Chorein-dependent microfilament organization in tumor cells

Abstract

Chorein is variably expressed in different cancer cells. In various non-malignant cell types, this protein regulates cytoskeleton microstructure and signaling. However, the role of chorein in regulating the actin cytoskeleton in tumor cells remains elusive. Here, we investigated chorein expression in various breast tumor cells and the involvement of this protein in microfilament organization. We used laser scanning microscopy to analyze microfilaments architecture, Triton X-100 fractionation to quantify G and Total actin levels, and quantitative RT-PCR to assess chorein gene transcription. We show that in line with previous observations, the less differentiated MCF7 breast cancer cells exhibited the highest relative expression of chorein compared to MDA-MB231 and T47D cell lines. Contrastingly, in less differentiated ZF rhabdomyosarcoma cells expressing high chorein levels, silencing of this protein was followed by clear depolymerization of actin microfilaments as apparent from IF morphological analysis. Quantification of G- and F-actin levels by Triton X-100 fractionation that revealed a significant increase in this ratio fully supported this finding. These results disclose that chorein is highly expressed in less differentiated tumor cells. In addition, silencing of this protein induces significant structural disorganization of the actin network, providing clear evidence that chorein regulates microfilament cytoskeleton architecture in tumor cells of higher malignant potential.

Keywords

• Chorein
• Tumor
• Actin
• Microfilament
• Gene Silencing
• Polymerization