ORC-associated replication factors as biomarkers for cancer.

Early detection and treatment of cancer are of central importance to improving patient prognoses. Traditional biomarkers of cell proliferation, such as Ki-67 and PCNA, have had a mixed clinical track record, proving to be good indicators of certain types of cancers but of limited use for many others. Recently, human counterparts of replication factors originally identified in budding yeast have shown great promise as new cancer biomarkers. Each of these factors has been shown to interact with the origin recognition complex (ORC) in yeast, and each has an essential role in the initiation of DNA replication. Studies with minichromosome maintenance (MCM) family proteins show that their levels are upregulated in tumor cells and are much better indicators of a wide variety of cancers than traditional biomarkers. Similarly encouraging results have been obtained in preliminary studies examining Cdc6 protein and Cdc7 kinase transcript levels in normal and cancerous cells.