Increased activity of insulin-like growth factor-binding protein in human thyroid papillary cancer tissue

IGF Bioregulation System in Benign and Malignant Thyroid Nodular Disease: A Systematic Review

BACKGROUND/AIM

The insulin-like growth factor bioregulation system is implicated in cancer biology. Herein, we aim to review the evidence on the expression of the insulin-like growth factor 1 and 2 (IGF1 and IGF2), their receptors (IGF-Rs) and IGF-binding proteins (IGFBPs) in thyroid tissue and their possible association with benign and malignant thyroid nodular diseases.

MATERIALS AND METHODS

We systematically reviewed Pubmed and Scopus databases up to May 2020. A total of 375 articles were retrieved and analyzed.

RESULTS

Among 375 articles, 45 were included in this systematic review study. IGF1 was investigated in 31 studies, IGF2 in 1, IGF1 receptor in 15 and IGF-binding proteins in 13 articles. IGF1 expression in humans was dependent on the number and compound of benign nodules as well as the method of measurement. In differentiated thyroid carcinoma, a positive correlation between IGF1 and immunohistological stage was documented in some studies while in others only a positive trend was observed. IGF-1R and IGFBPs expression was higher in malignant rather than benign lesions. There was only a positive trend for increased IGF2 expression in malignancy, while IGFBPs were in most studies statistically increased in various cancer types compared to benign nodular disease.

CONCLUSION

The present data demonstrate that in most studies there is statistically positive expression of IGF-1 and less of IGF-2 in thyroid cancer compared to normal thyroid tissue.

Microarray technology to investigate genes associated with papillary thyroid carcinoma

DNA microarray data on thyroid tissue from patients with papillary thyroid carcinoma (PTC) and from healthy controls were compared in order to investigate the regulatory genes and uncover the underlying regulatory network in PTC. The DNA microarray data set, GSE3678, was downloaded from Gene Expression Omnibus database. This included seven thyroid tissue samples from patients with PTC and seven samples from healthy controls. Raw data were processed and differentially expressed genes (DEGs) were identified using corresponding R packages. Gene regulation analysis was conducted using TRANSFAC® and TRED. A total of 171 DEGs were obtained. A regulatory network was then established, using 104 of the DEGs. Subsequently, pathway enrichment analyses of the genes were conducted using Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. Three differentially expressed transcription factors were identified: Trefoil factor 3, cut‑like homeobox 2 and forkhead box protein A2. The most significant pathways involving the 104 DEGs were pathways involved in cancer. Biological process analysis using DAVID, suggested that these genes were associated with the positive regulation of gene expression, gene transcription and metabolic processes. The present study identified a range of genes associated with the development of PTC. The results of the present study were beneficial for understanding the regulatory mechanisms involved in PTC, and for developing clinical diagnostic and therapeutic approaches for this disease.

Expression and significance of IGF-1 and IGF-1R in thyroid nodules

There are limitations in the diagnosis of thyroid nodules, especially follicular lesions, and their pathogenesis remains unclear. Insulin-like growth factor-1 (IGF-1) has been implicated in tumor cell apoptosis, transformation, invasion, and metastasis; however, its role in thyroid nodules is undetermined. The aim of this study is to investigate the relationship between expression of IGF-1 and thyroid nodule, and evaluate the role of IGF-1 in differential diagnosis and pathogenetic function of benign and malignant thyroid nodules. Sixty-two paraffin-embedded thyroid tissues from patients with thyroid nodules were selected, including 18 follicular adenomas (FA), 17 nodular goiters, 13 papillary thyroid carcinomas (PTC), 2 follicular thyroid carcinomas, and 12 normal controls. IGF-1 and IGF-1R protein and mRNA expression was detected by immunohistochemistry (IHC) and real-time quantitative PCR (qRT-PCR), respectively. Grouping comparisons were employed among the above groups based on the clinical and pathological subtypes. IGF-1 and IGF-1R expression was significantly higher in FA, nodular goiters, and PTC than that in the controls (all P < 0.01). Similarly, IGF-1 mRNA expression was also significantly higher in FA (P < 0.05), nodular goiters (P < 0.01), and PTC (P < 0.01) compared with the controls. IGF-1R mRNA expression was also significantly higher in FA, nodular goiters, and PTC (all P < 0.01) compared with the controls. Compared with FA and nodular goiters, PTC showed significantly higher IGF-1 and IGF-1R protein (P < 0.01, P < 0.05, respectively) and mRNA expression (P < 0.01, P < 0.05, respectively). IGF-1 probably plays an important role in the genesis and development of certain solid cold thyroid nodules, including PTC, nodular goiters, and FA. Detection of IGF-1 and IGF-1R expression in thyroid tissues by IHC or qRT-PCR is hard to distinguish malignant from benign lesions.

Insulin-like growth factor 1 expression in thyroid tumors

Insulin-like growth factor 1 (IGF-1) likely is involved in thyrocyte proliferation via autocrine mechanisms, but limited data are available on its in vivo expression in thyroid neoplasms. This prompted us to explore IGF-1 expression at the protein and mRNA levels and IGF-1 receptor (IGF-1rec) immunoreactivity in normal and neoplastic thyroids (50 adenomas and 53 carcinomas). We documented increased IGF-1 and IGF-1rec immunoreactivity in adenomas (31 of 50 and 40 of 50 cases, respectively) and carcinomas (38 of 53 and 42 of 53 cases) compared with normal thyroid, which only showed minimal immunoreactivity for the ligand and its receptor. A corresponding up-regulation of IGF-1 mRNA was documented in carcinomas, whereas adenomas exhibited down-regulated expression of IGF-1 mRNA. Immunoreactivity for IGF-1 and cognate receptor positively correlated with tumor diameter and wide intrathyroidal extension but not with patients' gender and age or with the stage of the tumors and the occurrence of lymph node metastases. These data emphasize a possible role of the IGF-1 system in thyroid tumorigenesis, as indicated by in vitro studies. In addition, the evaluation of IGF-1 and IGF-1rec immunoreactivity might have clinical implications, because it positively correlates with the aggressiveness of these tumors.