Chemoresistance is a main cause of chemotherapy failure and tumor recurrence. The effects of global protein SUMOylation on chemoresistance in colorectal cancer (CRC) remains to be investigated. Herein, we have proposed that the elevated SUMO2/3-modified proteins confer 5-fluorouracil (5-FU) chemoresistance acquisition in CRC. The SUMOylation levels of global proteins in CRC cell lines were elevated compared with normal colon cell line NCM460. 5-FU treatment obviously reduced SUMOylation of global proteins in 5-FU-sensitive CRC cells including HT29, HCT116 and HCT-8. However, in 5-FU-resistant HCT-8/5-FU cells, the expression level of SUMO2/3-modified proteins was increased under 5-FU exposure in a concentration-dependent manner. 5-FU treatment combined with SUMOylation inhibitor ML-792 significantly increased the sensitivity of 5-FU-resistant cells to 5-FU and reduced colony formation numbers in HCT-8/5-FU cells. And UBC9-mediated SUMOylation elevation contributes to 5-FU resistance in HCT116 cells. Moreover, we also identified RREB1 as a regulator of SUMOylation profiling of global cellular proteins via directly binding to the promoter of UBC9. Overexpression of RREB1 promoted 5-FU resistance in CRC, which was partially abolished by treatment of inhibitor ML-792. In conclusion, RREB1-enhanced protein SUMOylation contributes to 5-FU resistance acquisition in CRC.

Erianin, a bibenzyl compound found in dendrobium extract, has demonstrated broad anticancer activity. However, its mechanism of action in gastric cancer (GC) remains poorly understood. LKB1 is a tumor-suppressor gene, and its mutation is an important driver of various cancers. Yet some studies have reported contradictory findings. In this study, we combined bioinformatics and in vitro and in vivo experiments to investigate the effect and potential mechanism of Erianin in the treatment of GC. The results show that LKB1 was highly expressed in patients\' tumor tissues and GC cells, and it was associated with poor patient prognosis. Erianin could promote GC cell apoptosis and inhibit the scratch repair, migration, invasion, and epithelial-mesenchymal transition (EMT) characteristics. Erianin dose-dependently inhibited the expression of LKB1, SIK2, SIK3, and PARD3 but had no significant effect on SIK1. Erianin also inhibited tumor growth in CDX mice model. Unexpectedly, 5-FU also exhibited a certain inhibitory effect on LKB1. The combination of Erianin and 5-FU significantly improved the anti-tumor efficacy of 5-FU in the growth of GC cells and xenograft mouse models. In summary, Erianin is a potential anti-GC compound that can inhibit GC growth and EMT properties by targeting the LKB1-SIK2/3-PARD3-signaling axis. The synergistic effect of Erianin and 5-FU suggests a promising therapeutic strategy for GC treatment.

Chemotherapy-induced intestinal mucositis based on 5-fluorouracil (5-FU) slows down the progress of cancer treatment and causes significant suffering to patients. Pediococcus pentosaceus (P. pentosaceus), as a type of LAB, has a range of probiotic properties, including antioxidant, immune benefits, and cholesterol-lowering effects, which are attracting increasing attention. However, studies on the protective effect of P. pentosaceus against chemotherapeutic-induced intestinal mucositis caused by 5-FU remain unclear. Therefore, this study aimed to investigate the potential relieving effects of P. pentosaceus PP34 on 5-FU-induced intestinal mucositis and its mechanism. In the present study, a P. pentosaceus PP34 solution (2 × 109 CFU/mL) was administered daily by gavage followed by intraperitoneal injection of 5-FU to model intestinal mucositis. The body weight, serum biochemical indices, jejunal pathological organization, and expression levels of inflammatory cytokines in the jejunum were examined. The results indicated that the mice induced with 5-FU developed typical intestinal mucositis symptoms and histopathological changes with intense inflammatory and oxidative responses. Moreover, the gut microbiota was disturbed, while PP34 effectively decreased the oxidative reactions and the expression levels of inflammatory mediators and regulated the gut microbiota in 5-FU-exposed mice. Taken together, the study indicated that P. pentosaceus PP34 ameliorates 5-Fluorouracil-induced intestinal mucositis via inhibiting oxidative stress and restoring the gut microbiota.

In this study, based on Walker 256 in vitro experiments, CCK-8 assay, clone formation assay, wound healing assay, and flow cytometry were used to detect cell apoptosis and cell cycle. It was found that schisandrin may have significant anti-tumor effects in vitro by inhibiting TGF-β/Smad signaling pathway. In addition, in vivo experiments, immunohistochemistry was used to observe the expression of HIF-1α, VEGF and VEGFR-2 in tumor tissues. It was found that schisandrin could significantly improve the immunosuppression induced by 5-Fu and enhance the antitumor effect of 5-Fu. The mechanism may be related to the inhibition of Wnt-1/β-catenin signaling pathway.

