Mitotane effects in a H295R xenograft model of adjuvant treatment of adrenocortical cancer.

Adrenocortical cancer is one of the most aggressive endocrine malignancies. Growth through the capsule or accidental release of cancer cells during surgery frequently results in metastatic disease. We investigated the antitumoral effect of 2 adrenocorticolytic compounds, O, P'-DDD and MeSO2-DDE, in the adrenocortical cell line H295R both in vitro and as a xenograft model in vivo. H295R cells were injected s. c. in nude mice. O, P'-DDD, MeSO2-DDE, or oil (control) was administered i. p., either simultaneously with cell injection at day 0 (mimicking adjuvant treatment), or at day 48 (established tumors). Accumulation of PET tracers [ (11)C]methionine (MET), [ (11)C] metomidate (MTO), 2-deoxy-2-[ (18)F]fluoro-d-glucose (FDG), and [ (18)F]-l-tyrosine (FLT) in the aggregates were assessed +/- drug treatment in vitro. Tumor growth was significantly inhibited when O, P'-DDD was given at the same time as injection of tumor cells. No significant growth inhibition was observed after treatment with O, P'-DDD at day 48. A significant reduction in FLT uptake and an increased FDG uptake, compared to control, were observed following treatment with 15 microM O, P'-DDD (p<0.01) in vitro. MeSO2-DDE (15 microM) treatment gave rise to a reduced MET and an increased FLT uptake (p<0.01). Both compounds reduced the uptake of MTO compared to control (p<0.01). Treatment with O, P'-DDD simultaneously to inoculation of H295R cells in mice, imitating release of cells during surgery, gave a markedly better effect than treatment of established H295R tumors. We suggest that FLT may be a potential PET biomarker when assessing adrenocortical cancer treatment with O,P'-DDD. Further studies in humans are needed to investigate this.

Bone tissue composition, dimensions and strength in female rats given an increased dietary level of vitamin A or exposed to 3,3',4, 4',5-pentachlorobiphenyl (PCB126) alone or in combination with vitamin C.

In previous studies we have described structural and functional changes in rat bone tissue caused by 3,3',4,4',5-pentachlorobiphenyl (PCB126). Some of the effects caused by PCB126 resemble those found in vitamin C-deficient rats, as well as those found in rats with a high dietary intake of vitamin A. The present investigation was designed to determine if these PCB126-induced changes could be inhibited by addition of vitamin C to the drinking water and if they could be evoked by vitamin A administration. Five groups of female rats were used in this study, which lasted for 12 weeks. Three of the groups were exposed to PCB126 (total dose 320 microgram/kg, bw), either alone or in combination with vitamin C added to the drinking water (1 and 10 g/l, respectively). One group was given feed with increased level of vitamin A (600000 U/kg pellet) and the fifth group served as controls. Using peripheral quantitative computed tomography (pQCT), it was found that PCB126 increased trabecular density and cortical thickness, but reduced the trabecular area. Furthermore, maximum torque and stiffness of the humerus during torsional testing and serum osteocalcin levels were reduced by PCB126. Of the PCB126 induced effects observed, addition of vitamin C only inhibited the reduction of serum osteocalcin. Like PCB126 vitamin A supplementation increased the inorganic content and the bone density and also reduced the trabecular area and polar moment of inertia but did not increase the cortical thickness or reduce maximum torque, stiffness or serum osteocalcin level. Apparently, the effects induced by PCB126 are not mediated either via decreased vitamin C level or increased vitamin A level.