Use of the OM-11-906 monoclonal antibody for determining p62 c-myc expression by flow cytometry in relation to prognosis in colorectal cancer.

The expression of the c-myc protein product (p62 c-myc) and deoxyribonucleic acid (DNA) ploidy status was determined by a flow cytometric technique in 83 patients with colorectal cancer followed up for a median of 30 months (range 6-60 months). The OM-11-906 antibody, used to detect p62 c-myc, revealed a 62 kDa and 45 kDa band on Western blots in tumours. Correlation of quantitative dot blotting of tumour mRNA to flow cytometric p62 c-myc expression was good (r = 0.87, P less than 0.01). Levels of p62 c-myc varied in colorectal cancer and low levels (less than 20 fluorescein units) correlated with improved survival (log rank chi 2 = 4.69, df = 1, P = 0.03), and this was a better prognostic index than DNA ploidy (log rank analysis chi 2 = 2.38, df = 1, P less than 0.1). Although expression of the c-myc gene was found, using the OM-11-906 antibody, to be a prognostic feature in colorectal cancer, these and other results need to be interpreted with caution given the presence of two protein bands by Western blotting.