HLA-G is differentially expressed in thyroid tissues

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Human Leukocyte Antigen-G (HLA-G) is a nonclassical MHC molecule with immunomodulatory functions.
• Increased HLA-G expression in tumors is often linked to tumor progression and reduced patient survival.
• The role of HLA-G in thyroid cancer warrants detailed investigation.

Purpose of the Study:

• To evaluate HLA-G expression in various thyroid tissue types, including normal, goiter, benign, and malignant tumors.
• To correlate HLA-G expression levels with clinicopathological variables in thyroid cancer patients.

Main Methods:

• Immunohistochemistry was used to assess HLA-G expression in 72 papillary thyroid carcinomas (PTC), 19 follicular thyroid carcinomas (FTC), 22 follicular adenomas (FA), 22 colloid goiters (CG), and 14 normal thyroid glands (NT).
• HLA-G staining intensity was graded, and the percentage of stained tumor area was quantified.
• Statistical analysis was performed to compare HLA-G expression across different tissue types and correlate it with clinical data.

Main Results:

• HLA-G expression was significantly higher in PTC, FTC, and FA compared to NT and CG (p<0.001).
• Tumor area with HLA-G expression was larger in FTC (p=0.0059) and PTC (p=0.0330) than in FA.
• Papillary thyroid carcinoma tumors larger than 1 cm showed increased HLA-G staining (p=0.03), and aggressive subtypes had higher median stained tumor area.

Conclusions:

• A progressive increase in HLA-G expression was observed from hyperplasia to carcinomas.
• Strong HLA-G staining correlated with variables associated with poor prognosis in thyroid cancer.
• These findings support an unfavorable role for HLA-G in thyroid tumors, potentially by inhibiting cytotoxic immune cells and promoting tumor progression.