Cancer-testis antigens in canine histiocytic sarcoma and other malignancies

Area of Science:

• Oncology
• Immunology
• Veterinary Medicine

Background:

• Cancer-testis antigens (CTAs) are proteins aberrantly expressed in tumors but not normal tissues, making them ideal immunotherapy targets.
• Few CTAs have been identified in canine hematologic cancers, limiting immunotherapy development in veterinary oncology.
• This study aimed to discover novel CTAs in canine histiocytic sarcoma and lymphoma.

Purpose of the Study:

• To identify novel cancer-testis antigens (CTAs) in canine hematologic cancers.
• To evaluate the potential of these CTAs as targets for canine immunotherapy.
• To foster the development of new cancer treatments for dogs.

Main Methods:

• Mass spectrometry was used to identify peptides presented by the dog leukocyte antigen (DLA)-88*508:01 class I allele in a histiocytic sarcoma cell line.
• Identified peptides were mapped to known human CTAs and proteins with CTA characteristics.
• Quantitative and end-point RT-PCR were employed to assess the expression of candidate CTAs in tumor and normal canine tissues.

Main Results:

• Twenty-two peptides were identified, mapping to 5 human CTAs and 12 other proteins with CTA characteristics.
• The ortholog of IGF2BP3 showed high expression in peripheral blood mononuclear cells (PBMCs).
• NT5C1B was detected in T-cell lymphomas, with limited expression in some normal tissues, suggesting potential as a restricted target. AKR1E2, SPECC1, and TPX2 showed broader expression, limiting their utility.

Conclusions:

• The study demonstrated a feasible 'reverse approach' for discovering canine CTAs, starting from MHC class I-presented peptides.
• NT5C1B emerged as a promising, tissue-restricted candidate CTA for canine hematologic cancers.
• These findings support the development of CTA-based immunotherapies for canine cancers.