Accumulation of labelled vitamin B₁₂ in some transplanted tumours

Abstract

Vitamin BIZ is of importance for basic metabolic processes and is necessary for normal growth and reproduction in animals and some micro-organisms. Many different metabolic functions have been ascribed to the vitamin by various investigators, including participation in the synthesis of nucleic acids.It has been claimed that patients with neoplasms have a higher requirement for vitamin B12. The present investigation was made to study the accumulation of labelled vitamin B12 in some transplanted tumours and gain information on the degree of uptake in neoplastic, as compared to normal, tissues. MATERIAL AND METHODSThe labelled compounds used were vitamin B,, --T O , specific activity 109 and 255 mc/mg, vitamin B12-T O , specific activity 170 mc/mg and vitamin B,z-finCo, specific activity 4.68 mc/ mg. All the preparations were obtained from Philips-Duphar (Holland). The vitamin B,,-5*Co and vitamin B12 -'j°Co preparations were used in the autoradiographic studies, vitamin B , -"CO in the quantitative investigations. Tumours and transplantation procedureFour different kinds of tumour were used in the investigation, CBA mice carrying "Sr-induced

Accurate assessment and identification of naturally occurring cellular cobalamins

“…This result was not surprising, since it is well established that tumor cells take up and accumulate higher amounts of Cbl than normal cells in order to sustain high rates of cell division (37).…”

Vitamin-mediated targeting as a potential mechanism to increase drug uptake by tumours

“…One of the earliest reported examples of tumour imaging with vitamin B 12 was that of Flodh and coworkers [24][25][26]. These workers used 58 Co-VB 12 and 60 Co-VB 12 in autoradiographic studies of fibroblastic osteosarcomas, spontaneous mammary carcinomas, Ehlich ascities and Moloney virus-induced tumours in mice.…”

Imaging Cobalamin Uptake within Malignant Breast Tumors In Vivo

“…1) and time-dependent autoradiography [12]. [ 57 Co]CC additionally assisted in deciphering that transcobalamin (TC) was the sole transport protein in serum to selectively bind and deliver Cbl to every tissue type in humans, that holo-TC (TC carrying a single molecule of Cbl) underwent endocytosis by the dedicated transcobalamin receptor (TC-R) expressed on all human cell membranes [13], that holo-TC was primarily saturated with AC [14], and that AC was the major co-enzymatic form of Cbl (50-70 %) in both normal and malignant human cells [15].…”