Expression of MAGE-A4 and MAGE-C1 tumor-associated antigen in benign and malignant thyroid diseases

Pan-Cancer Analysis of Patient Tumor Single-Cell Transcriptomes Identifies Promising Selective and Safe Chimeric Antigen Receptor Targets in Head and Neck Cancer

Chimeric antigen receptor (CAR) T cell therapies have yielded transformative clinical successes for patients with blood tumors, but their full potential remains to be unleashed against solid tumors. One challenge is finding selective targets, which we define intuitively to be cell surface proteins that are expressed widely by cancer cells but minimally by healthy cells in the tumor microenvironment and other normal tissues. Analyzing patient tumor single-cell transcriptomics data, we first defined and quantified selectivity and safety scores of existing CAR targets for indications in which they are in clinical trials or approved. We then sought new candidate cell surface CAR targets that have better selectivity and safety scores than those currently being tested. Remarkably, in almost all cancer types, we could not find such better targets, testifying to the near optimality of the current target space. However, in human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSC), for which there is currently a dearth of existing CAR targets, we identified a total of twenty candidate novel CAR targets, five of which have both superior selectivity and safety scores. These newly identified cell surface targets lay a basis for future investigations that may lead to better CAR treatments in HNSC.

Expression of cancer/testis antigens MAGE-A, MAGE-C1, GAGE and CTAG1B in benign and malignant thyroid diseases

Despite considerable advances in the understanding of thyroid gland biology, correctly diagnosing thyroid nodules and treating high-grade thyroid carcinoma remains challenging. Cancer/testis (CT) antigens have emerged as potential diagnostic tools as well as targets of potential cancer vaccinations. In the present study, a total of 117 patients who underwent surgical therapy for thyroid disease were available for analysis. The expression levels of melanoma-associated antigen (MAGE) A, MAGE-C1/CT7, cancer/testis antigen 1B (CTAG1B) and G antigen (GAGE) were analyzed by immunohistochemistry. None of the CT antigens were expressed in the normal thyroid or goiter. In papillary and follicular carcinoma, MAGE-A was present in 8.1% of cases, GAGE in 10.8% and CT/7MAGE-C1 and CTAG1B in 2.7% each. In medullary carcinoma, CT antigen expression was as follows: MAGE-A in 42.9% of patients; MAGE-C1/CT7 in 46.5%; GAGE in 92.9%; and CTAG1B in 3.6%. A statistically significant association was observed between the expression of G MAGE-C1/CT7 and patient gender as well as patient clinical stage (P=0.029 and 0.031, respectively). In poorly differentiated and anaplastic carcinoma cases, CT antigen expression was as follows: MAGE-A in 61.8% of cases; MAGE-C1 in 57.1%; GAGE in 66.7%; and CTAG1B in 14.4%. There was a statistically significant association between expression of GAGE and gender (P=0.043). However, there was no association between CT antigen expression and patient survival in any of the tumor entities analyzed. The current study identified a distinct expression pattern of CT antigens in malignant thyroid tumors indicating that CT antigens have the potential to outperform existing thyroid cancer biomarkers. The prevalence of CT antigens in high-grade carcinomas suggests that they serve an important biological role within malignant tumors.

Potential role of 5-aza-2'-deoxycytidine induced MAGE-A4 expression in immunotherapy for anaplastic thyroid cancer

BACKGROUND

Melanoma antigen gene family (MAGE)-A4, a member of the cancer testis antigen family, has been reported in various cancers including melanoma, bladder, head and neck, oral, and lung, and is a potential target for T-cell-receptor-based immunotherapy. Baseline expression levels of the MAGE-A4 gene in thyroid cancer cell lines have not been previously studied thoroughly.

METHODS

Human thyroid cancer cell lines (8505c, HTh7, BCPAP, and TPC-1) were treated with either 10 μmol/L 5'-azacytidine (Aza) or 10 μmol/L 5-AZA-2'deoxycytidine (DAC) and evaluated for various MAGEA gene expression. Later melanoma cell lines A375 and 8505c were treated with PLX4720 in combination with DAC and evaluated for MAGE-A4 expression.

RESULTS

Only BCPAP cells expressed moderate levels of MAGE-A3 and MAGE-A6 at baseline. Treatment with DAC/Aza induced the expression of MAGE-A4 and MAGE-A1 in 8505c cells. PLX4720 treatment did not affect MAGE-A4 expression in 8505c cells, but increased its expression in A375 cells. In contrast, addition of PLX4720 to DAC-treated 8505c cells decreased the previously induced MAGE-A4 expression by DAC in these cells. A similar decrease in MAGE-A4 expression by DAC was also seen in 8505cBRAF(-/-) cells. Although DAC treatment resulted in demethylation of the MAGE-A4 promoter in 2 CpG sites, PLX addition to DAC did not affect the demethylation status.

CONCLUSION

Demethylating agents increased the expression of MAGE genes in thyroid cancer cells. The effect of BRAFV600E inhibitors on MAGE-A4 expression suggest the role of downstream MEK/BRAF signaling in its expression apart from promoter demethylation being the sole requirement. Expression of MAGE-A4 may make immunotherapeutic intervention possible in selected patients with thyroid cancer.