The boron uptake via LAT1 and survival analysis after boron neutron capture therapy in canine hemangiosarcoma cell...

Canine hemangiosarcoma (HSA) is a highly aggressive malignancy with limited effective therapies. Boron neutron capture therapy (BNCT) has begun to be recognized as a potential treatment in human angiosarcoma, but its applicability to canine HSA has not been explored. This study aimed to evaluate L-type amino acid transporter 1 (LAT1)-mediated uptake of boronophenylalanine (BPA), a ¹⁰B-containing compound, and the in vitro therapeutic potential of BNCT in canine HSA cells.

Three canine HSA cell lines (JuB2, Ud6, Re21) were assessed for BPA uptake using fluorescence measurements, fluorescence imaging, and inductively coupled plasma-atomic emission spectrometry. LAT1 involvement was examined using the LAT1 inhibitor BCH. Clonogenic assays following X-ray or neutron irradiation, with or without BPA pretreatment, were performed to calculate survival fractions, dose-response curves, D10, relative biological effectiveness (RBE), and compound biological effectiveness (CBE).

All cell lines demonstrated BPA uptake, which was significantly reduced by BCH, confirming LAT1-mediated transport. Time-course analysis revealed cell line-dependent differences in intracellular ¹⁰B accumulation. Neutron irradiation yielded greater cytotoxicity than X-rays, and BPA further enhanced this effect, consistent with the ¹⁰B(n, α)⁷Li reaction. CBE values were 2.60 (JuB2), 2.31 (Ud6), and 1.25 (Re21), aligning with differences in BPA uptake.

These findings demonstrate functional LAT1-dependent BPA uptake and BNCT-induced cytotoxicity in canine HSA cells. The results provide foundational radiobiological evidence supporting the feasibility of BNCT in canine HSA and justify further in vivo investigations.