title: Associations of chemo- and radio-resistant phenotypes with the gap junction, adhesion and extracellular matrix in a three-dimensional culture model of soft sarcoma.
abstract: BACKGROUND
  Three-dimensional (3D) culture models are considered to recapitulate the cell microenvironment in solid tumors, including the extracellular matrix (ECM), cell-cell interactions, and signal transduction. These functions are highly correlated with cellular behaviors and contribute to resistances against chemo- and radio-therapies. However, the biochemical effects and mechanisms remain unknown in soft sarcoma. Therefore, we developed an in vitro 3D model of sarcoma to analyze the reasons of the chemo- and radio-resistance in therapies.
  
  
  METHODS
  Four soft sarcoma cell lines, HT1080, RD, SW872, and human osteosarcoma cell line 1 (HOSS1), a cell line established from a patient-derived xenograft, were applied to 3D culture and treated with growth factors in methylcellulose-containing medium. Spheroids were examined morphologically and by western blotting, RT-qPCR, and immunofluorescence staining to analyze cell adhesion, gap junctions, ECM genes, and related factors. Proliferation and colony formation assays were performed to assess chemo- and radio-resistances between 3D and two-dimensional (2D) cell cultures. Annexin V and Propidium Iodide staining was used to detect early apoptotic sarcoma cells treated with Doxorubicin, Gemcitabine, and Docetaxel in the 3D model.
  
  
  RESULTS
  The four soft sarcoma cell lines formed spheres in vitro by culture in modified condition medium. Compared with 2D cell culture, expression of ECM genes and proteins, including COL1A1, LOX, SED1, FN1, and LAMA4, was significantly increased in 3D culture. Analysis of cadherin and gap junction molecules showed significant changes in the gene and protein expression profiles under 3D conditions. These changes affected cell-cell communication and were mainly associated with biological processes such as cell proliferation and apoptosis related to chemo- and radio-resistances.
  
  
  CONCLUSIONS
  Our findings revealed significant differences between 3D and 2D cell culture systems, and indicated that cellular responsiveness to external stress such as radiation and chemotherapeutics is influenced by differential expression of genes and proteins involved in regulation of the ECM, cell adhesion, and gap junction signaling.
authors.affiliation: Department Bone and Soft Tissue Tumor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, 100142, People's Republic of China.
authors.forename: Chujie
authors.initials: C
authors.lastname: Bai
authors.affiliation: Department of Gerontology, Beijing Shijitan Hospital, Capital Medical University, Beijing, 100038, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department Bone and Soft Tissue Tumor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, 100142, People's Republic of China.
authors.forename: Zhengfu
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Department Bone and Soft Tissue Tumor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, 100142, People's Republic of China.
authors.forename: Shu
authors.initials: S
authors.lastname: Li
authors.affiliation: Department Bone and Soft Tissue Tumor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, 100142, People's Republic of China.
authors.forename: Tian
authors.initials: T
authors.lastname: Gao
authors.affiliation: Department Bone and Soft Tissue Tumor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, 100142, People's Republic of China. zhiwei_fang66@163.com.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Fang
mesh_terms: D017209:Apoptosis; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005109:Extracellular Matrix / Q000378:metabolism*; D017629:Gap Junctions; D006801:Humans; D008968:Molecular Conformation; D010641:Phenotype; D012509:Sarcoma / Q000235:genetics* / Q000378:metabolism*