Cytotoxicity Of Oxaliplatin Research Articles

Tubeimoside-I, an inhibitor of HSPD1, enhances cytotoxicity of oxaliplatin by activating ER stress and MAPK signaling pathways in colorectal cancer

Ethnopharmacological relevanceTubeimoside-I (TBM) promotes various cancer cell death by increasing the reactive oxygen species (ROS) production. However, the specific molecular mechanisms of TBM and its impact on oxaliplatin-mediated anti-CRC activity are not yet fully understood. Aim of the studyTo elucidate the therapeutic effect and underlying molecular mechanism of TBM on oxaliplatin-mediated anti-CRC activity. Materials and methods3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, wound healing assays and flow cytometry were conducted to investigate the changes in cell phenotypes and ROS generation. Real-time quantitative PCR (qRT-PCR) and western blotting were performed to detect the expressions of related mRNA and proteins. Finally, mouse xenograft models demonstrated that synergistic anti-tumor effects of combined treatment with TBM and oxaliplatin. ResultsThe synergistic enhancement of the anti-tumor effects of oxaliplatin in colon cancer cells by TBM involved in the regulation of ROS-mediated endoplasmic reticulum (ER) stress, C-jun-amino-terminal kinase (JNK), and p38 MAPK signaling pathways. Mechanistically, TBM increased ROS generation in colon cancer cells by inhibiting heat shock protein 60 (HSPD1) expression. Knocking down HSPD1 increased TBM-induced antitumor activity and ROS generation in colon cancer cells. The mouse xenograft tumor models further validated that the combination therapy exhibited stronger anti-tumor effects than monotherapy alone. ConclusionsCombined therapy with TBM and oxaliplatin might be an effective therapeutic strategy for some CRC patients.

Tumor-Targeted Oxaliplatin(IV) Prodrug Delivery Based on ROS-Regulated Cancer-Selective Glycan Labeling.

Platinum-drug-based chemotherapy in clinics has achieved great success in clinical malignancy therapy. However, unpredictable off-target toxicity and the resulting severe side effects in the treatment are still unsolved problems. Although metabolic glycan labeling-mediated tumor-targeted therapy has been widely reported, less selective metabolic labeling in vivo limited its wide application. Herein, a novel probe of B-Ac3ManNAz that is regulated by reactive oxygen species in tumor cells is introduced to enhance the recognition and cytotoxicity of DBCO-modified oxaliplatin(IV) via bioorthogonal chemistry. B-Ac3ManNAz was synthesized from Ac4ManNAz by incorporation with 4-(hydroxymethyl) benzeneboronic acid pinacol ester (HBAPE) at the anomeric position, which is confirmed to be regulated by ROS and could robustly label glycans on the cell surface. Moreover, N3-treated tumor cells could enhance the tumor accumulation of DBCO-modified oxaliplatin(IV) via click chemistry meanwhile reduce the off-target distribution in normal tissue. Our strategy provides an effective metabolic precursor for tumor-specific labeling and targeted cancer therapies.

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.

The potential therapeutic effect of melatonin in oxaliplatin combination therapy against chemoresistant colorectal cancer cells.

Oxaliplatin is one of the main therapeutics in colorectal cancer (CRC) chemotherapy. However, in light of multidrug resistance (MDR) phenotype development, the efficacy of oxaliplatin has decreased. This study aimed to assess the potential therapeutic effect of melatonin in oxaliplatin combination therapy for drug-resistant colorectal cancer cells. Initially, the oxaliplatin-resistant cell line was created of LS174T (LS174T/DR) by using the oxaliplatin IC50 concentration and resting cycles. MTT assays and flow cytometry were applied for assessing cell viability and apoptotic cells. The mRNA expression level of Bax, Bcl2, MT1, MT2, and ABCB1 as well as protein levels of ABCB1, Bcl2, BAX were measured by the qRT-PCR and western blot techniques respectively. P-gp activity was assessed by Rho123 staining. The IC50 concentration of oxaliplatin in resistant cells was increased from 500.7 ± 0.2 nM to 7119 ± 0.1 nM. Bcl2, MT1, MT2, and ABCB1 mRNA plus protein expression levels of Bcl2 and ABCB1 were significantly reduced in resistant cells, along with a marked increase in Bax mRNA and protein levels compared to parental cells. Rho 123 staining revealed a marked reduction in P-gp activities in the combination-treated group compared to the oxaliplatin-treated group. The results of cytotoxicity assays, MTT, and flow cytometry revealed that the combination of melatonin and oxaliplatin exerts synergistic effects on induction of oxaliplatin's cytotoxicity in CRC. Our research suggests that combining the treatments of melatonin and oxaliplatin may be considered as a new approach to overcoming oxaliplatin resistance in CRC patients.

