through OMIM, GeneMap, TTD, DisGeNET, CTD, GeneCards, and other databases. After the intersection and mapping of drugs and disease, the protein-protein interaction (PPI) network and core targets were obtained using STRING database and CytoScape software. MetaScape database was used to analyze the core targets to obtain GO biological processes and KEGG pathways. <bold>Results</bold> BBD contained 495 chemical components with 204 active components screened out through the Swiss ADME database and 770 targets were obtained through the Swiss Target Prediction database. After the intersection of BBD and 775 targets of L-OHP with the CRC targets, it resulted in 74 potential targets. Twenty-four core targets were determined from the 74 intersection targets, which were related to the positive regulation of kinase activity, the positive regulation of cell migration, and peptidyl-serine modification in GO biological process. The KEGG pathway analysis showed that the core targets were related to pathway in cancer, proteoglycan in cancer, endocrine resistance, and microRNA in cancer, TNF signaling pathway, platinum resistance, and other pathways. Molecular docking showed that the core targets could bind to the most examined compounds. <bold>Conclusion</bold> Quercetin-7-olate, cyclo (L-tyrosyl-L-phenylalanyl), panaxadiol, and other compounds in BBD may play an anti-colorectal cancer effect in multiple pathways, including EGFR, AKT1, mTOR, and other targets in synergy with L-OHP.

Establishment of the menthol test as a clinical evaluation method for oxaliplatin-induced neuropathy.

To determine whether the tongue menthol test, which measures the cold sensation detection threshold (CDT) of the tongue, used before and after oxaliplatin administration is an objective evaluation method for oxaliplatin-induced peripheral neuropathy (OPN). The tongue menthol test was administered to patients both before and after undergoing chemotherapy containing oxaliplatin for colorectal cancer. The tongue menthol test was conducted by applying a menthol solution (a selective agonist of transient receptor potential cation channel subfamily M member 8 [TRPM8]) to the tongue and measuring the CDT. The mean CDT before the first dose of oxaliplatin was 0.34% (0.005%-1%; n=38), and the mean CDT after the first dose was 0.32% (0.005%-1%; n=38). The CDT appeared to decrease after the first dose, but this difference was not significant. In patients who received five courses of oxaliplatin, changes in CDT values were compared before and after the five courses. In patients with Neurotoxicity Criteria of Debiopharm (DEB-NTC) grade 2 neuropathy, the pre-oxaliplatin administration CDT was compared between before grade exacerbation and when exacerbation occurred, and was found to decline when grade exacerbation occurred. Moreover, when the CDTs before and after administration were compared before grade exacerbation, there was a significant decrease in CDT after administration (P=0.04). By performing a menthol test in oxaliplatin-treated patients, it may be possible to objectively predict the exacerbation of peripheral neuropathy at an early stage.

Inhibition of the PLK1-Coupled Cell Cycle Machinery Overcomes Resistance to Oxaliplatin in Colorectal Cancer.

Dysregulation of the cell cycle machinery leads to genomic instability and is a hallmark of cancer associated with chemoresistance and poor prognosis in colorectal cancer (CRC). Identifying and targeting aberrant cell cycle machinery is expected to improve current therapies for CRC patients. Here,upregulated polo‐like kinase 1 (PLK1) signaling, accompanied by deregulation of cell cycle‐related pathways in CRC is identified. It is shown that aberrant PLK1 signaling correlates with recurrence and poor prognosis in CRC patients. Genetic and pharmacological blockade of PLK1 significantly increases the sensitivity to oxaliplatin in vitro and in vivo. Mechanistically, transcriptomic profiling analysis reveals that cell cycle‐related pathways are activated by oxaliplatin treatment but suppressed by a PLK1 inhibitor. Cell division cycle 7 (CDC7) is further identified as a critical downstream effector of PLK1 signaling, which is transactivated via the PLK1‐MYC axis. Increased CDC7 expression is also found to be positively correlated with aberrant PLK1 signaling in CRC and is associated with poor prognosis. Moreover, a CDC7 inhibitor synergistically enhances the anti‐tumor effect of oxaliplatin in CRC models, demonstrating the potential utility of targeting the PLK1‐MYC‐CDC7 axis in the treatment of oxaliplatin‐based chemotherapy.

EVs delivery of miR-1915-3p improves the chemotherapeutic efficacy of oxaliplatin in colorectal cancer.

