AMR-Me inhibits PI3K/Akt signaling in hormone-dependent MCF-7 breast cancer cells and inactivates NF-κB in hormone-independent MDA-MB-231 cells

Recent nanotechnological interventions targeting PI3K/Akt/mTOR pathway: A focus on breast cancer

Breast cancer is the major cause of deaths in women worldwide. Detection and treatment of breast cancer at earlier stages of the disease has shown encouraging results. Modern genomic technologies facilitated several therapeutic options however the diagnosis of the disease at an advanced stage claim more deaths. Therefore more research directed towards genomics and proteomics into this area may lead to novel biomarkers thereby enhancing the survival rates in breast cancer patients. Phosphoinositide-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway was shown to be hyperactivated in most of the breast carcinomas resulting in excessive growth, proliferation, and tumor development. Development of nanotechnology has provided many interesting avenues to target the PI3K/Akt/mTOR pathway both at the pre-clinical and clinical stages. Therefore, the current review summarizes the underlying mechanism and the importance of targeting PI3K/Akt/mTOR pathway, novel biomarkers and use of nanotechnological interventions in breast cancer.

Ligand-Based Drug Design: Synthesis and Biological Evaluation of Substituted Benzoin Derivatives as Potential Antitumor Agents

Background:

Phosphoinositide 3-kinase α (PI3Kα) has emerged as a promising target for anticancer drug design.

Objectives:

Target compounds were designed to investigate the effect of the p-OCH3 motifs on ligand/PI3Kα complex interaction and antiproliferative activity.

Methods:

Synthesis of the proposed compounds, biological examination tests against human colon adenocarcinoma (HCT-116), breast adenocarcinoma (MCF-7), and breast carcinoma (T47D) cell lines, along with Glide docking studies.

Results:

A series of 1,2-bis(4-methoxyphenyl)-2-oxoethyl benzoates was synthesized and characterized by means of FT-IR, 1H and 13C NMR, and by elemental analysis. Biological investigation demonstrated that the newly synthesized compounds exhibit antiproliferative activity in human colon adenocarcinoma (HCT-116), breast adenocarcinoma (MCF-7), and breast carcinoma (T47D) cell lines possibly via inhibition of PI3Kα and estrogen receptor alpha (ERα). Additionally, results revealed that these compounds exert selective inhibitory activity, induce apoptosis, and suppress VEGF production. Compound 3c exhibited promising antiproliferative activity in HCT-116 interrogating that hydrogen bond-acceptor mediates ligand/PI3Kα complex formation on m- position. Compounds 3e and 3i displayed high inhibitory activity in MCF-7 and T47D implying a wide cleft discloses the o-attachment. Furthermore, compound 3g exerted selective inhibitory activity against T47D. Glide docking studies against PI3Kα and ERα demonstrated that the series accommodate binding to PI3Kα and/or ERα.

Conclusion:

The series exhibited a potential antitumor activity in human carcinoma cell lines encoding PI3Kα and/or ERα.

Targeting TPX2 suppresses proliferation and promotes apoptosis via repression of the PI3k/AKT/P21 signaling pathway and activation of p53 pathway in breast cancer

Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein required for mitosis and spindle assembly. Previous studies showed that TPX2 is overexpressed in various human cancers and promotes cancer progression. In this study, the differentially expressed genes including TPX2 were screened in GEO database for gene expression microarray of breast cancer. The TPX2 expression level was significantly increased in breast cancer cells and the breast malignant tissues compared with those controls. In vitro experiment further confirmed that knockdown of TPX2 by small hairpin RNA inhibited breast cancer cell proliferatio, migration, and induced cell apoptosis. TPX2 silencing decreased the expression of PI3K and extent of AKT phosphorylation, as well as increased expression of p53 and p21. Taken together, our findings indicate that TPX2 silencing negatively regulates the PI3K/AKT and activates p53 signaling pathway by which breast cancer cells proliferation were inhibited whereas cellulars apoptosis were accelerated, suggesting that TPX2 may be a potential target for anticancer therapy in breast cancer.

