[Correlation analysis between clinical phenotypes of keloids and polymorphism of p53 gene codon 72]

To observe the effect of gene expression of p53 and the polymorphism of p53 gene codon 72 on clinical phenotype of keloids.

The tissue and blood samples were taken from 35 patients with keloids, 19 males and 16 females, and the course of disease was from 4 months to 8 years. Meanwhile, autologous peripheral blood was collected for genotype analysis. According to the observing scope, the tissue samples of the keloids were divided into 2 groups: the central group involving the central part of the keloids (the central area within two-thirds of the radius) and the peripheral group involving the peripheral part of the keloids (the peripheral area within one-third of the radius). According to the largest diameter of the keloids, the two groups were divided into 3 subgroups: the small size group with 5 patients (< 1 cm), the medium size group with 21 patients (1-3 cm) and the large size group with 9 patients (> 3 cm). DNA of the tissue and blood samples were extracted, and the PCR followed by DNA sequencing was used to detect the polymorphism of p53 gene codon 72. The expression change of P53 was detected by immunohistochemical staining. The fibroblast apoptosis in keloid tissues was detected by TUNEL method.

The genetic genotype of p53 gene codon 72 in keloids included Arg/Arg in 7 cases, Pro/Arg in 21 cases, Pro/ Pro in 7 cases. The significant correlation was found between genotype and clinical phenotype (P < 0.05). Immunohistochemical staining revealed that P53 was detectable in peripheral and central groups of small-medium size keloids and central groups keloids, and detectable in few cells in peripheral groups of large size keloids. The absorbency value was 3 439.359 8 +/- 538.527 5 in Arg/Arg genotype, 3 273.186 2 +/- 375.213 9 in Arg/Pro genotype, 1 691.372 9 +/- 98.989 3 in Pro/Pro genotype. There were significant differences among the three genotypes (P < 0.05). The fibroblast apoptosis was detected by TUNEL, and the apoptotic cells were evenly distributed. The apoptosis index was 31.000 0 +/- 3.266 0 in peripheral group of large size keloids, 42.300 0 +/- 4.354 8 in peripheral group of medium size keloids, 44.600 0 +/- 5.253 6 in peripheral group of small size keloids. There were significant differences among the three groups (P < 0.05).

There is close relationship between the clinical phenotype of keloids and the expression of P53. The polymorphism variation of p53 gene codon 72 is beneficial for apoptosis of fibroblasts in keloids.