• GENE EXPRESSION
• COLORECTAL CANCER

Circulating tumour cells (CTCs) are being used for the prediction of disease progression and drug sensitivity for various types of cancers. Current CTC isolation depends on epithelial cell surface proteins which can therefore miss CTCs that are non-epithelial.

Shigeyasu et al 1 describe technology to capture, sort and characterise epithelial and non-epithelial CTCs using a green fluorescent protein (GFP)-expressing attenuated adenovirus, in which the telomerase promoter regulates viral replication (OBP-401). OBP-401 selectively labels cancer cells, including CTCs, that express telomerase, which should include the vast majority of any type of cancer cell, since cancer cells in general express telomerase.2 Shigeyasu et al isolated CTCs from patients with colon cancer using their adenoviral GFP labelling technology but have not yet tested the technology on normal patients to demonstrate specificity. This study is published in Gut.1

Shigeyasu et al 1 capture, image and characterise epithelial and mesenchymal CTCs in contrast to currently used methods which depend on the epithelial cells adhesion molecule (EpCAM) for capture. After sorting the GFP-expressing CTCs, direct sequencing or mutation-specific PCR detected various mutations in KRAS, BRAF and KIT genes in epithelial, mesenchymal or epithelial–mesenchymal transition-induced CTCs using model human cancer cell lines, as well as in blood samples from patients with colorectal cancer.

CTCs can have epithelial and mesenchymal characteristics. EpCAM-positive and EpCAM-negative CTCs from patients with breast cancer have been shown to have a high potential to metastasise to the lung and …