Anti-inflammation and Anti-Cancer Activity of Ethanol Extract of Antarctic Freshwater Microalga, Micractinium sp.

Inflammation mediated by the innate immune system is an organism’s protective mechanism against
infectious environmental risk factors. It is also a driver of the pathogeneses of various human
diseases, including cancer development and progression. Microalgae are increasingly being focused
on as sources of bioactive molecules with therapeutic potential against various diseases.
Furthermore, the antioxidant, anti-inflammatory, and anticancer potentials of microalgae and their
secondary metabolites have been widely reported. However, the underlying mechanisms remain to
be elucidated. Therefore, in this study, we investigated the molecular mechanisms underlying the
anti-inflammatory and anticancer activities of the ethanol extract of the Antarctic freshwater
microalga Micractinium sp. (ETMI) by several in vitro assays using RAW 264.7 macrophages and
HCT116 human colon cancer cells. ETMI exerted its anti-inflammatory activity by modulating the
main inflammatory indicators such as cyclooxygenase (COX)-2, interleukin (IL)-6, inducible nitric
oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and nitric oxide (NO) in a dose-dependent
manner. In addition, ETMI exerted cytotoxic activity against HCT116 cells in a dose-dependent
manner, leading to significantly reduced cancer cell proliferation. Further, it induced cell cycle arrest
in the G1 phase through the regulation of hallmark genes of the G1/S phase transition, including
CDKN1A, and cyclin-dependent kinase 4 and 6 (CDK4 and CDK6, respectively). At the transcriptional
level, the expression of CDKN1A gradually increased in response to ETMI treatment while that of
CDK4 and CDK6 decreased. Taken together, our findings suggest that the anti-inflammatory and
anticancer activities of the Antarctic freshwater microalga, Micractinium sp., and ETMI may provide a
new clue for understanding the molecular link between inflammation and cancer and that ETMI may
be a potential anticancer agent for targeted therapy of colorectal cancer.
The main purpose of this study was to assess the anti-inflammatory and cytotoxic effects of the ethanol extract from the polar microalga Micractinium sp. (ETMI) on the human colon cancer cell line, HCT116.