pomolic-acid and Breast-Neoplasms

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

The expression of matrix metalloproteinase-9 (MMP-9) and the phosphorylation of focal adhesion kinase (FAK) have been implicated in the invasion, metastasis and cell motility of cancer cells. It is considered that epidermal growth factor (EGF) may increase cell motility, an event involved in cancer cell invasion and metastasis. Pomolic acid (PA), an active triterpenoid from Euscaphis japonica, is known to inhibit the proliferation of a variety of cancer cells, but the effect of PA on the invasiveness of cancer cells is largely unknown. In this study, we first determined the molecular mechanism by which PA inhibits the migratory and invasive abilities of highly metastatic MDA-MB‑231 cells. Transwell invasion, wound-healing assay and F-actin reorganization showed that PA significantly inhibits the EGF-induced invasion, migration and cell motility by reducing expression of MMP-9 and FAK phosphorylation. In particular, PA potently suppressed the phosphorylation of nuclear factor (NF)-κB, extraceullar signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, PA treatment inhibited the DNA binding activity of NF-κB and activator protein (AP)-1, which is known to mediate the expression of EGFR and MMP-9. These results suggest that PA may be a potential therapeutic candidate for treatment of breast cancer metastasis.

Topics: Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Epidermal Growth Factor; Female; Focal Adhesion Kinase 1; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Signaling System; Matrix Metalloproteinase 9; Neoplasm Invasiveness; NF-kappa B; Oleanolic Acid; Phosphatidylinositol 3-Kinases; Phosphorylation

Salvia officinalis is used as a dietary supplement with diverse medicinal activity (e.g. antidiabetic and antiatherosclerotic effects). The plant also exerts profound cytotoxicity toward cancer cells. Here, we investigated possible modes of action to explain its activity toward drug-resistant tumor cells. Log10IC50 values of two constituents of S. officinalis (ursolic acid, pomolic acid) were correlated to the expression of ATP-binding cassette (ABC) transporters (P-glycoprotein/ABCB1/MDR1, MRP1/ABCC1, BCRP/ABCG2) and epidermal growth factor receptor (EGFR) or mutations in RAS oncogenes and the tumor suppressor gene TP53 of the NCI panel of cell lines. Gene expression profiles predicting sensitivity and resistance of tumor cells to these compounds were determined by microarray-based mRNA expressions, COMPARE, and hierarchical cluster analyses. Furthermore, the binding of both plant acids to key molecules of the NF-κB pathway (NF-κB, I-κB, NEMO) was analyzed by molecular docking. Neither expression nor mutation of ABC transporters, oncogenes, or tumor suppressor genes correlated with log10IC50 values for ursolic acid or pomolic acid. In microarray analyses, many genes involved in signal transduction processes correlated with cellular responsiveness to these compounds. Molecular docking indicated that the two plant acids strongly bound to target proteins of the NF-κB pathway with even lower free binding energies than the known NF-κB inhibitor MG-132. They interacted more strongly with DNA-bound NF-κB than free NF-κB, pointing to inhibition of DNA binding by these compounds. In conclusion, the lack of cross-resistance to classical drug resistance mechanisms (ABC-transporters, oncogenes, tumor suppressors) may indicate a promising role of the both plant acids for cancer chemotherapy. Genes involved in signal transduction may contribute to the sensitivity or resistance of tumor cells to ursolic and pomolic acids. Ursolic and pomolic acid may target different steps of the NF-κB pathway to inhibit NF-κB-mediated functions.

Topics: Antineoplastic Agents, Phytogenic; ATP Binding Cassette Transporter, Subfamily B; ATP-Binding Cassette Transporters; Breast Neoplasms; Drug Resistance, Neoplasm; Genes, erbB-1; Humans; Leupeptins; Molecular Structure; NF-kappa B; Oleanolic Acid; Pharmacogenetics; Plants, Medicinal; Salvia officinalis; Signal Transduction; Triterpenes; Ursolic Acid

AMP-activated protein kinase (AMPK) is a sensor of cellular energy status found in all eukaryotes. Recent studies indicate that AMPK activation strongly suppresses cell proliferation in tumor cells, which requires high rates of protein synthesis and de novo fatty acid synthesis for their rapid growth. Pomolic acid (PA) has been previously described as being active in inhibiting the growth of cancer cells. In this study, we investigated PA activated AMPK, and this activity was related to proliferation and apoptosis in MCF7 breast cancer cells. PA inhibited cell proliferation and induced sub-G(1) arrest, elevating the mRNA levels of the apoptotic genes p53 and p21. PA activated caspase-3, -9, and poly(ADP-ribose) polymerase, and this effect was inhibited by z-VAD-fmk. AMPK activation was increased by treating cells with PA, inactivated by treating cells with a compound C, and co-treatment consisting of PA and aminoimidazole carboxamide ribonucleotide (AICAR) synergistically activated AMPK. These anti-cancer potentials of PA were accompanied by effects on de novo fatty acid synthesis as shown by the decreased expression of fatty acid synthase, and decreased acetyl-CoA carboxylase activation and incorporation of [(3)H]acetyl-CoA into fatty acids. In addition, PA inhibited key enzymes involved in protein synthesis such as mammalian target of rapamycin (mTOR), 70 kDa ribosomal protein S6 kinase (p70S6K), and eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1). These results suggest that PA exerts anti-cancer properties through the modulation of AMPK pathways and its value as an anti-cancer agent in breast cancer therapy.

Topics: Acetyl-CoA Carboxylase; Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Antineoplastic Agents, Phytogenic; Apoptosis; Breast Neoplasms; Caspase 3; Caspase 9; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p21; Enzyme Activation; Fatty Acid Synthases; Fatty Acids; Female; G1 Phase; Gene Expression; Genes, p53; Humans; Oleanolic Acid; Phytotherapy; Plant Extracts; Poly(ADP-ribose) Polymerases; Protein Biosynthesis; Ribonucleotides; RNA, Messenger