Defective HLA class I antigen processing machinery in cancer

Area of Science:

• Immunology
• Oncology
• Molecular Biology

Background:

• Malignant transformation often involves defects in human leukocyte antigen (HLA) class I antigen processing machinery (APM) component expression.
• These HLA class I APM abnormalities can hinder tumor cell recognition by T cells.
• Such defects are linked to poor prognosis and resistance to immune checkpoint inhibitor (ICI) immunotherapy in various cancers.

Purpose of the Study:

• To review literature on HLA class I APM component expression abnormalities in diverse cancer types.
• To elucidate the molecular mechanisms behind these expression and function defects.
• To discuss the clinical significance of HLA class I APM abnormalities in malignant tumors.

Main Methods:

• Literature review of studies reporting HLA class I APM component expression in cancer.
• Analysis of reported frequencies of these abnormalities across different cancer types.
• Synthesis of information on molecular mechanisms and clinical implications.

Main Results:

• Abnormalities in HLA class I APM component expression are prevalent across all analyzed cancer types.
• Reported frequencies range from 35.8% in renal cancer to 87.9% in thyroid cancer for HLA class I heavy chains.
• Molecular mechanisms underlying these defects and their clinical significance were detailed.

Conclusions:

• Defective HLA class I APM component expression is a common feature in cancer.
• These defects have functional, prognostic, and therapeutic implications, particularly in immunotherapy.
• Understanding these abnormalities is crucial for improving cancer treatment strategies.