BMC Cancer (Aug 2020)
Increasing of malignancy of breast cancer cells after cryopreservation: molecular detection and activation of angiogenesis after CAM-xenotransplantation
Abstract
Abstract Background Ovarian tissue cryopreservation has a wide range of cancerous indications. Avoiding relapse becomes a specific concern that clinicians frequently encounter. The data about the comparative viability of cancer cells after cryopreservation are limited. This study aimed to evaluate the effect of cryopreservation on breast cancer cells. Methods We used in-vitro cultured ZR-75-1 and MDA-MB-231 cell lines. Cell samples of each lineage were distributed into the non-intervened and cryopreserved groups. The cryopreservation procedures comprised programmed slow freezing followed by thawing at 100 °C, 60 s. Biological phenotypes and the related protein markers were compared between the two groups. The EVOS FL Auto 2 Cell Image System was used to monitor cell morphology. Cell proliferation, motility, and penetration were characterized by CCK-8, wound-healing, and transmembrane assay, respectively. The expression of Ki-67, P53, GATA3, E-cadherin, Vimentin, and F-Actin was captured by immunofluorescent staining and western blotting as the proxy measurements of the related properties. The chorioallantoic membrane (CAM) xenotransplantation was conducted to explore angiogenesis induced by cancer cells. Results After 5 days in vitro culture, the cell concentration of cryopreserved and non-intervened groups was 15.7 × 104 vs. 14.4 × 104cells/ml, (ZR-75-1, p > 0.05), and 25.1 × 104 vs. 26.6 × 104 cells/ml (MDA-MB-231, p > 0.05). Some cryopreserved ZR-75-1 cells presented spindle shape with filopodia and lamellipodia and dissociated from the cell cluster after cryopreservation. Both cell lines demonstrated increased cell migrating capability and invasion after cryopreservation. The expression of Ki-67 and P53 did not differ between the cryopreserved and non-intervened groups. E-cadherin and GATA3 expression downregulated in the cryopreserved ZR-75-1 cells. Vimentin and F-actin exhibited an upregulated level in cryopreserved ZR-75-1 and MDA-MB-231 cells. The cryopreserved MDA-MB-231 cells induced significant angiogenesis around the grafts on CAM with the vascular density 0.313 ± 0.03 and 0.342 ± 0.04, compared with that of non-intervened cells of 0.238 ± 0.05 and 0.244 ± 0.03, p < 0.0001. Conclusions Cryopreservation promotes breast cancer cells in terms of epithelial-mesenchymal transition and angiogenesis induction, thus increasing metastasis risk.
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