The Study Of HRPT2 Mutations And Differential Expression Of Parafibromin In Sporadic Parathyroid Neoplasias

Objective The purpose of this study is 1. To investigate the relationship between HRPT2 and PC via direct sequencing of HRPT2; 2. To analyze the relationships between the HRPT2 mutations and clinical phenotypes in PC; 3. To detect the expression of Parafibromin encoded by HRPT2 tumor suppressor gene in parathyroid neoplasias, and to investigate whether it can be a tumor marker for identifying PC; 4. To analyze the relationships between the expression of Parafibromin and clinical phenotypes of PC.Subjects and design Paraffin-imbedding tissues of 21 primary PC from 19 patients with sporadic parathyroid carcinoma (PC),21 patients with sporadic parathyroid adenoma (PA), 7 patients with parathyroid hyperplasia (PH) were collected in Peking Unit Medical University Hospital(PUMCH) from 1980 to 2009,6 normal parathyroid(NP) paraffin-imbedding tissues as normal control. Twelve of PC patients'peripheral blood (PB) were collected. DNA was abstracted from the patients' PBs and paraffin-imbedding tissues. The 17 exons and slicing of HRPT2 gene were amplified by PCR, and the amplification productions were analyzed via direct sequencing. The relationships between HRPT2 mutations and pathologic category of parathyroid tumor and pathologic characteristics were analyzed. And Parafibromin immunostainings were performed via immunohistochemistry in paraffin imbedding parathyroid specimens, and the relationships between Parafibromin expression and pathologic category of parathyroid tumor and pathologic characteristics were performed.Results In PC, the result of DNA detection have shown that 6 (46.15%) mutations of heterozygosity of HRPT2 gene can be detected in tissue DNA from 13 PCs, including 2 nonsense mutations and 4 frameshift mutations,4/6(66.67%) can be ascertained as germline mutations among them, the other two cannot be determined.4 (33.33%) peripheral blood (PB) DNA of 12 PCs can be detected HRPT2 mutations. HRPT2 mutation is related with recurrence and metastasis (p<0.001). No mutation has been detected in benign parathyroid tumors. There was a significant difference in Parafibromin expressions between PCs and PAs/PHs/NPs(p<0.001), the sensitivity is 61.90%, the specificity is 96.43%. Combining detection of HRPT2 and Parafibromin, the sensitivity of diagnose for parathyroid carcinoma reaches to 92.31%, the specificity is 95.00%.Conclusion The HRPT2 mutations are common in PC. HRPT2 mutation is one of the pathogeny of PC. And HRPT2 mutation is related with the recurrence in PC. It is valuable for diagnose of PC to detect HRPT2 in early stage and postoperative following up. And it is necessary to follow up the patients carrying HRPT2 mutation and their family members. Loss of Parafibromin Expression and HRPT2 mutations had higher sensitivity and specificity for diagnose of PCs. So, it is valuable for differentiation of PC to detect Parafibromin and HRPT2 gene in the early stage.