Oxaliplatin regulates the autophagy of skin squamous cell carcinoma cell line through HMGB1 pathway

Purpose: To determine the influence of oxaliplatin on skin squamous cell carcinoma cell line, and the involvement of autophagy- regulating pathway of high mobility group box 1 (HMGB1) in the process.
 Methods: A431 cells cultured in vitro were used. The cells were divided into groups A (treated with different concentrations of oxaliplatin) and B (treated with different concentrations of oxaliplatin combined with autophagy inhibitor 5 mmol/l3-ma). Changes in expression levels of autophagy marker molecules LC3-Ⅰ, LC3-Ⅱ, p62 and HMGB1 in A431 cells treated with different concentrations of oxaliplatin and different concentrations of HMGB1 were evaluated by Western blotting. Viability of A431 cells in both groups was assessed by CCK-8 assay.
 Results: With increase in oxaliplatin concentration, LC3-Ⅱ levels in A431 cells were up-regulated, p62 expression decreased, while autophagy level was increased significantly (p < 0.05). With increase in HMGB1 protein concentration, LC3-Ⅱ level in A431 cells was raised, while p62 level was reduced, while the level of autophagy was significantly increased (p < 0.05). Oxaliplatin treatment led to significantly higher expression level of HMGB1 in the experimental group than in the control group without oxaliplatin treatment. The viability of oxaliplatin-treated group was dose-dependently and significantly lower (p < 0.05) than that of the control group. Compared with the control group, the cell viability of the 3-mA + oxaliplatin group also showed a downward trend, and the decrease was greater than that of oxaliplatin-treated group (p < 0.05).
 Conclusion: Oxaliplatin upregulates autophagy by promoting HMGB1 protein expression, which may be a protective mechanism of tumor cells against oxaliplatin cytotoxicity thereby making HMGB1 protein a potential target in skin cancer therapy.

Efficient in vitro oxaliplatin delivery with functionalized single-walled carbon nanotube for enhanced colon cancer treatment

BackgroundSite-specific transport of medicinal products to malignant cells and tissues is an intriguing area since it has an ability to safeguard healthy cells. Selective upregulation of folate receptors on colon cancer cells is usual. Consequently, folate receptors have become one of extensively studied target moieties for targeting the delivery of chemotherapeutics. Hence, the study aimed to anchor folic acid, chitosan and oxaliplatin to the functionalized nanotube (FA-CHI-FSWCNT-OXA) for targeting folate receptors on colon cancer cells. The purification process of single-walled carbon nanotubes (SWCNTs) involved the use of an ultrasonic-assisted acid digestion method. The developed complex was evaluated using FTIR, DSC, SEM, XRD and in vitro dissolution studies. SRB and MTT assays were used to assess in vitro cytotoxicity of oxaliplatin and FA-CHI-FSWCNT-OXA) against HT29 and COLO320DM cell lines. Further, progression of apoptosis in cells was investigated using flow cytometry.ResultsThe FTIR results corroborated drug attachment over carbon nanotube (CNT), whereas the TEM results validated the nanosizing (1–300 nm) of the developed system. Drug entrapment in CNT was found to be 93.43 ± 1.65%, and in vitro drug release was found to be 94.73 ± 0.90% after 24 h. The complex reduced viability of 92.35 ± 0.942% cells than oxaliplatin’s 66.58 ± 0.38% inhibition, revealed by MTT assay. In the SRB assay, the developed system showed 91.22 ± 0.90% inhibition, whereas oxaliplatin showed 76.69 ± 0.52% inhibition against HT29 cells.ConclusionsConclusively, the developed system exhibited better cytotoxicity effects as compared with plain oxaliplatin. Our findings are suggestive of the potential development of CNT-anchored antineoplastic agents for target-specific delivery.

