Targeted regulation of PI3K/Akt/mTOR/NF-κB signaling by indole compounds and their derivatives: mechanistic details and biological implications for cancer therapy

Phytochemicals and PI3K Inhibitors in Cancer-An Insight

In today's world of modern medicine and novel therapies, cancer still remains to be one of the prime contributor to the death of people worldwide. The modern therapies improve condition of cancer patients and are effective in early stages of cancer but the advanced metastasized stage of cancer remains untreatable. Also most of the cancer therapies are expensive and are associated with adverse side effects. Thus, considering the current status of cancer treatment there is scope to search for efficient therapies which are cost-effective and are associated with lesser and milder side effects. Phytochemicals have been utilized for many decades to prevent and cure various ailments and current evidences indicate use of phytochemicals as an effective treatment for cancer. Hyperactivation of phosphoinositide 3-kinase (PI3K) signaling cascades is a common phenomenon in most types of cancers. Thus, natural substances targeting PI3K pathway can be of great therapeutic potential in the treatment of cancer patients. This chapter summarizes the updated research on plant-derived substances targeting PI3K pathway and the current status of their preclinical studies and clinical trials.

Anti-hepatocarcinoma effect of cordycepin against NDEA-induced hepatocellular carcinomas via the PI3K/Akt/mTOR and Nrf2/HO-1/NF-κB pathway in mice

The purpose of the present study was to evaluate the effects of cordycepin (CA) on N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinomas (HCC) and explore its potential mechanisms. Mice were randomly assigned to four groups: control group, NDEA group, NDEA+CA (20mg/kg) group, NDEA+CA (40mg/kg) group. The animal of each group were given NDEA (100ppm) in drinking water. One hour later, CA, which was dissolved in PBS, were intragastrically administered for continuous seven days. The results showed that CA reduced the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in liver and serum. CA also reduced the levels of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), methane dicarboxylic aldehyde (MDA), and stored the activity of superoxygen dehydrogenises (SOD) in serum. CA could obviously attenuate the hepatic pathological alteration. Furthermore, CA effectively inhibited the phosphorylations of phosphatidylinositol 3 kinase(PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR). In conclusion, our research suggested that CA exhibited protective effects on NDEA-induced hepatocellular carcinomas via the PI3K/Akt/mTOR pathway.

Expression of miR-195 is associated with chemotherapy sensitivity of cisplatin and clinical prognosis in gastric cancer

Gastric cancer has higher morbidity and mortality than other cancers for the low diagnosis rate and few therapies. MiR-195 has been reported to be involved in the occurrence, development and prognosis of various cancers. However, the function of miR-195 in gastric cancer remains largely unknown. Herein, the aims of this study were to probe the functional mechanism of miR-195 and its chemotherapy sensitivity as well as clinical prognosis in gastric cancer. We screened out low-expressed miR-195 through microarray analysis and further confirmed miR-195 was widely down-regulated in gastric cancer cells. Subsequently, AKT3 was identified as the direct target gene of miR-195 by target gene prediction software, dual luciferase reporter assay and western blot. Functional assays indicated that miR-195 acted as a tumor suppressor through regulating the proliferative, migrated and invasive properties of gastric cancer cells in vitro, and intratumoral delivery of miR-195 significantly suppressed tumor growth in vivo. Additionally, we also found miR-195 overexpression could enhance the chemotherapy sensitivity of cisplatin in gastric cancer cells and prolong the overall survival and progression free survival of gastric cancer patients. Collectively, our findings demonstrate miR-195 may be of great significance on early diagnosis of gastric cancer, providing the theoretical basis for prognosis and recurrence risk.

Moringa isothiocyanate complexed with α-cyclodextrin: a new perspective in neuroblastoma treatment

BACKGROUND

Several lines of evidence suggest the consume of natural products for cancer prevention or treatment. In particular, isothiocyanates (ITCs) exerting anti-cancer properties, have received great interest as potential chemotherapeutic agents. This study was designed to assess the anti-proliferative activities of a new preparation of Moringa oleifera-derived 4-(α-L-rhamnopyranosyloxy)benzyl ITC (moringin) complexed with alpha-cyclodextrin (moringin + α-CD; MAC) on SH-SY5Y human neuroblastoma cells. This new formulation arises in the attempt to overcome the poor solubility and stability of moringin alone in aqueous media.

METHODS

SH-SY5Y cells were cultured and exposed to increasing concentrations of MAC (1.0, 2.5 and 5.0 μg). Cell proliferation was examined by MTT and cell count assays. The cytotoxic activity of the MAC complex was assessed by lactate dehydrogenase (LDH) assay and trypan blue exclusion test. In addition, western blotting analyses for the main apoptosis-related proteins were performed.

