Human oral cancer cells with increasing tumorigenic abilities exhibit higher effective membrane capacitance

Abstract

Objective: Although cells with tumorigenic / stem cell-like properties have been identified in many cancers, including oral squamous cell carcinoma (OSCC), their isolation and characterisation is still at early stages. The aim of this study was to characterise the electrophysiological properties of OSCC cells with different tumorigenic properties in order to establish if a correlation exists between tumorigenicity and electrical characteristics. Materials and Methods: Rapid adherence to collagen IV was used as a non-invasive, functional method to isolate subsets of cells with different tumorigenic abilities from one oral dysplastic and three OSCC-derived cell lines. The cell subsets identified and isolated by this method were further investigated independently using dielectrophoresis, a label-free method to determine their electrophysiological parameters. Cell membrane morphology was investigated using scanning electron microscopy (SEM) and modulated by use of 4-methylumbelliferone (4-MU). Results: The rapid adherent cells (RAC) to collagen IV, enriched for cells with increased tumorigenic ability, had significantly higher effective membrane capacitance than middle (MAC) and late (LAC) adherent cells. SEM showed that, in contrast to MAC and LAC, RAC displayed a rough surface, extremely rich in cellular protrusions. Treatment with 4-MU dramatically altered RAC cell membrane morphology by causing loss of filopodia, and decreased significantly their membrane capacitance, indicating that the highest membrane capacitance found in RAC was due to their particular cell membrane morphology. Conclusion: This is the first study showing that OSCC cells with higher tumour formation ability exhibit higher effective membrane capacitance than cells that are less tumorigenic. OSSC cells with different tumorigenic ability possessed different electrophysiological properties mostly due to their differences in the cell membrane morphology. The results suggest that dielectrophoresis may potentially be of use in the future for reliable, label-free isolation of putative tumorigenic cells.

The feasibility of using dielectrophoresis for isolation of glioblastoma subpopulations with increased stemness

“…In a consecutive study, we successfully demonstrated separation of aggressive ovarian cancer cells from their earlier stage progeny using dielectrophoresis . Other groups have demonstrated the alteration of dielectric properties of oral cancer cells with increased stem like properties . Mulhall et al showed that there is an increase in the intracellular conductivity of malignant oral keratinocytes grown in 3D comparing to the same cells in 2D culture .…”

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

“…Single-cell electrical properties (e.g., membrane capacitance or cytoplasm resistance) can be utilized as cellular biophysical markers to evaluate cellular status in a label-free manner [ 1 , 2 ]. They have been demonstrated to classify various types of tumor cells [ 3 , 4 , 5 ], stem cells [ 6 ] and blood cells [ 7 , 8 , 9 , 10 , 11 ].…”

“…Dielectrophoresis is demonstrated to quantify cellular electrical properties by curve fitting of the Clausius–Mossotti factor spectra or cell count spectra. However, since the spectra are not from the measurements of the same cells, only average electrical properties of a cell population can be obtained [ 3 , 4 , 12 , 13 , 14 , 15 , 16 , 17 ]. Patch-clamp devices characterize the activities of cellular ion channels by sucking a portion of cell membrane into a micropipette tip to form a high electrical resistance seal, enabling the quantification of specific membrane capacitance of single cells (an intrinsic size-independent electrical parameter of cells) [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Classification of Cells with Membrane Staining and/or Fixation Based on Cellular Specific Membrane Capacitance and Cytoplasm Conductivity

“…Single-cell electrical properties (e.g., specific membrane capacitance (Cspecific membrane) and cytoplasm conductivity (σcytoplasm)) are promising biophysical markers for understanding cellular functions and status [1][2][3][4], enabling cell type classification (e.g., tumor cells [5][6][7][8][9], stem cells [10], red blood cells [11,12], and white blood cells [13,14]). …”