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Selected Publication:

Schratter, G.
Cancerogenic action of GIRK1 on mammary epithelial cells
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] Graz Medical University; 2019. pp. 107 [OPEN ACCESS]


Authors Med Uni Graz:
Bauernhofer Thomas
Prassl Ruth
Schreibmayer Wolfgang

Several studies have shown that potassium channels are involved in the development of tumor and metastasis formation. Excessive protein and messenger ribonucleic acid (mRNA) levels of GIRK1 have been found in ER+ breast cancer samples. They are associated with lymph node metastasis and reduced the probability of survival of patients. GIRK1 poses a promising target for the prognosis and therapy of breast cancer. Substantial expression of GIRK1 mRNA and protein also occurs in several cell lines cultured from breast tumors. The malignant MCF7 breast cancer cell line expresses GIRK1 mRNA already at moderate levels. Therefore, this cell line provides an excellent model for increased GIRK1 expression in breast tumors. Ectopic hyperexpression of GIRK1 in MCF7 cell lines has shown to aggravate several cancer hallmarks, including increased cellular motility, invasiveness and angiogenesis and is, thereby providing an explanation for the observed impact under clinical conditions. In order to investigate whether GIRK1 also act cancerogenic on benign MCF10A mammary epithelial cells, overexpressing GIRK1 have been engineered. Validation and characterization of mammary epithelial cell (MEC) lines overexpressing GIRK1, examined by qPCR and Western Blot analysis. Membrane resting potentials (RPs) were compared to controls. Transcriptome analysis reverted that the overexpression of GIRK1 in benign MECs affects expression levels of about 1900 genes involved in several cellular pro-tumorigenic pathways. Visualization and Integrated Discovery (DAVID) Pathway Analysis revealed that many of these transcripts are regulated towards specific cellular functions and pro-tumorigenic actions. Heat maps display the quantitative effect on selected gene clusters and underscore the amount of cellular regulation exerted by GIRK1 overexpression. Upon GIRK1 overexpression, motility and cellular velocities of the benign MCF10A control lines were substantially increased and associated with transcriptional changes of genes that are linked to motility at the cellular level. The most prominently regulated functional cluster is upregulated and comprises downstream elements which are triggered by the cytokine interferon-γ (IF-γ). In the present study, overexpression of GIRK1 in MCF10A cell line triggered several downstream IF-γ signaling elements known to act pro-tumorigenic in MEC lines. We observe profound changes in cellular phenotype upon GIRK1 overexpression in benign MCF10A. In this examination, it was found that the overexpression of only one single K+-channel subunit, which is of high importance to a cell and, can shift the vital parameters of a benign MEC-line towards cancer hallmarks. Research has shown that disturbance with potassium 13 channels potentially offers a new therapeutic window for the subtype of estrogen receptor positive (ER+) breast cancer treatment. This enables physicians to carry out improved therapy planning.

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