MARK4

Microtubule affinity regulating kinase 4 (MARK4), which is overexpressed in various tumors, is involved in the regulation of cell division, proliferation, migration, and the cell cycle, and has been considered a potential marker for cancer; however, its mechanism of action in gastric cancer (GC) remains unclear. This study aimed to investigate the role of MARK4 in the proliferation, migration, and invasion of GC cell through the MAPK/ERK signaling pathway by targeting MARK4 knockdown.

Using The Cancer Genome Atlas data and clinical information, MARK4 expression and its relationship with prognosis were analyzed. Possible pathways involving MARK4 were explored using enrichment analysis. Western blotting and real-time quantitative polymerase chain reaction were used to detect MARK4 expression in GC. After targeted transfection of siRNA, the transfection efficiency of the experimental group was detected in AGS and HGC-27 cells. The effects of knockdown MARK4 on the proliferation, migration, and invasion of GC cells were verified using CCK-8, colony formation, wound healing, and transwell assays. Finally, the relationship between MARK4, the MAPK/ERK pathway, and epithelial-mesenchymal transition in GC was verified by western blotting.

MARK4 expression was upregulated in GC and associated with poor prognosis in patients with GC. Enrichment analysis showed that MARK4 was involved in the activation of the MAPK signaling pathway. Western blotting results indicated that MARK4 overexpression promoted the proliferation, migration, and invasion of GC cells through the MAPK/ERK pathway.

MARK4 expression was upregulated in GC and promoted the proliferation, migration, and invasion of GC cells through the MAPK/ERK pathway.

Methamphetamine (METH) is an illicit psychoactive substance that can damage various organs, with the urinary system being one of its significant targets. This study aims to explore the role of microtubule affinity-regulating kinase 4 (MARK4) in METH-induced acute kidney injury (AKI).

A total of 10 healthy adult male C57BL/6 mice were randomly divided into a control group and a METH group, 5 mice in each group. The METH group was administered METH (20 mg/kg, intraperitoneally, once daily for 3 consecutive days), while the control group received an equal volume of physiological saline. The mice were executed 24 hours after the final injection, and the success of the AKI model was detected by blood serum creatinine, blood urea nitrogen, and renal HE staining. Proteins differentially expressed between kidney tissues with METH-induced AKI and normal kidney tissues were screened by proteomics techniques and subjected to gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and bioinformatics analysis. The accuracy of proteomic data was validated using Western blotting, and the expression levels of MARK4 and cleaved caspase-3 in mouse kidneys were measured. We further explored the role of MARK4 in METH-induced AKI. Firstly, a METH toxicity model was established in BUMPT cells to screen the appropriate concentration and time of METH treatment; the viability of BUMPT cells after METH treatment and the expression of cleaved caspase-3 were detected by interfering with MARK4 expression through inhibitors.

The proteomic analysis of kidney tissues from METH and control groups screened for a total of 17 differentially expressed proteins, of which 11 were up-regulated and 6 were down-regulated (all P<0.05). The expression levels of MARK4 and cleaved caspase-3 were elevated in the kidneys of METH-treated mice (both P<0.05). The activity of BUMPT cells gradually decreased with increasing METH treatment concentration (all P<0.05), where the viability of BUMPT cells decreased to about 60% after METH treatment at 4 mmol/L. Compared with the control group, expression levels of MARK4 and cleaved caspase-3 were increased with higher METH concentrations and longer exposure times in a concentration- and time-dependent manner (all P<0.05). Inhibition of MARK4 expression improved METH-induced decrease in BUMPT cell activity, down-regulated the expression of cleaved caspase-3, and decreased the apoptosis of BUMPT cells induced by METH.

MARK4 is highly expressed in a mouse model of METH-induced AKI, and MARK4 mediates METH-induced AKI by regulating cell apoptosis.

Microtubule affinity-regulating kinase 4 (MARK4) is a serine-threonine kinase that phosphorylates microtubule-associated proteins (MAPs) and increases the microtubule dynamics.Due to its direct involvement in initiation, cell division, progression, and cancer metastasis, MARK4 is considered a potential therapeutic target.Here, we designed, synthesized, and characterized vanillin-isatin hybrids and evaluated their MARK4 inhibitory potential.All of the compounds strongly bind to MARK4 and interact closely with the active site residues.Finally, the compound VI-9 was selected for further investigation due to its high binding affinity and strong MARK4 inhibitory potential.Tau-phosphorylation assay has further confirmed that VI-9 significantly reduced the activity of MARK4.Compared with vanillin, VI-9 showed a better binding affinity and MARK4 inhibitory potential.Cell viability assays on human hepatocellular carcinoma (HCC) cell lines C3A and SNU-475 revealed that VI-9 inhibited their growth and proliferation.In addition, these compounds were nontoxic (up to 200 μM) for noncancerous (HEK-293) cells.Interestingly, VI-9 induces apoptosis and decreases the metastatic potential of the C3A and SNU-475 cell lines.The present work opens a newer avenue for vanillin-isatin hybrids and their derivatives in developing MARK4-targeted anticancer therapies.