Calmodulin-like effect of oncomodulin on cell proliferation.

Oncomodulin (OM) is a Ca2+ binding protein (CABP) structurally closely related to parvalbumin. Expression of OM is restricted to early embryonic stages, the placental cytotrophoblasts, and neoplastic tissues. The function of OM as a calmodulin (CaM)-like enzyme modulator is controversial. Two types of experiments demonstrate that OM may act in an analogous fashion to CaM in T14 and T10 cancerous cell lines, which both express OM. First, both OM transcript and protein levels increased at the G1/S boundary in a similar manner to CaM, though not to the same extent, in the chemically transformed rat fibroblast cell line T14 synchronized at mitosis by nocodazole. Second, antisense oligonucleotides specific to the OM ATG region inhibited growth of T14 in a similar dose-dependent manner as observed with CaM-specific antisense probes.