HSPC159 promotes proliferation and metastasis by inducing epithelial-mesenchymal transition and activating the PI3K/Akt pathway in breast cancer

HSPC159 is a novel human galectin‐related protein that has been shown to be involved in carcinogenesis. Little is known about HSPC159 expression and function in breast cancer. Herein we showed that HSPC159 was aberrantly expressed in both breast cancer cell lines and tumor tissues and that its expression was associated with poor prognosis of breast cancer patients. Using gain‐ and loss‐of‐function methods we found that HSPC159 enhanced breast cancer cell proliferation and metastasis in vitro and in vivo. Mechanistically, HSPC159 was found to induce epithelial‐mesenchymal transition (EMT) and the F‐actin polymerization process of breast cancer cells. Moreover, HSPC159 promoted proliferation, migration and invasion through activating the PI3K/Akt signaling pathway in breast cancer. In conclusion, our findings showed that HSPC159 contributed to breast cancer progression through the PI3K/Akt pathway and might serve as a potential therapeutic target for the treatment of breast cancer.

Anesthetic effects of isoflurane and the molecular mechanism underlying isoflurane‑inhibited aggressiveness of hepatic carcinoma

Anesthesia is produced by drugs or other methods, and refers to the attenuation of pain via reversible suppression of neuronal transmission in the central and peripheral nervous systems, during surgery. Clinical investigations have indicated that the anesthetic action of isoflurane is efficient to alleviate pain during tumor resection clinical trials. In addition, it has been reported that isoflurane can induce caspase-3 activation and is associated with apoptosis of tumor cells. The present study investigated the anesthetic effects and molecular mechanisms underlying isoflurane-induced apoptosis in patients with hepatic carcinoma. Furthermore, the pain of patients with hepatic carcinoma was evaluated during the perioperative period according to the pain index. The apoptotic rate of hepatic carcinoma cells was analyzed in tumor tissues using TUNEL assay. The expression levels of apoptosis-associated proteins were detected in liver cancer cells following anesthesia in patients. Phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and nuclear factor (NF)-κB signaling pathways were also analyzed in liver cancer cells following treatment with isoflurane. The results demonstrated that isoflurane inhibited growth and decreased viability of liver cancer cells in vitro and in vivo. In addition, the apoptotic rate was increased in cells obtained from isoflurane-treated patients. The results also demonstrated that isoflurane upregulated the expression levels of proapoptotic genes and downregulated anti-apoptotic mRNA expression. In addition, a molecular mechanism analysis indicated that isoflurane inhibited PI3K and AKT expression in liver cancer cells. Isoflurane also induced caspase-3 activation in liver cancer cells. Furthermore, isoflurane treatment attenuated NF-κB activity and inhibited migration and invasion of liver cancer cells. In conclusion, these findings indicated that isoflurane treatment efficiently attenuated surgical pain and inhibited tumor aggressiveness via regulation of NF-κB activity and the PI3K/AKT signaling pathway, thus suggesting that isoflurane is an efficient anesthetic drug that induces pain remission and promotes apoptosis of liver cancer cells.

Novel triterpenoids isolated from raisins exert potent antiproliferative activities by targeting mitochondrial and Ras/Raf/ERK signaling in human breast cancer cells

Raisins are produced in many regions of the world and may be eaten raw or used in cooking, baking and brewing. Bioactivity-guided fractionation of raisins was used to determine the chemical identity of bioactive constituents. Seven triterpenoids, including three novel triterpenoids, were isolated and identified. The novel triterpenoids were elucidated to be 3β,13β-dihydroxy-12,13-dihydrooleanolic acid (1), 3β,12β,13β-trihydroxy-12,13-dihydrooleanolic acid (2, TOA), and 3β,13β-dihydroxy-12,13-dihydroursolic acid (7), respectively. TOA showed the highest antiproliferative activity against MCF-7/DOX cells, with an EC50 value of 3.60 ± 0.55 μM. Compounds 1, 3 and 7 also exhibited potent antiproliferative activity against MCF-7/DOX cells, with an EC50 value of 7.10 ± 0.65, 10.22 ± 0.90 and 8.91 ± 1.12 μM. Compounds 1 and 2 also exhibited potent antioxidant activities. Moreover, the detailed cytotoxic mechanisms of TOA were investigated by targeting the mitochondrial and protein tyrosine kinase signaling (Ras/Raf/ERK). The results strongly demonstrated that the novel triterpenoids isolated from raisins could be promising candidates for therapy of breast cancer.