β-Caryophyllene Inhibits Oxaliplatin-Induced Peripheral Neuropathy in Mice: Role of Cannabinoid Type 2 Receptors, Oxidative Stress and Neuroinflammation.

Peripheral neuropathy is an important adverse effect caused by some chemotherapeutic agents, including oxaliplatin (OXA). OXA-induced peripheral neuropathy (OIPN) is a challenging condition due to diagnostic complexities and a lack of effective treatment. In this study, we investigated the antiallodynic effect of β-caryophyllene (BCP), a cannabinoid type 2 (CB2) receptor agonist, in a mouse model of OIPN. BCP treatment inhibited OXA-induced mechanical and cold allodynia in both preventive and therapeutic drug treatment regimens. Experiments with the CB2 receptor agonist GW405833 confirmed the role of CB2 receptors in OIPN. The CB2 antagonist SR144528 abrogated the anti-nociceptive effect of BCP on mechanical allodynia, without impacting OXA-induced sensitivity to cold. BCP decreased neuroinflammation, as inferred from TNF, IL-1β, IL-6, and IL-10 profiling, and also reduced ROS production, lipid peroxidation, and 4-hydroxynonenal protein adduct formation in the spinal cords of OXA-treated mice. BCP did not affect the antitumor response to OXA or its impact on blood cell counts, implying that the cytotoxicity of OXA was preserved. These results underscore BCP as a candidate drug for OIPN treatment via CB2 receptor-dependent mechanisms, and anti-inflammatory and antioxidant responses in the spinal cord.

Characterization of Chitosan-Hybridized Diatomite as Potential Delivery Systems of Oxaliplatin and 5-Fluorouracil Drugs: Equilibrium and Release Kinetics.

The current work involves the modification of diatomite's biosiliceous frustules employing chitosan polymer chains (CS/Di) to serve as low-cost, biocompatible, multifunctional, and enhanced pharmaceutical delivery systems for 5-fluorouracil (5-Fu) together with oxaliplatin (OXPL). The CS/Di carrier displayed strong loading characteristics, notably at saturation (249.17 mg/g (OXPL) and 267.6 mg/g (5-Fu)), demonstrating a substantial 5-Fu affinity. The loading of the two types of medications onto CS/Di was conducted based on the kinetic behaviors of the conventional pseudo-first-order theory (R2 > 0.90). However, while the loading of OXPL follows the isotherm assumptions of the classic Langmuir model (R2 = 0.99), the loading of 5-Fu displays Fruendlich isotherm properties. Therefore, the 5-Fu loading displayed physical, heterogeneous, and multilayer loading properties, whereas the loading of OXPL occurred in homogeneous and monolayer form. The densities of occupied active sites of CS/Di were 37.19 and 32.8 mg/g for the sequestrations of OXPL and 5-Fu, respectively. Furthermore, by means of multimolecular processes, each loading site of CS/Di can bind up to 8 molecules of OXPL and 9 molecules of 5-Fu in a vertical orientation. This observation explains the higher loading capacities of 5-Fu in comparison to OXPL. The loading energies, which exhibit values <40 kJ/mol, provide confirmation of the dominant and significant consequences of physical processes as the regulating mechanisms. The release patterns of OXPL and 5-Fu demonstrate prolonged features over a duration of up to 120 h. The release kinetic simulation and diffusion exponents which are more than 0.45 provide evidence of the release of OXP and 5-Fu via non-Fickian transportation characteristics and the erosion/diffusion mechanism. The CS/Di carrier exhibited a substantial enhancement in the cytotoxicity of OXPL and 5-Fu against HCT-116 carcinoma cell lines, resulting in a reduction in cell viability by 4.61 and 2.26% respectively.

