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Intracellular CD24 disrupts the ARF-NPM interaction and enables mutational and viral oncogene-mediated p53 inactivation.

Wang L, Liu R, Ye P, Wong C, Chen GY, Zhou P, Sakabe K, Zheng X, Wu W, Zhang P, Jiang T, Bassetti MF, Jube S, Sun Y, Zhang Y, Zheng P, Liu Y - Nat Commun (2015)

Bottom Line: CD24 competitively inhibits ARF binding to NPM, resulting in decreased ARF, increase MDM2 and decrease levels of p53 and the p53 target p21/CDKN1A.CD24 silencing prevents functional inactivation of p53 by both somatic mutation and viral oncogenes, including the SV40 large T antigen and human papilloma virus 16 E6-antigen.In support of the functional interaction between CD24 and p53, in silico analyses reveal that TP53 mutates at a higher rate among glioma and prostate cancer samples with higher CD24 mRNA levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.

ABSTRACT
CD24 is overexpressed in nearly 70% human cancers, whereas TP53 is the most frequently mutated tumour-suppressor gene that functions in a context-dependent manner. Here we show that both targeted mutation and short hairpin RNA (shRNA) silencing of CD24 retard the growth, progression and metastasis of prostate cancer. CD24 competitively inhibits ARF binding to NPM, resulting in decreased ARF, increase MDM2 and decrease levels of p53 and the p53 target p21/CDKN1A. CD24 silencing prevents functional inactivation of p53 by both somatic mutation and viral oncogenes, including the SV40 large T antigen and human papilloma virus 16 E6-antigen. In support of the functional interaction between CD24 and p53, in silico analyses reveal that TP53 mutates at a higher rate among glioma and prostate cancer samples with higher CD24 mRNA levels. These data provide a general mechanism for functional inactivation of ARF and reveal an important cellular context for genetic and viral inactivation of TP53.

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ShRNA silencing of CD24 restores tumour-suppressor activity of cancer-associated p53 mutants.(a) DU145 cells whose endogenous TP53 was silenced were transduced with cDNAs of cancer-associated p53 mutants used in Fig. 8e,f and then cultured in six-well plates in the presence of neomycin for 2 weeks before the colonies were photographed and counted. Representative image of each transfectant is shown. (b) ShRNA silencing of CD24 reactivates the tumour-suppressor activity of p53R273H as assessed by the number of DU145 colonies visualized by crystal violet. Data shown are means and s.d. of triplicate samples and have been normalized against the vector control (artificially defined as 100%) from DU145 cells transduced with either Scr or CD24 ShRNA. The data have been reproduced twice. (c) In silico analysis revealed an association between CD24 levels and TP53 status. The expression and mutational status data were obtained from the TCGA database as detailed in the Methods section. Glioblastoma, low-grade brain glioma and prostate cancer samples were divided into CD24hi (above the mean) and CD24lo (below the mean) groups based on RNA-seq data. The frequencies of the samples with somatic Tp53 mutations were compared using either Pearson’s χ2 tests with correction for low counts of mutant samples in the prostate cancer cohort. CFU, colony-forming unit.
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f10: ShRNA silencing of CD24 restores tumour-suppressor activity of cancer-associated p53 mutants.(a) DU145 cells whose endogenous TP53 was silenced were transduced with cDNAs of cancer-associated p53 mutants used in Fig. 8e,f and then cultured in six-well plates in the presence of neomycin for 2 weeks before the colonies were photographed and counted. Representative image of each transfectant is shown. (b) ShRNA silencing of CD24 reactivates the tumour-suppressor activity of p53R273H as assessed by the number of DU145 colonies visualized by crystal violet. Data shown are means and s.d. of triplicate samples and have been normalized against the vector control (artificially defined as 100%) from DU145 cells transduced with either Scr or CD24 ShRNA. The data have been reproduced twice. (c) In silico analysis revealed an association between CD24 levels and TP53 status. The expression and mutational status data were obtained from the TCGA database as detailed in the Methods section. Glioblastoma, low-grade brain glioma and prostate cancer samples were divided into CD24hi (above the mean) and CD24lo (below the mean) groups based on RNA-seq data. The frequencies of the samples with somatic Tp53 mutations were compared using either Pearson’s χ2 tests with correction for low counts of mutant samples in the prostate cancer cohort. CFU, colony-forming unit.

Mentions: The above data suggested that for a high proportion of p53 mutations, CD24 expression may be a necessary co-factor in cancer development. To explore this possibility, we searched the Cancer Genome Atlas (TCGA) database for a possible association between CD24 overexpression and TP53 mutation in cancer samples. We limited our search to cohorts that meet two criteria. First, both RNAseq and p53 status data are available. Second, the Cd24 RNA levels must show a broad distribution. Three cohorts, including low-grade glioma, glioblastoma and prostate cancer, satisfied both criteria. We divided the cancer samples into CD24hi (with CD24 mRNA above the median) and CD24lo (with CD24 mRNA below the median) and compared the mutation rates. As shown in Fig. 10c, in all three cancer types, we observed a significantly higher rate of TP53 mutation among the CD24hi groups. Based on odds ratio, the mutations TP53 were two to four times more likely to occur in CD24hi group. The association was not due to leukocyte infiltration as the RNA for CD45, a pan-leukocyte marker, did not correlate with either CD24 levels or TP53 mutation rate (Supplementary Fig. 9).