BACKGROUND: Determination of DPYD and UGT1A1 polymorphisms prior to 5-fluorouracil and irinotecan therapy is crucial for avoiding severe adverse drug effects. Hence, there is a pressing need for accurate and reliable genotyping methods for the most common DPYD and UGT1A1 polymorphisms. In this study, we introduce a novel polymerase chain reaction (PCR) melting curve analysis method for discriminating DPYD c.1236G > A, c.1679 T > G, c.2846A > T, IVS14 + 1G > A and UGT1A1*1, *28, *6 (G71R) genotypes.
METHODS: Following protocol optimization, this technique was employed to genotype 28 patients, recruited between March 2023 and October 2023, at the First Affiliated Hospital of Xiamen University. These patients included 20 with UGT1A1 *1/*1, 8 with UGT1A1 *1/*28, 4 with UGT1A1 *28/*28, 22 with UGT1A1*6 G/G, 6 with UGT1A1*6 G/A, 4 with UGT1A1*6 A/A, 27 with DPYD(c.1236) G/G, 3 with DPYD(c.1236) G/A, 2 with DPYD(c.1236) A/A, 27 with DPYD(c.1679) T/T, 2 with DPYD(c.1679) T/G, 3 with DPYD(c.1679) G/G, 28 with DPYD(c.2846A/T) A/A, 2 with DPYD(c.2846A/T) A/T, 2 with DPYD(c.2846A/T) T/T, 28 with DPYD(c.IVS14 + 1) G/G, 2 with DPYD(c.IVS14 + 1) G/G, and 2 with DPYD(c.IVS14 + 1) G/G, as well as 3 plasmid standards. Method accuracy was assessed by comparing results with those from Sanger sequencing or Multiplex quantitative PCR(qPCR). Intra- and inter-run precision of melting temperatures (Tms) were calculated to evaluate reliability, and sensitivity was assessed through limit of detection examination.
RESULTS: The new method accurately identified all genotypes and exhibited higher accuracy than Multiplex qPCR. Intra- and inter-run coefficients of variation for Tms were both ≤1.97 %, with standard deviations ≤0.95 °C. The limit of detection was 0.09 ng/μL of input genomic DNA.
CONCLUSIONS: Our developed PCR melting curve analysis offers accurate, reliable, rapid, simple, and cost-effective detection of DPYD and UGT1A1 polymorphisms. Its application can be easily extended to clinical laboratories equipped with a fluorescent PCR platform.

Imperceptible examination and unideal treatment effect are still intractable difficulties for the clinical treatment of pancreatic ductal adenocarcinoma (PDAC). At present, despite 5-fluorouracil (5-FU), as a clinical first-line FOLFIRINOX chemo-drug, has achieved significant therapeutic effects. Nevertheless, these unavoidable factors such as low solubility, lack of biological specificity and easy to induce immunosuppressive surroundings formation, severely limit their treatment in PDAC. As an important source of energy for many tumor cells, tryptophan (Trp), is easily degraded to kynurenine (Kyn) by indolamine 2,3- dioxygenase 1 (IDO1), which activates the axis of Kyn-AHR to form special suppressive immune microenvironment that promotes tumor growth and metastasis. However, our research findings that 5-FU can induce effectively immunogenic cell death (ICD) to further treat tumor by activating immune systems, while the secretion of interferon-γ (IFN-γ) re-induce the Kyn-AHR axis activation, leading to poor treatment efficiency. Therefore, a metal matrix protease-2 (MMP-2) and endogenous GSH dual-responsive liposomal-based nanovesicle, co-loading with 5-FU (anti-cancer drug) and NLG919 (IDO1 inhibitor), was constructed (named as ENP919@5-FU). The multifunctional ENP919@5-FU can effectively reshape the tumor immunosuppression microenvironment to enhance the effect of chemoimmunotherapy, thereby effectively inhibiting cancer growth. Mechanistically, PDAC with high expression of MMP-2 will propel the as-prepared nanovesicle to dwell in tumor region via shedding PEG on the nanovesicle surface, effectively enhancing tumor uptake. Subsequently, the S-S bond containing nanovesicle was cut via high endogenous GSH, leading to the continued release of 5-FU and NLG919, thereby enabling circulating chemoimmunotherapy to effectively cause tumor ablation. Moreover, the combination of ENP919@5-FU and PD-L1 antibody (αPD-L1) showed a synergistic anti-tumor effect on the PDAC model with abdominal cavity metastasis. Collectively, ENP919@5-FU nanovesicle, as a PDAC treatment strategy, showed excellent antitumor efficacy by remodeling tumor microenvironment to circulate tumor chemoimmunotherapy amplification, which has promising potential in a precision medicine approach.

