Elevated tumor expression of Astroprincin (FAM171A1) is an independent marker of poor prognosis in colon cancer

Background: Colon cancer (CC) is one of the most commonly diagnosed malignancies worldwide. Several biomarkers have been suggested for improved prognostic evaluation, but few have been implemented in clinical practice. There is a need for biomarkers that predict the tumor behavior in CC and allow stratification of patients that would benefit from adjuvant therapy. We recently identified and functionally characterized a previously unknown protein that we called ASTROPRINCIN (APCN) due to its abundance in astrocytes. APCN, also annotated as FAM171A1, is found in trophoblasts of early placenta. We demonstrated that high expression levels of APCN in cancer cells induced motility and ability of invasive growth in semisolid medium.

Methods: We screened by immunohistochemistry a tissue microarray material from the tumors of 429 CC patients with clinical follow-up in a test series and 255 CC patients in a validation series.

Results: We showed that low or absent APCN expression correlates with a favorable prognosis while high APCN expression was a sign of an adverse outcome. Cox uni- and multivariable analysis revealed that elevated tumor expression of APCN constitutes a robust marker of poor prognosis independent of stage, grade, patient's age, or gender.

Conclusion: Our findings demonstrate that APCN is a novel independent prognostic marker in CC and could potentially select patients for more intense postoperative adjuvant treatment and follow-up.