Melanoma-associated mutants within the serine-rich domain of PAK5 direct kinase activity to mitogenic pathways

Modeling Extraordinary Response Through Targeting Secondary Alterations in Fusion-Associated Sarcoma

PURPOSE

Targeted therapy in translocation-associated sarcomas has been limited to oncogenic activation of tyrosine kinases or ligands while gene fusions resulting in aberrant expression of transcription factors have been notoriously difficult to target. Moreover, secondary genetic alterations in sarcomas driven by translocations are uncommon, comprising mostly alterations in tumor suppressor genes (TP53, CDKN2A/B). Our study was triggered by an index patient showing a dramatic clinical response by targeting the secondary BRAF V600E mutation in a metastatic angiomatoid fibrous histiocytoma (AFH) harboring the typical EWSR1::CREB1 fusion.

MATERIALS AND METHODS

The patient, a 28-year-old female, was diagnosed with an AFH of the thigh and followed a highly aggressive clinical course, with rapid multifocal local recurrence within a year and widespread distant metastases (adrenal, bone, liver, lung). The tumor showed characteristic morphologic features, with histiocytoid cells intermixed with hemorrhagic cystic spaces and lymphoid aggregates. In addition to the pathognomonic EWSR1::CREB1 fusion, targeted DNA sequencing revealed in both primary and adrenal metastatic sites a hot spot BRAF V600E mutation and a CDKN2A/B deletion. Accordingly, the patient was treated with a BRAF-MEK inhibitor combination (encorafenib/binimetinib) showing an excellent but short-lived response.

RESULTS

Using a CRISPR-Cas9 approach, we introduced the BRAF c.1799 T>A point mutation in human embryonic stem (hES) cells harboring a conditional EWSR1 (exon7)::CREB1 (exon7) translocation and further differentiated to mesenchymal progenitors (hES-MP) before fusion expression. The cells maintained the fusion transcript expression and the AFH core gene signature while responding to treatment with encorafenib and binimetinib.

CONCLUSION

These results highlight that additional targeted DNA NGS in chemotherapy-resistant translocation-associated sarcomas may reveal actionable oncogenic drivers occurring as secondary genetic events during disease progression.

Differential Expression of Serum Exosomal Hsa-miR-487b-3p in Progressive Vitiligo Before and After Systemic Corticosteroid Treatment

Background

Vitiligo is an acquired skin depigmentation disease. It can be misdiagnosed at an early stage and tend to relapse. Serum markers are essential to monitoring the progression of vitiligo. Exosomal miRNAs act as the communication mediator between melanocytes and immune cells. Our study aimed to use serum exosomal miRNAs as a reference for evaluating vitiligo progression.

Methods

The miRNAs were extracted from the serum exosomes of ten progressive vitiligo patients (before and after treatment) and ten healthy individuals. We profiled miRNAs expression by RNA sequencing and screened out potential miRNAs and plotted their receiver operating characteristic (ROC) curves to explore their sensitivity and specificity as prognostic biomarkers in vitiligo progression. We examined the correlation between miRNA expression and the lesion area. Different databases were used to predict gene targets of miRNAs, which were analyzed by gene ontology and Kyoto encyclopedia of genes and genomes (KEGG).

Results

Our results showed that 141 miRNAs were differentially expressed in serum exosomes of progressive vitiligo patients, and 365 miRNAs were differentially expressed in these patients after treatment compared to healthy individuals. The expression of hsa-miR-487b-3p was significantly lower in these patients compared to healthy individuals. Still, there was no difference in its levels in patients after corticosteroid treatment compared to healthy controls. ROC curve analysis (area under curve = 0.840) indicated that hsa-miR-487b-3p could serve as a biomarker for the prognosis of vitiligo progression. Its expression positively correlated with the lesion area. A total of 41 target genes of hsa-miR-487b-3p were predicted via different databases. KEGG pathways were enriched in phenylalanine metabolism, glycan degradation, and protein export.

Conclusion

Serum exosomal hsa-miR-487b-3p can be a biomarker to detect vitiligo progression. The predicted target genes of hsa-miR-487b-3p were enriched in catabolism. Thus, its in progressive vitiligo may accelerate catabolism in melanocytes and cause its impairment.

MiR-139-5p inhibits invasion and migration of gastric cancer cells by targeting PAK5 gene to block Wnt/β-catenin signaling pathway

BACKGROUND

Gastric cancer (GC) is the most common type of cancer of the digestive system. Local or systemic metastasis is the main cause of poor prognosis. MicroRNAs (miRNAs) are an important regulatory factor in the development of gastric cancer. However, the effect and mechanism of miR-139-5p on the invasion and metastasis of gastric cancer cells are still unclear.

AIM

To explore the effect of miR-139-5p on the invasion and migration of gastric cancer cells and the underlying mechanism.

METHODS

Real-time fluorescent quantitative PCR (qRT-PCR) and Western blot were used to detect the expression of miR-139-5p and PAK5, respectively, in immortalized gastric mucosal cell line GES1 and gastric cancer cell lines SGC-7901, AGS, and BGC-823. MiR-139-5p mimic was transfected into gastric cancer SGC-7901 cells, and qRT-PCR was used detect the transfection efficiency. Transwell invasion and scratch assays were used to detect the effect of overexpression of miR-139-5p on the invasion and migration of SGC-7901 cells. Dual luciferase reporter gene assay and Western blot were used to detect the targeted regulation of miR-139-5p on PAK5. Western blot was used to detect the effect of overexpression of miR-139-5p on the activation of Wnt/β-catenin signaling pathway.

RESULTS

The expression level of miR-139-5p in gastric cancer cells was significantly lower than that of normal gastric mucosal cells (P < 0.05), and the expression of PAK5 mRNA and protein was significantly higher than that of normal gastric mucosal cells (P < 0.05). Transfection of miR-139-5p mimic up-regulated the expression of miR-139-5p in SGC-7901 cells. Overexpression of miR-139-5p significantly inhibited the invasion and migration of SGC-7901 cells. The results of dual luciferase reporter gene assay and Western blot showed that miR-139-5p can target and negatively regulate the expression of PAK5. After overexpression of miR-139-5p, the expression of Wnt3a, β-catenin, and Cyclin D1 proteins in SGC-7901 cells was significantly down-regulated.

CONCLUSION

MiR-139-5p inhibits the invasion and migration of gastric cancer cells by targeting the PAK5 gene to block the Wnt/β-catenin signaling pathway.

Human p21-activated kinase 5 (PAK5) expression and potential mechanisms in relevant cancers: Basic and clinical perspectives for molecular cancer therapeutics

An oncogenic role, p21-activated kinase 5 (PAK5), has proven as a significant mediator for many cellular progression, which is expressed highly in human organs such as lung, liver, kidney, blood vessels endothelial cells and inflammatory cells. PAK5 was primitively detected in the cerebrum and accelerated the filopodia formation in neurocytes. It can reverse the effect of Rho and adjust its activity to mediate maintenance and development of nerve axon by binding with Cdc42-GTP. Moreover, PAK5 has been suggested to mediate protean, multitudinous and inscrutable functions in cancer. Currently, many researches indicated that PAK5 was dysregulated in ovarian cancer, cervical cancer, melanoma, osteosarcoma, renal carcinoma, breast cancer, gastric cancer and so on, which was involved in cell proliferation, apoptosis, migration and invasion. This review focuses the latest knowledge on the structure, expression, signalling pathway of PAK5, emphasizing its function in cancer.