PAPOLA contributes to Cyclin D1 mRNA alternative polyadenylation and promotes breast cancer cells proliferation
Poly(A) polymerases add the poly(A) tail at the 3’ end of nearly all eukaryotic mRNA, are associated with proliferation and cancer. To elucidate the role of the most studied mammalian poly(A) polymerase α (PAPOLA) in cancer, we assessed its expression in 221 breast cancer samples and found it to correlate strongly with the aggressive triple-negative subtype. Silencing PAPOLA in MCF-7 and MDA-MB-231 breast cancer cells reduced proliferation and anchorage-independent growth by decreasing steady-state CCND1 mRNA and protein levels. Whereas the length of the CCND1 mRNA poly(A) tail was not affected, its 3' untranslated region (3'UTR) lengthened. Overexpressing PAPOLA caused CCND1 mRNA 3'UTR shortening with a concomitant increase in the corresponding transcript and protein, resulting in growth arrest in MCF-7 cells and DNA damage in HEK-293 cells, whereas in the P53 mutant MDA-MB-231 promoted proliferation.Our data suggest PAPOLA as a possible candidate target for the control of tumor growth, mostly relevant to triple-negative tumors, a group characterized by its overexpression and lacking alternative targeted therapies.