Oxaliplatin is a crucial component of the combinatorial chemotherapeutic standard of care for advanced colorectal cancer (CRC). Unfortunately, a serious barrier to effective oxaliplatin treatment is drug resistance due to epithelial-mesenchymal transitioning (EMT). Interestingly, stable oxaliplatin-resistant CRC cell lines show differential expression of miR-1915-3p; thus, this microRNA may represent a potential modifier of oxaliplatin resistance in CRC cells. miR-1915-3p was over-expressed in oxaliplatin-resistant CRC cells and a non-tumorigenic intestinal cell line (FHC) via lentiviral transduction. Extracellular vesicles (EVs) were purified from transduced FHC cells and co-incubated with CRC cells. Expression levels of miR-1915-3p and other RNA species were assessed by RT-qPCR, while protein expression levels were assessed by Western blotting. The effects of miR-1915-3p on CRC viability were evaluated by proliferation, apoptosis assays, and Transwell assays. Effects of miR-1915-3p over-expression on in vivo oxaliplatin sensitivity was tested via murine xenograft models. miRNA-1915-3p decreased EMT marker expression in oxaliplatin-resistant CRC cell lines and in vivo. FHC cells were able to produce and secrete miR-1915-3p-containingEVs, which we employed to mediate miR-1915-3p delivery to oxaliplatin-resistant CRC cells and increase their oxaliplatin sensitivity in vivo and in vitro. Mechanistically, miR-1915-3p overexpression downregulated the EMT-promoting oncogenes 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and ubiquitin carboxyl-terminal hydrolase 2 (USP2) as well as upregulated E-cadherin (a cell adhesionmediator). miR-1915-3p's effects on chemosensitivity and EMT were mediated by its regulation of PFKFB3 and USP2. Exosomal delivery of miR-1915-3p can improve the chemotherapeutic efficacy of oxaliplatin in CRC cells by suppressing the EMT-promoting oncogenes PFKFB3 and USP2.

Chemoresistance Mechanisms in Colon Cancer: Focus on Conventional Chemotherapy

Background: Colorectal cancer (CRC) is a widespread tumour type amongst men and women. Despite the available screening tests, advanced stage CRC is the most frequent diagnosis. It is treated with cytotoxic chemotherapeutics 5-fluorouracil (5-FU), oxaliplatin (Ox) and irinotecan (CPT-11) that eventually lose their effectiveness as chemoresistance develops. Methods: In this review, the compilation and analysis of PUBMED-retrieved literature data was comprehensively presented and some novel and/or previously poorly described molecular features of CRC unresponsiveness to conventional chemotherapy drugs identified using bioinformatics approach. Complex interactions between previously reported biomarkers of resistance to 5-FU, Ox and CPT-11 were analysed by STRING and cytoHubba accompanied by KEGG pathway enrichment analysis using DAVID functional annotation tool. Results: The bioinformatics analysis has revealed that 5-FU affects ribosome biogenesis and functioning (translational activity), leading to colon cancer cells resistance to 5-FU. Unresponsiveness of CRC to Ox was associated with Rap1 signalling pathway, which opens the possibility of using RAP1A inhibitors as an adjuvant to oxaliplatin in CRC. Furthermore, stem cell markers c-Myc and CD44 as well as Akt kinase emerged as novel resistance biomarkers whose pharmacological targeting could elevate the therapeutic efficacy of irinotecan. Lastly, several pathways common to the resistance to all three drugs were revealed, including miRNAs in cancer, proteoglycans in cancer, cellular senescence and the sphingolipid signalling pathway. Conclusion: This paper gives a comprehensive overview of resistance mechanisms to 5-FU, Ox and irinotecan in colon cancer and reveals several novel molecular players and associated mechanisms that could account for the development of chemoresistance and whose targeting might enable the design of novel combination strategies to overcome resistance to conventional treatment in CRC.

UPF1 promotes chemoresistance to oxaliplatin through regulation of TOP2A activity and maintenance of stemness in colorectal cancer

UPF1 is proved to dysregulate in multiple tumors and influence carcinogenesis. However, the role of UPF1 in oxaliplatin resistance in colorectal cancer (CRC) remains unknown. In our study, UPF1 is upregulated in CRC in mRNA and protein levels and overexpression of UPF1 predicts a poor overall survival (OS) and recurrence-free survival (RFS) in CRC patients and is an independent risk factor for recurrence. UPF1 promotes chemoresistance to oxaliplatin in vitro and in vivo. UPF1-induced oxaliplatin resistance can be associated with interaction between zinc finger of UPF1 and Toprim of TOP2A and increasing phosphorylated TOP2A in a SMG1-dependent manner. Moreover, UPF1 maintains stemness in a TOP2A-dependent manner in CRC. Taken together, UPF1 was overexpressed and predicted a poor prognosis in CRC. UPF1 enhanced chemoresistance to oxaliplatin in CRC, which may result from regulation of TOP2A activity and maintenance of stemness. Our findings could provide a new therapy strategy for chemoresistance to oxaliplatin in CRC patients.

