Fig. 3
Cisplatin resistance correlated with increased migratory capacity, invasiveness and tumorigenicity, and ability of resistant cells to form 3D multicellular spheroids. a Morphology of NOY-1 CisR was similar to parental NOY-1 cells, magnification 630x. b NOY-1 CisR cells formed tight 3D multicellular spheroids, when seeded into ultra-low attachment round bottom plates. Parental NOY-1 cells were not able form spheroids in 3D culture conditions, magnification 250x. c NOY-1 CisR cells migration was higher than parental NOY-1 cells in a wound healing assay. Confluent monolayers of NOY-1 CisR and NOY-1 cells were wounded and cell migration was observed by live-cell imaging for 48 h. Red line—initial scratch wound line, blue area—wounded area over time. d Quantitative evaluation of wound confluence demonstrated significantly increased migratory capacity of cisplatin-resistant NOY-1 CisR cells. Data are expressed as means of three independent measurements each run in quadruplicates ± SD. e NOY-1 and NOY-1 CisR cell lines were topically applied into the area defined by a silicone ring and formed micro-tumors in CAM tissue (indicated by arrows). f NOY-1 cells produced “micrometastasis” (indicated by arrow) outside the silicone ring. g H&E staining of CAMs with tumor cells adhered to ectoderm of the CAMs (marked by asterisks). Resistant NOY-1 CisR cells (outlined by dashed line) invaded into CAM and formed metastatic foci in the mesoderm (M). h Subcutaneously injected NOY-1 CisR cells produce bigger xenografts in comparison to NOY-1 cells, data show median tumor volume. 2 × 105 of NOY-1 and NOY-1 CisR cells were injected subcutaneously into the flank of immunodeficient mice, tumor volume was measured regularly. *P < 0.05