Fatty acid synthase (FASN) is a potential therapeutic target for treatment of cancer and obesity, and is highly elevated in 30% of HER2-overexpressing breast cancers. Considerable interest has developed in searching for novel FASN inhibitors as therapeutic agents in treatment of HER2-overexpressing breast cancers. Amentoflavone was found to be effective in suppressing FASN expression in HER2-positive SKBR3 cells. Pharmacological inhibition of FASN by amentoflavone specifically down-regulated HER2 protein and mRNA, and caused an up-regulation of PEA3, a transcriptional repressor of HER2. In addition, pharmacological blockade of FASN by amentoflavone preferentially decreased cell viability and induced cell death in SKBR3 cells. Palmitate reduced the cytotoxic effect of amentoflavone, as the percentage of viable cells was increased after the addition of exogenous palmitate. Amentoflavone-induced FASN inhibition inhibited the translocation of SREBP-1 in SKBR3 cells. Amentoflavone inhibited phosphorylation of AKT, mTOR, and JNK. The use of pharmacological inhibitors revealed that the modulation of AKT, mTOR, and JNK phosphorylation required synergistic amentoflavone-induced FASN inhibition and HER2 activation in SKBR3 cells. These results suggest that amentoflavone modulated FASN expression by regulation of HER2-pathways, and induced cell death to enhance chemopreventive or chemotherapeutic activity in HER2-positive breast cancers.

Pristimerin is a naturally occurring triterpenoid that causes cytotoxicity in several cancer cell lines. However, the mechanism of action for the cytotoxic effect of pristimerin has not been unexplored. The purpose of this study was to investigate the effect of pristimerin on cytotoxicity using the epidermal growth factor receptor 2 (HER2)-positive SKBR3 human breast cancer cell line. Pristimerin inhibited proliferation in dose-and time-dependent manners in cells. We found it to be effective for suppressing HER2 protein and mRNA expression. Fatty acid synthase (FASN) expression and FASN activity were downregulated by pristimerin. Adding of exogenous palmitate, the end product of de novo fatty acid synthesis, reduced the proliferation activity of pristimerin. The changes in HER2 and FASN expression induced by pristimerin altered the levels of Akt and mitogen-activated protein kinase (MAPK) phosphorylation (Erk1/2, p38, and c-Jun N-terminal kinase (JNK)). Pristimerin lowered the levels of phosphorylated mammalian target of rapamycin (mTOR) and its downstream targets such as phosphoprotein 70 ribosomal protein S6 kinase and 4E binding protein1. Pristimerin inhibited migration and invasion of cells, and co-treatment with the mTOR inhibitor rapamycin additionally suppressed these activities. Pristimerin-induced apoptosis was evaluated using Western blotting for caspase-3, -8, -9, and poly (ADP-ribose) polymerase expression and flow cytometric analysis for propidium iodide labeling. These results suggest that pristimerin is a novel HER2-downregulated compound that is able to decrease fatty acid synthase and modulate the Akt, MAPK, and mTOR signaling pathways to influence metastasis and apoptosis. Pristimerin may be further evaluated as a chemotherapeutic agent for HER2-positive breast cancers.

PurposeThe aim of this study was to evaluate the correlation between central lymph node (CLN) metastasis and clinicopathologic characteristics of papillary thyroid cancer (PTC). In addition, we investigated the incidence and risk factors for contralateral CLN metastasis in unilateral PTC. This study suggests the appropriate surgical extent for CLN dissection.MethodsA prospective study of 500 patients with PTC who underwent total thyroidectomy and prophylactic bilateral CLN dissection was conducted.ResultsOf 500 patients, 255 had CLN metastases. The rate of CLN metastasis was considerably higher in cases of younger patients (<45 years old) (P < 0.001; odds ratio [OR], 2.357) and of a maximal tumor size greater than 1 cm (P < 0.001; OR, 3.165). Ipsilateral CLN metastasis was detected in 83.1% of cases (133/160) of unilateral PTC, only contralateral CLN metastases in 3.7% of cases (6/160), and bilateral CLN metastases in 13.1% of cases (21/160). The rate of contralateral CLN metastasis was considerably higher in cases of PTC with a large tumor size (≥1 cm) (P = 0.019; OR, 4.440) and with ipsilateral CLN metastasis (P = 0.047; OR, 2.613).ConclusionYounger age (<45 years old) and maximal tumor size greater than 1 cm were independent risk factors for CLN metastasis. Maximal tumor size greater than 1 cm and presence of ipsilateral CLN macrometastasis were independent risk factors for contralateral CLN metastasis. Therefore, both CLN dissections should be considered for unilateral PTC with a maximal tumor size greater than 1 cm or presence of ipsilateral CLN macrometastasis.

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. Key words AMP-activated protein kinase; pomolic acid; breast cancerBioactive natural products provide structures that will become major sources of novel agents with pharmacological promise. 1) Among the well known anti-cancer drugs are the so-called vinca alkaloids (vinblastin and vincristine), isolated from Catharanthus roseus, and the podophylotoxins (etoposide and teniposide), which are semisynthetic derivatives of epipodophyllotoxin, extracted from Podophyllum peltatum.2)The anti-tumoral activities of certain di-and tri-terpenes have been reported. For instance, the di-terpene, Taxol (Paclitaxel), initially isolated from the bark of Taxus brevifolia, has provided a major renewable natural source of anti-cancer drugs which have displayed activity against several cancers. 3)Pomolic acid (PA), a pentacyclic triterpene, was highly effective in inhibiting the growth of leukemia cell lines.2) Apart from its capacity to induce apoptosis, the mechanisms of PA activity are presently unclear. As part of an evaluation of potential of new anti-cancer compounds, this study investigated the molecular pathways of PA-induced cell death, including apoptosis.AMP-activated protein kinase (AMPK), an evolutionarily conserved fuel-sensing enzyme, is a heterotrimeric serine/ threonine protein kinase that is composed of a catalytic α-subunit and regulatory β-and γ-subunits. AMPK activity is allosterically...