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BCR/ABL1 and BCR are under the transcriptional control of the MYC oncogene.

Sharma N, Magistroni V, Piazza R, Citterio S, Mezzatesta C, Khandelwal P, Pirola A, Gambacorti-Passerini C - Mol. Cancer (2015)

Bottom Line: A luciferase reporter assay was used to confirm its activity on BCR promoter.Accordingly, silencing of MYC expression in various BCR/ABL1 positive cell lines causes significant downregulation of BCR and BCR/ABL1, which consequently leads to decreased proliferation and induction of cell death.Since MYC is frequently over-expressed in BC, this phenomenon could play a critical role in BCR/ABL1 up-regulation and blast aggressiveness acquired during CML evolution.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Sciences, University of Milano Bicocca, Monza, Italy. niteshsharma700@gmail.com.

ABSTRACT

Background: Chronic Myeloid Leukaemia (CML) is caused by the BCR/ABL1 fusion gene. Both the presence and the levels of BCR/ABL1 expression seem to be critical for CML progression from chronic phase (CP) to blast crisis (BC). After the oncogenic translocation, the BCR/ABL1 gene is under the transcriptional control of BCR promoter but the molecular mechanisms involved in the regulation of oncogene expression are mostly unknown.

Methods: A region of 1443bp of the functional BCR promoter was studied for transcription factor binding sites through in-silico analysis and Chromatin Immunoprecipitation experiments. BCR and BCR/ABL1 expression levels were analysed in CML cell lines after over-expression or silencing of MYC transcription factor. A luciferase reporter assay was used to confirm its activity on BCR promoter.

Results: In the present study we demonstrate that MYC and its partner MAX bind to the BCR promoter, leading to up-regulation of BCR and BCR/ABL1 at both transcriptional and protein levels. Accordingly, silencing of MYC expression in various BCR/ABL1 positive cell lines causes significant downregulation of BCR and BCR/ABL1, which consequently leads to decreased proliferation and induction of cell death.

Conclusions: Here we describe a regulatory pathway modulating BCR and BCR/ABL1 expression, showing that the BCR promoter is under the transcriptional control of the MYC/MAX heterodimer. Since MYC is frequently over-expressed in BC, this phenomenon could play a critical role in BCR/ABL1 up-regulation and blast aggressiveness acquired during CML evolution.

No MeSH data available.


Related in: MedlinePlus

Biological role of MYC silencing in CML cell lines. Immunoblots for MYC, PARP-1 and Actin in LAMA-84 (a) and KCL-22 (c) cell lines encoding MYC-shRNA (shMYC) or the control shRNA (shNC). The PARP-1 antibody recognizes total (116kDA) and cleaved PARP-1 (85/25kDa). Cell viability of the same cells (b,d) was determined by the MTS assay. Values represent the mean normalized percentage of survival compared to control cells (n = 5 wells; ± SD). (***: p < 0.001). (e) Flow cytometry analysis of propidium iodide (PI) stained KCL-22 cells after 72h of MYC silencing
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Fig4: Biological role of MYC silencing in CML cell lines. Immunoblots for MYC, PARP-1 and Actin in LAMA-84 (a) and KCL-22 (c) cell lines encoding MYC-shRNA (shMYC) or the control shRNA (shNC). The PARP-1 antibody recognizes total (116kDA) and cleaved PARP-1 (85/25kDa). Cell viability of the same cells (b,d) was determined by the MTS assay. Values represent the mean normalized percentage of survival compared to control cells (n = 5 wells; ± SD). (***: p < 0.001). (e) Flow cytometry analysis of propidium iodide (PI) stained KCL-22 cells after 72h of MYC silencing

Mentions: Finally, given the recognized role of MYC in v-ABL1 transforming potential [21], we confirmed that MYC silencing in CML cell lines resulted, together with BCR and BCR/ABL1 down-modulation, in a highly significant growth arrest (p < 0.0001) (Fig. 4b and d) and in induction of cell death (Fig. 4a, c and e).Fig. 4


BCR/ABL1 and BCR are under the transcriptional control of the MYC oncogene.

