The MCM protein family has six highly conserved subunits, MCM2 to 7, and is essential for initiation
and elongation of DNA replication in all eukaryotes. Deregulation of the MCM function and expression
resulted in cells undergoing tumorigenesis. Therefore, these proteins are potential diagnostic markers for
cancer and promising targets for anticancer drug development. On the other hand, recently marine
organisms are regarded as attractive sources of novel anticancer compounds due to their tremendous
biodiversity. In this study, we screened several seaweed for down-regulatory compound of MCM and
selected Corallina pilulifera as candidate. Ethanolic extract of Corallina pilulifera (EECP) reduced MCM
expression in a dose-dependent manner(0-200μg/ml). EECP showed cytotoxic and antiproliferative
activity against six human cancer cells tested such as HeLa, HT29, T24, HepG2, A549 and Jurkat E6-1.
A 30% of tumor mass volume reduction was observed in vivo experiment using mouse bearing Sarcoma
180 cells after treatment of EECP for 14 days, and antitumor efficacy was 72.1%. Oligonucleotide
microarray analysis identified 69 up-regulated genes and 79 down-regulated genes in HeLa cells after
EECP treatment. The deregulated genes were involved in various biological process including cell cycle
regulation and cell proliferation, signal transduction, apoptosis, and predominantly down-regulated genes
were mainly associated with cell cycle.

Keywords: MCM protein, Corallina pilulifera, Cytotoxicity, Microarray, Antitumor efficacy