Integrin αvβ3 receptor is expressed on several types of cancer cells, including pancreatic cancer cells, and plays an important role in tumor growth and metastasis. The ability to target the integrin αvβ3 receptor on cancer cells increases the efficacy of targeted therapy and reduces the side effects. The aim of this study is to develop a novel arginine-glycine-aspartic acid (RGD) peptide-conjugated albumin nanoparticle to enhance the intracellular uptake of anticancer drug into the pancreatic cancer cells through receptor-mediated endocytosis. In cellular uptake studies, the fluorescent signal of RGD-conjugated BSANPs in BxPC3 cells was higher than that of BSANPs without RGD conjugation as determined by fluorescence spectrophotometer. We also found that BSANPs bound to BxPC3 cells in a time- and concentration-dependent manner. The uptake of RGD-conjugated BSANPs by pancreatic cancer cells was inhibited by an excess amount of free RGD peptide, indicating that the binding and/or uptake were mediated by the αvβ3 receptor. Furthermore, the nanoparticles were found to be located close to the nuclei by using laser scanning confocal microscopy. Besides, no significant in vitro cytotoxicity was observed as measured with MTT assay. Both in vitro and in vivo antitumor efficacy was improved by targeting gemcitabine-loaded nanoparticles to BxPC-3 cells using RGD peptides. Therefore, the RGD-conjugated BSANPs hold great potential as an effective drug delivery system to deliver therapeutic agents to pancreatic cancer.

Background: Oxaliplatin resistance usually leads to therapeutic failure and poor prognosis in colorectal cancer (CRC), while the underlying mechanisms are not yet fully understood. Metabolic reprogramming is strongly linked to drug resistance, however, the role and mechanism of metabolic reprogramming in oxaliplatin resistance remain unclear. Here, we aim to explore the functions and mechanisms of purine metabolism on the oxaliplatin-induced apoptosis of CRC. Methods: An oxaliplatin-resistant CRC cell line was generated, and untargeted metabolomics analysis was conducted. The inosine 5ʹ-monophosphate dehydrogenase type II (IMPDH2) expression in CRC cell lines was determined by quantitative real-time polymerase chain reaction (qPCR) and western blotting analysis. The effects of IMPDH2 overexpression, knockdown and pharmacological inhibition on oxaliplatin resistance in CRC were assessed by flow cytometry analysis of cell apoptosis in vivo and in vitro. Results: Metabolic analysis revealed that the levels of purine metabolites, especially guanosine monophosphate (GMP), were markedly elevated in oxaliplatin-resistant CRC cells. The accumulation of purine metabolites mainly arose from the upregulation of IMPDH2 expression. Gene set enrichment analysis (GSEA) indicated high IMPDH2 expression in CRC correlates with PURINE_METABOLISM and MULTIPLE-DRUG-RESISTANCE pathways. CRC cells with higher IMPDH2 expression were more resistant to oxaliplatin-induced apoptosis. Overexpression of IMPDH2 in CRC cells resulted in reduced cell death upon treatment with oxaliplatin, whereas knockdown of IMPDH2 led to increased sensitivity to oxaliplatin through influencing the activation of the Caspase 7/8/9 and PARP1 proteins on cell apoptosis. Targeted inhibition of IMPDH2 by mycophenolic acid (MPA) or mycophenolate mofetil (MMF) enhanced cell apoptosis in vitro and decreased in vivo tumour burden when combined with oxaliplatin treatment. Mechanistically, the Wnt/β-catenin signalling was hyperactivated in oxaliplatin-resistant CRC cells, and a reciprocal positive regulatory mechanism existed between Wnt/β-catenin and IMPDH2. Blocking the Wnt/β-catenin pathway could resensitize resistant cells to oxaliplatin, which could be restored by the addition of GMP. Conclusions: IMPDH2 is a predictive biomarker and therapeutic target for oxaliplatin resistance in CRC.

Colorectal cancer (CRC) is the third most malignant tumour worldwide, with high mortality and recurrence. Chemoresistance is one of the main factors leading to metastasis and poor prognosis in advanced CRC patients. By analysing the Gene Expression Omnibus data set, we found higher hexokinase 2 (HK2) expression levels in patients with metastatic CRC than in those with primary CRC. Moreover, we observed higher enrichment in oxaliplatin resistance‐related gene sets in metastatic CRC than in primary CRC. However, the underlying relationship has not yet been elucidated. In our study, HK2 expression was significantly elevated in CRC patients. Gene set enrichment analysis (GSEA) revealed multi‐drug resistance and epithelial‐mesenchymal transition (EMT) pathways related to high HK2 expression. Our results showed that knockdown of HK2 significantly inhibited vimentin and Twist1 expression and promoted TJP1 and E‐cadherin expression in CRC cells. Additionally, transcriptional and enzymatic inhibition of HK2 by 3‐bromopyruvate (3‐bp) impaired oxaliplatin resistance in vitro and in vivo. Mechanistically, HK2 interacts with and stabilized Twist1 by preventing its ubiquitin‐mediated degradation, which is related to oxaliplatin resistance, in CRC cells. Overexpression of Twist1 reduced the apoptosis rate by HK2 knockdown in CRC cells. Collectively, we discovered that HK2 is a crucial regulator that mediates oxaliplatin resistance through Twist1. These findings identify HK2 and Twist1 as promising drug targets for CRC chemoresistance.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been demonstrated to induce cell apoptosis in many types of tumors, while many hepatocellular carcinoma (HCC) cells display high resistance to TRAIL. Another outstanding limitation of TRAIL is the short half-life in vivo. Stem cell-based therapies provide a promising approach for the treatment of many types of tumors because of the ability of tropism. Therefore, as a new therapeutic strategy, the combination of chemotherapeutic agents and TRAIL gene modified MSCs (TRAIL-MSCs) would improve the therapeutic efficacy of HCC in vivo. This is the first time to show the potential of combination of chemotherapeutic agents and MSCs as a gene vector in the therapy of HCC.

Aims and background: As a powerful technique allowing analysis of large numbers of cells, fluorescence-activated cell sorting (FACS) is used more and more widely. For FACS analysis, adherent cells are usually detached by trypsinization, followed by centrifugation and resuspension. However, trypsinization can cut off some receptors from the cell surface like fine scissors, which will affect the accuracy of FACS results. Though non-enzymatic methods such as citric saline buffer have been used to determine cell surface receptors, how much of the receptors is cut off by trypsinization has been rarely studied. This work aimed to investigate whether different methods of detaching adherent cells could affect the detection of cell surface receptors. Methods: Human hepatocellular carcinoma cell lines (HepG2, Huh7 and Hep3B) were detached enzymatically with trypsin-EDTA solution or non-enzymatically with citric saline buffer, and then the receptors of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were detected by FACS analysis. Cell viability, cell cycle and apoptosis (sub-G1 fraction detected by FACS) of the trypsin-EDTA group and citric saline buffer group were also studied. Results: Different methods of detaching adherent cells could significantly affect the detection of TRAIL receptors. Compared to the conventional trypsin-EDTA group, the non-enzymatic group showed a 3.42-fold increase in the mean fluorescence intensity index of DcR HepG2 and a 1.25-fold increase in DR Huh 7 (P <0.05). However, the viability, cell cycle and apoptosis of these cells were not affected. Conclusions: Citric saline buffer might be recommended as the first choice to detach adherent cells for FACS analysis of cell surface receptors.