Corosolic acid attenuates platelet-derived growth factor signaling in macrophages and smooth muscle cells of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease that is characterized by vascular remodeling of the pulmonary artery. Pulmonary vascular remodeling is primarily caused by the excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), which are facilitated by perivascular inflammatory cells including macrophages. Corosolic acid (CRA) is a natural pentacyclic triterpenoid that exerts anti-inflammatory effects. In the present study, the effects of CRA on the viability of macrophages were examined using monocrotaline (MCT)-induced PAH rats and human monocyte-derived macrophages. Although we previously reported that CRA inhibited signal transducer and activator of transcription 3 (STAT3) signaling and ameliorated pulmonary vascular remodeling in PAH, the inhibitory mechanism remains unclear. Therefore, the underlying mechanisms were investigated using PASMCs from idiopathic PAH (IPAH) patients. In MCT-PAH rats, CRA inhibited the accumulation of macrophages around remodeled pulmonary arteries. CRA reduced the viability of human monocyte-derived macrophages. In IPAH-PASMCs, CRA attenuated cell proliferation and migration facilitated by platelet-derived growth factor (PDGF)-BB released from macrophages and PASMCs. CRA also downregulated the expression of PDGF receptor β and its signaling pathways, STAT3 and nuclear factor-κB (NF-κB). In addition, CRA attenuated the phosphorylation of PDGF receptor β and STAT3 following the PDGF-BB simulation. The expression and phosphorylation levels of PDGF receptor β after the PDGF-BB stimulation were reduced by the small interfering RNA knockdown of NF-κB, but not STAT3, in IPAH-PASMCs. In conclusion, CRA attenuated the PDGF-PDGF receptor β-STAT3 and PDGF-PDGF receptor β-NF-κB signaling axis in macrophages and PASMCs, and thus, ameliorated pulmonary vascular remodeling in PAH.

Corosolic acid ameliorates vascular remodeling in pulmonary arterial hypertension via the downregulation of STAT3 signaling

Pulmonary arterial hypertension (PAH) is a progressive and fatal disease that is characterized by vascular remodeling of the pulmonary artery. PAH remodeling is primarily caused by the excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs). Therefore, an inhibitory mechanism is expected as a target for the treatment of PAH. Corosolic acid (CRA) is a pentacyclic triterpenoid extracted from the leaves of Banaba (Lagerstroemia speciosa) that exerts anti-diabetic, anti-inflammatory, and anti-tumor effects. In the present study, the effects of CRA on PAH remodeling were examined using PASMCs from idiopathic pulmonary arterial hypertension (IPAH) patients and monocrotaline (MCT)-induced pulmonary hypertensive (PH) rats. CRA inhibited the excessive proliferation of IPAH-PASMCs in a concentration-dependent manner (IC₅₀ = 14.1 μM). It also reduced the migration of IPAH-PASMCs. The CRA treatment downregulated the expression of signal transducer and activator of transcription 3 (STAT3) in IPAH-PASMCs. In MCT-PH rats, the administration of CRA (1 mg/kg/day) attenuated increases in right ventricular systolic pressure, pulmonary vascular remodeling, and right ventricular hypertrophy. CRA also decreased the expression of STAT3 in pulmonary arterial smooth muscles from MCT-PH rats. In conclusion, the anti-proliferative and anti-migratory effects of CRA in PASMCs ameliorated PAH remodeling by downregulating STAT3 signaling pathways.

Extraction, isolation, characterization and antimicrobial activities of non-extractable polyphenols from pomegranate peel

Non-extractable polyphenols (NEPPs) in pomegranate peel were released by acid hydrolysis followed by extraction using ethyl acetate (EtOAc). Ten NEPPs were identified in the hydrolysate using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Six compounds were then isolated from the EtOAc extracts whose structures were identified as β-sitosterol-3-O-glycoside (1), β-sitosterol (2), ursolic acid (3), corosolic acid (4), asiatic acid (5) and arjunolic acid (6) using a wide range of spectroscopic analyses. Compounds 4-6 were isolated for the first time from pomegranate peel. Antimicrobial experiments revealed that compound 3 and 5 showed significant antimicrobial activity against a range of pathogens, particularly compound 5 which exhibited selective inhibitive activity towards Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 16 μg/ml. The present study has provided new insights into the composition of bound chemicals in pomegranate peel and laid a foundation for improving its further processing and utilization.