Predictive value of clinical toxicities of chemotherapy with fluoropyrimidines and oxaliplatin in colorectal cancer by DPYD and GSTP1 gene polymorphisms

BackgroundFluoropyrimidines and platinum are still widely used for colorectal cancer (CRC) management. Several studies have reported that mutations of dihydropyrimidine dehydrogenase (DPYD) and glutathione S-transferase pi-1 (GSTP1) polymorphisms are related to chemotherapy-related adverse events. In the present study, we purposed to assess the impact of DPYD and GSTP1 variants on the toxicity of adjuvant chemotherapy risk among the Hakka population, minimize adverse events, and to maximize therapy outcome for individualized treatment.MethodsGenotyping was examined in 104 patients diagnosed with CRC cases and receiving fluoropyrimidine and platinum drug-based chemotherapy regimen by direct sequencing of DPYD and GSTP1 polymorphisms. Three DPYD variants including *2A, *5A, *9A, and GSTP1 c.313A>G were analyzed and clinical outcomes were assessed.ResultsThe data suggest that the incidence of DPYD*5A, DPYD*9A, and GSTP1 c.313A>G variants were 38.4%, 24%, and 32.7%, respectively. DPYD*2A variant was not found. A total of 23 patients (22.1%) suffered severe vomiting and 19 patients (18.3%) suffered severe anemia. DPYD*5A polymorphism was found significantly associated with grade 3/4 ulceration (p = 0.001). GSTP1 was determined to be an independent risk factor for severe vomiting and skin ulceration (p = 0.042 and p = 0.018, respectively). Patients with GSTP1 c. 313A>G mutant type contributed to a higher risk for grade severe toxicity compared with wild genotype (p = 0.027). Nevertheless, no significant difference was found between patients with DPYD*2A, *5A, and *9A for chemotherapeutic toxicity.ConclusionsThe results demonstrated that GSTP1 polymorphisms were useful predictors of severe events. Screening of single-nucleotide polymorphisms of GSTP1 in colorectal cancer patients before chemotherapy may help to realize personalized therapy.

Exosomal transfer of circular RNA FBXW7 ameliorates the chemoresistance to oxaliplatin in colorectal cancer by sponging miR-18b-5p.

Circular RNA F-box and WD repeat domain containing 7 (circ-FBXW7) has been revealed to be involved in the tumorigenesis of colorectal cancer (CRC). Exosomes are critical mediators of intercellular communication. However, the role of exosomal circ-FBXW7 in the CRC oxaliplatin resistance remains unknown. Cell viability, apoptosis, motility, and drug efflux were measured by the cell counting kit-8 assay, flow cytometry, transwell assay, and atomic absorption spectrophotometry, respectively. The expression of circ-FBXW7 and microRNA (miR)-18b-5p was detected using the quantitative real-time polymerase chain reaction. Western blot was used to determine multidrug resistance protein 1 (MRP1), myeloid cell leukemia-1 (MCL-1), CD9, CD63, Caspase3, E-cadherin, and N-cadherin. Exosomes were isolated and captured using the ultracentrifugation method and transmission electron microscopy. The interaction between circ-FBXW7 and miR-18b-5p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. In vivo experiments were conducted using the murine xenograft model. Our results showed that circ-FBXW7 was decreased in oxaliplatin-resistant CRC patients and cells. circ-FBXW7 was secreted by circ-FBXW7-transfected FHC cells and could be transferred to resistant CRC cells through the exosome secretion. Subsequently, in vitro and in vivo studies demonstrated exosomal circ-FBXW7 led resistant cells sensitive to oxaliplatin, increased the oxaliplatin-induced apoptosis, inhibited oxaliplatin-induced epithelial-mesenchymal transition, and suppressed oxaliplatin efflux. miR-18b-5p was increased in oxaliplatin-resistant CRC patients and cells and was confirmed to be a target of circ-FBXW7. Immediately, the rescue assay showed exosome-mediated transfer of circ-FBXW7 enhanced oxaliplatin sensitivity by binding to miR-18b-5p in vitro and in vivo. To conclude, the circ-FBXW7 delivery by exosomes could ameliorate chemoresistance to oxaliplatin in CRC by directly binding to miR-128-3p, suggesting a promising therapeutic strategy for oxaliplatin-resistant CRC patients.

