Effects of glucose and hypoxia on tamoxifen response of MCF7 human breast cancer cells in microcarrier culture

Breast cancer affects one in ten women. This work was undertaken in order to further the understanding of the effects of physiologically-relevant concentrations of metabolites, such as glucose and oxygen, on tumor cell growth, metabolism, and response to therapeutics. Growth, primary metabolism, and the response to the therapeutic tamoxifen (TAM) of MCF7 human breast cancer cells was characterized in microcarrier culture under conditions of reduced glucose or oxygen supply. A spinner flask culture apparatus was designed to enable cells on microcarrier beads to be maintained in a homogeneous environment with respect to oxygenation and nutrient supply. The glucose concentrations that were investigated represented standard tissue culture levels (6 mM or 24 mM) or tumor blood levels (0.5 mM). The dissolved oxygen level studied was also representative of standard tissue culture (20% oxygen) or tumor blood (2% oxygen).; Reduced oxygen tension decreased MCF7 proliferation. After five days, TAM-treated cultures grew to 30% and 75% of control cultures under 20% (normoxic) and 2% (hypoxic) oxygen atmospheres, respectively. The decreased effect of TAM on cell growth in hypoxic conditions was due to the reduced growth rate of the control cultures; the final cell density of the TAM-treated cultures was not affected by dissolved oxygen concentration. In 20% oxygen, TAM decreased glucose metabolism as has been reported previously. After five days in culture, the specific glucose uptake rate and lactate dehydrogenase (LDH) activity in cultures treated with 1μM TAM were reduced to 41% and 46% of the values observed in untreated cultures, respectively.; This work represents an important first step in understanding the growth, metabolism, and response to the therapeutic TAM of MCF7 human breast cancer cells in extreme environments. The design of a batch microcarrier culture system that allows for easy manipulation of environmental conditions enabled quantitative measurements of metabolite utilization that would be significantly more labor intensive using standard surface cell culture systems (e.g. multi-well plates maintained in an incubator). The effects of glucose and oxygen on growth, metabolism, and response to TAM were quantified, yielding new insight into the mechanisms of action of the therapeutic TAM as well as the ability of MCF7 cells to survive in extreme environments. (Abstract shortened by UMI.)...