Functional interactions between Choline kinase α, epidermal growth factor receptor and c-Src in breast cancer cell proliferation

ABSTRACT DNA topoisomerase I (Topo I) is a molecular target for the anticancer agent topotecan in the treatment of small cell lung cancer and ovarian carcinomas. However, the molecular mechanisms by which topotecan treatment inhibits cancer cell proliferation are unclear. We describe here the identification of Topo I as a novel endogenous interaction partner for transcription factor c-Jun. Reciprocal coimmunoprecipitation analysis showed that Topo I and c-Jun interact in transformed human cells in a manner that is dependent on JNK activity. c-Jun target gene epidermal growth factor receptor (EGFR) was identified as a novel gene whose expression was specifically inhibited by topotecan. Moreover, Topo I overexpression supported c-Jun-mediated reporter gene activation and both genetic and chemical inhibition of c-Jun converted cells resistant to topotecan-elicited EGFR downregulation. Topotecan-elicited suppression of proliferation was rescued by exogenously expressed EGFR. Furthermore, we demonstrate the cooperation of the JNK-c-Jun pathway, Topo I, and EGFR in the positive regulation of HT-1080 cell proliferation. Together, these results have identified transcriptional coactivator Topo I as a first endogenous cofactor for c-Jun in the regulation of cell proliferation. In addition, the results of the present study strongly suggest that inhibition of EGFR expression is a novel mechanism by which topotecan inhibits cell proliferation in cancer therapy.

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Anti-Tumor Activity of Metformin in Human Epidermal Growth Factor Receptor 2 Positive Breast Cancer Cells

Sains Malaysiana ◽

10.17576/jsm-2021-5005-18 ◽

2021 ◽

Vol 50 (5) ◽

pp. 1393-1405

Author(s):

Fathul Huda Fathul Huda ◽

Sari Ekawati Sari Ekawati ◽

Anindy Putri Addina Anindy Putri Addina ◽

Ahmad Faried Ahmad Faried ◽

Afiat Berbudi Afiat Berbudi ◽

...

Keyword(s):

Breast Cancer ◽

Cell Proliferation ◽

Cell Death ◽

Epidermal Growth Factor Receptor ◽

Cell Migration ◽

Growth Factor ◽

Clonogenic Assay ◽

Growth Factor Receptor ◽

Colony Number ◽

Epidermal Growth

Breast Cancer (BC) is the leading cause of cancer death in women. One BC subtype is very aggressive with amplification of human epidermal growth factor receptor 2 (HER2) protein. Although specific HER2+ targeting agents are available, most of HER2+ BC patients develop resistant to these agents. Recent studies show that metformin, is able to become anti-tumor in various cancer cells. This research aims to evaluate anti-tumor activities of metformin to HER2+ BC cells in both sensitive and resistant to trastuzumab. A series of assays were performed to evaluate metformin anti-tumor activities in HCC-1954 and SKBR-3 HER2+ BC cells. MTT assay was performed to evaluate cell death, and inhibitory concentration (IC50), while scratch assay was performed to assess inhibition of cell migration and clonogenic assay to assess cell proliferation. p<0.05 was considered to be significant. Metformin could suppress the number of HER2+ BC cells. Viability assay showed suppression of viable cells after metformin incubation of 60 and 600 µM compared to control, 30 and 90%, respectively. Surprisingly, IC50 of metformin was smaller in HER2+ BC HCC-1954 cells that resistant to trastuzumab compare to the sensitive one (SKBR-3). Both were below 1 µM, with R2 more than 0.95. Additionally, clonogenic assay showed less colony number and colony area with at least p < 0.05 in colony number and p < 0.01 in the area. In addition, metformin inhibited cell migration of HER2+ BC cells. Metformin shows a potency as anti-tumor by inducing cell death, inhibiting cell proliferation and cell migration of HER2+ BC cells.

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