Expression of growth differentiation factor 15 in papillary thyroid carcinoma and its clinical significance / 肿瘤研究与临床

ABSTRACT

Objective:To investigate the expression and clinical significance of growth differentiation factor 15 (GDF-15) in papillary thyroid carcinoma (PTC).Methods:The tumor tissues and metastatic lymph node tissues of 3 PTC patients who underwent radical surgery of thyroid cancer in the First Hospital of Hunan University of Chinese Medicine from January to February 2019 were collected, and the differential expressed genes were screened by high-throughput sequencing; 20 cases of primary tumor tissues and metastatic lymph node tissues were collected to verify the sequencing results. Another 20 cases of primary PTC tissues and adjacent tissues (>2 cm away from the tumor edge) were collected to verify the expression of target genes in tumor tissues and adjacent tissues. Sixty-four pathological specimens of PTC patients who underwent radical surgery of thyroid cancer in the First Hospital of Hunan University of Chinese Medicine from January to December 2014 were collected, of which 31 patients had lymph node metastasis. The real-time fluorescent quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of GDF-15 and verify the sequencing results; immunohistochemistry was used to detect the expression of GDF-15 protein in the primary PTC tissues, adjacent tissues and metastatic lymph node tissues. According to the expression of GDF-15 protein in the primary tumor tissues of PTC patients, the patients were divided into high-expression group (35 cases) and low-expression group (29 cases), and the relationship between GDF-15 expression level and clinicopathological characteristics of patients was analyzed; Kaplan-Meier method was used to analyze the 5-year tumor-free survival rate of the two groups.Results:The mRNA high-throughput sequencing results of 3 cases of PTC primary and metastatic tissues showed that the top 10 differential expressed genes were CDH2, CDF15, DKK1, GLIPR1, PCDH7, ID3, FBN1, MYPN, UBASH3B and CCDC80. The expression of GDF-15 mRNA in 20 cases of PTC primary tumor tissues and adjacent tissues were 4.1±0.5 and 2.8±0.3, and the difference was statistically significant ( t = 2.220, P = 0.032). The expression of GDF-15 mRNA in another 20 cases of PTC primary tumor tissues and metastatic lymph node tissues were 3.1±0.4 and 5.8±0.7, and the difference was statistically significant ( t = 3.556, P = 0.001). The results of immunohistochemistry showed that GDF-15 had the immunohistochemical scores of (4.0±0.3) points, (6.1±0.3) points and (9.0±0.4) points in PTC adjacent tissues, primary tumor tissues and metastasis tissues. The expressions of GDF-15 protein between PTC primary tumor tissues and adjacent tissues, metastatic tissues and adjacent tissues, and metastatic tissues and primary tumor tissues were significantly different (all P < 0.01). The differences in composition ratios of tumor long-axis diameter, tumor T stage and N stage between GDF-15 high-expression group and low-expression group were statistically significant (all P<0.05). The 5-year tumor-free survival rates in GDF-15 high-expression group and low-expression group were 60% and 83%, and the difference was statistically significant ( P = 0.033). Conclusions:The expressions of GDF-15 in PTC adjacent tissues, tumor tissues and metastatic lymph node tissues gradually increase, and its expression level is related to tumor progression, recurrence and metastasis. It can be used as a potential clinical prognostic warning molecule and therapeutic target.