Synergistic Effect of Caffeine in B16f10 Cells in Combination with Doxorubicin and Oxaliplatin

Caffeine is a commonly consumed psychoactive substance that has been shown to have various effects on cellular processes, including cell growth and survival. In this study, we investigated the potential of Caffeine to enhance the cytotoxic effects of two commonly used chemotherapeutic agents, doxorubicin and oxaliplatin, on B16F10 cells. We evaluated the cytotoxicity, calculated the IC50 and combination index of the medications, estimated the cell cycle of the cells, and evaluated the apoptotic and anti-apoptotic genes through gene expression analysis. Our results demonstrated that Caffeine significantly potentiated the cytotoxicity of both doxorubicin and oxaliplatin, resulting in a more significant reduction in cell viability compared to treatment with the chemotherapeutic agents alone. Additionally, Caffeine also enhanced the pro-apoptotic effects of the chemotherapeutic agents, leading to increased levels of apoptosis in the B16F10 cells. The combination of doxorubicin and oxaliplatin with Caffeine was found to be synergistic. These findings suggest that caffeine may have the potential to improve the efficacy of current chemotherapeutic regimens and may offer a novel approach to enhance cancer treatment.

Abstract 420: Dicer-dependent of ERK activation promotes the acquired oxaliplatin resistance in colorectal cancer

Abstract Introduction: Chemoresistance is one of the major challenges for cancer therapy. Oxaliplatin is the first-line therapy for most cancers, including colorectal cancer (CRC). However, the underlying mechanisms of oxaliplatin resistance remain elusive. Previous reports indicated that microRNAs might regulate the development of CRC. Dicer, an endonuclease involved in miRNA biogenesis, may play a critical role in oxaliplatin resistance. Here, we investigated the mechanism of Dicer-mediated oxaliplatin resistance in CRC. Materials and Methods: Oxaliplatin-resistant CRC cells were established. Colony formation, migration, invasion, and sphere formation assays were performed to characterize the properties of oxaliplatin-resistant CRC cells. cDNA microarray and NGS were used to identify the altered expression of mRNAs and miRNAs in oxaliplatin-resistant cells. RT-qPCR determined gene expression. A connectivity map (CMAP) database was used to find the potential drugs which can reduce cell viability in oxaliplatin-resistant cells. CCK-8 assay was used to measure the anti-tumor effect of those potential drugs in oxaliplatin-resistant CRC cells. PANTHER was used to find the potential pathways that may involve drug resistance in CRC. Both reporter assay and western blot analyzed the activation of the Wnt/β-catenin and MAPK signaling pathways. Results: Dicer is overexpressed in oxaliplatin-resistant CRC cells and CRC recurrent patients. Overexpressed Dicer attenuated the cytotoxicity of oxaliplatin and promoted the cell migration, invasion, and stem cell properties of the oxaliplatin-resistant cells. Knocked-down of Dicer restored the chemosensitivity and decreased all of those abilities in oxaliplatin-resistant CRC cells. The expression of several potential mRNAs and microRNAs was changed in drug-resistant cells and chemo-resistant CRC patients' plasma. MAPK and Wnt/β-catenin pathways are hyper-activated in oxaliplatin-resistant CRC cells. PRI-724, a Wnt/β-catenin pathway inhibitor, can increase the cell apoptosis of oxaliplatin-resistant CRC cells. Trametinib, the MEK inhibitor, can induce cell apoptosis in oxaliplatin-resistant CRC cells and present an anti-tumor effect in oxaliplatin-resistant CRC cell-derived xenograft tumors. Knocked-down expression of Dicer did not affect the Wnt/β-catenin pathway but attenuated the ERK activation. A combination of oxaliplatin and trametinib can synergistically inhibit tumor growth and reverses oxaliplatin resistance in vitro and in vivo. Conclusion: Dicer might be an acquired factor contributing to cancer malignancies in oxaliplatin-resistant CRC cells via activating the ERK pathway. The activation of the MAPK signaling pathway is Dicer-dependent in oxaliplatin-resistant CRC cells. Wnt/β-catenin inhibitors and ERK inhibitors have an anti-tumor effect in oxaliplatin-resistant cells. Citation Format: Yu-Heng Kuan, Ming-Ern Wong, Liang-Yi Hung. Dicer-dependent of ERK activation promotes the acquired oxaliplatin resistance in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 420.

