P16 Expression And The C-Kit Gene Mutation Of The Small Gastrointestinal Stromal Tumor In Stomach

[Background] Gastrointestinal stromal tumors(GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract that account for 80% of all gastrointestinal mesenchymal tumor. According to the tumor size, mitotic index and location, GISTs can be divided into very low, low, intermediate, high risk category respectively. Small GISTs defined as less than 2.0cm in diameter. Overt-GISTs defined as larger than 2.0cm in diameter. The clinical manifestations, biology behavior, genetics and prognosis between small GISTs and overt-GISTs are obviously different. The characteristic of the C-Kit mutation frequency and mutation type between small GISTs and overt-GISTs is controversial.P16 as an important tumor suppressor gene, the study on the relationship between the p16 expression and the clinical pathological characteristics of GISTs was still in the stage of superficial. [Purposes] Observe the clinical pathological features of the different size of the GISTs, discuss the difference of the C-Kit mutation and P16 expression between small GISTs and overt-GISTs. [Methods] A cohort of 200 GISTs cases were accrued from the First Affiliated Hospital of Fujian Medical University from January 2006 and December 2014, including 124 overt-GISTs examples,76 Small GISTs examples. Observe the different size of the GISTs for the clinical pathological morphology and immunohistochemical staining of P16 protein, direct sequencing method to detect the characteristics of C-Kit gene exon 9,11,13,17 mutations. [Results] 1. The GISTs in male incidence is slightly higher than the female, in small GISTs, the mean age of onset is relatively higher than the overt-GISTs. 3.The rate of C-Kit11 mutation in GISTs is47/100(47.00%).There was no significant difference of C-Kit11 gene mutation frequency between the overt-GISTs and small GISTs[26/50(52%)vs21/50(42%)].The main mutation type is point mutation(29%),followed by deleted mutation(12%),complex deletions/insertions detected only in the overt-GISTs. 4. C-Kit-11 exon mutation in the second half stomach GISTs are more than in the upper stomach. 5. No discover the mutation of C-Kit exon 9, 13, 17 in the 50 small GISTs and 50 the overt-GISTs. 6.The P16 positive staining rate of the GISTs in stomach is 51%, the frequency of the expression of the P16 protein in overt-GISTs is significantly higher than in small GISTs. The P16 expression of occur in the upper stomach GISTs is higher than in the second half stomach. [Conclusion] 1. GISTs happen in each part of stomach did not exite different. The morphology is similarity in the overt-GISTs and the small GISTs, but in stromal reaction, the overt-GISTs are more prone to myxoid change, and the small GISTs is often appear dystrophic calcification. The small GISTs stromal reaction arise dystrophic calcification tips it is associated with the block development of GISTs. 2 More than half of the GISTs express the P16 protein, the expression of P16 has an impact on the malignant transformation of GISTs. 3 There was no significant difference of C-Kit-11 gene mutation frequency between the overt-GISTs and the small GISTs, the mutation rate of C-Kit exon9, 13 and 17 is very low. 4 The morphology is similarity in the overt-GISTs and the small GISTs, but the drive gene C-Kit exon9, 11, 13 and 17 mutation is not obvious difference, whether suggests they may be other key signaling pathways in promoting the progress of GISTs deserves further research.