Mechanism of acquired 5FU resistance and strategy for overcoming 5FU resistance focusing on 5FU metabolism in colon cancer cell lines

Resistance to 5-fluorouracil: The molecular mechanisms of development in colon cancer cells

Colon cancer is a significant health problem worldwide as it is one of the most common and deadliest cancers. The standard approach for the treatment of colon cancer is 5-fluorouracil (5-FU) based chemotherapy, which is limited by the development of resistance to this drug. Therefore, our study aimed to establish 5-FU resistance in SW-480 and HT-29 colon cancer cells and to precisely determine the molecular mechanisms and biomarkers that contribute to its development, both after short-term exposure and in cells with already developed resistance (SW-480-5FUR and HT-29-5FUR). The expression of various molecules involved in the different mechanisms of resistance development was monitored at the gene (qPCR) and protein (immunocytochemistry) levels. Based on the obtained results, alterations in the 5-FU anabolic pathway, biotransformation, drug efflux, mismatch repair, and apoptosis process together contributed to the development of 5-FU resistance in SW-480 and HT-29 colon cancer cells. In addition, UMPS, ABCC1, ABCC5, and MLH1, as well as the disturbed ratio of pro-apoptotic BAX and anti-apoptotic BCL2, should be taken into consideration as potential targets for the discovery of 5-FU resistance-related biomarkers in colon cancer cells. We suggest that future investigations focus on further validation of these findings by additional in vitro and in vivo testing, which is a limitation of our study.

Metal-Organic Frameworks (MOFs): Classification, Synthesis, Modification, and Biomedical Applications

Metal-organic frameworks (MOFs) are a new variety of solid crystalline porous functional materials. As an extension of inorganic porous materials, it has made important progress in preparation and application. MOFs are widely used in various fields such as gas adsorption storage, drug delivery, sensing, and biological imaging due to their high specific surface area, porosity, adjustable pore size, abundant active sites, and functional modification by introducing groups. In this paper, the types of MOFs are classified, and the synthesis methods and functional modification mechanisms of MOFs materials are summarized. Finally, the application prospects and challenges of metal-organic framework materials in the biomedical field are discussed, hoping to promote their application in multidisciplinary fields.

Sitagliptin synergizes 5-fluorouracil efficacy in colon cancer cells through MDR1-mediated flux impairment and down regulation of NFκB2 and p-AKT survival proteins

5-fluorouracil (5-FU) is an inexpensive treatment for colon cancer; however, its efficacy is limited by chemoresistance. This study investigates the combination therapy approach of 5-FU with Sitagliptin (Sita), a diabetic drug with potential cancer-modulating effects. The combination was evaluated in vitro and in silico, focusing on the effects of Sita and 5-FU on colon cancer cells. The results showed that the addition of Sita significantly decreased the IC50 of 5-FU compared to 5-Fu monotherapy. The study also found that Sita and 5-FU interact synergistically, with a combination index below 1. Sita successfully lowered the 5-FU dosage reduction index, decreasing the expression of MDR1 mRNA and p-AKT and NFκB2 subunits p100/p52 protein. Molecular docking analyses confirmed Sita's antagonistic action on MDR1 and thymidylate synthase proteins. The study concludes that sitagliptin can target MDR1, increase apoptosis, and significantly reduce the expression of p-AKT and NFκB2 cell-survival proteins. These effects sensitize colon cancer cells to 5-FU. Repurposing sitagliptin may enhance the anticancer effects of 5-FU at lower dosages.

Anticancer sensitivity and biological aspect of 5-fluorouracil-resistant human colorectal cancer HCT116 cells in three-dimensional culture under high- and low-glucose conditions

5-Fluorouracil (5-FU) is a commonly used anticancer drug for colorectal cancer (CRC). Therefore, it is crucial to elucidate the mechanisms that contribute to 5-FU resistance. We established an acquired 5-FU resistant cell line, HCT116RF10, derived from CRC cells and investigated its energy metabolism as well as the underlying mechanism of 5-FU resistance. We examined the sensitivity to 5-FU and the formation of tumor spheres in parental HCT116 cells and 5-FU-resistant HCT116RF10 cells under 3D culture conditions at high-glucose (HG 25 mM) and low-glucose (LG 5.5 mM) concentrations. These results suggested that the tumor spheres of parental HCT116 cells displayed higher sensitivity to 5-FU under LG conditions than under HG conditions. HCT116RF10 tumor spheres exhibited comparable sensitivity to 5-FU under HG and LG conditions. Furthermore, under HG conditions, there was a marked decrease in extracellular lactate in the HCT116RF10 tumor sphere compared to that in the LG tumor sphere. Similarly, HCT116 tumor spheres showed decreased extracellular lactate levels under LG conditions compared to those grown under HG conditions. Moreover, the evidence reveals that the tumor spheres of HCT116RF10 and HCT116 cells exhibit disparate dependencies on energy metabolism, glycolysis, and mitochondrial respiration under both HG and LG conditions. These results have important clinical implications for overcoming 5-FU resistance and enhancing antitumor treatment strategies.

