Nuclear multidrug-resistance related protein 1 contributes to multidrug-resistance of mucoepidermoid carcinoma mainly via regulating multidrug-resistance protein 1: a human mucoepidermoid carcinoma cells model and Spearman's rank correlation analysis

Short Caco-2 model for evaluation of drug permeability: A sodium valerate-assisted approach

The human colorectal adenocarcinoma cell line Caco-2, widely used for studying intestinal drug permeability, is typically grown on permeable filter supports and matures in 21 days with frequent media changes. The process is labor-intensive, prone to contamination, and has low throughput, contributing to the overall high utilization cost. Efforts to establish a low-cost, high-throughput, short-duration model have encountered obstacles, such as weaker tight junctions causing monolayer leaks, incomplete differentiation resulting in low transporter expression, intricate and challenging protocols, and cytotoxicity, limiting the usability. Hence, this study aimed to develop a low-cost, efficient, and short-duration model by addressing the aforementioned concerns by customizing the media and finding a safe differentiation inducer. We generated a new rapid model using sodium valerate, which demonstrated sufficient transporter activity, improved monolayer integrity, and higher levels of differentiation markers than the 21-day model. Furthermore, this model exhibited consistent and reliable results when used to evaluate drug permeability over multiple days of repeated use. This study demonstrates the potential of a sodium valerate-assisted abbreviated model for drug permeability assessment with economic and practical advantages.

An Improved In Vitro Blood-Brain Barrier Model for the Evaluation of Drug Permeability Using Transwell with Shear Stress

The development of drugs targeting the central nervous system (CNS) is challenging because of the presence of the Blood-Brain barrier (BBB). Developing physiologically relevant in vitro BBB models for evaluating drug permeability and predicting the activity of drug candidates is crucial. The transwell model is one of the most widely used in vitro BBB models. However, this model has limitations in mimicking in vivo conditions, particularly in the absence of shear stress. This study aimed to overcome the limitations of the transwell model using immortalized human endothelial cells (hCMEC/D3) by developing a novel dish design for an orbital shaker, providing shear stress. During optimization, we assessed cell layer integrity using trans-endothelial electrical resistance measurements and the % diffusion of lucifer yellow. The efflux transporter activity and mRNA expression of junctional proteins (claudin-5, occludin, and VE-cadherin) in the newly optimized model were verified. Additionally, the permeability of 14 compounds was evaluated and compared with published in vivo data. The cell-layer integrity was substantially increased using the newly designed annular shaking-dish model. The results demonstrate that our model provided robust conditions for evaluating the permeability of CNS drug candidates, potentially improving the reliability of in vitro BBB models in drug development.

NDRG2 ablation reprograms metastatic cancer cells towards glutamine dependence via the induction of ASCT2

Background: Metastasis is the most common cause of lethal outcome in various types of cancers. Although the cell proliferation related metabolism rewiring has been well characterized, less is known about the association of metabolic changes with tumor metastasis. Herein, we demonstrate that metastatic tumor obtained a mesenchymal phenotype, which is obtained by the loss of tumor suppressor NDRG2 triggered metabolic switch to glutamine metabolism.

Methods: mRNA-seq and gene expression profile analysis were performed to define the differential gene expressions in primary MEC1 and metastatic MC3 cells and the downstream pathways of NDRG2. NDRG2 regulation of Fbw7-dependent c-Myc stability were determined by immunoprecipitation and protein half-life assay. Luciferase reporter and ChIP assays were used to determine the roles of Akt and c-Myc in mediating NDRG2-dependent regulation of ASCT2 in in both tumor and NDRG2-knockout MEF cells. Finally, the effect of the NDRG2/Akt/c-Myc/ASCT2 signaling on glutaminolysis and tumor metastasis were evaluated by functional experiments and clinical samples.

Results: Based on the gene expression profile analysis, we identified metastatic tumor cells acquired the mesenchymal-like characteristics and displayed the increased dependency on glutamine utilization. Further, the gain of NDRG2 function blocked epithelial-mesenchymal transition (EMT) and glutaminolysis, potentially through suppression of glutamine transporter ASCT2 expression. The ASCT2 restoration reversed NDRG2 inhibitory effect on EMT program and tumor metastasis. Mechanistic study indicates that NDRG2 promoted Fbw7-dependent c-Myc degradation by inhibiting Akt activation, and subsequently decreased c-Myc-mediated ASCT2 transcription, in both tumor and NDRG2-knockout MEF cells. Supporting the biological significance, the reciprocal relationship between NDRG2 and ASCT2 were observed in multiple types of tumor tissues, and associated with tumor malignancy.

Conclusions: NDRG2-dependent repression of ASCT2 presumably is the predominant route by which NDRG2 rewires glutaminolysis and blocks metastatic tumor survival. Targeting glutaminolytic pathway may provide a new strategy for the treatment of metastatic tumors.

