Preclinical Evaluation of U87 Cell Line: In Vitro and In Vivo studies.

Abstract

Purpose: A preclinical testing of U87 cell line conducted through in vitro investigation and in vivo imaging analysis. In vitro phase investigated U87 cell line, to assess the expression levels of specific proteins, providing insights into cellular mechanisms. In vivo phase focused on animal models implanted with U87 cells, to evaluate the biodistribution of 177Lu-FAPI-46 and 161Tb-FAPI-46. A comparative analysis was performed to assess tumour retention using PSMA-617 datasets. Methods: In vitro studies were conducted using U87 cells, which were cultured in medium with appropriate supplementation. Western blot analysis performed on U87 cell lysates derived from different tissues to assess the expression of CXCR4 and ACKR3. In vivo animal studies, mice were implanted with LNCaP (PSMA+) or U87 (FAPI+) cells for tumour formation. Then injected with PSMA-617 or FAPI-46, each labelled with different isotopes and imaged with SPECT/CT or PET/CT at various time points. During imaging analysis, regions of interest (ROIs) were delineated on tumours and selected organs to obtain quantitative measurements. Standardized Uptake Values (SUVs) were calculated to quantify the concentration of radiotracers within the ROIs. Results: In the SUVmean graph within 1hour, 68Ga-PSMA exhibited the highest uptake in all tissue where the tumour uptake reached 2.2. 161Tb-FAPI-46 shows higher uptake in tumour compared to 177Lu-FAPI-46. At 24hours, the SUVmean graph showed 161Tb-PSMA exhibited higher tumour uptake of 1.5 compared to the other two tracers. Conclusion: In vitro phase indicates that CXCR4 and ACKR3 are highly expressed in tumour tissue, playing a role in the treatment and molecular imaging of U87 cells. In vivo phase showed high tumour uptake for 177Lu-FAPI-46, 161Tb-FAPI-46, and 68Ga-PSMA-617 within 1hour. Notably, 161Tb-FAPI-46 showed higher uptake in tumour than 177Lu-FAPI-46. By 24hours, only 161Tb-PSMA-617 remained in the tumour, indicating lower tumour persistence for FAPI- labelled radionuclides.