Biological effects of corosolic acid as an anti-inflammatory, anti-metabolic syndrome and anti-neoplasic natural compound

Accumulating evidence has indicated that corosolic acid exerts anti-diabetic, anti-obesity, anti-inflammatory, anti-hyperlipidemic and anti-viral effects. More importantly, corosolic acid has recently attracted much attention due to its anticancer properties and innocuous effects on normal cells. Furthermore, the increasing proportion of obese and/or diabetic populations has led to an epidemic of non-alcoholic fatty liver disease (NAFLD), which frequently progresses to hepatocellular carcinoma (HCC). Evidence has indicated that NAFLD is closely associated with the development of HCC and comprises a high risk factor. The present review summarizes the anticancer effects of corosolic acid in vitro and in vivo, and its related molecular mechanisms. It also describes the inhibitory effects of corosolic acid on the progression of NAFLD and its associated molecular mechanisms, providing guidance for future research on corosolic acid in NAFLD-related HCC prevention and treatment. To the best of our knowledge, a review of corosolic acid as an anticancer agent has not yet been reported. Due to its multitargeted activity in cancer cells, corosolic acid exerts anticancer effects when administered alone, and acts synergistically when administered with chemotherapeutic drugs, even in drug-resistant cells. In addition, as a novel tool to treat metabolic syndromes, corosolic acid uses the same mechanism in its action against cancer as that used in the progression of NAFLD-related HCC. Therefore, corosolic acid has been suggested as an agent for the prevention and treatment of NAFLD-related HCC.

Pygenic Acid A (PA) Sensitizes Metastatic Breast Cancer Cells to Anoikis and Inhibits Metastasis In Vivo

Metastasis is the main cause of cancer-related deaths. Anoikis is a type of apoptosis caused by cell detachment, and cancer cells become anoikis resistant such that they survive during circulation and can successfully metastasize. Therefore, sensitization of cancer cells to anoikis could prevent metastasis. Here, by screening for anoikis sensitizer using natural compounds, we found that pygenic acid A (PA), a natural compound from Prunella vulgaris, not only induced apoptosis but also sensitized the metastatic triple-negative breast cancer cell lines, MDA-MB-231 cells (human) and 4T1 cells (mouse), to anoikis. Apoptosis protein array and immunoblotting analysis revealed that PA downregulated the pro-survival proteins, including cIAP1, cIAP2, and survivin, leading to cell death of both attached and suspended cells. Interestingly, PA decreased the levels of proteins associated with anoikis resistance, including p21, cyclin D1, p-STAT3, and HO-1. Ectopic expression of active STAT3 attenuated PA-induced anoikis sensitivity. Although PA activated ER stress and autophagy, as determined by increases in the levels of characteristic markers, such as IRE1α, p-elF2α, LC3B I, and LC3B II, PA treatment resulted in p62 accumulation, which could be due to PA-induced defects in autophagy flux. PA also decreased metastatic characteristics, such as cell invasion, migration, wound closure, and 3D growth. Finally, lung metastasis of luciferase-labeled 4T1 cells decreased following PA treatment in a syngeneic mouse model when compared with the control. These data suggest that PA sensitizes metastatic breast cancer cells to anoikis via multiple pathways, such as inhibition of pro-survival pathways and activation of ER stress and autophagy, leading to the inhibition of metastasis. These findings suggest that sensitization to anoikis by PA could be used as a new therapeutic strategy to control the metastasis of breast cancer.