A hederagenin saponin isolated from Clematis ganpiniana induces apoptosis in breast cancer cells via the mitochondrial pathway

Natural plants offer a treasure trove of resources for anticancer drug development. Clematis are widely used in Traditional Chinese Medicine. However, studies on the active substances in Clematis are scarce. In the present study, four monomer compounds were successfully extracted from this species and their inhibitory effects on the growth of breast cancer cells were investigated using bioactivity tests. Among them, Clematis hederagenin saponin (CHS) belongs to the class of triterpenoid saponins. CHS showed cytotoxic effects on breast cancer cells in a dose- and time-dependent manner. The compound also induced apoptosis in breast cancer cells in a time-dependent manner. Further investigation into the underlying mechanisms of apoptosis induction in breast cancer cells showed that the compound significantly reduced mitochondrial Apaf-1 and cytochrome c proteins in breast cancer cells. In addition, it upregulated the activities of caspase-3 and −9. In conclusion, CHS induced apoptosis in breast cancer cells through regulation of the mitochondrial apoptosis pathway. The results suggest that the hederagenin saponin extracted from Clematis ganpiniana offers great potential as a novel anti-breast cancer drug.

Anticancer effect of celastrol on human triple negative breast cancer: possible involvement of oxidative stress, mitochondrial dysfunction, apoptosis and PI3K/Akt pathways

Signaling via the phosphatidylinositol-3 kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) is crucial for divergent physiological processes including transcription, translation, cell-cycle progression and apoptosis. The aim of work was to elucidate the anti-cancer effect of celastrol and the signal transduction pathways involved. Cytotoxic effect of celastrol was assessed by MTT assay on human triple negative breast cancer cells (TNBCs) and compared with that of MCF-7. Apoptosis induction was determined by AO/EtBr staining, mitochondrial membrane potential by JC-1, Annexin binding assays and modulation of apoptotic proteins and its effect on PI3K/Akt/mTOR pathway by western blotting. Celastrol induced apoptosis in TNBC cells, were supported by DNA fragmentation, caspase-3 activation and PARP cleavage. Meanwhile, celastrol triggered reactive oxygen species production with collapse of mitochondrial membrane potential, down-regulation of Bcl-2 and up-regulation of Bax expression. Celastrol effectively decreased PI3K 110α/85α enzyme activity, phosphorylation of Akt(ser473) and p70S6K1 and 4E-BP1. Although insulin treatment increased the phosphorylation of Akt(ser473), p70S6K1, 4E-BP1, celastrol abolished the insulin mediated phosphorylation. It clearly indicates that celastrol acts through PI3k/Akt/mTOR axis. We also found that celastrol inhibited the Akt/GSK3β and Akt/NFkB survival pathway. PI3K/Akt/mTOR inhibitor, PF-04691502 and mTOR inhibitor rapamycin enhanced the apoptosis-inducing effect of celastrol. These data demonstrated that celastrol induces apoptosis in TNBC cells and indicated that apoptosis might be mediated through mitochondrial dysfunction and PI3K/Akt signaling pathway.

Natural inhibitors of PI3K/AKT signaling in breast cancer: emphasis on newly-discovered molecular mechanisms of action

Epidermal growth factor receptor (EGFR) plays a critical role in the initiation and progression of a variety of human cancers, including breast cancer. An important signaling pathway downstream of EGFR is the PI3K/AKt pathway, which regulates cellular processes as diverse as cell growth, survival, proliferation and migration. Deregulated activity of this pathway may lead to uncontrolled cell growth, survival, migration and invasion, contributing to tumor formation. In this review, we evaluate natural compounds that, in vitro (breast cancer cell lines) and/or in vivo (animal model, clinical) studies, suppress breast cancer cells or tumors mainly by suppressing the PI3K/AKT signaling pathway. The effect of these compounds on cell cycle arrest, inhibition of cell migration and invasion, tumor angiogenesis and metastasis in breast cancer are discussed.

Oleanane triterpenoids in the prevention and therapy of breast cancer: current evidence and future perspectives

