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PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics.

ABSTRACT: Myeloid cell leukemia sequence 1 (MCL1), an anti-apoptotic BCL2 family protein, is a key regulator of intrinsic apoptosis. Normal cells require strict control over MCL1 expression with aberrant MCL1 expression linked to the emergence of various diseases and chemoresistance. Previous studies have detailed how MCL1 expression is regulated by multiple mechanisms both transcriptionally and translationally. However, characterization of the post-transcriptional regulators of MCL1 mRNA is limited. Polypyrimidine tract binding protein 1 (PTBP1) is a known regulator of post-transcriptional gene expression that can control mRNA splicing, translation, stability and localization. Here we demonstrate that PTBP1 binds to MCL1 mRNA and that knockdown of PTBP1 upregulates MCL1 expression in cancer cells by stabilizing MCL1 mRNA and increasing MCL1 mRNA accumulation in cytoplasm. Further, we show that depletion of PTBP1 protects cancer cells from antitubulin agent-induced apoptosis in a MCL1-dependent manner. Taken together, our findings suggest that PTBP1 is a novel regulator of MCL1 mRNA by which it controls apoptotic response to antitubulin chemotherapeutics.

SUBMITTER: Cui J

PROVIDER: S-EPMC5041196 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics.

Cui J J Placzek W J WJ

Cell death and differentiation 20160701 10

Myeloid cell leukemia sequence 1 (MCL1), an anti-apoptotic BCL2 family protein, is a key regulator of intrinsic apoptosis. Normal cells require strict control over MCL1 expression with aberrant MCL1 expression linked to the emergence of various diseases and chemoresistance. Previous studies have detailed how MCL1 expression is regulated by multiple mechanisms both transcriptionally and translationally. However, characterization of the post-transcriptional regulators of MCL1 mRNA is limited. Poly ...[more]

PMID: 27367564

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Project description:The effective use of targeted therapy is highly dependent on the identification of responder patient populations. Loss of FBW7, which encodes a tumour-suppressor protein, is frequently found in various types of human cancer, including breast cancer, colon cancer and T-cell acute lymphoblastic leukaemia (T-ALL). In line with these genomic data, engineered deletion of Fbw7 in mouse T cells results in T-ALL, validating FBW7 as a T-ALL tumour suppressor. Determining the precise molecular mechanisms by which FBW7 exerts antitumour activity is an area of intensive investigation. These mechanisms are thought to relate in part to FBW7-mediated destruction of key proteins relevant to cancer, including Jun, Myc, cyclin E and notch 1 (ref. 9), all of which have oncoprotein activity and are overexpressed in various human cancers, including leukaemia. In addition to accelerating cell growth, overexpression of Jun, Myc or notch 1 can also induce programmed cell death. Thus, considerable uncertainty surrounds how FBW7-deficient cells evade cell death in the setting of upregulated Jun, Myc and/or notch 1. Here we show that the E3 ubiquitin ligase SCF(FBW7) (a SKP1-cullin-1-F-box complex that contains FBW7 as the F-box protein) governs cellular apoptosis by targeting MCL1, a pro-survival BCL2 family member, for ubiquitylation and destruction in a manner that depends on phosphorylation by glycogen synthase kinase 3. Human T-ALL cell lines showed a close relationship between FBW7 loss and MCL1 overexpression. Correspondingly, T-ALL cell lines with defective FBW7 are particularly sensitive to the multi-kinase inhibitor sorafenib but resistant to the BCL2 antagonist ABT-737. On the genetic level, FBW7 reconstitution or MCL1 depletion restores sensitivity to ABT-737, establishing MCL1 as a therapeutically relevant bypass survival mechanism that enables FBW7-deficient cells to evade apoptosis. Therefore, our work provides insight into the molecular mechanism of direct tumour suppression by FBW7 and has implications for the targeted treatment of patients with FBW7-deficient T-ALL.

Dataset Information

PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics.

Publications

PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics.

Similar Datasets

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