Schizandrin A (Sch A) exert anticancer and multidrug resistance-reversing effects in a variety of tumors, but its effect on 5-fluorouracil (5-Fu) in gastric cancer (GC) cells remains unclear. The aim of the present study was to examine the resistance-reversing effect of Schizandrin A and assess its mechanisms in 5-Fu-resistant GC cells.5-Fu-sensitive GC cells were treated with 5-Fu and 5-Fu-resistant GC cells AGS/5-Fu and SGC7901/5-Fu were were established. These cells were stimulated with Schizandrin A alone or co-treated with 5-Fu and their effect on tumor cell growth, proliferation, migration, invasion and ferroptosis-related metabolism were investigated both in vitro and in vivo. A number of additional experiments were conducted in an attempt to elucidate the molecular mechanism of increased ferroptosis. The results of our study suggest that Schizandrin A in combination with 5-Fu might be useful in treating GC by reverse drug resistance. It was shown that Schizandrin A coadministration suppressed metastasis and chemotherapy resistance in 5-Fu-resistant GC cells through facilitating the onset of ferroptosis, which is an iron-dependent form of cell death, which was further demonstrated in a xenograft nude mouse model. Mechanistically, Schizandrin A co-administration synergistically increased the expression of transferin receptor, thus iron accumulates within cells, leading to lipid peroxidation, which ultimately results in 5-Fu-resistant GC cells death. The results of this study have provided a novel strategy for increasing GC chemosensitivity, indicating Schizandrin A as a novel ferroptosis regulator. Mechanistically, ferroptosis is induced by Schizandrin A coadministration via increasing transferrin receptor expression.

BACKGROUND: The crucial role of STOML2 in tumor progression has been documented recently in various cancers. Previous studies have shown that STOML2 promoted cancer cell proliferation, but the underlying mechanism is not fully illustrated.
RESULTS: The expression and clinical relevance of STOML2 in pan-cancer was analyzed by TIMER2 web platform in pan-cancer. The prognostic significance of STOML2 in HCC was evaluated utilizing KM curve and a nomogram model. Signaling pathways associated with STOML2 expression were discovered by GSEA. CCK-8 assay was performed to evaluate the proliferative capacity of HCC cells after manipulating STOML2 expression. Flow cytometry was utilized to analyze cell cycle progression. Results indicated that increased STOML2 expression in HCC linked to unfavorable clinical outcomes. Cell cycle and cell division related terms were enriched under conditions of elevated STOML2 expression via GSEA analysis. A notable decrease in cell proliferation was observed in MHCC97H with STOML2 knocked-down, accompanied by G1-phase arrest, up-regulation of p21, down-regulation of CyclinD1 and its regulatory factor MYC, while STOML2 overexpression in Huh7 showed the opposite results. These results indicated that STOML2 was responsible for HCC proliferation by regulating the expression level of MYC/cyclin D1 and p21. Furthermore, an inverse correlation was found between STOML2 expression and 5-FU sensitivity.
CONCLUSIONS: STOML2 promotes cell cycle progression in HCC which is associated with activation of MYC/CyclinD1/p21 pathway, and modulates the response of HCC to 5-FU.

Introduction: The majority of individuals diagnosed with advanced colorectal cancer (CRC) will ultimately acquire resistance to 5-FU treatment. An increasing amount of evidence indicates that aerobic glycolysis performs a significant function in the progression and resistance of CRC. Nevertheless, the fundamental mechanisms remain to be fully understood. Methods: Proteomic analysis of 5-FU resistant CRC cells was implemented to identify and determine potential difference expression protein. Results: These proteins may exhibit resistance mechanisms that are potentially linked to the process of aerobic glycolysis. Herein, we found that nucleolar protein 58 (NOP58) has been overexpressed within two 5-FU resistant CRC cells, 116-5FuR and Lovo-5FuR. Meanwhile, the glycolysis rate of drug-resistant cancer cells has increased. NOP58 knockdown decreased glycolysis and enhanced the sensitivity of 116-5FuR and Lovo-5FuR cells to 5FU. Conclusion: The proteomic analysis of chemoresistance identifies a new target involved in the cellular adaption to 5-FU and therefore highlights a possible new therapeutic strategy to overcome this resistance.

NSUN2 is a critical methyltransferase for adding m5C to RNA. Its upregulation promotes the growth and metastasis of several tumors including gastric cancer (GC). However, it is unclear if NSUN2 can improve the chemosensitivity of GC to treatment with therapeutic agents such as cisplatin (CDDP) and 5-fluorouracil (5-FU). Flow cytometry was used to measure the effects of knocked-down NSUN2 expression on GC cell apoptosis and cell cycle progression. Western blot analysis examined specific signaling pathways through which NSUN2 mediates control of responses underlying the GC tumorous phenotype. NSUN2 expression was upregulated in GC tissues and its levels of rises were related to the extent of lymph node metastasis and increases in Ki67 proliferative marker expression. NSUN2 shRNA transfection suppressed rises in ERK1/2 phosphorylation status and downregulated anti-apoptosis protein Bcl-2 and upregulated pro-apoptosis protein Bax. Overall, the results reveal that NSUN2 downregulation promotes the GC chemosensitivity to inverse modulation by chemotherapeutic agents of Bcl-2 and Bax expression levels and declines in ERK1/2-induced proliferation. Our results indicate that inhibition of NSUN2 activation may be an effective procedure to enhance the efficacy of chemotherapeutic agents used to clinically treat GC.