Silymarin induces inhibition of growth and apoptosis through modulation of the MAPK signaling pathway in AGS human gastric cancer cells

Apoptosis is regarded as a therapeutic target because it is typically disturbed in human cancer. Silymarin from milk thistle (Silybum marianum) has been reported to exhibit anticancer properties via regulation of apoptosis as well as anti-inflammatory, antioxidant and hepatoprotective effects. In the present study, the effects of silymarin on the inhibition of proliferation and apoptosis were examined in human gastric cancer cells. The viability of AGS human gastric cancer cells was assessed by MTT assay. The migration of AGS cells was investigated by wound healing assay. Silymarin was revealed to significantly decrease viability and migration of AGS cells in a concentration-dependent manner. In addition, the number of apoptotic bodies and the rate of apoptosis were increased in a dose-dependent manner as determined by DAPI staining and Annexin V/propidium iodide double staining. The changes in the expression of silymarin-induced apoptosis proteins were investigated in human gastric cancer cells by western blotting analysis. Silymarin increased the expression of Bax, phosphorylated (p)-JNK and p-p38, and cleaved poly-ADP ribose polymerase, and decreased the levels of Bcl-2 and p-ERK1/2 in a concentration-dependent manner. The in vivo tumor growth inhibitory effect of silymarin was investigated. Silymarin (100 mg/kg) significantly decreased the AGS tumor volume and increased apoptosis, as assessed by the TUNEL assay, confirming its tumor-inhibitory effect. Immunohistochemical staining revealed elevated expression of p-JNK and p-p38 as well as reduced expression of p-ERK1/2 associated with silymarin-treatment. Silymarin was revealed to reduce tumor growth through inhibition of p-ERK and activation of p-p38 and p-JNK in human gastric cancer cells. These results indicated that silymarin has potential for development as a cancer therapeutic due to its growth inhibitory effects and induction of apoptosis in human gastric cancer cells.

Corosolic acid reduces 5‑FU chemoresistance in human gastric cancer cells by activating AMPK

5‑Fluorouracil (5‑FU) is one of the most commonly used chemotherapeutic agents for gastric cancer. Resistance to 5‑FU‑based chemotherapy remains the major obstacle in the treatment of gastric cancer. A growing body of evidence has suggested that adenosine monophosphate‑activated protein kinase (AMPK) is pivotal for chemoresistance. However, the mechanism by which AMPK regulates the chemosensitivity of gastric cancer remains unclear. In the present study, how corosolic acid enhanced the chemosensitivity of gastric cancer cells to 5‑FU via AMPK activation was investigated. A 5‑FU‑resistant gastric cancer cell line (SNU‑620/5‑FUR) was established, which had a marked increase in thymidine synthase (TS) expression but reduced AMPK phosphorylation when compared with the parental cell line, SNU‑620. AMPK regulation by 5‑aminoimidazole‑4‑carboxamide ribonucleotide or compound c was revealed to be markedly associated with TS expression and 5‑FU‑resistant cell viability. In addition, corosolic acid activated AMPK, and decreased TS expression and the phosphorylation of mammalian target of rapamycin/4E‑binding protein 1 in a dose‑dependent manner. Corosolic acid treatment significantly reduced cell viability while compound c reversed corosolic acid‑induced cell growth inhibition. The 5‑FU‑resistance sensitization effect of corosolic acid was determined by the synergistic reduction of TS expression and inhibition of cell viability in the presence of 5‑FU. The corosolic acid‑induced AMPK activation was markedly increased by additional 5‑FU treatment, while compound c reversed AMPK phosphorylation. In addition, compound c treatment reversed corosolic acid‑induced apoptotic markers such as capase‑3 and PARP cleavage, and cytochrome c translocation to cytosol, in the presence of 5‑FU. Corosolic acid treatment in the presence of 5‑FU induced an increase in the apoptotic cell population based on flow cytometry analysis. This increase was abolished by compound c. In conclusion, these results implied that corosolic acid may have therapeutic potential to sensitize the resistance of gastric cancer to 5‑FU by activating AMPK.

Corosolic Acid Induces Non-Apoptotic Cell Death through Generation of Lipid Reactive Oxygen Species Production in Human Renal Carcinoma Caki Cells

