Differential Tumorigenic Properties of Mesenchymal Cells From Neoplastic and Non-Neoplastic Human Lung in NSCLC

the pathogenesis and management of lung cancer. A relevant component of the niche is represented by supportive stromal cells that control the fate of CICs by a reciprocal cross-talk. The understanding of these cellular events could represent a significant advancement in cancer biology and treatment. Recent observations by our and other laboratories have suggested that mesenchymal stromal cells (MSC) regulate lung cancer growth and resistance, thus generating large expectations in novel anti-cancer strategies. The aim of our study was to determine whether MSC isolated from NSCLC and from non-neoplastic human lung samples possess different biologic properties and tumorigenic potential. Methods: Fresh samples of neoplastic and spared lungs from 58 male patients (80% smokers) affected by primary pulmonary adenocarcinoma undergoing surgical resection were processed. Stromal cells were separated from epithelial cells by negative selection using EpCAM (CD326)-based immunomagnetic sorting. After further enrichment, we could expand for at least 14 passages a population of CD90, CD105, CD73 and CD44 positive MSC from lung cancer (Lc-MSC) and non-neoplastic (Nn-MSC) lung tissue. The oncogenic potential of these cells from the same patient was tested on a Calu-3-based in vitro model of NSCLC by co-culture and conditioned media (CM) and in vivo by xenotransplantation in Balb/c Nude mice. In vivo cell tracking was achieved by pre-labeling MSC with Quantum dots 585 (Qdots). Morphometric assessment of tissue composition and immunofluorescence combined with FISH analysis of human X and Y chromosomes was performed on xenografted tumors. Results: Nearly 30x106 cells could be typically obtained after 3 passages in each case, however, compared to Nn- MSC, cultures of Lc-MSC displayed lower growth kinetic and mitotic index while higher survival and HIF-1-alpha (Hypoxia-inducible-factor-1) upregulation in response to hypoxia was observed. A larger fraction of Lc-MSC expressed transcription factors involved in stemness (Oct3/4, SOX2) and in bronchioalveolar (TTF1, ETS-1, CCL10) commitment. Co-cultures demonstrated that Lc-MSC significantly increased Calu-3 growth as compared to Nn-MSC in transwell assay and by contact. CM from Lc-MSC similarly promoted Calu-3 expansion as compared to Nn-MSC. When 2.5x106 Lc-MSC or Nn- MSC from the same patient were subcutaneously co-injected with Calu-3, a 38% and 17% increase in tumor volume was respectively observed, compared to the injection of an equal number of Calu-3 alone (CTRL). Lc-MSC or Nn-MSC injected alone did not generate tumors. Quantitative estimation of the in vivo expansion of neoplastic cells indicated that the addition of Lc-MSC increased by 6-fold and 29-fold Calu-3 replication compared to Nn-MSC and CTRL, respectively. Cell tracking documented that Qdots labelled MSC were located at the boundary of neoplastic epithelial glands generated by X-chromosome polysomic Calu-3 cells. A comparative molecular analysis of Lc-MSC and Nn-MSC is ongoing for the identification of distinctive signalling pathways implicated in the microenvironemental control of CIC on NSCLC development. Conclusion: Profound differences exist in the biology and oncogenic potential of intratumoral and normal lung MSC strongly supporting the notion that the tumor microenvironment may represent a potential target of new customized therapeutic strategies.