Analysis of Epithelial and Mesenchymal Markers in Ovarian Cancer Reveals Phenotypic Heterogeneity and Plasticity
Figure 1
Primary ovarian cancer cultures are heterogeneous and contain putative CSCs.
A) Tumor biopsies and primary cultures stain positive for ovarian cancer markers CA-125 (green) and CEA (red) and show higher heterogeneity than the established cell line SKOV3-ip1. Shown are ovc316-biospy, ovc316-PC, and ovc316-X. Analysis of ovc1208-biopsy, ovc1208-PC, ovc0117-biopsy, ovc0117-PC, ovc100506-biopsy, and ovc100506-PC revealed the same heterogeneity. B) Light microscopy of ovarian cancer culture ovc316-XC. The culture contains two distinct populations with regards to trypsin sensitivity. Left panel: an early passage culture untreated (left), after 10 min trypsin treatment (center), and after trypsin-sensitive cells were removed (right). Right panel: Tumor formation after transplantation of trypsin-resistant (TR) and trypsin-sensitive (TS) cells into SCID-beige mice. Tumor formation was evaluated 3 months after inoculation. TIC TR: 1/185, TIC TS: 1/109. Chi-square = 0.0524. C) Immunofluorescence analysis for a human-specific mitochondrial (Mx) marker, the cancer marker CEA, the epithelial marker E-cadherin, and the mesenchymal marker laminin in clonal cultures derived from ovc316-XC. Clonal cultures contain human cancer cells with either epithelial (upper panel), mesenchymal (center) or both phenotypes (E/M hybrid clone, lower). D) Tumor-forming abilities after transplantation of 105 E, M, or E/M cells into SCID-beige mice. Tumor formation was evaluated 4 months after inoculation. E) Xenograft tumors derived from E/M hybrid clones. The human origin of tumor cells is shown by staining for a human specific mitochondria marker (green). Staining for the epithelial antigen AE1/3 and the tumor antigen CEA reveals phenotypic heterogeneity in tumors that are derived from clonal E/M cultures. Laminin-expression is largely restricted to vascularized regions. F) H&E staining of a xenograft derived from an ovc316-XC E/M clone and from a patient biopsy (ovc316-biopsy) showing that xenografts from resemble the histology of human tumors in situ. The scale bar is 40µm.