Baicalin-induced Cytotoxicity and Apoptosis in Multidrug-resistant MC3/5FU Mucoepidermoid Carcinoma Cell Line

Background:

Multidrug Resistance (MDR) is a serious hindrance to cancer chemotherapy and profoundly influences the clinical findings. Many Traditional Chinese Medicines (TCM) have been tested with the aim of developing effective resistance modulators or anticancer drugs to overcome the MDR of human cancers.

Methods:

The anticancer effect of baicalin on multidrug-resistant MC3/5FU (5-fluorouracil) cells was investigated by MTT test and xenografts in nude mice. Cell apoptosis was studied by transmission electron microscopy, Hoechst-33342 staining, DNA fragmentation detection, and flow cytometry. RT-PCR and Rhodamine 123 efflux assay was also used to detect its effect on ABC drug transporter proteins, ABCB1 (P-glycoprotein, P-gp) and ABCC1 (multidrug resistance protein 1, MRP1).

Results:

The results indicate that there was no significant effect of baicalin on ABC transporters expression or efflux function, although it induced potent growth inhibition in MC3/5FU cells. Flow cytometry, Hoechst 33342 staining and transmission electron microscope revealed that baicalin caused MC3/5FU cell death through the induction of apoptosis. It is demonstrated that baicalininduced apoptosis could be mediated by up-regulation of Bax and caspase-3 protein levels and downregulation of Bcl-2 protein levels. In addition, daily intraperitoneal injection of baicalin (100 and 200 mg/kg) for 2 weeks significantly inhibited the growth of MC3/5FU cells xenografts in nude mice.

Conclusion:

Our results suggest that baicalin possesses considerable cytotoxic activity in multidrug resistance MC3/5FU cells in vitro and in vivo.

Subcellular drug distribution: mechanisms and roles in drug efficacy, toxicity, resistance, and targeted delivery

After administration, drug molecules usually enter target cells to access their intracellular targets. In eukaryotic cells, these targets are often located in organelles, including the nucleus, endoplasmic reticulum, mitochondria, lysosomes, Golgi apparatus, and peroxisomes. Each organelle type possesses unique biological features. For example, mitochondria possess a negative transmembrane potential, while lysosomes have an intraluminal delta pH. Other properties are common to several organelle types, such as the presence of ATP-binding cassette (ABC) or solute carrier-type (SLC) transporters that sequester or pump out xenobiotic drugs. Studies on subcellular drug distribution are critical to understand the efficacy and toxicity of drugs along with the body's resistance to them and to potentially offer hints for targeted subcellular drug delivery. This review summarizes the results of studies from 1990 to 2017 that examined the subcellular distribution of small molecular drugs. We hope this review will aid in the understanding of drug distribution within cells.

Nuclear Multidrug Resistance-Related Protein 1 Is Highly Associated with Better Prognosis of Human Mucoepidermoid Carcinoma through the Suppression of Cell Proliferation, Migration and Invasion

Objectives

Multidrug resistance-related protein 1 (MRP1) overexpression is a well acknowledged predictor of poor response to chemotherapy, but MRP1 also correlated to better prognosis in some reports, especially for patients not pretreated with chemotherapy. In our previous study, we found nuclear translocation of MRP1 in mucoepidermoid carcinoma (MEC) for the first time. The purpose of this study was to further investigate the function of nuclear MRP1 in MEC.

Materials and Methods

Human MEC tissue samples of 125 patients were selected and stained using immunohistochemistry. The expression level of total MRP1/nuclear MRP1 of each sample was evaluated by expression index (EI) which was scored using both qualitative and quantitative analysis. The correlations between the clinicopathologic parameters and the EI of nuclear MRP1 were analyzed using Spearman’s rank correlation analysis, respectively. The effects of RNAi-mediated downregulation of nuclear MRP1 on MEC cells were assessed using flow cytometric analysis, MTT assay, plate colony formation assay, transwell invasion assay and monolayer wound healing assay.

Results

In this study, we found the EI of nuclear MRP1 was negatively correlated to the pathologic grading (r = -0.498, P<0.01) / clinical staging (r = -0.41, P<0.01) / tumor stage (r = -0.28, P = 0.02) / nodal stage (r = -0.29, P<0.01) of MEC patients. The RNAi-mediated downregulation of nuclear MRP1 further proved that the downregulation of nuclear MRP1 could increase the cell replication, growth speed, colony formation efficiency, migration and invasion ability of MEC cells.

Conclusion

Our results suggested that nuclear MRP1 is highly associated with better prognosis of human mucoepidermoid carcinoma and further study of its function mechanism would provide clues in developing new treatment modalities of MEC.