Luteinizing hormone receptor mediated proliferation of isolated canine T lymphoma cells


   

Luteinizing hormone receptor mediated proliferation of isolated canine T lymphoma cells 
Camryn Flint, Sabrina Gust, Michelle Kutzler 

Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 
  

Luteinizing hormone receptor (LHR) have been identified in nonreproductive tissues, including in 
canine lymphoma and isolated canine T lymphoma cells.1 The objective was to determine if the LHR in 
canine T lymphoma cells was functional. It was hypothesized that stimulation of the LHR by human 
chorionic gonadotropin (hCG) or canine LH (cLH) induces proliferation of canine T lymphoma cells in 
vitro. Immortalized T cell lines from 3 dogs with multicentric T cell lymphoma donated from Dr. Takuya 
Mizuno at Yamaguchi University, Japan were plated in 96 well plates in RPMI 1640 (phenol and protein 
free) media (#02-0105, VWR Life Science, Sanborn, NY) at 370C with 5% CO2. For each cell line, 
standard curves from 10 to 500 x 103 cells/well were plated in triplicate. Increasing concentrations of 
hCG (4 - 40,000 u/ml, Chorulon®, Merck Animal Health, Madison, NJ) or canine LH (0.002 to 20 ng/ml, 
#QP604-EC, EnQuire BioReagents, Denver, CO) were added to wells containing 100 x 103 cells plated in 
triplicate. Plates were incubated for 24, 48, and 72 hours for hCG or 48, 72, 96, and 120 hours for cLH 
before cells were counted using an MTT cell proliferation assay kit (#10009365, Cayman Chemical, Ann 
Arbor, MI) following manufacturer's instructions. Average ± SD cell number was compared among 
hormone concentrations using one way ANOVA. Significance was defined as p < 0.05. Activation of 
LHR in isolated canine T lymphoma cells induced significant cell proliferation in all 3 cell lines with both 
hCG and cLH, but varied among concentrations and incubation times. Greatest proliferation from hCG 
occurred with 40,000 u/ml after 72 hours of incubation in all 3 cell lines. Greatest proliferation from cLH 
occurred with 2 ng/ml after 96 hours of incubation in all 3 cell lines. However, there was a significant 
decrease in cell counts following administration of cLH at the highest concentration (20 ng/ml) at all 
times of incubation. To the author's knowledge, this was the first study to provide evidence that LHR in 
nonreproductive tissues is functional. These findings provided an explanation for why gonadectomized 
dogs are 3 - 4 times more likely to develop lymphoma.2,3 Clinical trials are planned to include LH 
downregulation with conventional chemotherapy in efforts to prolong survival times in dogs.     
 
Keywords: Cancer, dog, human chorionic gonadotropin, lymphocyte, MTT assay 
 
References 
1. Ettinger A, Gust S, Kutzler MA: Luteinizing hormone receptor expression in normal and neoplastic canine 

lymphocytes. Am J Vet Res (accepted 9/13/2018). 
2. Torres de la Riva G, Hart BL, Farver TB, et al: Neutering dogs: Effects on joint disorders and cancers in Golden 

Retrievers. PLoS ONE. 2013;8(2). 
3. Zink MC, Farhoody P, Elser SE, et al: Evaluation of the risk and age of onset of cancer and behavioral disorders in 

gonadectomized Vizslas. J Am Vet Med Assoc 2014;244:309-319.  
 

477 Clinical Theriogenology • Volume 11,  Number 3 • September 2019



478Clinical Theriogenology • Volume 11,  Number 3 • September 2019


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