RESULTS

Treatment of SH-SY5Y cells with the MAC complex reduced cell growth in concentration dependent manner. Specifically, MAC exhibited a potent action in inhibiting the PI3K/Akt/mTOR pathway, whose aberrant activation was found in many types of cancer. MAC was also found to induce the nuclear factor-κB (NF-κB) p65 activation by phosphorylation and its translocation into the nucleus. Moreover, treatment with MAC was able to down-regulate MAPK pathway (results focused on JNK and p38 expression). Finally, MAC was found to trigger apoptotic death pathway (based on expression levels of cleaved-caspase 3, Bax/Bcl-2 balance, p53 and p21).

CONCLUSION

These findings suggest that use of MAC complex may open novel perspectives to improve the poor prognosis of patients with neuroblastoma.

The PI3K/Akt pathway: a critical player in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is thought to be the primary cause of low back pain, a severe public health problem worldwide. Current therapy for IDD aims to alleviate the symptoms and does not target the underlying pathological alternations within the disc. Activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway protects against IDD, which is attributed to increase of ECM content, prevention of cell apoptosis, facilitation of cell proliferation, induction or prevention of cell autophagy, alleviation of oxidative damage, and adaptation of hypoxic microenvironment. In the current review, we summarize recent progression on activation and negative regulation of the PI3K/Akt signaling pathway, and highlight its impact on IDD. Targeting this pathway could become an attractive therapeutic strategy for IDD in the near future.

Two likely targets for the anti-cancer effect of indole derivatives from cruciferous vegetables: PI3K/Akt/mTOR signalling pathway and the aryl hydrocarbon receptor

Diets containing high quantities of plant foods are linked with a decreased likelihood of incidence of cancer. Several common plant-based dietary components exert effects on DNA methylation levels, and can positively influence genome stability and the transcription of tumor suppressors and oncogenes. Indole-3-carbinol (I3C) is a substance present in vegetables of the Brassicaeae family, especially broccoli, white cabbage, Brussels sprouts and cauliflower. The in vivo biological effects of I3C are ascribed to a series of oligomeric products (including 3,3'-diindolylmethane), developed under acidic conditions. I3C is one of the many natural products and bioactive compounds found in foods which have recently received much attention for its potential effects in cancer prevention and treatment. In vitro studies report that I3C suppresses the proliferation of different tumor cells, including those isolated from breast, prostate, endometrium, and colon cancers. I3C resulted to be a potent in vivo chemopreventive agent for certain hormone-dependent cancers, including breast and cervical cancer. However, the mechanisms underlying these effects are not well defined. In this review, we have analysed recent literature on the use of indole derivatives against various forms of cancer, and have identified the main signalling pathways involved in their anti-cancer effect as PI3K/Akt/mTOR and the aryl hydrocarbon receptor.

Antihepatocarcinoma Effect of Portulaca oleracea L. in Mice by PI3K/Akt/mTOR and Nrf2/HO-1/NF-κB Pathway

The purpose of the present study was to evaluate the pharmacological effects of Portulaca oleracea L. (Purslane) (PL) on N-nitrosodiethylamine- (NDEA-) induced hepatocellular carcinomas (HCC) and explore its potential mechanism. Mice were randomly assigned to four groups: control group, NDEA group, NDEA + Purslane (100 mg/kg) group, and NDEA + Purslane (200 mg/kg) group. The animal of each group was given NDEA (100 ppm) in drinking water. 1 h later, Purslane dissolved in PBS was intragastrically administered for continuous seven days. The results showed that Purslane reduced the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in liver and serum. Purslane also reduced the contents of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), and methane dicarboxylic aldehyde (MDA) and restored the activity of superoxygen dehydrogenises (SOD) in serum. Purslane could obviously attenuate the hepatic pathological alteration. Furthermore, treatment with Purslane effectively inhibited the phosphorylations of phosphatidylinositol 3 kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR), nuclear factor-kappa B (NF-κB), and inhibitor of NF-κBα (IκBα) and upregulated the expressions of NF-E2-related factor 2 (Nrf2) and heme oxygenase- (HO-) 1. In conclusion, our research suggested that Purslane exhibited protective effects on NDEA-induced hepatocellular carcinomas by anti-inflammatory and antioxidative properties via the PI3K/Akt/mTOR and Nrf2/HO-1/NF-κB pathway.