Corosolic acid is one of the pentacyclic triterpenoids isolated from Lagerstroemia speciose and has been reported to exhibit anti-cancer and anti-proliferative activities in various cancer cells. In the present study, we investigated the molecular mechanisms of corosolic acid in cancer cell death. Corosolic acid induces a decrease of cell viability and an increase of cell cytotoxicity in human renal carcinoma Caki cells. Corosolic acid-induced cell death is not inhibited by apoptosis inhibitor (z-VAD-fmk, a pan-caspase inhibitor), necroptosis inhibitor (necrostatin-1), or ferroptosis inhibitors (ferrostatin-1 and deferoxamine (DFO)). Furthermore, corosolic acid significantly induces reactive oxygen species (ROS) levels, but antioxidants (N-acetyl-l-cysteine (NAC) and trolox) do not inhibit corosolic acid-induced cell death. Interestingly, corosolic acid induces lipid oxidation, and α-tocopherol markedly prevents corosolic acid-induced lipid peroxidation and cell death. Anti-chemotherapeutic effects of α-tocopherol are dependent on inhibition of lipid oxidation rather than inhibition of ROS production. In addition, corosolic acid induces non-apoptotic cell death in other renal cancer (ACHN and A498), breast cancer (MDA-MB231), and hepatocellular carcinoma (SK-Hep1 and Huh7) cells, and α-tocopherol markedly inhibits corosolic acid-induced cell death. Therefore, our results suggest that corosolic acid induces non-apoptotic cell death in cancer cells through the increase of lipid peroxidation.

Preventive effect of Actinidia valvata Dunn extract on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal cancer in rats

PURPOSE

This study was conducted to assess the preventive effect of Actinidia valvata Dunn (AVD) extract on an animal model of gastrointestinal carcinogenesis on the basis of changes in tumor incidence, cell proliferation, and apoptosis.

MATERIALS AND METHODS

Seventy-five male Wistar rats were divided into five different treatment groups with 15 rats in each group. Group I was given normal feed, whereas Groups II to IV were treated with 10% sodium chloride in the first six weeks and 100 ug/mL of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 24 weeks. Group II was then given normal feed, whereas Group III was given AVD extract (0.24 g/kg/day) for 12 weeks. Group IV was given AVD extract from the first week to the 36th week, whereas Group V was treated with AVD extract alone for 36 weeks. All rats were sacrificed at the end of the 36-week experiment and assessed for the presence of gastrointestinal tumors. The occurrence of cancer was evaluated by histology. Bax, Bcl-2, Caspase-3, and cyclinD1 were determined by immunohistochemical staining and Western blotting.

RESULTS

The incidences of gastric cancer were 0% in Group I, 73.3% in Group II, 33.3% in Group III, 26.7% in Group IV, and 0% in Group V. Bcl-2 and cyclinD1 expression was decreased in AVD extract treated groups, whereas Bax and Caspase-3 expression was increased. Comparison with group II revealed significant differences (p<0.01).

CONCLUSIONS

AVD extract exhibits an obvious preventive effect on gastrointestinal carcinogenesis induced by MNNG in rats through the regulation of cell proliferation and apoptosis.

Corosolic acid ameliorates acute inflammation through inhibition of IRAK-1 phosphorylation in macrophages

Corosolic acid (CA), a triterpenoid compound isolated from Lagerstroemia speciosa L. (Banaba) leaves, exerts anti-inflammatory effects by regulating phosphorylation of interleukin receptor- associated kinase (IRAK)-2 via the NF-κB cascade. However, the protective effect of CA against endotoxic shock has not been reported. LPS (200 ng/mL, 30 min) induced phosphorylation of IRAK-1 and treatment with CA (10 μM) significantly attenuated this effect. In addition, CA also reduced protein levels of NLRP3 and ASC which are the main components of the inflammasome in BMDMs. LPS-induced inflammasome assembly through activation of IRAK-1 was down-regulated by CA challenge. Treatment with Bay11-7082, an inhibitor of IκB-α, had no effect on CA-mediated inhibition of IRAK-1 activation, indicating that CA-mediated attenuation of IRAK-1 phosphorylation was independent of NF-κB signaling. These results demonstrate that CA ameliorates acute inflammation in mouse BMDMs and CA may be useful as a pharmacological agent to prevent acute inflammation. [BMB Reports 2016; 49(5): 276-281]

Evaluation of pentacyclic triterpenes found in Perilla frutescens for inhibition of skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate

