Downregulating CREBBP inhibits proliferation and cell cycle progression and induces daunorubicin resistance in leukemia cells

Abstract

Low expression levels of CREB-binding protein (CREBBP) have been demonstrated to be associated with high minimal residual disease at the end of induction therapy and adverse long-term outcomes in pediatric patients with acute lymphoblastic leukemia (ALL). However, the effect of low CREBBP expression on the prognosis of ALL has not yet been investigated. In the present study, CREBBP was downregulated and overexpressed in ALL cell lines (Jurkat and Reh). Sensitivity to chemotherapy and cell proliferation activity was determined via a Cell Counting Kit-8 assay. Cell cycle analysis was performed using flow cytometry. Immunofluorescence confocal microscopy and co-immunoprecipitation (Co-IP) assays were performed to determine the interaction between CREBBP and E2F transcription factor 3a (E2F3a). The binding of CREBBP to downstream gene caspase 8 associated protein 2 (CASP8AP2) promoters was assessed using a chromatin immunoprecipitation assay, and mRNA expression levels were detected via reverse transcription-quantitative PCR. Western blot analysis was performed to detect protein expression of CREBBP, E2F3a and CASP8AP2. Downregulation of CREBBP increased the IC 50 value of daunorubicin; however, no significant affects were observed on the IC 50 values of vincristine and L-asparaginase. Furthermore, downregulation of CREBBP notably inhibited leukemia cell proliferation, accumulated cells in the G 0 /G 1 phase and decreased cell proportions in the S and G 2 /M phases. Co-IP analysis demonstrated that CREBBP interacted with E2F3a, a transcription factor involved in G 1 /S transition. Immunofluorescence confocal microscopy indicated co-localization of CREBBP and E2F3a at the cell nucleus. Furthermore, E2F3a protein expression decreased in CREBBP RNA interference treated Jurkat and Reh cells. CASP8AP2, a target gene of E2F3a, was also identified to be a downstream gene of CREBBP. In addition, decreased IC 50 value and cell proportions in the G 0 /G 1 phase, accelerated cell proliferation and upregulated E2F3a and CASP8AP2 expression were exhibited in CREBBP overexpressed cells. Taken together, the results of the present study suggested that CREBBP downregulation affects proliferation and cell cycle progression in leukemia cells, potentially via the interaction and regulation of E2F3a, resulting in chemotherapy resistance. Thus, targeting CREBBP may be a therapeutic strategy for treating pediatric patients with ALL.

An easy-to-use nomogram predicting overall survival of adult acute lymphoblastic leukemia

“…IKZF1 deletion is a critical poor prognostic biomarker in ALL ( 41 ), the mutation of which drives normal lymphocytes to develop into leukemia ( 42 ).It was reported that HSCT could improve clinical outcomes of patients with IKZF1 mutation ( 43 ). While CREBBP mutation is associated with drug resistance and recurrence in ALL ( 44 , 45 ). The mutation of this gene frequently occurred in childhood ALL and was rare in adults ( 46 ).…”

Proteomic profiling of the oncogenic septin 9 reveals isoform‐specific interactions in breast cancer cells

“…Notably, isoform 4-specific interactions with factors such as CREBBP and GML that interface with the oestrogen receptor as well as the BRCA1 and p53 tumour suppressors suggest isoform-specific roles in the pathogenesis and treatment of breast cancer [86,120]. By downregulating cell proliferation, SEPT9_i4 may impact the response of cancer cells to chemotherapy as observed with alterations in the expression of CREBBP and GML, which also regulate cell proliferation [69,87]. Of note, SEPT9 isoforms have been implicated in cellular adaptation to anti-cancer drugs [38,41].…”

“…This reduction in nuclear size reduction was accompanied by an overall reduction in cell size and the growth rates of MCF-7 cells expressing GFP-SEPT9_i4 (Figure S5C and S5E), while cell morphology was not altered as indicated by quantification of cell complexity (ratio of perimeter length to surface area) (Figure S5D). These data suggest that SEPT9_i4 may regulate nuclear size and cell growth by suppressing CREBBP functions in nuclear size and cell proliferation [67][68][69].…”

Genetic or pharmacological inactivation of CREBBP sensitizes B-cell Acute Lymphoblastic Leukemia to Ferroptotic Cell Death upon BCL2 Inhibition

“…We subjected the 697 isogenic cell lines to a targeted drug screen, using a wide range of concentrations, focussed on clinically-actionable drugs in classes implicated or hypothesized to show differential sensitivity in published models of B-cell lymphoma and other CREBBP-mutated malignancies (Extended Data Table 1) 3,4,[10][11][12]17,19,20 . CREBBP-mutated 697 cells were not differentially sensitive to traditional cytotoxic chemotherapy, and paradoxically showed a degree of sensitization to the glucocorticoid Dexamethasone, used in current ALL induction regimens (Fig.…”