Uptake and distribution of the boron-containing ether lipid B-Et-11-OMe in tumor-bearing mice

Ether lipids in general are accumulated in tumor tissue with a favorable tumor/healthy tissue ratio. The uptake of the boron-containing analog rac-1-(9-o-carboranyl)nonyl-2-methyl-glycero-3-phosphocholine (B-Et-11-OMe) was studied in C3H mice bearing the murine mammary carcinoma AT17 and in BALB/c mice bearing an osteosarcoma. Boron concentrations of tumor, blood, liver and kidney were followed up to 48 h by inductively coupled plasma emission spectrometry and inductively coupled plasma mass spectrometry. Boron concentration in AT17 mamma carcinoma rose up to 2 mg/kg and the tumor/blood ratio rose to 0.5. The bulk was taken up by the liver. Osteosarcoma did not take up B-Et-11-OMe. This result constitutes a significant contrast to the behavior of published (non-boron-containing) analogs. It is interpreted in terms of critical micellar concentration (CMC). Whereas earlier work with ether lipids was done well below CMC, this study was undertaken above. Further studies will concentrate on syntheses of high CMC analogs.