Evaluation of the Genetic Response of U937 and Jurkat Cells to 10-Nanosecond Electrical Pulses (nsEP)

<div><p>Nanosecond electrical pulse (nsEP) exposure activates signaling pathways, produces oxidative stress, stimulates hormone secretion, causes cell swelling and induces apoptotic and necrotic death. The underlying biophysical connection(s) between these diverse cellular reactions and nsEP has yet to be elucidated. Using global genetic analysis, we evaluated how two commonly studied cell types, U937 and Jurkat, respond to nsEP exposure. We hypothesized that by studying the genetic response of the cells following exposure, we would gain direct insight into the stresses experienced by the cell and in turn better understand the biophysical interaction taking place during the exposure. Using Ingenuity Systems software, we found genes associated with cell growth, movement and development to be significantly up-regulated in both cell types 4 h post exposure to nsEP. In agreement with our hypothesis, we also found that both cell lines exhibit significant biological changes consistent with mechanical stress induction. These results advance nsEP research by providing strong evidence that the interaction of nsEPs with cells involves mechanical stress.</p></div

Oxidative stress related protein levels in U937 and Jurkat cells exposed to nsEP.

<p>A) Levels of oxidative stress proteins for U937 at 4 h post exposure. B) Levels of oxidative stress proteins for Jurkat at 4 h post exposure. C) Levels of oxidative stress proteins for U937 at 8 h post exposure. D) Levels of oxidative stress proteins for Jurkat at 8 h post exposure. E) Levels of oxidative stress proteins for U937 at 12 h post exposure. F) Levels of oxidative stress proteins for Jurkat at 12 h post exposure. Error bars represent standard deviation (SD).</p

Scatter dot plot for each qRT-PCR validation sample.

<p>A) Comparison of the expression levels of JUN for U937 cells exposed to nsEP. B) Comparison of the expression levels of JUN for Jurkat cells exposed to nsEP. C) Comparison of the expression levels of DUSP10 for U937 cells exposed to nsEP. D) Comparison of the expression levels of DUSP10 for Jurkat cells exposed to nsEP. E) Comparison of the expression levels of HPRT1 for U937 cells exposed to nsEP. F) Comparison of the expression levels of HPRT1 for Jurkat cells exposed to nsEP. Mean and standard deviation are plotted as the green and black lines respectively.</p

Volcano plots of significant gene expression.

<p>A) U937 cells exposed to nsEP had 327 genes significantly up-regulated as compared to sham (≥2 log ratio and p-value ≤ 0.05). 225 genes were significantly down regulated (≤-2 log ratio and p-value ≤ 0.05). B) Jurkat cells exposed to nsEP had 215 genes significantly up-regulated as compared to sham (≥2 log ratio and p-value ≤ 0.05). 206 genes were significantly down regulated (≤-2 log ratio and p-value ≤ 0.05).</p

Top 20 genes up- and down-regulated in Jurkat cells exposed to nsEP.

<p>Top 20 genes up- and down-regulated in Jurkat cells exposed to nsEP.</p

Top Canonical Pathways.

<p>Top Canonical Pathways.</p

Genes up- or down-regulated in common by nsEP exposure in Jurkat and U937 cells.

<p>Genes up- or down-regulated in common by nsEP exposure in Jurkat and U937 cells.</p

Blumlein line cuvette-based, 10 ns pulser apparatus.

<p>A) Drawing of the complete 10-ns set up, including the Tektronix ocilloscope, Glassman high voltage power supply and custom contol module for regulating the pressure of SF6 in the spark gap chamber. B) This is an enhanced view of the cuvette and its placement/orientation in regards to the pulser.</p