High-Expressing Cftr Interacts with HDAC2 to Promote the Development of Ph+ Leukemia through HDAC2-Mediated PENT Pathway

The cystic fibrosis transembrane conductance regulator (CFTR) is a member of the ATP-binding cassette (ABC) transporter superfamily and mediates the transportion of Cl- and HCO3-. Recent studies have reported that CFTR is not only an anion channel protein, but also is used as a regulator to regulate the function of other proteins through interaction with other proteins. Our previous study found that CFTR protein expression in Ph+ acute leukemia cells K562, SUP-B15 and Ph+ primary leukemia blasts was significantly higher than that in normal control cells, and CFTRinh-172 (a CFTR specific inhibitor) had the significant anti-proliferative, apoptosis- inducing and cell-cycle-arrest effect on the CFTR-high expression Ph+ leukemia cells, suggesting that high-CFTR expression might be involved in the incidence and development of Ph+ acute leukemia. At the present study, we found with co-immunoprecipitation (co-IP) and LC-MC assay that HDAC2 protein existed in the fragment pulled down by CFTR antibody in K562 cells; Western Blot assay further confirmed that pretreatment with CFTRinh-172 reduced the expression of HDAC2 protein, but not HDAC2 mRNA in the K562 and SUP-B15: Immunfluorescence analysis testified the co-localization of CFTR and HDAC2 in situ in K562 and SUP-B15 cells; What's more, high expression of HDAC2 protein not mRNA were exhibited in the HEK 273 cell with CFTR cDNA transfect, meanwhile, CFTRinh-172 reduced the expression of HDAC2 protein not mRNA in the CFTR-transfect HEK 293 cells. Moreover, MG132, a proteasome inhibitor, recovered partly the expression of HDAC2 reduced by CFTRinh-172. These results demonstrated that CFTR could interact with HDAC2, and the combination of two proteins protected HDAC2 from the degradation via ubiquitin-proteasome pathway and keep HDAC2 high-expression; Next, Chip/qPCR assay were used to check the relation of HDAC2 and PENT transcript in two Ph+ leukemia cells, the results showed that HDAC2 protein bound in the promote region of PENT gene, and the mRNA and protein of PENT decreased when pre-treated by HDAC2 inhibitor as well as CFTRinh-172, in the meantime, PDK1 and mTOR (down-dream signaling of PENT) activity also decreased. At last, MTT test revealed that CFTRinh-172 raised the anti-proliferation of HDAC2 inhibitor. In conclusion The research has provided the strong evidence that high-expression CFTR plays an important role in the development of Ph+ leukemia through HDAC2-mediated PTEN pathway. The work was supported by the Foundation of the Science & Technology Department of Sichuan Province (NO. 2015SZ0234-5)