Dihydroartemisinin synergistically enhances the cytotoxic effects of oxaliplatin in colon cancer by targeting the PHB2-RCHY1 mediated signaling pathway.

Dihydroartemisinin (DHA) has recently attracted increasing attention for its low toxicity and high antitumor activity. DHA has been reported to have synergistic anticancer effects with a variety of drugs in the clinic; however, the molecular mechanism by which DHA inhibits tumorigenesis and improves oxaliplatin cytotoxicity in colon cancer cells is still not well understood. In this study, we found that DHA can inhibit cell proliferation and colony formation in a dose-dependent manner. Prohibitin 2 (PHB2) is a potential target by which DHA exerts its antitumor and cytotoxic effects. The function and molecular mechanism of PHB2 in colon cancer tumorigenesis were fully studied to determine the regulatory mechanism between DHA and PHB2. We found that PHB2, a mitochondrial inner membrane scaffold protein, has a higher expression level in colon cancer tissues than in adjacent nontumor tissues and is mainly localized in mitochondria. Overexpression of PHB2 can promote cell proliferation and colony formation in vitro and accelerate tumor growth in vivo. We also found that the expression level of PHB2 was inversely related to the cytotoxicity of DHA and oxaliplatin in colon cancer cells. The molecular mechanism of PHB2 in tumorigenesis and cancer therapy was further studied. The results showed that 20 μM DHA can downregulate PHB2 expression in a ubiquitylation-dependent manner and subsequently block PHB2-induced RCHY1 upregulation and p53 and p21 downregulation. In this process, RCHY1 is necessary for PHB2 to play a tumor-promoting role. Thus, PHB2 and RCHY1 are effective targets for colon cancer therapy, and DHA has synergistic anticancer effects with oxaliplatin via promoting PHB2 degradation in colon cancer cells.

Fermented Ginger Extract in Natural Deep Eutectic Solvent Enhances Cytotoxicity by Inhibiting NF-κB Mediated CXC Chemokine Receptor 4 Expression in Oxaliplatin-Resistant Human Colorectal Cancer Cells.

Ginger extracts have been shown to have health-promoting pharmacological activity and beneficial effects, including antioxidant and anticancer properties. The extraction of ginger by natural deep eutectic solvents (NaDES) has been shown to enhance bioactivity, but the cytotoxicity of NaDES extracts needs to be further determined. Signaling through the CXC chemokine receptor 4 (CXCR4) expressed on colorectal cancer (CRC) cells has a pivotal role in tumor cell chemosensitivity. Oxaliplatin is a third-generation platinum compound used as an effective chemotherapeutic drug for CRC treatment. However, whether ginger extract and oxaliplatin could induce a synergistic cytotoxic effect in oxaliplatin-resistant CRC cells through modulating CXCR4 expression is not known. In this study, oxaliplatin-resistant HCT-116 (HCT-116/R) cells were generated first. Ginger was extracted using the NaDES mixture betaine/lactate/water (1:2:2.5). Lactobacillus reuteri fermentation of NaDES-ginger extract increased the total polyphenol content (12.42 mg gallic acid/g in non-fermented NaDES-ginger extract and 23.66 mg gallic acid/g in fermented NaDES-ginger extract). It also increased the antioxidant activity by about 20–30% compared to non-fermented NaDES-ginger extract. In addition, it achieved low cytotoxicity to normal colonic mucosal cells and enhanced the anticancer effect on HCT-116/R cells. On the other hand, the inhibition of NF-κB activation by fermented NaDES-ginger extract significantly decreased the CXCR4 expression (p < 0.05) in HCT-116/R cells. The inactivation of NF-κB by pharmacological inhibitor pyrrolidine dithiocarbamate further enhanced the fermented NaDES-ginger extract-reduced CXCR4 expression levels (p < 0.05). Moreover, fermented NaDES-ginger extract could synergistically increase the cytotoxicity of oxaliplatin by inhibiting CXCR4 expression and inactivating NF-κB, resulting in HCT-116/R cell death. These findings demonstrate that fermented NaDES-ginger extract reduces the NF-kB-mediated activation of CXCR4 and enhances oxaliplatin-induced cytotoxicity in oxaliplatin-resistant CRC cells.