A series of pentacyclic tritperpenes found in Perilla frutescens (P. frutescens), including ursolic acid (UA), oleanolic acid (OA), corosolic acid (CA), 3-epi-corosolic acid (3-epiCA), maslinic acid (MA), and 3-epi-maslinic acid (3-epiMA) were evaluated for their effects on epidermal cell signaling, proliferation, and skin inflammation in relation to their ability to inhibit skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) and compared to UA as the prototype compound. All compounds were given topically 30 min prior to each TPA application and significantly inhibited skin tumor promotion. 3-epiCA and MA were significantly more effective than UA at inhibiting tumor development. All of these compounds significantly inhibited epidermal proliferation induced by TPA, however, CA, 3-epiCA and MA were more effective than UA. All compounds also reduced skin inflammation (assessed by infiltration of mast cells and T-cells) and inflammatory gene expression induced by TPA, however, 3-epiCA and MA were again more effective than UA. The greater ability of 3-epiCA and MA to inhibit skin tumor promotion was associated with greater reduction of Cox-2 and Twist1 proteins and inhibition of activation (i.e., phosphorylation) of IGF-1R, STAT3 and Src. Further study of these compounds, especially 3-epiCA and MA, for chemopreventive activity in other cancer model systems is warranted.

Corosolic acid inhibits the proliferation of osteosarcoma cells by inducing apoptosis

Corosolic acid (CRA), a pentacyclic triterpene isolated from medicinal herbs, has been reported to exhibit anticancer properties in several cancers. However, the anticancer activity of CRA in osteosarcoma cells is still unclear. In the present study, the inhibitory effect of CRA in osteosarcoma MG-63 cells was investigated, and the results revealed that CRA significantly inhibited the viability of MG-63 cells in a dose- and time-dependent manner. A typical apoptotic hallmark such as DNA ladder was detected by agarose gel electrophoresis following treatment with CRA. Further experiments demonstrated that CRA induced apoptosis of MG-63 cells by flow cytometry using propidium iodide and annexin V staining. In addition, it was observed that the apoptosis of MG-63 cells induced by CRA was closely associated with activation of caspase-3 and caspase-9, loss of mitochondrial membrane potential, and release of cytochrome c from mitochondria, suggesting that CRA may trigger the activation of the mitochondria-mediated apoptosis pathway. In addition, the inhibition of caspase activity attenuated the CRA-induced apoptosis of MG-63 cells, which further confirmed the role of the mitochondrial pathway in CRA-induced apoptosis. These results indicated that CRA could induce the apoptosis of osteosarcoma cells through activating the mitochondrial pathway, which provides an evidence that CRA may be a useful chemotherapeutic agent for osteosarcoma.

Impact of c-erbB-2 protein on 5-year survival rate of gastric cancer patients after surgery: a cohort study and meta-analysis

OBJECTIVE

To explore the association of c-erbB-2 protein expression with clinicopathological characteristics and prognosis of gastric cancer (GC) after surgery.

METHODS

A total of 133 patients undergoing surgical resection for GC between March 2006 and January 2009 in the Second Affiliated Hospital of Wenzhou Medical University were included in this study. c-erbB-2 protein expression was determined by immunohistochemistry. Afterwards, a meta-analysis was performed to further confirm the association between c-erbB-2 protein expression and GC by employing stringent inclusion and exclusion criteria. All data analyses were conducted with STATA 12.0 and SPSS 19.0.

RESULTS

There was no significant difference in c-erbB-2 expression among patients with various parameters including age, gender and histological types (all p>0.05). Among 133 GC patients, 32 patients presented c-erbB-2-positive expression and 101 presented c-erbB-2-negative expression (24.1% vs. 75.9%). The c-erbB-2-positive expression rate was significantly higher in GC tissues of patients with lymph node metastasis than those without. Similarly, a significant increase in c-erbB-2 expression was observed in well/moderately differentiated GC tissues compared with poorly differentiated GC. Patients with negative c-erbB-2 expression had a higher 5-year survival rate than those with positive c-erbB-2 expression, which was consistent with the results of the meta-analysis (OR = 0.54, 95% CI 0.37-0.80, p = 0.002).

CONCLUSIONS

Our study demonstrated that high expression of c-erbB-2 protein was strongly associated with lymph node metastasis, histological differentiation and 5-year survival rate in GC patients after surgery.