Resveratrol as sensitizer in colorectal cancer plasticity

Despite tremendous medical treatment successes, colorectal cancer (CRC) remains a leading cause of cancer deaths worldwide. Chemotherapy as monotherapy can lead to significant side effects and chemoresistance that can be linked to several resistance-activating biological processes, including an increase in inflammation, cellular plasticity, multidrug resistance (MDR), inhibition of the sentinel gene p53, and apoptosis. As a consequence, tumor cells can escape the effectiveness of chemotherapeutic agents. This underscores the need for cross-target therapeutic approaches that are not only pharmacologically safe but also modulate multiple potent signaling pathways and sensitize cancer cells to overcome resistance to standard drugs. In recent years, scientists have been searching for natural compounds that can be used as chemosensitizers in addition to conventional medications for the synergistic treatment of CRC. Resveratrol, a natural polyphenolic phytoalexin found in various fruits and vegetables such as peanuts, berries, and red grapes, is one of the most effective natural chemopreventive agents. Abundant in vitro and in vivo studies have shown that resveratrol, in interaction with standard drugs, is an effective chemosensitizer for CRC cells to chemotherapeutic agents and thus prevents drug resistance by modulating multiple pathways, including transcription factors, epithelial-to-mesenchymal transition-plasticity, proliferation, metastasis, angiogenesis, cell cycle, and apoptosis. The ability of resveratrol to modify multiple subcellular pathways that may suppress cancer cell plasticity and reversal of chemoresistance are critical parameters for understanding its anti-cancer effects. In this review, we focus on the chemosensitizing properties of resveratrol in CRC and, thus, its potential importance as an additive to ongoing treatments.

scFv biofunctionalized nanoparticles to effective and safe targeting of CEA-expressing colorectal cancer cells

Colorectal cancer (CRC) is one of the deadliest cancers worldwide, with the 5 year survival rate in metastatic cases limited to 12%. The design of targeted and effective therapeutics remains a major unmet clinical need in CRC treatment. Carcinoembryonic antigen (CEA), a glycoprotein overexpressed in most colorectal tumors, may constitute a promising molecule for generating novel CEA-targeted therapeutic strategies for CRC treatment. Here, we developed a smart nanoplatform based on chemical conjugation of an anti-CEA single-chain variable fragment (scFv), MFE-23, with PLGA-PEG polymers to deliver the standard 5-Fluorouracil (5-FU) chemotherapy to CRC cells. We confirmed the specificity of the developed CEA-targeted NPs on the internalization by CEA-expressing CRC cells, with an enhance of threefold in the cell uptake. Additionally, CEA-targeted NPs loaded with 5-FU induced higher cytotoxicity in CEA-expressing cells, after 24 h and 48 h of treatment, reinforcing the specificity of the targeted NPs. Lastly, the safety of CEA-targeted NPs loaded with 5-FU was evaluated in donor-isolated macrophages, with no relevant impact on their metabolic activity nor polarization. Altogether, this proof of concept supports the CEA-mediated internalization of targeted NPs as a promising chemotherapeutic strategy for further investigation in different CEA-associated cancers and respective metastatic sites.Authors: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Maria José] Last name [Silveira]. Author 7 Given name: [Maria José] Last name [Oliveira]. Also, kindly confirm the details in the metadata are correctokAffiliations: Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.ok.

In Vitro Assessment of the Synergistic Effect of Aspirin and 5-Fluorouracil in Colorectal Adenocarcinoma Cells

Although remarkable progress has been made, colorectal cancer remains a significant global health issue. One of the most challenging aspects of cancer treatment is the resistance of tumor cells to classical chemotherapy. Conventional therapy for colorectal cancer often involves the use of 5-fluorouracil as a chemotherapeutic agent. Aspirin, a drug used primarily to prevent cardiovascular complications, became a focus of attention due to its potential use as an antitumor agent. The purpose of the study was to evaluate the potential synergistic cytotoxic effects of aspirin and 5-fluorouracil on colorectal adenocarcinoma cells. The viability of cells, the impact on the morphology and nuclei of cells, the potential antimigratory effect, and the impact on the expression of the major genes associated with cell apoptosis (Bcl-2, Bax, Bad), as well as caspases 3 and 8, were evaluated. The results indicated that the two compounds exerted a synergistic effect, causing a reduction in cell viability accompanied by changes characteristic of the apoptosis process-the condensation of nuclei and the reorganization of actin filaments in cells, the reduction in the expression of the Bcl-2 gene, and the increase in the expression of Bax and Bad genes, along with caspases 3 and 8. Considering all these findings, it appears that aspirin may be investigated in depth in order to be used in conjunction with 5-fluorouracil to increase antitumor activity.