Blockage of Wnt/β-catenin Signaling Pathway in Colorectal Cancer Resistant Cells by Nitazoxanide Effects on Peptidylarginine Deiminases Expression.

Multidrug resistance (MDR) is a major cause of unsuccessful cancer treatment in which drugs are not effective. Therefore, it is necessary to identify the critical mechanisms of the development of MDR and target those with novel compounds. Accordingly, the current study is the first to investigate the combination effect and molecular mechanism of nitazoxanide (NTZ) and oxaliplatin (OXP) on LS174T/OXP-resistant cells. The effect of NTZ on OXP cytotoxicity in LS174T and LS174T/OXP cell lines was evaluated by MTT assay. Changes in expression levels of MDR1, MRP1, CTNNB1, peptidylarginine deiminase (PAD)2, and PAD4 genes and proteins were evaluated by RT-qPCR and western blotting methods, respectively. Lastly, the apoptosis assay was performed by flow cytometer. OXP resistant and sensitive cells were identified based on the IC50 values (11567 nM vs. 1745 nM, p<0.05 for 24 h treatment; and 5161 nM vs. 882 nM, p<0.05 for 48 h incubation). The combination of NTZ and OXP for 48 h led to a reduction in IC50 values in resistant cells (2154 nM, p<0.05). The effect of NTZ plus OXP significantly decreased the expression of MDR1 (p<0.001), MRP1 (p<0.05), and CTNNB1 (p<0.001), while PAD2 and PAD4 expression was significantly increased (p<0.001). This combination therapy enhanced the percentage of the sub-G1 population (apoptosed) compared to other groups. The results showed that NTZ leads to notable upregulation of PAD2 and PAD4, which can disrupt the Wnt/β-catenin signaling pathway and reverse the MDR by reducing MDR1 and MRP1 expression.

The structural maintenance of chromosomes 5 is a possible biomarker for individualized treatment of colorectal cancer.

Although the understanding of resistance to oxaliplatin (OXA) chemotherapy in colorectal cancer (CRC) has been sought for many years, drug tolerance remains a major challenge for cancer therapy. Revealing the molecular mechanism of OXA resistance could help to explain the poor prognosis of patients. Gene expression omnibus (GEO) database was searched, GSE83129, which contains RNA profiling in metastatic CRC patients treated first-line with OXA, was chosen for the following analysis. Differential expressed genes (DEGs) between the adenocarcinoma and adjacent_normal team, respectively, in the OXA responders and no-responders were analyzed. The Gene Ontology (GO) and hub genes in the protein-protein interaction (PPI) network were used for the molecular mechanism of OXA resistance. Tumor-related databases were used for the clinical relevance of the structural maintenance of chromosomes 5 (SMC5) in CRC. The in vitro assays were used to detect the molecular function of SMC5 in CRC cells. Quantitative real-time PCR (qRT-PCR) and western blot were used to detect the expression of the structural maintenance of chromosomes 5/6 (SMC5/6) complex components upon OXA and raltitrexed (RTX) treatment. CCK-8 was used to detect the cell viability of cells with different treatment. SMC5 was downregulated in CRC tissues of OXA no-response patients. Lower expression of SMC5 was correlated with a poor prognosis in CRC patients, improved this gene expression, inhibited the CRC cell growth and invasion in vitro. Furthermore, SMC5 was downregulated upon OXA treatment in CRC cells, while RTX would reverse its expression, and the combination of these two drugs restored the SMC5 level to the normal situation. Finally, RTX treatment enhanced the OXA cytotoxicity. SMC5 is a tumor suppressor, that low expression of this gene is benefit for the development of CRC. Combination treatment with RTX and OXA may be more suitable for those OXA no-responders with lower SMC5.

Comparative Study of Autophagy in Oxaliplatin-Sensitive and Resistant SNU-C5 Colon Cancer Cells.

