Stromal Cells Derived from Visceral and Obese Adipose Tissue Promote Growth of Ovarian Cancers

<div><p>Obesity, and in particular visceral obesity, has been associated with an increased risk of developing cancers as well as higher rates of mortality following diagnosis. The impact of obesity on adipose-derived stromal cells (ASC), which contribute to the formation of tumor stroma, is unknown. Here we hypothesized that visceral source and diet-induced obesity (DIO) changes the ASC phenotype, contributing to the tumor promoting effects of obesity. We found that ASC isolated from subcutaneous (SC-ASC) and visceral (V-ASC) white adipose tissue(WAT) of lean(Le) and obese(Ob) mice exhibited similar mesenchymal cell surface markers expression, and had comparable effects on ovarian cancer cell proliferation and migration. Obese and visceral derived ASC proliferated slower and exhibited impaired differentiation into adipocytes and osteocytes <i>in vitro</i> as compared to ASC derived from subcutaneous WAT of lean mice. Intraperitoneal co-injection of ovarian cancer cells with obese or visceral derived ASC, but not lean SC-ASC, increased growth of intraperitoneal ID8 tumors as compared to controls. Obese and V-ASC increased stromal infiltration of inflammatory cells, including CD3+ T cells and F4/80+ macrophages. Obese and visceral derived ASC, but not lean SC-ASC, increased expression of chemotactic factors IL-6, MIP-2, and MCP-1 when cultured with tumor cells. Overall, these results demonstrate that obese and V-ASC have a unique phenotype, with more limited proliferation and differentiation capacity but enhanced expression of chemotactic factors in response to malignant cells which support infiltration of inflammatory cells and support tumor growth and dissemination.</p></div

Ovarian tumor growth promotion by ASC.

<p>ASC were coinjected with luciferase-expressing ID8 tumor cells into C57BL/6 mice intraperitoneally (1:1 ratio, 10⁶/each). N = 5 per group. <b>A</b>, Comparison of tumor burden measured by luciferase expression at abdominal side between Ob-SC-ASC and Le-SC-ASC groups. Error bar: 90% confidence interval. <b>B</b>, Comparison of tumor burden measured by luciferase expression at abdominal side between Ob-V-ASC and Le-V-ASC groups. Error bar: 90% confidence interval. <b>C</b>, Comparison of tumor initiation among groups. <b>D</b>, Luciferase signal measurement of abdominal side in the mice at day 46.</p

ID8 tumor growth pairwise comparison between groups

<p>Shown as Statistic results of ID8 tumor growth between groups based on a linear mixed effect model with repeat measures to evaluate the effect of ASC source (V/SC) and obesity status (obese/lean) versus control group across multiple time points. Note that the difference was between two groups averaged over all time points because there was not significant interaction between treatment group and time point. SE: standard error.</p><p>ID8 tumor growth pairwise comparison between groups</p

Secretion of VEGF, IL-6, MIP2 and MCP1 by ASC cells in ID8 spheroid-CM.

<p>ASC were plated at a density of 20,000/ml in cultured in spheroid medium(control) or medium contained 50% ID8 spheroid-CM for 5 days. Supernatant were collected for Luminex assay. Concentration of VEGF (<b>A</b>) IL-6 (<b>B</b>), MIP2(<b>C</b>) and MCP1 (<b>D</b>).(Shown are mean ± SEM. *, <i>P</i> < 0.05; **, <i>P</i> < 0.01, ***, P<0.001 and ****, P<0.0001. Student <i>t</i> test, two tailed.)</p

Characterization of SC-ASC and V-ASC from obese and lean mice.

<p><b>A</b>, Morphology of adherent cells showing similarity of SC-ASC and V-ASC from obese and lean mice. Scale bar, 1μm. <b>B</b>, Adipogenesis of SC-ASC and V-ASC. Differentiated cells were stained with oil red-O and quantified by percentage of pixels of oil red-O in images. Error bars, SEM. **, <i>P</i> < 0.01(Mann-Whitney test). Scale bar, 100μm.<b>C</b>, Osteogenesis of SC-ASC and V-ASC. Differentiated cells were stained with alizarin red S. Error bars, SEM. **, <i>P</i> < 0.01(Mann-Whitney test). Scale bar, 100μm. <b>D</b>, Quantitative RT-PCR analysis of mRNA levels for genes hallmarking adipocyte differentiation and lypolysis normalized to 18s RNA expression in indicated ASC at baseline and 14 days after adipogenesis induction. Error bar: SEM.</p