Doxorubicin and octreotide induce a 40 kDa breakdown product of p53 in human hepatoma and tumoral colon cell lines

Abstract

The chemotherapeutic drug doxorubicin and the anti-proliferative long-acting somatostatin analogue octreotide, both used in cancer treatment, have been shown to increase the expression of the p53 tumour suppressor protein. In the present study, we demonstrate by Western-blot analysis that, in addition to the p53 protein, these molecules were able to induce the expression of a shorter protein with an apparent molecular mass of 40 kDa (p40), recognized by antibodies raised against the N-terminus of p53. This induction was present in tumoral and non-tumoral cells and did not depend on the status of the endogenous p53 protein. The p40 protein was significantly induced after 3 h of cell treatment with doxorubicin or octreotide, remained stable until 24 h and was located in the nuclear extract. Using reverse primers corresponding to each exon of the p53 gene, only one transcript was amplified by reverse transcriptase-PCR. This suggested that p40 was issued from a post-translational modification and not from an alternative splicing. This protein was not recognized by the PAb421 antibody, suggesting that it was issued from a cleavage of the p53 C-terminal region (p40deltaC). Furthermore, this cleavage was not dependent on caspase activity. In conclusion, these results support the hypothesis that this post-translational modification plays a significant role in the regulation of multiple p53 signalling pathways. These results also suggest that octreotide, a molecule with different signalling pathways, was able as doxorubicin to generate a p53 breakdown product.

p53 Cooperates with Sp1 to Regulate Breed-Dependent Expression of Glucocorticoid Receptor in the Liver of Preweaning Piglets

“…Doxorubicin, a well- known activator of the p53 pathway [44], [45], significantly increased p53 protein content in HepG2 cell lysates, as reported previously in other cell types [46], [47]. The Dox-induced activation of p53 pathway was associated with significantly increased transcriptional activity of porcine GR 1–9/10 promoter and higher content of endogenous GR protein in HepG2 cells.…”

p53 Cooperates with Sp1 to Regulate Breed-Dependent Expression of Glucocorticoid Receptor in the Liver of Preweaning Piglets

“…Doxorubicin, a well- known activator of the p53 pathway [44], [45], significantly increased p53 protein content in HepG2 cell lysates, as reported previously in other cell types [46], [47]. The Dox-induced activation of p53 pathway was associated with significantly increased transcriptional activity of porcine GR 1–9/10 promoter and higher content of endogenous GR protein in HepG2 cells.…”

Fludarabine nucleoside induces accumulations of p53, p63 and p73 in the nuclei of human B‐lymphoid cell lines, with cytosolic and mitochondrial increases in p53

“…We have previously reported that Raji cells treated with 2‐FaraA (3 μM, 48 h) accumulate multiple forms of nuclear p53 with molecular weights of ∼47, 43 and 40 kDa . Similarly, Sadji‐Ouatas et al demonstrated with human hepatoma cells that doxorubicin induces strand breaks in DNA with appearance of an N‐terminal truncated form of p53 of 40 kDa . DNA damage might also lead to formation of low molecular weight derivatives of cytosolic and mitochondrial p53 .…”

Fludarabine Induces Differential Expression of Proteins in Human Leukemia and Lymphoma Cells

“……”

p53 Cooperates with Sp1 to Regulate Breed-Dependent Expression of Glucocorticoid Receptor in the Liver of Preweaning Piglets

“…Doxorubicin, a well- known activator of the p53 pathway [44], [45], significantly increased p53 protein content in HepG2 cell lysates, as reported previously in other cell types [46], [47]. The Dox-induced activation of p53 pathway was associated with significantly increased transcriptional activity of porcine GR 1–9/10 promoter and higher content of endogenous GR protein in HepG2 cells.…”

Fludarabine nucleoside induces accumulations of p53, p63 and p73 in the nuclei of human B‐lymphoid cell lines, with cytosolic and mitochondrial increases in p53

“…We have previously reported that Raji cells treated with 2‐FaraA (3 μM, 48 h) accumulate multiple forms of nuclear p53 with molecular weights of ∼47, 43 and 40 kDa . Similarly, Sadji‐Ouatas et al demonstrated with human hepatoma cells that doxorubicin induces strand breaks in DNA with appearance of an N‐terminal truncated form of p53 of 40 kDa . DNA damage might also lead to formation of low molecular weight derivatives of cytosolic and mitochondrial p53 .…”

Fludarabine Induces Differential Expression of Proteins in Human Leukemia and Lymphoma Cells

“……”

p53 Cooperates with Sp1 to Regulate Breed-Dependent Expression of Glucocorticoid Receptor in the Liver of Preweaning Piglets

“…Doxorubicin, a well- known activator of the p53 pathway [44], [45], significantly increased p53 protein content in HepG2 cell lysates, as reported previously in other cell types [46], [47]. The Dox-induced activation of p53 pathway was associated with significantly increased transcriptional activity of porcine GR 1–9/10 promoter and higher content of endogenous GR protein in HepG2 cells.…”

Fludarabine nucleoside induces accumulations of p53, p63 and p73 in the nuclei of human B‐lymphoid cell lines, with cytosolic and mitochondrial increases in p53

“…We have previously reported that Raji cells treated with 2‐FaraA (3 μM, 48 h) accumulate multiple forms of nuclear p53 with molecular weights of ∼47, 43 and 40 kDa . Similarly, Sadji‐Ouatas et al demonstrated with human hepatoma cells that doxorubicin induces strand breaks in DNA with appearance of an N‐terminal truncated form of p53 of 40 kDa . DNA damage might also lead to formation of low molecular weight derivatives of cytosolic and mitochondrial p53 .…”

Fludarabine Induces Differential Expression of Proteins in Human Leukemia and Lymphoma Cells

“……”