Membrane potential bistability in human breast cancer MDA-MB-231 cells: A ‘Hodgkin-Huxley type’ model

The plasma membrane voltage ( V _m ) is well known to have significant involvement in a wide range of cellular functions including cancer progression. Voltage imaging revealed that V _m of MDA-MB-231 breast cancer cells is ‘bistable’ with hyperpolarising voltage transients (HVTs). Here, we formulate a model of V _m incorporating the ion channels Na _v 1.5, Ca _v 3.2, and K _Ca 1.1. V _m is governed by the Hodgkin-Huxley formalism coupled to intracellular Ca ²⁺ dynamics, via Ca ²⁺ influx through Ca _v 3.2 and Ca ²⁺ -dependent efflux of K ⁺ through K _Ca 1.1. Stochastic fluctuations—arising from sparse ion channel expression and Ca ²⁺ -induced Ca ²⁺ release (CICR)—drive V _m transitions between the otherwise stable depolarised and hyperpolarised states. The model qualitatively reproduces the key experimental observations of HVTs, and their suppression by specific inhibitors of Na _v 1.5 or K _Ca 1.1. It is predicted that inhibition of CICR should also lead to suppression of HVTs. Our model promises to help the understanding of the dynamic electrical activity of the MDA-MB-231 cell model and its functional consequences, and may inspire future bioelectricity-based cancer diagnosis and therapy.