In summary, in patients with insulinoma, 1) plasma leptin levels and leptin mRNA are elevated; 2) a direct relationship exists between leptin, both circulating protein and mRNA, and insulin concentrations; and 3) plasma leptin returns to normal levels after tumor removal.
Whether or not leptin and leptin receptor expression play a role in the development and/or progression of lipoblastoma and other tumors is not clear to date.Copyrightz1999S.KargerAG, Basel
We also emphasize a new role for leptin, linking the nutritional and body fat status to digestive cancer susceptibility by stimulating the invasive capacity of colonic epithelial cells at early stages of neoplasia.
Mouse leptin-specific transcripts could be detected only in MCF-7IL-1 alpha cell-derived tumors, which suggests that IL-1 alpha increases leptin expression in stromal cells recruited into the tumor microenvironment.
We hypothesize that the balance between androgen and leptin levels may facilitate the increase in the ratio of androgen-independent prostate cancer cells to androgen-dependent cells in the tumour.
Studies in our laboratory focusing on the role of energy balance and genetic susceptibility in mice deficient in one (+/-) or both (-/-) alleles of the p53 tumor suppressor gene and mice with a mutant APC allele (APC(Min)) showed that calorie restriction decreases tumor burden, increases tumor latency, and decreases serum insulin-like growth factor (IGF)-1 and leptin levels.
Although all the mechanism(s) by which leptin contributes to tumor development are unknown, it appears leptin stimulates an increase in cell numbers, and the expression of VEGF/VEGF-R2.
The purpose of this study was to compare the effects of leptin-stimulated colon epithelial cells differing in adenomatous polyposis coli (Apc) genotype (gatekeeper tumor suppressor gene for colon cancer) on angiogenesis.
The aim of this study was to investigate the expression of leptin and its receptors Ob-Ra and Ob-Rb in parotid salivary gland tumors, with particular regard to a potential use of leptin as a tumor marker.
Expression of either protein was associated with greater neoplasm size (leptin expression, 32.0 +/- 10.7 vs 20.5 +/- 8.4 mm; P = .001; leptin receptor expression, 27.9 +/- 11.5 vs 21.4 +/- 9.0 mm; P = .032).