pomolic-acid and Neoplasm-Metastasis

High mortality of cancer-mediated deaths is due to metastasis. CXC chemokine receptor type 4 (CXCR4) signaling has been demonstrated to be involved in migration of breast cancer. Thus, identification of CXCR4 inhibitor has been challenged constantly as an anticancer drug. This study is aimed to investigate the CXCR4 inhibitor that could inhibit tumor metastasis from natural products. We demonstrated that pomolic acid (PA), a component of Euscaphis japonica, could downregulate CXCR4 expression in breast cancer cells. Treatment with proteasomal and lysosomal inhibitors did not show significant effects on PA's ability. When we further explored the molecular mechanism, suppression of CXCR4 occurred at transcriptional level and was correlated with inhibition of nuclear factor-kappaB (NF-κB) activation. Downregulation of CXCR4 by PA was accompanied by the inhibition of CXC motif chemokine 12 (CXCL12)-induced invasion of breast cancer cells. Overall, our results indicate that PA, as a novel inhibitor of CXCR4, can be a promising therapeutic agent for treatment of cancer metastasis.

Topics: Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Down-Regulation; Female; Gene Expression Regulation, Neoplastic; Humans; MCF-7 Cells; Neoplasm Invasiveness; Neoplasm Metastasis; Oleanolic Acid; Receptors, CXCR4

Expression of the CXC chemokine receptor-4 (CXCR4), a G protein-coupled receptor, and HER2, a receptor tyrosine kinase, strongly correlates with tumor progression and metastatic potential of breast cancer cells. We report the identification of pomolic acid (PA) as a novel regulator of HER2 and CXCR4 expression. We found that PA downregulated the expression of HER2 and CXCR4 in SKBR3 cells in a dose- and time-dependent manner. When investigated for the molecular mechanism(s), it was found that the downregulation of HER2 and CXCR4 was not due to proteolytic degradation but rather to transcriptional regulation as indicated by downregulation of mRNA expression. Moreover, we show that PA inhibits phosphorylation of ERK and reduces NF-κB activation. Suppression of CXCR4 expression by PA correlated with the inhibition of CXCL12-induced invasion of HER2-overexpressing breast cancer cells. Overall, our results demonstrate for the first time that PA is a novel inhibitor of HER2 and CXCR4 expression via kinase pathways and may play a critical role in determining the metastatic potential of breast cancer cells.

Topics: Breast Neoplasms; Cell Line, Tumor; Female; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Signaling System; Neoplasm Invasiveness; Neoplasm Metastasis; Oleanolic Acid; Receptor, ErbB-2; Receptors, CXCR4