3,3'-Diindolylmethane Suppresses Adipogenesis Using AMPKα-Dependent Mechanism in 3T3-L1 Adipocytes and Caenorhabditis elegans

3,3'-diindolylmethane is a major in vivo metabolite of indole-3-carbinol, a bioactive compound found in cruciferous vegetables. Although 3,3'-diindolylmethane has been implicated to possess antitumorigenic and anti-inflammatory properties, the effect of 3,3'-diindolylmethane on adipogenesis has not been explored previously. Thus, the present study was conducted to determine if 3,3'-diindolylmethane affects adipogenesis using 3T3-L1 adipocytes and Caenorhabditis elegans. Treatment of 3,3'-diindolylmethane significantly reduced fat accumulation without affecting viability in 3T3-L1 adipocytes. 3,3'-diindolylmethane suppressed expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT-enhancer-binding protein α (C/EBPα), fatty acid binding protein 4 (FABP4), and perilipin. In addition, 3,3'-diindolylmethane activated AMP-activated protein kinase α (AMPKα), which subsequently inactivated acetyl CoA carboxylase (ACC), resulting in reduced fat accumulation. These observations were further confirmed in C. elegans as treatment with 3,3'-diindolylmethane significantly reduced body fat accumulation, which was partly associated with aak-1, but not aak-2, orthologs of AMPKα catalytic subunits α1 and α2, respectively. The current results demonstrate that 3,3'-diindolylmethane, a biologically active metabolite of indole-3-carbinol, may prevent adipogenesis through the AMPKα-dependent pathway.

Phosphatidylinositol 3-kinase inhibition induces vasodilator effect of sevoflurane via reduction of Rho kinase activity

AIMS

This study was aimed to examine whether a volatile anesthetic sevoflurane in clinical doses reduces vasoconstriction under the inhibition of phosphatidylinositol 3-kinase (PI3K) in the rat and human arteries and whether the intravenous administration of the PI3K inhibitor decreases blood pressure in rats under the sevoflurane inhalation.

MATERIALS AND METHODS

Rat arteries (n=5-6) and human omental arteries (n=5-6) were subjected to isometric force recordings and western immunoblotting for Rho kinase, mitogen-activated protein kinase, and protein kinase C. Some arteries were incubated with sevoflurane (1.5% or 3%), a selective PI3K inhibitor LY294002 (3×10^-6mol/L) or the combination. Mean arterial pressure (MAP) and heart rate (HR) in rats (n=7) were evaluated with or without intravenous injection of LY294002 (3×10^-6mol/L) under 2% sevoflurane inhalation.

KEY FINDINGS

Sevoflurane with LY294002, but not sevoflurane or LY294002 solely, inhibited the phenylephrine-induced contraction (32% to 52% decrease at phenylephrine [3×10^-6mol/L] in rat arteries and [3×10^-5mol/L] in human arteries). Sevoflurane (3%) only with LY294002 decreased Rho kinase activity in the rat aorta into 30%. Intravenous LY294002 reduced MAP (8.1-12.4mmHg decrease), but not HR, in rats under 2% sevoflurane inhalation.

SIGNIFICANCE

Clinical sevoflurane doses with PI3K inhibition reduce the contraction of rat and human arteries ex vivo resulting from Rho kinase inhibition, and systemic blood pressure of rats in vivo. These results suggest that sevoflurane potentially causes vasodilation and hypotension in patients receiving anti-cancer therapy that inhibits PI3K.

Cancer Chemoprevention by Phytochemicals: Nature's Healing Touch

Phytochemicals are an important part of traditional medicine and have been investigated in detail for possible inclusion in modern medicine as well. These compounds often serve as the backbone for the synthesis of novel therapeutic agents. For many years, phytochemicals have demonstrated encouraging activity against various human cancer models in pre-clinical assays. Here, we discuss select phytochemicals—curcumin, epigallocatechin-3-gallate (EGCG), resveratrol, plumbagin and honokiol—in the context of their reported effects on the processes of inflammation and oxidative stress, which play a key role in tumorigenesis. We also discuss the emerging evidence on modulation of tumor microenvironment by these phytochemicals which can possibly define their cancer-specific action. Finally, we provide recent updates on how low bioavailability, a major concern with phytochemicals, is being circumvented and the general efficacy being improved, by synthesis of novel chemical analogs and nanoformulations.

Characterization of the in vitro effects of gallic acid-grafted-chitooligosaccharides in the suppression of AGS human gastric cancer cell proliferation

G-COS was compared with COS for its influence on the proliferation of AGS human gastric cancer cells, showing an increase in the accumulation of cells in the sub-G1 phase and early apoptosis.

Non-coding RNA/microRNA-modulatory dietary factors and natural products for improved cancer therapy and prevention: Alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins

Non-coding small RNA molecules, the microRNAs (miRNAs), contribute decisively to the epigenetic regulation processes in cancer cells. Problematic pathogenic properties of cancer cells and the response of cancers towards anticancer drugs are highly influenced by miRNAs. Both increased drug activity and formation of tumor resistance are regulated by miRNAs. Further to this, the survival and proliferation of cancer cells and the formation of metastases is based on the modulated expression of certain miRNAs. In particular, drug-resistant cancer stem-like cells (CSCs) depend on the presence and absence of specific miRNAs. Fortunately, several small molecule natural compounds were discovered that target miRNAs involved in the modulation of tumor aggressiveness and drug resistance. This review gives an overview of the effects of a selection of naturally occurring small molecules (alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins) on miRNAs that are closely tangled with cancer diseases.

