Cancer is a serious group of disease that could be resulted from different genetic alterations at molecular level, which could be followed by the unbalancing processes like high cell growth, proliferation, no programmed cell death, high affinity to invade through the tissues, and metastasis, which are normally highly regulated in normal cells. To these days, there are well-known therapeutic treatments in cancer therapy, but they are not giving promising results. By its nature, cancer cells have similar features to embryonic progenitor cells, which was a key element for developing the idea of that embryonic remnants are present in differentiated tissues, which may be linked to development of tumor lesions and aggressive cancer cells could be reprogrammed to less aggressive cells using embryonic microenvironment. Thus, understanding of at what molecular level embryonic microenvironment could have a suppressive effect against cancer cell development and inhibition may be a part of developmental strategy which may give insightful values in cancer therapy. Therefore, chicken embryo extract was used in cancer cell reprogramming.
Along with MCF-7 breast cancer cells, normal breast epithelial cells were used in cell reprogramming with the use of embryonic microenvironment. Chicken embryo extract (CEE) was used as a model of treatment derived obtained from the 12 days old fertilized chicken eggs. 4% of CEE concentration was prepared each time to treat breast cancer cells. Effect of CEE on cell viability, survival, proliferation, colony formation, cell migration, cancer cell morphology was tested. Furthermore, aldehyde dehydrogenase activity within normal and cancer cells were tested by measuring enzyme concentrations using aldehyde dehydrogenase assay.
Exposure of cancer cells to CEE demonstrated high level of cell survival after 2 % of treatment for 2 days and relative cell number for MCF-7 proliferation after CEE treatment had significantly decreased, as control samples demonstrated twice as high as cells than CEE exposed cells. Oxidative stress resistance of cancer cells were decreased with the exposure of MCF-7 cells to CEE, which demonstrated about 2x105 cells in comparison to samples without treatment (266200 cells). In order to demonstrate whether concentration of CEE is applied to cells were toxic or not, it was decided to use different concentrations of CEE were applied to the cells and percentage of viability was identified. Results were indicated that 2% of CEE was the optimal concentration for those cells, as it was demonstrated 75% viability after 2 days of exposure. The trend of cell migration has decreased for cancer cell lines compared to untreated cells, as the migration trend has decreased with the increase of time. By the end of 24 hours’ time point percentage of migration for cancer cells has decreased three times than in untreated cells(from 3.44% to 0.15%). In terms of colony formation, CEE demonstrated sufficient reduction of colony formation after treatment(2500 cells in untreated cells and 1700 cells after treatment)and it was indicated CEE seems to have a role in changing of cell edges, as it was appeared that roughness of edges has changed to smoother and rounder edges with the treatment. Furthermore, CEE was able to affect the morphometric characteristics of the cells, where the cancer cells treated with CEE have demonstrated smaller and rounder nucleus with enlarged cytoskeleton. Effectiveness of CEE as a treatment was followed by the reduction of ALDH activity in breast cancer cells, where concentration of cells before treatment was 1.8 nmol NADH/proteins, after CEE treatment it decreased to 1.2 nmol NADH/min/mg protein.
Use of CEE as innovative approach in cancer cell reprogramming demonstrated that effectiveness of embryonic microenvironment was resulted in decrease of migration pattern as well as morphometric characteristics of breast cancer cells. Similar results were obtained in the cell proliferation, oxidative stress, and colony formation. All in all, chicken embryo extract as a treatment in cancer cell reprogramming indicated different effect on cancer features, which may give arise to sufficient therapeutic approaches that could be used in cancer cell inhibition and may derive more understanding of biology of this disease.
Key words: Cancer, cancer cells, migration, metastasis, colony formation, chicken embryo extract, viral genes, cell proliferation, soft agar, cancer cell morphology, aldehyde dehydrogenase activity, reprogramming.