Few studies have evaluated the role of autophagy in the development of oxaliplatin (OXT) resistance in colon cancer cells. In this study, we compared the role of autophagy between SNU-C5 colon cancer cells and OXT-resistant SNU-C5 (SNU-C5/OXTR) cells. At the same concentration of OXT, the cytotoxicity of OXT or apoptosis was significantly reduced in SNU-C5/OXTR cells compared with that in SNU-C5 cells. Compared with SNU-C5 cells, SNU-C5/OXTR cells exhibited low levels of autophagy. The expression level of important autophagy proteins, such as autophagy-related protein 5 (Atg5), beclin-1, Atg7, microtubule-associated proteins 1A/1B light chain 3B I (LC3-I), and LC3-II, was significantly lower in SNU-C5/OXTR cells than that in SNU-C5 cells. The expression level of the autophagy-essential protein p62 was also lower in SNU-C5/OXTR cells than in SNU-C5 cells. In SNU-C5/OXTR cells, the production of intracellular reactive oxygen species (ROS) was significantly higher than that in SNU-C5 cells, and treatment with the ROS scavenger N-acetylcysteine restored the reduced autophagy levels. Furthermore, the expression of antioxidant-related nuclear factor erythroid 2-related factor 2 transcription factor, heme oxygenase-1, and Cu/Zn superoxide dismutase were also significantly increased in SNU-C5/OXTR cells. These findings suggest that autophagy is significantly reduced in SNU-C5/OXTR cells compared with SNU-C5 cells, which may be related to the production of ROS in OXT-resistant cells.

Thymopentin-Mediated Inhibition of Cancer Stem Cell Stemness Enhances the Cytotoxic Effect of Oxaliplatin on Colon Cancer Cells.

Thymopentin (TP5) is an immunomodulatory pentapeptide that has been widely used in malignancy patients with immunodeficiency due to radiotherapy and chemotherapy. Here, we propose that TP5 directly inhibits the stemness of colon cancer cells HCT116 and therefore enhances the cytotoxicity of oxaliplatin (OXA) in HCT116 cells. In the absence of serum, TP5 was able to induce cancer stemness reduction in cultured HCT116 cells and significantly reduced stemness-related signals, such as the expression of surface molecular markers (CD133, CD44 and CD24) and stemness-related genes (ALDH1, SOX2, Oct-4 and Nanog), and resulted in altered Wnt/β-catenin signaling. Acetylcholine receptors (AchRs) are implicated in this process. OXA is a common chemotherapeutic agent with therapeutic effects in various cancers. Although TP5 had no direct effect on the proliferation of HCT116, this pentapeptide significantly increased the sensitivity of HCT116 to OXA, where the effect of TP5 on the stemness of colon cancer cells through stimulation of AchRs may contribute to this process. Our results provide a promising strategy for increasing the sensitivity of colon cancer cells to chemotherapeutic agents by incorporating immunomodulatory peptides.

Inhibition of the DSB repair protein RAD51 potentiates the cytotoxic efficacy of doxorubicin via promoting apoptosis-related death pathways

The anthracycline derivative doxorubicin (Doxo) induces DNA double-strand breaks (DSBs) by inhibition of DNA topoisomerase type II. Defective mismatch repair (MMR) contributes to Doxo resistance and has been reported for colon and mammary carcinomas. Here, we investigated the outcome of pharmacological inhibition of various DNA repair-related mechanisms on Doxo-induced cytotoxicity employing MMR-deficient HCT-116 colon carcinoma cells. Out of different inhibitors tested (i.e. HDACi, PARPi, MRE11i, RAD52i, RAD51i), we identified the RAD51-inhibitor B02 as the most powerful compound to synergistically increase Doxo-induced cytotoxicity. B02-mediated synergism rests on pleiotropic mechanisms, including pronounced G2/M arrest, damage to mitochondria and caspase-driven apoptosis. Of note, B02 also promotes the cytotoxicity of oxaliplatin and 5-fluoruracil (5-FU) in HCT-116cells and, furthermore, also increases Doxo-induced cytotoxicity in MMR-proficient colon and mammary carcinoma cells. Summarizing, pharmacological inhibition of RAD51 is suggested to synergistically increase the cytotoxic efficacy of various types of conventional anticancer drugs in different tumor entities. Hence, pre-clinical in vivo studies are preferable to determine the therapeutic window of B02 in a clinically oriented therapeutic regimen.

