HLA-G 3'UTR polymorphisms associated with a greater magnitude of HLA-G production were associated with differentiated thyroid tumours and with variables implicated in poor prognosis. These findings corroborate the unfavourable role of HLA-G in thyroid cancer.

Background Increasing evidence shows that chronic inflammation plays an important role in thyroid tumorigenesis. Cytokines as central mediators in inflammatory microenvironment can present both pro‐tumour and anti‐tumour effects and cytokine release may be influenced by soluble HLA‐G (sHLA‐G), an immune checkpoint molecule whose expression can also be induced by certain cytokines. Aim To understand the role of these soluble factors in papillary thyroid cancer (PTC). Methods We evaluated plasma levels of sHLA‐G and of 13 cytokines using ELISA and flow cytometry, respectively, in PTC patients at two time points: pre‐ and post‐thyroidectomy; and control subjects. Results Compared with controls, IL‐6 levels were increased, while IL‐1β, IFN‐α and TGF‐β1 levels were decreased in pre‐thyroidectomy PTC patients. IFN‐α and TGF‐β1 efficiently discriminated patients from controls and were associated with extrathyroidal extension and lymph node metastasis, respectively. In addition, TNF and IL‐13 were associated with male gender, lymph node metastasis and Hashimoto thyroiditis, and sHLA‐G with tumour invasion. Compared with pre‐thyroidectomy, IL‐4, IL‐10, TNF, IFN‐α and TGF‐β1 levels were increased in post‐thyroidectomy. Conclusion There are significant changes in the cytokine profile after surgical removal of the thyroid tumour, and IFN‐α e TGF‐β1 showed to be promising cytokines for discriminating PTC patients from controls. We also found that different cytokines are associated with clinicohistopathological characteristics of PTC related to poor prognosis, suggesting that cytokines seem to play an important role in PTC development and management.

Aim: To evaluate HLA-G coding and regulatory (promoter and 3' untranslated region-3'UTR) haplotypes in papillary thyroid carcinoma (PTC) patients and their associations with clinical and histopathological features. Methods: We studied 185 PTC patients and polymorphic sites distributed along the three different HLA-G gene regions were characterized by Sanger sequencing. HLA-G haplotype associations were analyzed using the Fisher exact test, calculating odds ratio (OR), confidence interval (CI) andP-values. Results: More than 90 variation sites were observed along the whole gene. Considering the promoter region, i) 010101d haplotype was less frequent in patients presenting classical histological variant of PTC (OR = 0.2789, CI 95% = 0.0755-1.0304, P = 0.0499), ii) 0104a haplotype was less frequent in patients presenting tumor multicentricity (OR = 0.3360, CI 95% = 0.1446-0.7810, P = 0.0089), and iii) 0103a haplotype was more frequent in patients presenting advanced stage of PTC at diagnosis (TNM staging III and IV) (OR = 0.3541, CI 95% = 0.1360-0.9219, P = 0.0370). Regarding the coding region, the GÃ01:01:12 (+324G) allele was associated with the presence of tumor multicentricity (OR = 11.2857, CI 95% = 1.3438-94.7784, P = 0.0094) and Hashimoto's thyroiditis (OR = 6.4851, CI 95%=1.2383-33.9649, P = 0.0224). At 3'UTR, the UTR-02 haplotype was overrepresented (OR = 1.6759, CI 95% = 1.0616-2.6456, P = 0.0328) and UTR-03 haplotype was underrepresented (OR = 0.4106, CI 95% = 0.1912-0.8815, P = 0.0200) in patients presenting tumor multicentricity. No association regarding tumor size, local invasion, metastasis at diagnosis and extrathyroidal extension was observed. Conclusions: Although HLA-G is expressed in more than 80% of PTC specimens, HLA-G alleles were primarily associated with tumor morbidity, indicating that local factors may transcriptional and posttranscriptionally modulate HLA-G expression.

Human leukocyte antigen (HLA)-G is an immune checkpoint molecule that is highly expressed in papillary thyroid carcinoma (PTC). The HLA-G gene presents several functional polymorphisms distributed across the coding and regulatory regions (5′URR: 5′ upstream regulatory region and 3′UTR: 3′ untranslated region) and some of them may impact HLA-G expression and human malignancy. To understand the contribution of the HLA-G genetic background in PTC, we studied the HLA-G gene variability in PTC patients in association with tumor morbidity, HLA-G tissue expression, and plasma soluble (sHLA-G) levels. We evaluated 185 PTC patients and 154 healthy controls. Polymorphic sites defining coding, regulatory and extended haplotypes were characterized by sequencing analyses. HLA-G tissue expression and plasma soluble HLA-G levels were evaluated by immunohistochemistry and ELISA, respectively. Compared to the controls, the G0104a(5′URR)G*01:04:04(coding)UTR-03(3’UTR) extended haplotype was underrepresented in the PTC patients, while G0104a(5′URR)G*01:04:01(coding)UTR-03(3′UTR) was less frequent in patients with metastatic and multifocal tumors. Decreased HLA-G tissue expression and undetectable plasma sHLA-G were associated with the G010102a(5′URR)G*01:01:02:01(coding)UTR-02(3′UTR) extended haplotype. We concluded that the HLA-G variability was associated with PTC development and morbidity, as well as the magnitude of the encoded protein expression at local and systemic levels.