Abstract P5-14-01: Docosahexanoic acid's modulation of survival and invasion is associated with altered CCL20/CCR6 chemokine levels and signaling in hyperplastic, DCIS and metastatic breast cancer cell lines

Introduction: High dietary intake of docosahexanoic acid is associated with a lower risk of breast cancer and reduced metastasis. Epidemiological and preclinical studies suggest that the regulation of monocyte recruitment may play an important role in lowering breast cancer risk and decreasing breast cancer metastasis. In addition to promoting the recruitment of pro-inflammatory leukocytes, the CCL20/CCR6 chemokine axis has been implicated in promoting breast cancer cell migration and invasion. We hypothesize that one mechanism by which DHA suppresses breast cancer progression and metastasis is through the suppression of CCL20/CCR6 signaling. Methods: The 21PT, 21NT and 21MT-1 cell lines have been previously described as reflecting the characteristics of hyperplastic, in situ and metastatic breast cells, respectively. We measured the impact of physiological DHA concentrations on cell survival and cell proliferation using colony formation and MTT assays respectively. Invasion of 21PT, 21NT and 21MT-1 cells were evaluated using invasion chambers. Changes in CCL20 and CCR6 expression were measured using qPCR. The activity and expression levels of JNK, ERK1/2 and c-Jun, downstream modulators of the CCL20/CCR6 axis, were evaluated using Western blot analyses. Results: Following a 24 hr exposure to 20 uM DHA and 5-7 days of recovery, colony counts of all three cell lines were significantly suppressed, with 21NT cells experiencing the largest percent reduction. Invasion capacity of 21PT, 21NT and 21MT-1 accurately mirrored the stages of breast cancer they represent. Treatment with DHA reduced the invasion capacity of 21MT-1 to the levels of its hyperplastic counterpart. CCL20 mRNA levels were reduced when cells were exposed to DHA for 48 hrs. Western blot analyses suggest that activation of ERK1/2 and JNK signaling may be critical in orchestrating DHA-associated reduction of invasion. Conclusions: With the support from epidemiological and preclinical studies, the use of omega-3 based preventive regimen may prove useful for reducing breast cancer risk and breast cancer metastasis. In vitro studies using premalignant breast cancer can provide invaluable insights to the molecular mechanisms accountable for preventive properties of omega-3 fatty acids. DHA-associated regulation of CCL20/CCR6 signal transduction may be an important preventive mechanism and future studies will warrant deepened understanding of how nutraceutical compounds can prevent breast cancer. Citation Format: Ching Hui Chen, Laura Garcia, Carol Fabian, Stephen Hursting, Linda deGraffenried. Docosahexanoic acid9s modulation of survival and invasion is associated with altered CCL20/CCR6 chemokine levels and signaling in hyperplastic, DCIS and metastatic breast cancer cell lines [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-14-01.