Breast cancer is one of the most frequently diagnosed cancers and major cause of death in women in the world. Emerging evidence underscores the value of dietary and non-dietary phytochemicals, including triterpenoids, in the prevention and treatment of breast cancer. Oleanolic acid, an oleanane-type pentacyclic triterpenoid, is present in a large number of dietary and medicinal plants. Oleanolic acid and its derivatives exhibit several promising pharmacological activities, including antioxidant, anti-inflammatory, hepatoprotective, cardioprotective, antipruritic, spasmolytic, antiallergic, antimicrobial and antiviral effects. Numerous studies indicate that oleanolic acid and other oleanane triterpenoids modulate multiple intracellular signaling pathways and exert chemopreventive and antitumor activities in various in vitro and in vivo model systems. A series of novel synthetic oleanane triterpenoids have been prepared by chemical modifications of oleanolic acid and some of these compounds are considered to be the most potent anti-inflammatory and anticarcinogenic triterpenoids. Accumulating studies provide extensive evidence that synthetic oleanane derivatives inhibit proliferation and induce apoptosis of various cancer cells in vitro and demonstrate cancer preventive or antitumor efficacy in animal models of blood, breast, colon, connective tissue, liver, lung, pancreas, prostate and skin cancer. This review critically examines the potential role of oleanolic acid, oleanane triterpenoids and related synthetic compounds in the chemoprevention and treatment of mammary neoplasia. Both in vitro and in vivo studies on these agents and related molecular mechanisms are presented. Several challenges and future directions of research to translate already available impressive preclinical knowledge to clinical practice of breast cancer prevention and therapy are also presented.

Simultaneous disruption of estrogen receptor and Wnt/β-catenin signaling is involved in methyl amooranin-mediated chemoprevention of mammary gland carcinogenesis in rats

Methyl-amoorain (methyl-25-hydroxy-3-oxoo-lean-12-en-28-oate, AMR-Me), a novel synthetic oleanane triterpenoid, exerts a striking chemopreventive effect against 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumorigenesis through antiproliferative and proapoptotic actions. Nevertheless, the underlying mechanisms of action remain to be established. As estrogen receptor (ER) and canonical Wnt/b-catenin signaling are involved in the development and progression of breast cancer, the current study was designed to investigate the effects of AMR-Me treatment on the expressions of ER-a, ER-b, b-catenin and cyclin D1 in rat mammary tumors induced by DMBA. Mammary tumor samples were harvested from an 18-week chemopreventive study in which AMR-Me (0.8–1.6 mg/kg) was shown to inhibit mammary carcinogenesis in a dose–response manner. The expressions of ER-a, ER-b, b-catenin, and cyclin D1 were determined by immunohistochemistry and reverse transcription-polymerase chain reaction. AMR-Me downregulated the expression of intratumor ER-a and ER-b and lowered the ratio of ER-a to ER-b. AMR-Me also reduced the expression, cytoplasmic accumulation, and nuclear translocation of b-catenin, the essential transcriptional cofactor for Wnt signaling. Furthermore, AMR-Me modulated the expression of cell growth regulatory gene cyclin D1, which is a downstream target for both ER and Wnt signaling. AMR-Me at 1.6 mg/kg for 18 weeks did not exhibit any hepatotoxicity or renotoxicity. The results of the present study coupled with our previous findings indicate that simultaneous disruption of ER and Wnt/b-catenin signaling possibly contributes to antiproliferative and apoptosis-inducing effects implicated in AMR-Me-mediated chemoprevention of DMBA-induced breast tumorigenesis in rats. Our results also suggest a possible crosstalk between two key regulatory pathways, namely ER and Wnt/b-catenin signaling, involved in mammary carcinogenesis and the value of simultaneously targeting these pathways to achieve breast cancer chemoprevention.

The apoptotic effect of D Rhamnose β-hederin, a novel oleanane-type triterpenoid saponin on breast cancer cells

There is growing interest in development of natural products as anti-cancer and chemopreventive agents. Many triterpenoids have been proved as potential agents for chemoprevention and therapy of breast cancer. Ginsenosides from ginseng, which mostly belong to dammarane-type triterpenoids, have gained great attention for their anti-breast cancer activity with diverse mechanisms. However, studies of other kinds of triterpenoid saponins on breast cancer are limited. Previously, we purified and identified a novel oleanane-type triterpene saponin named D Rhamnose β-hederin (DRβ-H) from Clematis ganpiniana, a Chinese traditional anti-tumor herb. In the present study, DRβ-H showed strong inhibitory activity on the growth of various breast cancer cells and induced apoptosis in these cells. DRβ-H inhibited PI3K/AKT and activated ERK signaling pathway. PI3K inhibitor LY294002 synergistically enhanced DRβ-H-induced apoptosis whereas MEK inhibitor U0126 reduced the apoptosis rate. Moreover, DRβ-H regulated the ratio of pro-apoptotic and anti-apoptotic Bcl-2 family proteins. Furthermore, DRβ-H induced depolarization of mitochondrial membrane potential which released Apaf-1 and Cytochrome C from the inter membrane space into the cytosol, where they promoted caspase-9 and caspase-3 activation. This is the first report on the pro-apoptotic effects of DRβ-H, a novel oleanane-type triterpenoid saponin, on breast cancer cells and its comprehensive apoptosis pathways. It implied that oleanane-type triterpenoid saponin DRβ-H could be a promising candidate for chemotherapy of breast cancer.

