Abstract 3908: The mechanism of premetastatic niche formation through FBXW7/NOTCH/CCL2 pathway and clinical trial using CCL2 inhibitor “SK-818” for breast cancer patients
Authors: Noda Miwa , Masuda Takaaki , Hayashi Naoki , Kogawa Takahiro , Ohno Shinji , Nakayama Keiichi , Kuroda Yohsuke , Eguchi Hidetoshi , Ito Shuhei , Inomata Masafumi , Mimori Koshi 
Published: July 2017

Background Metastasis is a major cause of death in cancer patients, & elucidation of the mechanisms is expected to provide a basis for the development of new cancer treatment. Premetastatic niche whereby tumors prepare defined organs for metastasized cells is considered to be crucial for the development of metastasis, which consists of host cells such as monocytes, macrophages, & other inflammatory cells. However, the mechanism of how tumor cells communicate with host cells to develop a premetastatic niche remains unclear. FBXW7 is the F-box protein component of an SCF-type ubiquitin ligase, in which it functions as a receptor responsible for substrate recognition followed by the degradation of the substrate. Some part of the substrates of FBXW7 regulates the recruitment of monocytes, macrophages, & other inflammatory cells. Therefore, we hypothesized that expression of FBXW7 in the host cells is a key determinant of the formation of premetastatic niches.

Materials & Methods To investigate the role of FBXW7 in the formation of premetastatic niche, we developed bone marrow-specific FBXW7-deficient mice.

1. We transferred B16F10 melanoma cells or E0771 mouse breast cancer cells into the tail vein or mammary fat pad of the mice & the wild type mice to evaluate the metastatic potential to lung.

2. We examined the serum concentrations of various cytokines or chemokines in the mice before & after E0771 cells transplantation using cytokine array.

3. To examine whether the enhanced metastasis apparent in FBXW7-deficient mice is dependent on the CCL2/CCR2 pathway, we treated FBXW7-deficient mice with SK-818, a CCR2 antagonist.

4. We measured the expression of FBXW7 mRNA in peripheral blood of breast cancer patients by qRT-PCR & examined the relationship between FBXW7 mRNA expression & prognosis.

Results

1. The extent of lung metastasis of B16F10 or E0771 cell was markedly enhanced in FBXW7-deficient mice.

2. FBXW7-deficient mice exhibited increased serum levels of CCL2. Moreover, accumulation of NOTCH & consequent transcriptional activation of CCL2 was observed in bone marrow-derived stromal cells of FBXW7-deficient mice.

3. Administration of SK-818 blocked the enhancement of lung metastasis in FBXW7-deficient mice.

4. In human breast cancer patients, low FBXW7 mRNA expression in peripheral blood showed high concentration of CCL2 in serum & poor prognosis.

Conclusions We found that the FBXW7/NOTCH/CCL2 pathway play a key role in the regulation of cancer metastasis through the formation of premetastatic niches, & that SK-818 inhibit cancer metastasis in mice. SK-818 is currently administered clinically for the treatment of patients with hepatitis B virus infection in Japan. Based on these findings, we have been conducting Phase I clinical trial to assess the safety of SK-818 for breast cancer patients.

Citation Format: Miwa Noda, Takaaki Masuda, Naoki Hayashi, Takahiro Kogawa, Shinji Ohno, Keiichi Nakayama, Yohsuke Kuroda, Hidetoshi Eguchi, Shuhei Ito, Masafumi Inomata, Koshi Mimori. The mechanism of premetastatic niche formation through FBXW7/NOTCH/CCL2 pathway and clinical trial using CCL2 inhibitor “SK-818” for breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3908. doi:10.1158/1538-7445.AM2017-3908