Ursolic acid and its natural derivative corosolic acid suppress the proliferation of APC-mutated colon cancer cells through promotion of β-catenin degradation

Ursolic acid (UA) and corosolic acid (CA), naturally occurring pentacyclic triterpene acids, exhibit antiproliferative activities against various cancer cells, but a clear chemopreventive mechanism of these triterpenoids in colon cancer cells remains to be answered. Here we used a cell-based reporter system for detection of β-catenin response transcription (CRT) to identify UA as an antagonist of the Wnt/β-catenin pathway. UA promoted the degradation of intracellular β-catenin that was accompanied by its N-terminal phosphorylation at Ser33/37/Thr41 residues, marking it for proteasomal degradation. Consistently, UA down-regulated the intracellular β-catenin level in colon cancer cells with inactivating mutations of adenomatous polyposis coli (APC). In addition, UA repressed the expression of β-catenin/T-cell factor (TCF)-dependent genes, thereby inhibiting cell proliferation in colon cancer cells. The functional group analysis revealed that the major structural requirements for UA-mediated β-catenin degradation are a carboxyl group at position 17 and a methyl group at position 19. Notably, CA (2α-hydroxyursolic acid) was also found to decrease the level of intracellular β-catenin and to suppress the growth of APC-mutated colon cancer cells. Our findings suggest that UA and CA exert their anticancer activities against colon cancer cells by promoting the N-terminal phosphorylation and subsequent proteasomal degradation of β-catenin.

A novel strategy for inducing the antitumor effects of triterpenoid compounds: blocking the protumoral functions of tumor-associated macrophages via STAT3 inhibition

There are many types of nontumor cells, including leukocytes, fibroblasts, and endothelial cells, in the tumor microenvironment. Among these cells, infiltrating macrophages have recently received attention as novel target cells due to their protumoral functions. Infiltrating macrophages are called tumor-associated macrophages (TAMs). TAMs polarized to the M2 phenotype are involved in tumor development and are associated with a poor clinical prognosis. Therefore, the regulation of TAM activation or M2 polarization is a new strategy for antitumor therapy. We screened natural compounds possessing an inhibitory effect on the M2 polarization of human macrophages. Among 200 purified natural compounds examined, corosolic acid (CA) and oleanolic acid (OA), both are categorized in triterpenoid compounds, inhibited macrophage polarization to M2 phenotype by suppressing STAT3 activation. CA and OA also directly inhibited tumor cell proliferation and sensitized tumor cells to anticancer drugs, such as adriamycin and cisplatin. The in vivo experiments showed that CA significantly suppressed subcutaneous tumor development and lung metastasis in a murine sarcoma model. The application of triterpenoid compounds, such as CA and OA, is a potential new anticancer therapy targeting macrophage activation, with synergistic effects with anticancer agents.

Corosolic acid induces apoptotic cell death in HCT116 human colon cancer cells through a caspase-dependent pathway

Corosolic acid (CA), a pentacyclic triterpene isolated from Lagerstroemia speciosa L. (also known as Banaba), has been shown to exhibit anticancer properties in various cancer cell lines. However, the anticancer activity of CA on human colorectal cancer cells and the underlying mechanisms remain to be elucidated. In this study, we investigated the effects of CA on cell viability and apoptosis in HCT116 human colon cancer cells. CA dose-dependently inhibited the viability of HCT116 cells. The typical hallmarks of apoptosis, such as chromatin condensation, a sub-G1 peak and phosphatidylserine externalization were detected by Hoechst 33342 staining, flow cytometry and Annexin V staining following treatment with CA. Western blot analysis revealed that CA induced a decrease in the levels of procaspase-8, -9 and -3 and the cleavage of poly(ADP-ribose) polymerase (PARP). The apoptotic cell death induced by CA was accompanied by the activation of caspase-8, -9 and -3, which was completely abrogated by the pan-caspase inhibitor, z-VAD‑FMK. Furthermore, CA upregulated the levels of pro-apoptotic proteins, such as Bax, Fas and FasL and downregulated the levels of anti-apoptotic proteins, such as Bcl-2 and survivin. Taken together, our data provide insight into the molecular mechanisms of CA-induced apoptosis in colorectal cancer (CRC), rendering this compound a potential anticancer agent for the treatment of CRC.

