Microsatellite stable Left Colon Cancer distinct in Indigenous African patients versus other ethnic groups

A large proportion of indigenous African (IA) colorectal cancer (CRC) patients in South Africa are young (<50years), with no unique histopathological or molecular characteristics. Anatomical site as well as microsatellite instability (MSI) status have shown to be associated with different clinicopathological and molecular features. This study aimed to ascertain key histopathological and miRNA expression patterns in microsatellite stable (MSS) and low-frequency MSI (MSI-L) patients, to provide insight into the mechanism of the disease. This study revealed distinct histopathological features for Left Colon Cancer (LCC), and suggests BAT25/26, miRNAs let-7a-5p and miRNA-125a/b-5p as negative prognostic markers in African CRC patients. qPCR gene expression profiling. RNA from FFPE tumour tissue from 3-4 CRC tumour samples were pooled according to their molecular subgroup status: 1) MSI-L LCC, 2) MSI-L RCC, 3) MSS LCC and 4) MSS RCC. Equal amount total RNA from each sample was pooled prior to gene expression analysis.