Requirement of wild-type p53 protein for maintenance of chromosomal integrity

Abstract

Chromosomal double‐strand breaks (DSBs) occurring in mammalian cells can initiate genomic instability, and their misrepairs result in chromosomal deletion, amplification, and translocation, common findings in human tumors. The tumor‐suppressor protein p53 is involved in maintaining genomic stability. In this study, we demonstrate that the deficiency of wild‐type p53 protein may allow unrepaired DSBs to initiate chromosomal instability. The human lymphoblastoid cell line TK6‐E6 was established by transfection with human papilloma virus 16 (HPV16) E6 cDNA into parental TK6 cells via a retroviral vector. Abrogation of p53 function by E6 resulted in an increase in the spontaneous mutation frequencies at the heterozygous thymidine kinase (TK) locus but not at the hemizygous hypoxanthine phosphoribosyl transferase (HPRT) locus. Almost all TK‐deficient mutants from TK6‐E6 cells exhibited loss of heterozygosity (LOH) with the hemizygous TK allele. LOH analysis with microsatellite loci spanning the long arm of chromosome 17, which harbors the TK locus, showed that LOH extended over half of 17q toward the terminal end. Cytogenetic analysis of LOH mutants by chromosome painting indicated a mosaic of chromosomal aberrations involving chromosome 17, in which partial chromosome deletions, amplifications, and multiple translocations appeared heterogeneously in a single mutant. We speculate that spontaneous DSBs trigger the breakage‐fusion bridge cycle leading to such multiple chromosome aberrations. In contrast, no chromosomal alterations were observed in TK‐deficient mutants from TK6‐20C cells expressing wild‐type p53. In wild‐type p53 cells, spontaneous DSBs appear to be promptly repaired through recombination between homologous chromosomes. These results support a model in which p53 protein contributes to the maintenance of genomic integrity through recombinational repair. Mol. Carcinog. 28:203–214, 2000. © 2000 Wiley‐Liss, Inc.

BAP1 depletion in human B‐lymphoblast cells affects the production of innate immune cytokines and chemokines

“…BAP1 KO cells did not show significant increases of mutants and there was no obvious loss of DNA repair capacity (data not shown). This is in contrast with the results of the p53 function by HPV16 E6 gene or BLM KO experiments by Honma et al (2000) and Suzuki et al (2016).…”

BAP1 depletion in human B‐lymphoblast cells affects the production of innate immune cytokines and chemokines

“…BAP1 KO cells did not show significant increases of mutants and there was no obvious loss of DNA repair capacity (data not shown). This is in contrast with the results of the p53 function by HPV16 E6 gene or BLM KO experiments by Honma et al (2000) and Suzuki et al (2016).…”

Cisplatin resistance conferred by the RAD51D (E233G) genetic variant is dependent upon p53 status in human breast carcinoma cell lines

“…We have previously demonstrated that the cell inviable phenotype conferred by a Rad51d ‐deletion was rescued by disruption of the Trp53 tumor suppressor gene, suggesting that Rad51d functions are monitored by p53 3. Cell‐based recombination, protein association studies and biochemical analyses provide strong evidence of a role for p53 in the maintenance of chromosomal integrity by repression of abnormal HR levels 17–22. The data presented here strongly suggest that the RAD51D (E233G) genetic variant impacts a p53‐regulated cellular function of RAD51D that affects cisplatin resistance and cell growth.…”

Role of genetic background in induced instability

“…An extensive characterization of the positive correlation between reduced levels of normal TP53 and several instability end points has been demonstrated in human cell lines (Honma et al, 1997(Honma et al, , 2000Schwartz et al, 2001;Leger and Drobetsky, 2002). Further work using unstable clones from the human chromosome 4 hamster-hybrid system (GM10115) has shown that the radiosensitive phenotype was related to the efficiency of DNA repair (Limoli et al, 2001), supporting earlier results in GADD45 À/À mice.…”

BAP1 depletion in human B‐lymphoblast cells affects the production of innate immune cytokines and chemokines

“…BAP1 KO cells did not show significant increases of mutants and there was no obvious loss of DNA repair capacity (data not shown). This is in contrast with the results of the p53 function by HPV16 E6 gene or BLM KO experiments by Honma et al (2000) and Suzuki et al (2016).…”

Cisplatin resistance conferred by the RAD51D (E233G) genetic variant is dependent upon p53 status in human breast carcinoma cell lines

“…We have previously demonstrated that the cell inviable phenotype conferred by a Rad51d ‐deletion was rescued by disruption of the Trp53 tumor suppressor gene, suggesting that Rad51d functions are monitored by p53 3. Cell‐based recombination, protein association studies and biochemical analyses provide strong evidence of a role for p53 in the maintenance of chromosomal integrity by repression of abnormal HR levels 17–22. The data presented here strongly suggest that the RAD51D (E233G) genetic variant impacts a p53‐regulated cellular function of RAD51D that affects cisplatin resistance and cell growth.…”

Role of genetic background in induced instability

“…An extensive characterization of the positive correlation between reduced levels of normal TP53 and several instability end points has been demonstrated in human cell lines (Honma et al, 1997(Honma et al, , 2000Schwartz et al, 2001;Leger and Drobetsky, 2002). Further work using unstable clones from the human chromosome 4 hamster-hybrid system (GM10115) has shown that the radiosensitive phenotype was related to the efficiency of DNA repair (Limoli et al, 2001), supporting earlier results in GADD45 À/À mice.…”

BAP1 depletion in human B‐lymphoblast cells affects the production of innate immune cytokines and chemokines

“…BAP1 KO cells did not show significant increases of mutants and there was no obvious loss of DNA repair capacity (data not shown). This is in contrast with the results of the p53 function by HPV16 E6 gene or BLM KO experiments by Honma et al (2000) and Suzuki et al (2016).…”

Cisplatin resistance conferred by the RAD51D (E233G) genetic variant is dependent upon p53 status in human breast carcinoma cell lines

“…We have previously demonstrated that the cell inviable phenotype conferred by a Rad51d ‐deletion was rescued by disruption of the Trp53 tumor suppressor gene, suggesting that Rad51d functions are monitored by p53 3. Cell‐based recombination, protein association studies and biochemical analyses provide strong evidence of a role for p53 in the maintenance of chromosomal integrity by repression of abnormal HR levels 17–22. The data presented here strongly suggest that the RAD51D (E233G) genetic variant impacts a p53‐regulated cellular function of RAD51D that affects cisplatin resistance and cell growth.…”

Role of genetic background in induced instability

“…An extensive characterization of the positive correlation between reduced levels of normal TP53 and several instability end points has been demonstrated in human cell lines (Honma et al, 1997(Honma et al, , 2000Schwartz et al, 2001;Leger and Drobetsky, 2002). Further work using unstable clones from the human chromosome 4 hamster-hybrid system (GM10115) has shown that the radiosensitive phenotype was related to the efficiency of DNA repair (Limoli et al, 2001), supporting earlier results in GADD45 À/À mice.…”