Single nucleotide polymorphism profiles of canine T-cell and null-cell lymphomas

Abstract

Background: The histopathological classification of T-cell lymphoma (TCL) in humans has distinctive mutational genotyping that suggests different lymphomagenesis. A similar concept is assumed to be observed in dogs with different TCL phenotypes.

Objective: This study aimed to identify the previously reported single-nucleotide polymorphisms (SNPs) in both human beings and dogs in canine TCLs and null-cell lymphomas (NCLs) and to design compatible oligonucleotides from each variant based on the multiplex polymerase chain reaction.

Methods: Genomic DNA was extracted from 68 tumor specimens (62 TCLs and 6 NCLs) and 5 buffy coat samples from dogs with TCL. Four TCL subtypes and NCL were analyzed in 44 SNPs from 21 genes using the MassARRAY.

Results: The greatest incidences of SNPs observed in all TCL subtypes and NCL ware SATB1 c.1259A > C, KIT c.1275A > G, SEL1L c.2040 + 200C > G, and TP53 c.1024C > T, respectively. Some SNP locations were statistically significant associated with NCL, including MYC p.S75F (p = 0.0003), TP53 p.I149N (p = 0.030), PDCD1 p.F37LX (p = 0.012), and POT1 p.R583* (p = 0.012).

Conclusion: Each TCL histological subtype and NCL are likely to contain distinctive mutational genetic profiles, which might play a role in lymphoma gene-risk factors and might be useful for selecting therapeutic target drugs for each canine patient.

Keywords: SNPs; cutaneous T-cell lymphoma; dog; intestinal T-cell lymphoma; nodal T-cell lymphoma; null-cell lymphoma.

Figure 1

Nodal null-cell lymphoma. (A) The nuclei of neoplastic cells are large >2× of a red blood cell, finely stipple to vesiculate chromatin, and contain 1–2 prominent nucleoli with a scant amount of cytoplasm. H&E. Bar = 10 μm. The neoplastic cells show cytoplasmic immunolabeling with CD45 (B) and are negative for CD20 (C), CD79a (D), CD3 (E), CD18 (F), CD117 (G), and MUM1 (H). IHC. Bar = 10 μm.

Figure 2

Landscape of single-nucleotide polymorphisms in canine T-cell and null-cell lymphomas. Genomic analysis of 21 mutated genes was harbored in 68 dogs with 4 T-cell lymphoma variants: peripheral T-cell lymphoma (PTCL), epitheliotropic cutaneous T-cell lymphoma (ECTCL), non-epitheliotropic cutaneous T-cell lymphoma (NECTCL), enteropathy-associated T-cell lymphoma (EATCL), and null-cell lymphoma (NCL). *No call indicates a failure to detect either a wild-type or mutant peak.

Figure 3

Cluster plots present mass spectra from each lymphoma dog in four single nucleotide polymorphisms significantly associated with the null-cell lymphoma subtype. (A) MYC c.224C > T (p = 0.0003), (B) TP53 c.446 T > A (p = 0.03), (C) PDCD1 c.108_109insCT (p = 0.012), and (D) POT1 c.1747C > T (p = 0.012) were generally seen in NCL comparing to other subtypes (red oval). Blue triangle = wild type; green square; and yellow inverted triangle = mutant; red circle = no call; EATCL, enteropathy associated T-cell lymphoma; ECTCL, epitheliotropic cutaneous T-cell lymphoma; NCL, null-cell lymphoma; NECTCL, non-epitheliotropic cutaneous T-cell lymphoma; PTCL, peripheral T-cell lymphoma.

Figure 4

Bar chart illustrates SNP detection as germline or somatic in five canine TCLs.

Figure 5

Potential pathways of 21 targeted genes contribute to lymphoma development.