Abstract 630: Co-injection of human fibroblasts significantly enhances tumorigenicity of orthotopically implanted human non-small cell lung cancer cells in immunocompromised mice
Authors: Oswald Eva , Santo Vitor E. , Rudisch Albin , Brito Catarina , Sommergruber Wolfgang , Dolznig Helmut , Schüler Julia B. 
Published: July 2016

Human tumor xenografts in immunodeficient mice have led to valuable insights into the biology of human cancer. The corresponding limitations and pitfalls of xenograft models have been described extensively. To tackle some limitations, we supplemented the murine tumor microenvironment (TME) with human stromal fibroblasts to mirror tumor-stroma cross-talk in vivo.

Non-small cell lung cancer (NSCLC) cell lines Calu-1 and H1437 were co-injected with different types of fibroblasts into NOG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice in 3 independent experiments (n = 4-6/group; 106 in total). Human Dermal Fibroblasts (HDFs), lung cancer associated fibroblasts (CAFs), corresponding normal fibroblasts (NFs) and NSCLC cells were implanted into the lungs of 4-6 week old recipient mice. The influence of extracellular matrix components was evaluated by using either a matrigel/collagen mixture or alginate capsules. Tumor load was determined via overall survival (OS) and flow cytometry (FC). When mice had to be sacrificed, organs were collected and analyzed by FC and patho-histological examination. In a subsequent experiment, mice were sacrificed and tumors analyzed at defined time points and similar analyses performed.

OS and metastatic pattern were similar in both cell lines when injected in mono-culture. OS of Calu-1 injected mice was not influenced when cells were co-injected with HDF but prolonged when co-injected with CAFs or NFs. In H1437 bearing mice, OS was significantly reduced when cells were co-injected with HDF or NF (Log-rank [Mantel-cox] test; p&lt; 0.002 & 0.005), whereas CAFs had no influence on OS. Co-injection of HDF and Calu-1 enhanced the number of tumor cells in bronchoalveolar lavage fluid, whereas CAFs had the opposite effect (1way ANOVA for all following statistics, p&lt; 0.0001). Consistently, the number of circulating Calu-1 cells was highest in co-culture with HDF and significantly lower in mice bearing Calu-1 and CAF or NF (p&lt;0.0021). Co-injection of fibroblasts enhanced the H1437 tumor load in all compartments. Of note, the effect was not statistically significant. The use of alginate capsules was favorable compared to matrigel/collagen, improving fibroblast engraftment in all investigated organs. Furthermore, alginate capsules enhanced the number of circulating H1437 cells when co-injected with HDF as compared to matrigel/collagen (p&lt;0.0001).

Our results demonstrate the major impact of fibroblasts on tumor cell behavior in a preclinical setting. With the successful co-cultivation of human fibroblast and NSCLC cells in vivo, it will be possible to study tumor-stroma interactions in a clinically relevant mouse model. Once validated by a compound screening approach, this model will help to reduce drug failure rates and contribute to a more efficient development of urgently needed novel anti-cancer treatments.

Citation Format: Eva Oswald, Vitor E. Santo, Albin Rudisch, Catarina Brito, Wolfgang Sommergruber, Helmut Dolznig, Julia B. Schüler. Co-injection of human fibroblasts significantly enhances tumorigenicity of orthotopically implanted human non-small cell lung cancer cells in immunocompromised mice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 630.