Cthrc1 overexpression is an independent prognostic marker in gastric cancer

Collagen triple helix repeat containing 1 (CTHRC1) was identified as a novel gene expressed in the adventitia and neointima on arterial injury and was found to be overexpressed in several malignant tumors, such as breast cancer and malignant melanoma. However, the expression of Cthrc1 and its role in gastric cancer progression remain unknown. We investigated the expression of the Cthrc1 protein by immunohistochemistry in 30 normal tissues from the control subjects and 166 gastric carcinomas and analyzed its correlation with various clinicopathological features, including patient outcome. Cthrc1 immunoreactivity was overexpressed in gastric carcinoma cases compared with normal tissues (P < .001). High Cthrc1 expression was found in 108 (65.06%) of these 166 carcinomas and was positively correlated with the American Joint Committee on Cancer stage classification, depth of gastric wall invasion, lymph node metastasis, lymphovascular space involvement, and recurrence but not with age, tumor site, and carcinoembryonic antigen level. Patients with high Cthrc1 expression had significantly poorer overall survival and disease-free survival compared with patients with low expression of Cthrc1 (P = .001 and P = .002, respectively). Multivariate analysis showed that high Cthrc1 expression was an independent prognostic factor for both overall survival and disease-free survival of patients with gastric carcinoma (both P = .005). These results showed that high Cthrc1 expression was associated with progression and prognosis of gastric carcinoma.

Anti-Proliferative Activities and Apoptosis Induction by Triterpenes Derived from Eriobotrya japonica in Human Leukemia Cell Lines

Eriobotrya japonica leaf is a traditional herbal medicine that contains numerous triterpenes, which have various pharmacological properties. In this study, we investigated the anti-proliferative activity of four triterpenes derived from E. japonica, including corosolic acid (CA), ursolic acid (UA), maslinic acid (MA) and oleanolic acid (OA), in human leukemia cell lines. CA showed the strongest anti-proliferative activity in all of the leukemia cell lines tested, but not in normal human skin fibroblast cell lines. To determine the mechanism underlying the anti-proliferative effect of CA, we examined the effect of CA on molecular events known as apoptosis induction. CA induced chromatin condensation, DNA fragmentation, sub-G₁ phase DNA, activation of caspase-3, -8 and -9 and the cleavage of PARP in HL-60. CA also activated Bid and Bax, leading to the loss of mitochondrial membrane potential (Δψ_m) and cytochrome c release into the cytosol, whereas Bcl-2 and Bcl-xL were unaffected by CA. These results suggest that CA has an anti-proliferative effect on leukemia cells via the induction of apoptosis mediated by mitochondrial dysfunction and caspase activation. CA may be a potential chemotherapeutic agent for the treatment of human leukemia.

Corosolic acid impairs tumor development and lung metastasis by inhibiting the immunosuppressive activity of myeloid-derived suppressor cells

SCOPE

Recent studies demonstrated that myeloid cells are associated with systemic immunosuppression in tumor-bearing hosts. In particular, myeloid cells positive for Gr-1 and CD11b in tumor-bearing mice are called myeloid-derived suppressor cells (MDSC) because of their suppression of T-cell activation. In this study, we investigated the antitumor effects of corosolic acid (CA) in murine sarcoma model.

METHODS AND RESULTS

The results from the in vivo study showed that CA administration did not suppress the tumor proliferation index, but significantly impaired subcutaneous tumor development and lung metastasis. Furthermore, CA administration inhibited signal transducer and activator of transcription-3 (Stat3) activation and increased in the number of infiltrating lymphocytes in tumor tissues. Ex vivo analysis demonstrated that a significant immunosuppressive effect of MDSC in tumor-bearing mice was abrogated and the mRNA expressions of cyclooxygenase-2 and CCL2 in MDSC were significantly decreased by CA administration. Furthermore, CA enhanced the antitumor effects of adriamycin and cisplatin in in vitro.

CONCLUSION

Since Stat3 is associated with tumor progression not only in osteosarcoma, but also in other malignant tumors, our findings indicate that CA might be widely useful in anticancer therapy by targeting the immunosuppressive activity of MDSC and through its synergistic effects with anticancer agents.

