Studies have shown that a subpopulation of cells known as cancer stem cells (CSCs) exist within tumours and are proposed to be the underlying cause of efficient tumour metastasis. Although this malignant colon cancer cell population is estimated to typically account for 9 percent or less of the cells in tumours, only some of these cells have the capacity to form new tumours. To advance therapeutic approaches targeting CSCs, it is important to study them using the cell surface markers that identify them. This study focused on identifying the relationship between the CSC markers ABGC2, Cripto-1, CD271, EPCAM, OCT4 or SSEA1 and pathology samples derived from human colorectal cancer (CRC) patients.
Surgically excised CRC pathology samples were categorised by immunohistochemistry as either negative, low positive, positive or high positive regions of staining within the defined tumour sections. The different types of colorectal cancers, including polyps (n = 10), primary adenocarcinoma (n = 20) or metastatic groups (n = 20), were categorised and immunostained and, in some cases, compared to the adjacent normal colon with antibodies against ABGC2, Cripto-1, CD271, EPCAM, OCT4 or SSEA1. The percentages of negative, weakly positive, positive and highly positive stained regions as a proportion of the total area from each of the patient’s cancer samples were compared to each other and were then averaged across the same sample types using the methods for quantifying immunostaining.
In summary, the analysis of the putative CSC markers was identified to confirm the low level of expression of these markers within tumour sections from the primary tumour samples of human CRC patients. Interestingly, the levels of highly positive expression were obtained in the more advanced metastatic tumour samples, with co-expression as a common finding suggesting that they are involved in the CSC phenotype.