Abstract B37: hnRNP K in acute promyelocytic leukemia cells NB4 and NB4-R2: Involvement in cell survival and differentiation

• Published in: Molecular cancer research 2016-04, Vol.14 (4_Supplement), p.B37-B37
• Main Authors: Padovani, Karina Stringhetta, Annichini, María Sol Brassesco, Rego, Eduardo Magalhães, Curti, Carlos, Greene, Lewis Joel, Leopoldino, Andréia Machado
• Format: Article
• Language: English
• ISSN: 1541-7786; 1557-3125
• DOI: 10.1158/1557-3125.DEVBIOLCA15-B37

hnRNP K has been reported to be overexpressed in myeloid leukemia and it is downregulated during all-trans retinoic acid (ATRA) induced differentiation of Acute Promyelocytic Leukemia (APL) cells. The aim of the present study was to establish role of hnRNP K in APL using responsive (NB4) and resistant (NB4-R2) cells to the all-trans retinoic acid treatment as well as the possible role of hnRNPK in ATRA-induced cellular differentiation. After demonstration, by Western blotting analysis, that hnRNP K is overexpressed (10 fold) in APL (NB4 and NB4-R2) cell lines compared to controls (bone marrow and polymorphonuclear cells), we knocked-down the protein by short hairpin RNA (shRNA) interference in these cell lines and assessed involvement of hnRNP K in ATRA-induced differentiation, by flow cytometry in cells incubated with Cd11bPE antibody, as well as the contribution of hnRNP K to proliferation, with growth curve, using Trypan Blue, and survival, by propidium iodide incorporation analysis in flow cytometer. The knockdown of hnRNP K in NB4 (72%) and NB4-R2 (60%) leads to loss of viability mainly in NB4-R2 (42,43% of viability) vs NB4 (75,33% of viability). The loss of viability was more accentuated after ATRA treatment, NB4-R2 (6,13% of viability) vs NB4 (70% of viability). hnRNP K knockdown increases APL cells differentiation and was more accentuated in association with ATRA treatment, NB4-R2 (+59,13%) vs NB4 ( +14,06%). Furthermore, knockdown of hnRNP K leads to decreased in proliferation in NB4 (-95,98%) and NB4-R2 (-97,5%). hnRNP K knockdown promotes decrease of Bcl-xl, PML-RARα, procaspase-3 and increases of SET protein levels in both cells, demonstrated by Western blotting. The extracellular signal-regulated kinase ERK is a positive hnRNP K regulator, so the treatment with the ERK inhibitor at 10 μM U0126 produces effects similar to hnRNP K knockdown on cell viability in NB4-R2 cells, and in levels of BCL-xl and SET proteins. We concluded that, hnRNP K knockdown decreases the cell proliferation and viability of NB4 and NB4-R2 cells and increases cell differentiation, via MEK-ERK-hnRNP K-SET signaling. hnRNP K represent a potential target in APL ATRA resistant cells. Citation Format: Karina Stringhetta Padovani, María Sol Brassesco Annichini, Eduardo Magalhães Rego, Carlos Curti, Lewis Joel Greene, Andréia Machado Leopoldino. hnRNP K in acute promyelocytic leukemia cells NB4 and NB4-R2: Involvement in cell survival and differentiation. [abstract]. In: Pro