Ursane-type pentacyclic triterpenoids as useful platforms to discover anticancer drugs

This review highlights the potential of natural and semisynthetic ursane-type triterpenoids as candidates for the design of multi-target bioactive compounds, with focus on their anticancer effects. A brief illustration of the biosynthesis, sources, and general biological effects of the main classes of naturally occurring pentacyclic triterpenoids (PTs) are provided.

Growth suppression of HER2-overexpressing breast cancer cells by berberine via modulation of the HER2/PI3K/Akt signaling pathway

Berberine (BBR) is a natural alkaloid with significant antitumor activities against many types of cancer cells. This study investigated the molecular mechanisms by which BBR suppresses the growth of HER2-overexpressing breast cancer cells. The results show that BBR induces G1-phase cell cycle arrest by interfering with the expression of cyclins D1 and E and that it induces cellular apoptosis through the induction of a mitochondria/caspase pathway. The data also indicate that BBR inhibits cellular growth and promotes apoptosis by down-regulating the HER2/PI3K/Akt signaling pathway. Furthermore, it is also shown that a combination of taxol and BBR significantly slows the growth rate of HER2-overexpressing breast cancer cells. In conclusion, this study suggests that BBR could be a useful adjuvant therapeutic agent in the treatment of HER2-overexpressing breast cancer.

Interaction between adipose tissue stromal cells and gastric cancer cells in vitro

Adipose tissue exists in the gastric submucosa and subserosa. Thus, adipose tissue stromal cells (ATSCs), which include mesenchymal stem cells (MSCs), seem critical for the progression of gastric cancer but their interaction with the cancer cells is unknown. We demonstrated an interaction between these cells, using immunohistochemistry, Western blot and the collagen gel invasion assay system, in which the adenocarcinoma cells (well and poorly differentiated types, MKN28 and MKN45, respectively) were cultured on a ATSC-embedded or ATSC-non-embedded gel. ATSCs promoted the expression of the growth marker, proliferation cell nuclear antigen but inhibited that of the apoptosis marker, single-stranded DNA, in the cancer cell types. ATSCs accelerated the invasion of only MKN28 into the gel and promoted the expression of mitogen-activated protein kinase (MAPK, pERK-1/2) but decreased that of the molecularly targeted protein, HER2, in the cancer cells. ATSCs did not affect the expression of the prostaglandin biosynthetic enzyme cyclooxgenase-2 (COX-2) in the cancer cells. The COX-2 inhibitor celecoxib did not affect the morphology or invasion of the cancer cells. The cancer cell types in turn promoted the display of the myofibroblast marker, α-smooth muscle actin, whereas they decreased that of some MSC markers, e.g., CD44 and CD105, in ATSCs. The data suggest that (1) ATSCs influence the progression of gastric cancer by increasing their growth/invasion and decreasing their apoptosis through MAPK activation in a COX-2-independent way; (2) ATSCs adversely affect HER2-targeted therapy; (3) the cancer cells induce the cancer-associated myofibroblast phenotype in ATSCs.

Corosolic acid triggers mitochondria and caspase-dependent apoptotic cell death in osteosarcoma MG-63 cells

The response of osteosarcoma MG-63 cells to corosolic acid treatment has been investigated. The results showed that corosolic acid significantly inhibited cell viability in both a dose and a time dependent manner. It was found that corosolic acid increased the Bax/Bcl-2 ratio by up-regulating Bax expression, disrupted mitochondrial membrane potential and triggered the release of cytochrome c from mitochondria into the cytoplasm. Corosolic acid treatment triggered the activation of caspase-8, 9 and 3. The apoptosis was obviously inhibited by pretreatment with a general caspase inhibitor, z-VAD-FMK. Moreover, pretreatment of CsA, a cyclophilin D ligand that inhibits mitochondria potential uncoupling, prevented the activation of caspase-9 and caspase-3, but not caspase-8, and the apoptosis of MG-63 cells, triggered by corosolic acid. All these results indicated that corosolic acid-induced apoptosis was associated with the activation of caspases via a mitochondrial pathway.