Mannose Inhibits the Pentose Phosphate Pathway in Colorectal Cancer and Enhances Sensitivity to 5-Fluorouracil Therapy

Colorectal cancer (CRC) is one of the leading cancers and causes of death in patients. 5-fluorouracil (5-FU) is the therapy of choice for CRC, but it exhibits high toxicity and drug resistance. Tumorigenesis is characterized by a deregulated metabolism, which promotes cancer cell growth and survival. The pentose phosphate pathway (PPP) is required for the synthesis of ribonucleotides and the regulation of reactive oxygen species and is upregulated in CRC. Mannose was recently reported to halt tumor growth and impair the PPP. Mannose inhibitory effects on tumor growth are inversely related to the levels of phosphomannose isomerase (PMI). An in silico analysis showed low PMI levels in human CRC tissues. We, therefore, investigated the effect of mannose alone or in combination with 5-FU in human CRC cell lines with different p53 and 5-FU resistance statuses. Mannose resulted in a dose-dependent inhibition of cell growth and synergized with 5-FU treatment in all tested cancer cell lines. Mannose alone or in combination with 5-FU reduced the total dehydrogenase activity of key PPP enzymes, enhanced oxidative stress, and induced DNA damage in CRC cells. Importantly, single mannose or combination treatments with 5-FU were well tolerated and reduced tumor volumes in a mouse xenograft model. In summary, mannose alone or in combination with 5-FU may represent a novel therapeutic strategy in CRC.

The critical role of circular RNAs in drug resistance in gastrointestinal cancers

Nowadays, drug resistance (DR) in gastrointestinal (GI) cancers, as the main reason for cancer-related mortality worldwide, has become a serious problem in the management of patients. Several mechanisms have been proposed for resistance to anticancer drugs, including altered transport and metabolism of drugs, mutation of drug targets, altered DNA repair system, inhibited apoptosis and autophagy, cancer stem cells, tumor heterogeneity, and epithelial-mesenchymal transition. Compelling evidence has revealed that genetic and epigenetic factors are strongly linked to DR. Non-coding RNA (ncRNA) interferences are the most crucial epigenetic alterations explored so far, and among these ncRNAs, circular RNAs (circRNAs) are the most emerging members known to have unique properties. Due to the absence of 5' and 3' ends in these novel RNAs, the two ends are covalently bonded together and are generated from pre-mRNA in a process known as back-splicing, which makes them more stable than other RNAs. As far as the unique structure and function of circRNAs is concerned, they are implicated in proliferation, migration, invasion, angiogenesis, metastasis, and DR. A clear understanding of the molecular mechanisms responsible for circRNAs-mediated DR in the GI cancers will open a new window to the management of GI cancers. Hence, in the present review, we will describe briefly the biogenesis, multiple features, and different biological functions of circRNAs. Then, we will summarize current mechanisms of DR, and finally, discuss molecular mechanisms through which circRNAs regulate DR development in esophageal cancer, pancreatic cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma.

Enhancement of the antitumor effect of 5-fluorouracil with modulation in drug transporters expression using PI3K inhibitors in colorectal cancer cells

AIMS

5-Fluorouracil (5-FU) represents the cornerstone for colorectal cancer therapy. However, resistance to its action is a major hindrance. This study aimed to investigate the effectiveness of suppressing the activity of PI3K/Akt/mTOR signaling pathway on the chemosensitivity of colorectal cancer cells to 5-FU, as well as to delineate the possible underlying cellular mechanisms and the expected modulation in the expression of specific ABC drug transporters.

MAIN METHODS

HCT116 and Caco-2 cells were incubated with 5-FU, LY294002, or PI-103 individually or in combination. Cell viability was monitored using MTT assay. The expression of a panel of drug transporters was evaluated by RT-PCR. Immunofluorescence staining was applied to evaluate the expression pattern of phospho-AKT, phospho-mTOR, and ABGG2. HPLC evaluated the enhancement in the 5-FU cellular uptake. Cell apoptosis was detected by flow cytometry, and cell morphological changes following treatment were inspected under a fluorescence microscope. Additionally, the migration ability of cells following our suggested treatment combination was examined by wound healing assay.

