Description of PTPRG genetic variants identified in a cohort of Chronic Myeloid Leukemia patients and their ability to influence response to Tyrosine kinase Inhibitors.

Tyrosine kinase inhibitors (TKIs) have remarkably transformed Ph+ chronic myeloid leukemia (CML) management; however, TKI resistance remains a major clinical challenge. Mutations in BCR-ABL1 are well studied but fail to explain 20-40% of resistant cases, suggesting the activation of alternative, BCR-ABL1-independent pathways. Protein Tyrosine Phosphatase Receptor Gamma (PTPRG), a tumor suppressor, was found to be well expressed in CML patients responsive to TKIs and remained at low level in resistant patients. In this study, we aimed to identify genetic variants in PTPRG that could potentially modulate TKIs response in CML patients. DNA was extracted from peripheral blood samples collected from two CML cohorts (Qatar and Italy) and targeted exome sequencing was performed. Among 31 CML patients, six were TKI-responders and 25 were TKI-non-responsive. Sequencing identified ten variants, seven were annotated and three were novel SNPs (c.1602_1603insC, c.85+14412delC, and c.2289-129delA). Among them, five variants were identified in 15 resistant cases. Of these, one novel exon variant (c.1602_1603insC), c.841-29C>T (rs199917960) and c.1378-224A>G (rs2063204) were found to be significantly different between the resistant cases compared to responders. Our findings suggest that PTPRG variants may act as an indirect resistance mechanism of BCR-ABL1 to affect TKI treatment.

Long non-coding RNA BDNF-AS inhibits the proliferation and migration of renal cancer cells by regulating PI3K-AKT signaling pathway through protein tyrosine phosphatase receptor type G / 肿瘤研究与临床

Objective:To investigate the expression of long non-coding RNA (lncRNA) BDNF-AS in kidney cancer tissues, and its effect on the proliferation and migration ability of kidney cancer cells and the molecular mechanism.Methods:Real-time reverse quantitative polymerase chain reaction (rRT-PCR) was used to detect the expression levels of BDNF-AS gene in renal cancer tissues, tumor-adjacent tissues of 67 renal cancer patients and normal renal tubular epithelial cells HK-2 and renal cancer cell lines A498, ACHN, OS-RC-2, Caki-1, 786-O in Huangshi Central Hospital of Edong Medical Group from May 2017 to July 2018. The kidney cancer cell line with the lowest expression of BDNF-AS was taken as the research object. Transient transfection with BDNF-AS overexpression plasmid was treated as the experiment group or a plasmid carrying meaningless sequences was treated as the control group. rRT-PCR was used to detect transfection efficiency. After the transfection with Caki-1 for 24 h, methythiazolyl tetrazolium (MTT) method was used to detect the proliferation of cells in both groups, Transwell migration assay was applied to detect the cell migration ability, rRT-PCR was used to detect the expression level of protein tyrosine phosphatase receptor type G (PTPRG) mRNA and Western blot was used to detect the expression level of PI3K-AKT pathway related-proteins.Results:The relative expression level of BDNF-AS in kidney cancer tissues was lower than that in tumor-adjacent tissues (0.96±0.24 vs. 4.62±0.84, t = 41.76, P < 0.01). The relative expression of BDNF-AS in kidney cancer cell lines was lower than that in normal renal tubular epithelial cells HK-2 (all P < 0.05), and the relative expression in Caki-1 cells was the lowest (0.10±0.01). The relative expression of BDNF-AS in the experimental group was higher than that in the control group ( P < 0.01). From the second day of transfection, the proliferation ability of Caki-1 cells in the experimental group was lower than that in the control group (all P < 0.05). The number of Caki-1 migrated cells in the experimental group was lower than that in the control group after migration for 15 h of Caki-1 cells transfected for 24 h [(51±8) vs. (192±25), t = 5.31, P < 0.01]. After 48 h transfection, the relative expression of PTPRG mRNA in Caki-1 cells ( P < 0.01) and protein expression of the experimental group were higher than those of the control group, the expression levels of PI3K-AKT signaling pathway related-proteins p-PI3K, p-AKT, p-Tpl2 in Caki-1 cells of the experimental group were lower than those of the control group. Conclusions:The expression of BDNF-AS is down-regulated in kidney cancer tissues and cell lines. Overexpression of BDNF-AS can inhibit the proliferation and migration ability of kidney cancer Caki-1 cells. The molecular mechanism may be related to the transduction that BDNF-AS promotes PTPRG gene expression and interferes with PI3K-AKT signaling pathway.