Preparation and in vitro evaluation of PEGylated liposomes as effective nanocarrier for delivery of oxaliplatin

The effectiveness of using PEGylated soy lecithin liposome in oxaliplatin (OXA) delivery was investigated. Liposomes were prepared from soy lecithin, cholesterol, and methoxy poly(ethylene glycol)-cholesterol by thin lipid film hydration. The obtained OXA-loaded PEGylated liposome was characterized as ~ 189 nm diameter spheroid-like vesicles, negative charge, and drug-loading efficiency of ~ 44%. The nanocarrier exhibited in vitro sustained release patterns with ~ 31% of the initial drug was released in 24 h. The colloidal systems showed excellent stability in terms of particle size, polydispersity index, and zeta potential when being stored for 30 days at 2–8 °C. Moreover, the in vitro cytotoxicity assays revealed that PEGylated liposomes could enhance the activity of OXA on human breast cancer cells MCF-7 and reduced the cytotoxicity of OXA on mouse fibroblast cells L929. These results indicated that OXA-loaded PEGylated liposome has great potential in antitumor treatment. PEGylated liposomes enhanced in vitro stability and oxaliplatin delivery >

MiR-325 Promotes Oxaliplatin-Induced Cytotoxicity Against Colorectal Cancer Through the HSPA12B/PI3K/AKT/Bcl-2 Pathway

Oxaliplatin is one of the most effective chemotherapeutic drugs used for the treatment of colorectal cancer (CRC). However, intervention that attenuates the resistance of oxaliplatin is still required in the treatment of CRC. To investigate the role of miR-325 in changing the oxaliplatin sensitivity to CRC cells. Expression of miR-325 in colorectal cancer tissues and cell lines was measured by using qRT-PCR analysis. Cytotoxicity of oxaliplatin to control or miR-325-overexpressed HT29 and SW480 cells was evaluated by CCK-8 assays. Luciferase reporter assay was used to confirm the regulation of miR-325 on HSPA12B. Flow cytometry was performed to detect the mitochondrial membrane potential and cell apoptosis. Expression of miR-325 was decreased in colorectal cancer tissues and cell lines. However, overexpression of miR-325 can decrease the 50% inhibiting concentration of oxaliplatin to colorectal cancer cell lines HT29 and SW480. Mechanically, we confirmed that miR-325 targeted HSPA12B in colorectal cancer. Therefore, overexpression of miR-325 inhibited the phosphorylation of PI3K and AKT and decreased the expression of Bcl-2 to promote the oxaliplatin-induced mitochondrial apoptosis in colorectal cancer. MiR-325 sensitizes the colorectal cancer cells to oxaliplatin-induced cytotoxicity through the HSPA12B/PI3K/AKT/Bcl-2 pathway.

Oral administration of Cystine and Theanine ameliorates oxaliplatin-induced chronic peripheral neuropathy in rodents

Oxaliplatin frequently causes severe peripheral neuropathy as a dose-limiting toxicity. However, this toxicity lacks a strategy for prevention. Cystine/Theanine is a supplement, which includes precursors for the biosynthesis of glutathione. In this study, we investigated the effects of Cystine/Theanine on oxaliplatin-induced peripheral neuropathy using an in vivo model. Repeated injection of oxaliplatin (4 mg/kg intraperitoneally twice a week for 2 weeks) caused mechanical allodynia, cold hyperalgesia and axonal degeneration of the sciatic nerve in rats. Mechanical allodynia and axonal degeneration, but not cold hyperalgesia, were ameliorated by daily co-administration of Cystine [200 mg/kg orally (p.o.)] and Theanine (80 mg/kg p.o.). Moreover, co-administration of Cystine and Theanine to rats significantly increased the glutathione level in the sciatic nerve compared with the oxaliplatin group. Furthermore, Cystine and Theanine did not attenuate the tumour cytotoxicity of oxaliplatin in C-26 tumour cell-bearing mice. These findings suggest that Cystine and Theanine may be beneficial for preventing oxaliplatin-induced peripheral neuropathy.