101P HIF1-α depletion overcomes resistance to oxaliplatin in colorectal cancer via ERK signalling pathway

Chemoresistance is a major reason for treatment failure and results in poor prognosis in patients with advanced colorectal cancer (CRC). Hypoxia-inducible factor-1 (HIF1-α) is a regulator of the transcriptional response to oxygen deprivation in cancer cells and activates the transcription of genes that are involved in angiogenesis, cell survival and invasion. However, the effect of HIF1-α activation on oxaliplatin resistance in CRC is unclear. This study aimed to investigate the effects and potential mechanism of HIF1-α on oxaliplatin resistance in CRC. Oxaliplatin-resistant cells were generated from HCT116 cells. Cell Counting Kit-8, flow cytometry, Transwell assay were used to compare the characteristics of oxaliplatin resistant HCT116 (HCT116_OxR) cells and the corresponding parental HCT116 cells. The expression of HIF1-α, extracellular signal-related kinase (ERK), and transforming growth factor β (TGFβ) were confirmed by RT-PCR and western blotting in HCT116_OxR and HCT116 cells. Next, we evaluated the combination efficacy of inhibitors of HIF1-α (YC-1), ERK (Ravoxertinib), and TGFβ1 (SB431542) with oxaliplatin by in vitro and in vivo experiments. We found that cell viability of HCT116_OxR was higher than that in parental cells in the presence of oxaliplatin. The relative expression of HIF1-α was significantly increased in HCT116_OxR cells compared with the parental HCT116 cells. Downregulation of HIF1-α in HCT116_OxR cells increased oxaliplatin sensitivity, and diminished cell survival and invasion. Significantly, ERK signaling in HCT116_OxR cells is dependent on TGFβ1, promoting oxaliplatin resistance by activating HIF1-α. Inhibition of ERK by Ravoxertinib or TGFβ1 by SB431542 efficiently overcame oxaliplatin resistance in vitro and in vivo. HIF1-α activation is regulated by TGFβ1/ERK axis in HCT116_OxR cells. Hence, HIF1-α, ERK, and TGFβ1 are potential therapeutic targets for overcoming oxaliplatin resistance in patients with CRC.

Thioredoxin domain-containing protein 9 (TXNDC9) contributes to oxaliplatin resistance through regulation of autophagy-apoptosis in colorectal adenocarcinoma

Colorectal cancer (CRC) is the third most commonly malignancy worldwide. The incidence of CRC is on the rise and leads to indisputable society burden due to the high cost of cancer treatments. Resistance to oxaliplatin-chemotherapy is the major cause for treatment failure and CRC-related death. In this study, we anticipated that TXNDC9 might demonstrate a protective role in oxaliplatin-resistant CRC cells. TXNDC9 was found significantly upregulated when treated with oxaliplatin. Manipulation of TXNDC9 expression largely affected the oxaliplatin-induced cell death. Moreover, TXNDC9 regulates autophagy and apoptosis in response to oxaliplatin treatment in HT29 cells via the Nrf2 pathway. Taken together, our findings explore the biological role of TXNDC9 in oxaliplatin resistance in CRC cells and may identify a novel therapeutic target to counteract drug resistance to oxaliplatin in CRC.

A role for ceramide glycosylation in resistance to oxaliplatin in colorectal cancer

There is growing evidence to support a role for the ceramide-metabolizing enzyme, glucosylceramide synthase (GCS), in resistance to a variety of chemotherapeutic agents. Whether GCS contributes to oxaliplatin resistance in colorectal cancer (CRC) has not yet been determined. We have addressed this potentially important clinical issue by examining GCS function in two panels of oxaliplatin-resistant, isogenic CRC cell lines. Compared to parental cell lines, oxaliplatin-resistant cells have increased expression of GCS protein associated with increased levels of the pro-survival ceramide metabolite, glucosylceramide (GlcCer). Inhibition of GCS expression by RNAi-mediated gene knockdown resulted in a reduction in cellular GlcCer levels, with restored sensitivity to oxaliplatin. Furthermore, oxaliplatin-resistant CRC cells displayed lower ceramide levels both basally and after treatment with oxaliplatin, compared to parental cells. GlcCer, formed by GCS-mediated ceramide glycosylation, is the precursor to a complex array of glycosphingolipids. Differences in cellular levels and species of gangliosides, a family of glycosphingolipids, were also seen between parental and oxaliplatin-resistant CRC cells. Increased Akt activation was also observed in oxaliplatin-resistant CRC cell lines, together with increased expression of the anti-apoptotic protein survivin. Finally, this study shows that GCS protein levels are greatly increased in human CRC specimens, compared to matched, normal colonic mucosa, and that high levels of UGCG gene expression are significantly associated with decreased disease-free survival in colorectal cancer patients. These findings uncover an important cellular role for GCS in oxaliplatin chemosensitivity and may provide a novel cellular target for augmenting chemotherapeutic drug effectiveness in CRC.