Loss of heterozygosity and allelic imbalance data has shown that there are two distinct regions of loss on chromosome 18q associated with the progression of prostate cancer (CaP). To investigate the functional significance of chromosome 18q loci in CaP, we utilized the technique of microcell-mediated chromosome transfer to introduce an intact chromosome 18 into the human prostate cancer cell line, PC-3. Three of the resulting hybrid lines were compared to the PC-3 cells in vitro and in vivo. The hybrid cell lines, containing an intact copy of the introduced chromosome 18, exhibited a substantial reduction in anchorage-dependent and independent growth in vitro. These hybrid cell lines also made smaller tumors in nude mice following subcutaneous injection compared to PC-3 cells. Because tumor growth was not completely eliminated by introduction of chromosome 18, we assessed the ability of the hybrids to metastasize to bone after intra-cardiac inoculation in a nude mouse model. Mice inoculated with PC-3 hybrids containing intact copies of chromosome 18 had significantly fewer bone metastases and dramatically improved survival compared to PC-3 cells. In addition, the introduction of chromosome 18 significantly reduced tumor burden in extraskeletal sites. This was not because of differences in growth rates because mice bearing hybrids were monitored for metastases over twice as long as mice bearing PC-3 cells. Taken together, these data suggest that chromosome 18 has a functional role in CaP to suppress growth and metastases. Identification of the responsible gene(s) may lead to molecular targets for drug discovery.

Recent data have implicated macrophage inflammatory protein-1alpha (MIP-1alpha) in multiple myeloma (MM)-associated osteolysis. However, it is unclear whether the chemokine's effects are direct, to enhance osteolysis, or indirect and mediated through a reduction in tumor burden, or both. It is also unclear whether MIP-1alpha requires other factors such as receptor activator of nuclear factor-kappaB ligand (RANKL) for its effects on bone. In murine 5TGM1 (Radl) myeloma-bearing mice, administration of neutralizing anti-MIP-1alpha antibodies reduced tumor load assessed by monoclonal paraprotein titers, prevented splenomegaly, limited development of osteolytic lesions, and concomitantly reduced tumor growth in bone. To determine the effects of MIP-1alpha on bone in vivo, Chinese hamster ovary (CHO) cells secreting human MIP-1alpha (CHO/MIP-1alpha) were inoculated into athymic mice. Mice bearing intramuscular CHO/MIP-1alpha tumors developed lytic lesions at distant skeletal sites, which occurred earlier and were larger than those in mice with CHO/empty vector (EV) tumors. When experimental metastases were induced via intracardiac inoculation, mice bearing CHO/MIP-1alpha tumors developed hypercalcemia and significantly more osteolytic lesions than mice bearing CHO/EV tumors, with intramedullary CHO/MIP-1alpha tumors associated with significantly more tartrate-resistant acid phosphatase-positive (TRAP+) osteoclasts. Injection of recombinant MIP-1alpha over calvariae of normal mice evoked a striking increase in osteoclast formation, an effect dependent on RANK/RANKL signaling because MIP-1alpha had no effect in RANK-/- mice. Together, these results establish that MIP-1alpha is sufficient to induce MM-like destructive lesions in bone in vivo. Because, in the 5TGM1 model, blockade of osteoclastic resorption in other situations does not decrease tumor burden, we conclude that MIP-1alpha exerts a dual effect in myeloma, on osteoclasts, and tumor cells.

This study evaluates the effects of 13 days of total parenteral nutrition (TPN) on body weight, carcass mass and nitrogen balance in rats with and without a transplanted Morris No. 7777 hepatoma. Groups of rats without a tumor as well as rats with a tumor of about 3% of body weight or less were shown to maintain carcass weight as well as maintain a positive nitrogen balance when fed totally by vein. The present experiment was done under the same conditions as a previously reported experiment except that the size of the tumor in the rats was considerably smaller. These past studies showed that as the hepatoma gets much larger than 3% of the body weight, it was inhibitory to carcassweight gain even when the rats were given TPN. Thus, the size of the tumor influences the ability of TPN to sustain carcass weight.