EGFR Transgene Stimulates Spontaneous Formation of MCF7 Breast Cancer Cells Spheroids with Partly Loss of HER3 Receptor

Abstract

Multicellular spheroids with 3D cell–cell interactions are a useful model to simulate the growth conditions of cancer. There is evidence that in tumor spheroids, the expression of various essential molecules is changed compared to the adherent form of cell cultures. These changes include growth factor receptors and ABC transporters and result in the enhanced invasiveness of the cells and drug resistance. It is known that breast adenocarcinoma MCF7 cells can spontaneously form 3D spheroids and such spheroids are characterized by high expression of EGFR/HER2, while the natural phenotype of MCF7 cells is EGFRlow/HER2low. Therefore, it was interesting to reveal if high epidermal growth factor receptor (EGFR) expression is sufficient for the conversion of adherent MCF7 to spheroids. In this study, an MCF7 cell line with high expression of EGFR was engineered using the retroviral transduction method. These MCF7-EGFR cells assembled in spheroids very quickly and grew predominantly as a 3D suspension culture with no special plates, scaffolds, growth supplements, or exogenous matrixes. These spheroids were characterized by a rounded shape with a well-defined external border and 100 µM median diameter. The sphere-forming ability of MCF7-EGFR cells was up to 5 times stronger than in MCF7wt cells. Thus, high EGFR expression was the initiation factor of conversion of adherent MCF7wt cells to spheroids. MCF7-EGFR spheroids were enriched by the cells with a cancer stem cell (CSC) phenotype CD24−/low/CD44− in comparison with parental MCF7wt cells and MCF7-EGFR adhesive cells. We suppose that these properties of MCF7-EGFR spheroids originate from the typical features of parental MCF7 cells. We showed the decreasing of HER3 receptors in MCF7-EGFR spheroids compared to that in MCFwt and in adherent MCF7-EGFR cells, and the same decrease was observed in the MCF7wt spheroids growing under the growth factors stimulation. To summarize, the expression of EGFR transgene in MCF7 cells stimulates rapid spheroids formation; these spheroids are enriched by CSC-like CD24−/CD44− cells, they partly lose HER3 receptors, and are characterized by a lower potency in drug resistance pomp activation compared to MCF7wt. These MCF7-EGFR spheroids are a useful cancer model for the development of anticancer drugs, including EGFR-targeted therapeutics.

EGFR Suppression Inhibits the Sphere Formation of MCF7 Cells Overexpressing EGFR

“…Ранее нами была получена линия клеток MCF7 аденокарциномы молочной железы человека с повышенной экспрессией EGFR и установлено, что избыток EGFR в клетках MCF7 приводит к спонтанному образованию сфер в стандартных условиях культивирования [10,11]. Сфероиды MCF7-EGFR имеют округлую форму с четко выраженной внешней границей и медианным диаметром, равным 100 мкм; размер крупных сфероидов может превышать 400 мкм.…”

“…Клеточная линия аденокарциномы молочной железы человека MCF7-EGFR, формирующая сфероиды, описана ранее [10]. Сфероиды MCF7-EGFR культивировали в стандартных условиях в планшетах с неадгезивным покрытием (Nest Bio-technology Co., Китай).…”

“…Earlier, we obtained an MCF7 human breast adenocarcinoma cell line that manifested an increased expression of EGFR. The study revealed that excessive EGFR in MCF7 cells led to the spontaneous formation of spheres under standard culture conditions [ 10 , 11 ]. MCF7-EGFR spheroids have a round shape with a well-defined outer boundary and a median diameter of 100 μm, with the size of large spheroids likely to exceed 400 μm.…”

The Optimization of Methods for the Establishment of Heterogeneous Three-Dimensional Cellular Models of Breast Cancer

“…сфероидов является получение «раздавленных» препаратов сфероидов, когда сфероид помещается на предметное стекло, которое затем накрывают покровным стеклом[23]. При этом предполагают, что расположение клеток в препарате будет соответствовать расположению клеток в сфероиде[24]. ТакиеРис.…”

Advances in Gynecological Cancers

“…In this first edition of the Special Issue “Advances in Gynecological Cancers”, current advances in the field of molecular landscape, the prognosis, diagnosis, and treatment of gynecologic malignancies, as well as novel therapeutic strategies and future directions are presented. Troitskaya, O. et al [ 1 ] demonstrated that a high expression of epidermal growth factor receptor (EGFR) in the MCF7 cell line transformed the adherent cell culture into a three-dimensional (3D) in vitro cell culture, which is known to closely resemble the in vivo disease environment, providing a rather accurate model for cancer therapeutics efficacy testing. Moreover, MCF7-EGFR spheroids, which represent self-assembled cancer cell aggregates, seem to induce plasticity with regards to cellular markers, such as human epidermal growth factor receptor 3 (HER3), determining drug resistance and tumor progression.…”