Sharma N, Magistroni V, Piazza R, Citterio S, Mezzatesta C, Khandelwal P, Pirola A, Gambacorti-Passerini C - Mol. Cancer (2015)

Biological role of MYC silencing in CML cell lines. Immunoblots for MYC, PARP-1 and Actin in LAMA-84 (a) and KCL-22 (c) cell lines encoding MYC-shRNA (shMYC) or the control shRNA (shNC). The PARP-1 antibody recognizes total (116kDA) and cleaved PARP-1 (85/25kDa). Cell viability of the same cells (b,d) was determined by the MTS assay. Values represent the mean normalized percentage of survival compared to control cells (n = 5 wells; ± SD). (***: p < 0.001). (e) Flow cytometry analysis of propidium iodide (PI) stained KCL-22 cells after 72h of MYC silencing
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4504180&req=5

Fig4: Biological role of MYC silencing in CML cell lines. Immunoblots for MYC, PARP-1 and Actin in LAMA-84 (a) and KCL-22 (c) cell lines encoding MYC-shRNA (shMYC) or the control shRNA (shNC). The PARP-1 antibody recognizes total (116kDA) and cleaved PARP-1 (85/25kDa). Cell viability of the same cells (b,d) was determined by the MTS assay. Values represent the mean normalized percentage of survival compared to control cells (n = 5 wells; ± SD). (***: p < 0.001). (e) Flow cytometry analysis of propidium iodide (PI) stained KCL-22 cells after 72h of MYC silencing
Mentions: Finally, given the recognized role of MYC in v-ABL1 transforming potential [21], we confirmed that MYC silencing in CML cell lines resulted, together with BCR and BCR/ABL1 down-modulation, in a highly significant growth arrest (p < 0.0001) (Fig. 4b and d) and in induction of cell death (Fig. 4a, c and e).Fig. 4

Bottom Line: A luciferase reporter assay was used to confirm its activity on BCR promoter.Accordingly, silencing of MYC expression in various BCR/ABL1 positive cell lines causes significant downregulation of BCR and BCR/ABL1, which consequently leads to decreased proliferation and induction of cell death.Since MYC is frequently over-expressed in BC, this phenomenon could play a critical role in BCR/ABL1 up-regulation and blast aggressiveness acquired during CML evolution.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Sciences, University of Milano Bicocca, Monza, Italy. niteshsharma700@gmail.com.

ABSTRACT

Background: Chronic Myeloid Leukaemia (CML) is caused by the BCR/ABL1 fusion gene. Both the presence and the levels of BCR/ABL1 expression seem to be critical for CML progression from chronic phase (CP) to blast crisis (BC). After the oncogenic translocation, the BCR/ABL1 gene is under the transcriptional control of BCR promoter but the molecular mechanisms involved in the regulation of oncogene expression are mostly unknown.

Methods: A region of 1443bp of the functional BCR promoter was studied for transcription factor binding sites through in-silico analysis and Chromatin Immunoprecipitation experiments. BCR and BCR/ABL1 expression levels were analysed in CML cell lines after over-expression or silencing of MYC transcription factor. A luciferase reporter assay was used to confirm its activity on BCR promoter.

Results: In the present study we demonstrate that MYC and its partner MAX bind to the BCR promoter, leading to up-regulation of BCR and BCR/ABL1 at both transcriptional and protein levels. Accordingly, silencing of MYC expression in various BCR/ABL1 positive cell lines causes significant downregulation of BCR and BCR/ABL1, which consequently leads to decreased proliferation and induction of cell death.

Conclusions: Here we describe a regulatory pathway modulating BCR and BCR/ABL1 expression, showing that the BCR promoter is under the transcriptional control of the MYC/MAX heterodimer. Since MYC is frequently over-expressed in BC, this phenomenon could play a critical role in BCR/ABL1 up-regulation and blast aggressiveness acquired during CML evolution.

No MeSH data available.


Related in: MedlinePlus