47P - Differential expression of discriminative markers in matched invasion fronts and tumour buds in CRC

Background

In CRC molecular studies have shown that there is a great inter-tumour heterogeneity (ITH) within each UICC TNM stage and therefore a range of other transcriptional and protein biomarkers need to be investigated independently of the UICC TNM staging. In CRC, one of these adverse prognostic factors is tumour budding, Typically, tumour budding is assessed using H&E-stained specimens but scoring methods and grading schemes vary widely. A retrospective study was carried out to study the differential expression of discriminative markers in matched invasion fronts and tumour buds of 44 patients with stage 3/4 CRC disease.

Methods

A retrospective study was done on 44 Formalin Fixed paraffin embedded tissue sections with at least stage 3/4 CRC disease. These cases were used to study the expression differences between the central portion of the tumour, the invasion front and the tumour buds using the Luminex bead-based assay. The different tumoral compartments were assessed by a pathologist on a H&E stained slide and a 0.5mm core was obtained from each respective area on the specimen block. The core was lysed for 18 – 22 hrs at 58°C. After overnight incubation, hybridization-based assay was performed to study the expression of 50 different genes. Data analysis was carried out to see if there is any statistically significant difference between the central portion of the tumour, the invasion front and tumour buds.

Results

A statistically significant differences was noted in the expression of TRIB1 and CCND3 when comparing the central portion of the tumour to the tumour buds. The expression of TRIB1 and CCND3was higher in the buds than that of the central tumour. A statistically significant difference was seen in the expression of CDX2 when comparing the invasion front to the tumour bud. CDX2 was higher in the invasion front than in the tumour buds. A statistically significant difference was also seen in the expression of MCL1 which was higher in the invasion fronts when compared to the central tumour part.

Conclusions

With the use of a bead based multiplex assay we were able to carry out differential expression of a number of genes related to invasiveness, metastasis and treatment resistance in matched central tumour, invasion fronts and tumour buds in CRC patients.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

Emanuele Cancer Research Foundation Malta.

Disclosure

All authors have declared no conflicts of interest.