Canine splenic hemangiosarcoma cells express and activate luteinizing hormone receptors in vitro

OBJECTIVETo determine luteinizing hormone receptor (LHR) expression and response to LHR activation in isolated canine splenic hemangiosarcoma cell lines in vitro. SAMPLESIn vitro cultures of commercially available canine splenic hemangiosarcoma cell lines (EFS, GRACE-HSA, and DAL-4). PROCEDURESThe percentage of each cell line expressing LHR was determined by immunocytochemistry. Cells were then treated with increasing doses (7.5 ng/mL, 75 ng/mL) of recombinant canine luteinizing hormone (cLH) for 48 hours and evaluated using a cell proliferation assay. RESULTSThe percentage of cells expressing LHR was 17.2 ± 4.5%, 11.8 ± 3.1%, and 6.9 ± 2.5% in EFS, GRACE-HSA, and DAL-4, respectively. There was significant increase in cell count in the DAL-4 and EFS cell lines following a 48-hour incubation at the highest cLH concentration (P = .028 and P = .019, respectively). There was not a significant increase in cell count in the GRACE-HSA cell line at either cLH concentration. CLINICAL RELEVANCEActivation of LHR results in cell proliferation in some canine splenic hemangiosarcoma cell lines. These results may explain why spayed and castrated dogs with high circulating LH concentrations may develop hemangiosarcoma more frequently than intact dogs.