Intracellular CD24 disrupts the ARF-NPM interaction and enables mutational and viral oncogene-mediated p53 inactivation.

Wang L, Liu R, Ye P, Wong C, Chen GY, Zhou P, Sakabe K, Zheng X, Wu W, Zhang P, Jiang T, Bassetti MF, Jube S, Sun Y, Zhang Y, Zheng P, Liu Y - Nat Commun (2015)

ShRNA silencing of CD24 restores tumour-suppressor activity of cancer-associated p53 mutants.(a) DU145 cells whose endogenous TP53 was silenced were transduced with cDNAs of cancer-associated p53 mutants used in Fig. 8e,f and then cultured in six-well plates in the presence of neomycin for 2 weeks before the colonies were photographed and counted. Representative image of each transfectant is shown. (b) ShRNA silencing of CD24 reactivates the tumour-suppressor activity of p53R273H as assessed by the number of DU145 colonies visualized by crystal violet. Data shown are means and s.d. of triplicate samples and have been normalized against the vector control (artificially defined as 100%) from DU145 cells transduced with either Scr or CD24 ShRNA. The data have been reproduced twice. (c) In silico analysis revealed an association between CD24 levels and TP53 status. The expression and mutational status data were obtained from the TCGA database as detailed in the Methods section. Glioblastoma, low-grade brain glioma and prostate cancer samples were divided into CD24hi (above the mean) and CD24lo (below the mean) groups based on RNA-seq data. The frequencies of the samples with somatic Tp53 mutations were compared using either Pearson’s χ2 tests with correction for low counts of mutant samples in the prostate cancer cohort. CFU, colony-forming unit.
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Related In: Results  -  Collection

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f10: ShRNA silencing of CD24 restores tumour-suppressor activity of cancer-associated p53 mutants.(a) DU145 cells whose endogenous TP53 was silenced were transduced with cDNAs of cancer-associated p53 mutants used in Fig. 8e,f and then cultured in six-well plates in the presence of neomycin for 2 weeks before the colonies were photographed and counted. Representative image of each transfectant is shown. (b) ShRNA silencing of CD24 reactivates the tumour-suppressor activity of p53R273H as assessed by the number of DU145 colonies visualized by crystal violet. Data shown are means and s.d. of triplicate samples and have been normalized against the vector control (artificially defined as 100%) from DU145 cells transduced with either Scr or CD24 ShRNA. The data have been reproduced twice. (c) In silico analysis revealed an association between CD24 levels and TP53 status. The expression and mutational status data were obtained from the TCGA database as detailed in the Methods section. Glioblastoma, low-grade brain glioma and prostate cancer samples were divided into CD24hi (above the mean) and CD24lo (below the mean) groups based on RNA-seq data. The frequencies of the samples with somatic Tp53 mutations were compared using either Pearson’s χ2 tests with correction for low counts of mutant samples in the prostate cancer cohort. CFU, colony-forming unit.
Mentions: The above data suggested that for a high proportion of p53 mutations, CD24 expression may be a necessary co-factor in cancer development. To explore this possibility, we searched the Cancer Genome Atlas (TCGA) database for a possible association between CD24 overexpression and TP53 mutation in cancer samples. We limited our search to cohorts that meet two criteria. First, both RNAseq and p53 status data are available. Second, the Cd24 RNA levels must show a broad distribution. Three cohorts, including low-grade glioma, glioblastoma and prostate cancer, satisfied both criteria. We divided the cancer samples into CD24hi (with CD24 mRNA above the median) and CD24lo (with CD24 mRNA below the median) and compared the mutation rates. As shown in Fig. 10c, in all three cancer types, we observed a significantly higher rate of TP53 mutation among the CD24hi groups. Based on odds ratio, the mutations TP53 were two to four times more likely to occur in CD24hi group. The association was not due to leukocyte infiltration as the RNA for CD45, a pan-leukocyte marker, did not correlate with either CD24 levels or TP53 mutation rate (Supplementary Fig. 9).

Bottom Line: CD24 competitively inhibits ARF binding to NPM, resulting in decreased ARF, increase MDM2 and decrease levels of p53 and the p53 target p21/CDKN1A.CD24 silencing prevents functional inactivation of p53 by both somatic mutation and viral oncogenes, including the SV40 large T antigen and human papilloma virus 16 E6-antigen.In support of the functional interaction between CD24 and p53, in silico analyses reveal that TP53 mutates at a higher rate among glioma and prostate cancer samples with higher CD24 mRNA levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.

ABSTRACT
CD24 is overexpressed in nearly 70% human cancers, whereas TP53 is the most frequently mutated tumour-suppressor gene that functions in a context-dependent manner. Here we show that both targeted mutation and short hairpin RNA (shRNA) silencing of CD24 retard the growth, progression and metastasis of prostate cancer. CD24 competitively inhibits ARF binding to NPM, resulting in decreased ARF, increase MDM2 and decrease levels of p53 and the p53 target p21/CDKN1A. CD24 silencing prevents functional inactivation of p53 by both somatic mutation and viral oncogenes, including the SV40 large T antigen and human papilloma virus 16 E6-antigen. In support of the functional interaction between CD24 and p53, in silico analyses reveal that TP53 mutates at a higher rate among glioma and prostate cancer samples with higher CD24 mRNA levels. These data provide a general mechanism for functional inactivation of ARF and reveal an important cellular context for genetic and viral inactivation of TP53.

Show MeSH
Related in: MedlinePlus