A novel synthetic oleanane triterpenoid suppresses adhesion, migration, and invasion of highly metastatic melanoma cells by modulating gelatinase signaling axis

A methyl derivative natural triterpenoid amooranin (methyl-25-hydroxy-3-oxoolean-12-en-28-oate, AMR-Me) has been found to possess antiproliferative, proapoptotic, and antiinflammatory effects against established tumor cells. Large-scale synthesis of pure AMR-Me has eliminated the need of the natural phytochemical for further development of AMR-Me as an anticancer drug. Metastatic melanoma is a fatal form of cutaneous malignancy with poor prognosis and limited therapeutic options. It was hypothesized that antitumor pharmacological effect of AMR-Me could be linked to AMR-Me-mediated suppression of the metastatic potential of B16F10 murine melanoma. AMR-Me was assessed for its antimetastatic efficacy by cell adhesion, migration, and invasion assays in B16F10 cells. The signaling crosstalk was explored by gelatin zymography, Western blot, ELISA, and immunocytochemistry. The results elicited that AMR-Me was successful in restricting the adhesion, migration, and invasion of highly metastatic cells. The antimetastatic potential of this compound may be attributed to the reduced expression of membrane type 1 metalloproteinase (MT1-MMP) and matrix metalloproteinases (MMP-2 and MMP-9). AMR-Me was found to downregulate vascular endothelial growth factor (VEGF)/phosphorylated forms of focal adhesion kinase (pFAK397 )/Jun N-terminus kinase (pJNK)/extracellular signal-regulated kinase (pERK). This, in turn, inhibited transcription factor nuclear factor-κB (NF-κB) and transactivation of MMPs. Moreover, the activation of tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) might have influenced the downmodulation of MT1-MMP, MMP-2, and MMP-9. AMR-Me suppresses the activity of MT1-MMP, MMP-2, and MMP-9 by downregulation of VEGF/pFAK397 /pJNK/pERK/NF-κB and activation of TIMP-1 and TIMP-2 in metastatic melanoma cell line, B16F10. AMR-Me has the potential as an effective anticancer drug for metastatic melanoma which is a dismal disease.

Suppression of inflammatory cascade is implicated in methyl amooranin-mediated inhibition of experimental mammary carcinogenesis

Breast cancer represents the second leading cause of cancer-related deaths among women worldwide and preventive therapy could reverse or delay the devastating impact of this disease. Methyl-amooranin (methyl-25-hydroxy-3-oxoolean-12-en-28-oate, AMR-Me), a novel synthetic oleanane triterpenoid, reduced the incidence and burden of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats through antiproliferative and proapoptotic effects. Since chronic inflammation plays an important role in the pathogenesis of breast cancer and several synthetic oleanane compounds are known potent anti-inflammatory agents, we aim to investigate anti-inflammatory mechanisms of AMR-Me by monitoring various proinflammatory and stress markers, such as cyclooxygenase-2 (COX-2) and heat shock protein 90 (HSP90), and nuclear factor-κB (NF-κB) signaling during DMBA mammary tumorigenesis in rats. Mammary tumors were harvested from a chemopreventive study in which AMR-Me (0.8-1.6 mg/kg) was found to inhibit mammary carcinogenesis in a dose-response manner. The expressions of COX-2, HSP90, NF-κB, and inhibitory κB-α (IκB-α) were determined by immunohistochemistry and reverse transcription-polymerase chain reaction. AMR-Me downregulated the expression of intratumor COX-2 and HSP90, suppressed the degradation of IκB-α, and reduced the translocation of NF-κB from cytosol to nucleus. Our present study provides the first in vivo evidence that NF-κB-evoked inflammatory cascade is a major target of AMR-Me in breast cancer. Our current results together with our previous findings suggest that disruption of NF-κB signaling contributes to anti-inflammatory, antiproliferative, and apoptosis-inducing mechanisms involved in AMR-Me-mediated chemoprevention of rat mammary carcinogenesis. These encouraging mechanistic results coupled with a safety profile should facilitate the clinical development of AMR-Me as breast cancer chemopreventive drug.