The Effect of Cholesterol in MCF7 Human Breast Cancer Cells

Cholesteryl ester transfer protein knock-down in conjunction with a cholesterol-depleting agent decreases tamoxifen resistance in breast cancer cells

The cholesterogenic phenotype, encompassing de novo biosynthesis and accumulation of cholesterol, aids cancer cell proliferation and survival. Previously, the role of cholesteryl ester (CE) transfer protein (CETP) has been implicated in breast cancer aggressiveness, but the molecular basis of this observation is not clearly understood, which this study aims to elucidate. CETP knock-down resulted in a >50% decrease in cell proliferation in both 'estrogen receptor-positive' (ER+; Michigan Cancer Foundation-7 (MCF7) breast cancer cells) and 'triple-negative' breast cancer (TNBC; MDA-MB-231) cell lines. Intriguingly, the abrogation of CETP together with the combination treatment of tamoxifen (5 μM) and acetyl plumbagin (a cholesterol-depleting agent) (5 μM) resulted in twofold to threefold increase in apoptosis in both cell lines. CETP knockdown also showed decreased intracellular CE levels, lipid raft and lipid droplets in both cell lines. In addition, RT2 Profiler PCR array (Qiagen, Germany)-based gene expression analysis revealed an overall downregulation of genes associated in cholesterol biosynthesis, lipid signalling and drug resistance in MCF7 cells post-CETP knock-down. On the contrary, resistance in MDA-MB-231 cells was reduced through increased expression in cholesterol efflux genes and the expression of targetable surface receptors by endocrine therapy. The pilot xenograft mice study substantiated CETP's role as a cancer survival gene as knock-down of CETP stunted the growth of TNBC tumour by 86%. The principal findings of this study potentiate CETP as a driver in breast cancer growth and aggressiveness and thus targeting CETP could limit drug resistance via the reduction in cholesterol accumulation in breast cancer cells, thereby reducing cancer aggressiveness.

Sphingomyelin Metabolism Modifies Luminal A Breast Cancer Cell Line under a High Dose of Vitamin C

The role of sphingomyelin metabolism and vitamin C in cancer has been widely described with conflicting results ranging from a total absence of effect to possible preventive and/or protective effects. The aim of this study was to establish the possible involvement of sphingomyelin metabolism in the changes induced by vitamin C in breast cancer cells. The MCF7 cell line reproducing luminal A breast cancer and the MDA-MB-231 cell line reproducing triple-negative breast cancer were used. Cell phenotype was tested by estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 expression, and proliferation index percentage. Sphingomyelin was localized by an EGFP-NT-Lys fluorescent probe. Sphingomyelin metabolism was analyzed by RT-PCR, Western blotting and UFLC-MS/MS. The results showed that a high dose of vitamin C produced reduced cell viability, modulated cell cycle related genes, and changed the cell phenotype with estrogen receptor downregulation in MCF7 cell. In these cells, the catabolism of sphingomyelin was promoted with a large increase in ceramide content. No changes in viability and molecular expression were observed in MB231 cells. In conclusion, a high dose of vitamin C induces changes in the luminal A cell line involving sphingomyelin metabolism.

Molecular, Cellular, and Technical Aspects of Breast Cancer Cell Lines as a Foundational Tool in Cancer Research

Breast cancer comprises about 30% of all new female cancers each year and is the most common malignant cancer in women in the United States. Breast cancer cell lines have been harnessed for many years as a foundation for in vitro analytic studies to understand the use of cancer prevention and therapy. There has yet to be a compilation of works to analyze the pitfalls, novel discoveries, and essential techniques for breast cancer cell line studies in a scientific context. In this article, we review the history of breast cancer cell lines and their origins, as well as analyze the molecular pathways that pharmaceutical drugs apply to breast cancer cell lines in vitro and in vivo. Controversies regarding the origins of certain breast cancer cell lines, the benefits of utilizing Patient-Derived Xenograft (PDX) versus Cell-Derived Xenograft (CDX), and 2D versus 3D cell culturing techniques will be analyzed. Novel outcomes from epigenetic discovery with dietary compound usage are also discussed. This review is intended to create a foundational tool that will aid investigators when choosing a breast cancer cell line to use in multiple expanding areas such as epigenetic discovery, xenograft experimentation, and cancer prevention, among other areas.