[Relevant molecular characteristics analysis on malignant transformation of interstitial cells induced by tumor stem...

Objective: A variety of interstitial cells in tumor microenvironment (TME) based on glioma stem cells(GSC) have the function to promote malignant progression of tumors, but whether these interstitial cells have already undergone malignant transformation and their related molecular characteristics are still poorly understood. Methods: Human SU3-RFP glioma stem cells (GSC) stably transfected with red fluorescent protein (RFP) and interstitial cells from enhanced green fluorescent protein (EGFP) transgenic nude mice were co-cultured in vitro. SU3-RFP cells were also inoculated in different tissues of EGFP-Balb/c nude mice. Immortal EGFP(+) cells were monocloned either from co-culture cells in vitro, or from their xenografts in vivo. These immortal EGFP(+) cells were confirmed to bear characteristics of tumor cell via chromosomal analysis and tumorigenicity assay. Related molecular phenotypes of these cells were further detected through RT-PCR, flow cytometry and immunochemistry(IHC) techniques. Results: (1) Two EGFP(+) cell lines were obtained in vitro, and 5 EGFP(+) cell lines were obtained in vivo tumorigenic experiments. Seven EGFP(+) cell lines all have characteristics of self-renewal, heteroploid of chromosomes and 100% tumorigenicity. (2) Cell surface marker analysis showed cell origin of these cell lines were macrophages (tMΦ1 and tMΦ2 ), dendritic cells (tDC1 and tDC2), fibroblasts (tFB), oligodendrocytes (tOG) and BMSC cells (tBMSC), respectively. (3)All of these seven cell lines co-expressed Sca-1 and c-myc, and have Sox-2 or Nanog expression also, which suggest that they may bear molecular characteristics of mesenchymal stem cells or pluripotent stem cells. Conclusions: (1) Tumor stromal cells in TME have undergone malignant transformation, which is related to the tissue remodeling of TME by GSCs, and not limit to the specific type of their parasitic tissues. (2) Tumor cells originated from GSC and tumor interstitial cells, respectively, are two major types of tumor cells with different origins in glioma parenchyma, can not be simply regarded as tumor heterogeneity, transformed interstitial cells of TME may have the potential to serve as new targets for target diagnosis and therapy.