KEY FINDINGS

The results reveal a notable enhancement in the cytotoxicity of a low dose of 5-FU when combined with a PI3K inhibitor (LY294002 or PI-103). This enhancement was influenced by the significant reduction in the expression of p-AKT and p-mTOR and was also mediated by a significant suppression in the expression of ABCG2 and ABCC5. Consequently, we detected an increase in the cellular uptake and concentration of 5-FU in cells treated with this combination rather than a single 5-FU treatment. Our Suggested combination treatment also induced cell apoptosis and reduced the migration ability of cells.

SIGNIFICANCE

Our data provide evidence that survival signaling pathways represent distinctive targets for the enhancement of chemotherapeutic sensitivity. The antitumor efficacy of 5-FU is enhanced when combined with a PI3K inhibitor, and this effect was mediated by alterations in the expression of specific drug transporters.

Regulation of thymidylate synthase: an approach to overcome 5-FU resistance in colorectal cancer

Thymidylate synthase is the rate-limiting enzyme required for DNA synthesis and overexpression of this enzyme causes resistance to cancer cells. Long treatments with 5-FU cause resistance to Thymidylate synthase targeting drugs. We have also compiled different mechanisms of drug resistance including autophagy and apoptosis, drug detoxification and ABC transporters, drug efflux, signaling pathways (AKT/PI3K, RAS-MAPK, WNT/β catenin, mTOR, NFKB, and Notch1 and FOXM1) and different genes associated with resistance in colorectal cancer. We can overcome 5-FU resistance in cancer cells by regulating thymidylate synthase by natural products (Coptidis rhizoma), HDAC inhibitors, mTOR inhibitors, Folate antagonists, and several other drugs which have been used in combination with TS inhibitors. This review is a compilation of different approaches reported for the regulation of thymidylate synthase to overcome resistance in colorectal cancer cells.

5-fluorouracil treatment of patient-derived scaffolds from colorectal cancer reveal clinically critical information

BACKGROUND

Colorectal cancer is a commonly diagnosed cancer worldwide. Unfortunately, many patients do not respond to standard chemotherapy treatments and develop disease relapse and metastases. Besides cancer cell specific genetic changes, heterogeneity in the tumor microenvironment contribute to the clinical presentation of the disease and can potentially also influence drug resistance. By using a recently developed patient-derived scaffold method monitoring how a standardized reporter cancer cell line adapts to various microenvironments treated with chemotherapy, we wanted to clarify how individual patient specific microenvironments influence the chemotherapy response in colorectal cancer.

METHODS

Surgically resected colorectal cancer specimens from 89 patients were decellularized to produce patient-derived scaffold, which were seeded with HT29 cells, cultured for 3 weeks, and treated with 5-fluorouracil. Gene expression changes of adapted and treated HT29 cells were monitored by qPCR and compared with clinical parameters including disease-free survival.

RESULTS

The effects of 5-fluorouracil treatment varied between different patient-derived scaffold, but generally induced a reduced expression of proliferation genes and increased expression of pluripotency and epithelial-to-mesenchymal transition genes. Interestingly, patient-derived scaffold cultures obtained from patients with disease recurrences showed a significantly less pronounced anti-proliferative effect of 5-fluorouracil and more pronounced increase of pluripotency, with MKI67 and POU5F1 being among the most significant genes linked to disease relapse in colorectal cancer.

CONCLUSIONS

Colorectal patient-derived scaffold can decode clinically relevant tumor microenvironmental influence of 5-fluorouracil treatment effects opening up for optimized precision medicine in colorectal cancer treatment.

Trapping of 5-Fluorodeoxyuridine Monophosphate by Thymidylate Synthase Confers Resistance to 5-Fluorouracil

The major metabolite of the anticancer agent 5-fluorouracil (5-FU) is 5-fluorodeoxyuridine monophosphate (FdUMP), which is a potent inhibitor of thymidylate synthase (TS). Recently, we hypothesized that 5-FU-resistant colorectal cancer (CRC) cells have increased levels of TS protein relative to 5-FU-sensitive CRC cells and use a fraction of their TS to trap FdUMP, which results in resistance to 5-FU. In this study, we analyzed the difference between the regulation of the balance of the free, active form of TS and the inactive FdUMP-TS form in 5-FU-resistant HCT116 cells and parental HCT116 cells. Silencing of TYMS, the gene that encodes TS, resulted in greater enhancement of the anticancer effect of 5-FU in the 5-FU-resistant HCT116R^F10 cells than in the parental HCT116 cells. In addition, the trapping of FdUMP by TS was more effective in the 5-FU-resistant HCT116R^F10 cells than in the parental HCT116 cells. Our observations suggest that the regulation of the balance between the storage of the active TS form and the accumulation of FdUMP-TS is responsible for direct resistance to 5-FU. The findings provide a better understanding of 5-FU resistance mechanisms and may enable the development of anticancer strategies that reverse the sensitivity of 5-FU resistance in CRC cells.