Celastrol negatively regulates cell invasion and migration ability of human osteosarcoma via downregulation of the PI3K/Akt/NF-κB signaling pathway in vitro

Osteosarcoma (OS) is a primary malignant tumor of the bone, with a tendency to metastasize early. Despite the advances in treatment options, more than 30% of patients develop distant metastases, and the prognosis of these patients with metastases is extremely poor. Celastrol has been demonstrated to manifest multiple pharmacological activities, including induction of apoptosis in numerous types of cancer cell lines. Our previous studies have also suggested that Celastrol is capable of inducing apoptosis of human osteosarcoma cells via the mitochondrial-dependent pathway. The purpose of this study was to investigate the effects of Celastrol on the migration and invasion of human osteosarcoma U-2OS cells in vitro. Cell migration and invasion were investigated using wound healing and Boyden chamber Transwell assays. We observed that Celastrol suppressed cell invasion and migration in human osteosarcoma U-2OS cells. Furthermore, protein expression levels of phosphorylated phosphatidylinositol 3-kinase (PI3K), Akt, inhibitor of κB kinase α/β, inhibitor of κB α, nuclear factor-κB (NF-κB subunit p65) and matrix metalloproteinase (MMP)-2 and -9 were measured by western blot analysis. We observed that the PI3K/Akt/NF-κB signaling pathway was inhibited following Celastrol treatment. In addition, the expression levels of MMP-2 and -9 proteins were also reduced significantly following Celastrol treatment. Therefore, we confirmed that Celastrol suppressed osteosarcoma U-2OS cell metastasis via downregulation of the PI3K/Akt/NF-κB signaling pathway in vitro.

Docosahexaenoic Acid Modulates Invasion and Metastasis of Human Ovarian Cancer via Multiple Molecular Pathways

OBJECTIVE

We investigated the effect of docosahexaenoic acid (DHA) on the invasion and metastasis of ovarian cancer cells (A2780, HO8910, and SKOV-3).

METHODS

Cytotoxicity assay was performed to determine the optimal doses of DHA in this experiment. The effects of DHA on invasion ability were assessed by invasion assay. The expressions of messenger RNA and/or proteins associated with invasion or metastasis were detected by quantitative Real Time-Polymerase Chain Reaction or Western blot. The effect of DHA on cell metastasis was assessed in xenograft model of zebrafish.

RESULTS

Docosahexaenoic acid and α-linolenic acid could reduce the cell vitalities in dose-dependent manner. However, DHA inhibited the invasion and metastasis of ovarian cancer cells, but α-linolenic acid did not (**P < 0.01). Docosahexaenoic acid could downregulate the expressions of WAVE3, vascular endothelial cell growth factor, and MMP-9, and upregulate KISS-1, TIMP-1, and PPAR-γ, which negatively correlated with cell invasion and metastasis (*P < 0.05). Docosahexaenoic acid restrained the development of subintestinal vessels and cancer cell metastasis in xenograft model of zebrafish (**P < 0.01).

CONCLUSIONS

Docosahexaenoic acid inhibited the invasion and metastasis of ovarian cancer cells in vitro and in vivo through the modulation of NF-κB signaling pathway, suggesting that DHA is a promising candidate for ovarian cancer therapy.

Roles of Dietary Phytoestrogens on the Regulation of Epithelial-Mesenchymal Transition in Diverse Cancer Metastasis

Epithelial-mesenchymal transition (EMT) plays a key role in tumor progression. The cells undergoing EMT upregulate the expression of cell motility-related proteins and show enhanced migration and invasion. The hallmarks of EMT in cancer cells include changed cell morphology and increased metastatic capabilities in cell migration and invasion. Therefore, prevention of EMT is an important tool for the inhibition of tumor metastasis. A novel preventive therapy is needed, such as treatment of natural dietary substances that are nontoxic to normal human cells, but effective in inhibiting cancer cells. Phytoestrogens, such as genistein, resveratrol, kaempferol and 3,3′-diindolylmethane (DIM), can be raised as possible candidates. They are plant-derived dietary estrogens, which are found in tea, vegetables and fruits, and are known to have various biological efficacies, including chemopreventive activity against cancers. Specifically, these phytoestrogens may induce not only anti-proliferation, apoptosis and cell cycle arrest, but also anti-metastasis by inhibiting the EMT process in various cancer cells. There have been several signaling pathways found to be associated with the induction of the EMT process in cancer cells. Phytoestrogens were demonstrated to have chemopreventive effects on cancer metastasis by inhibiting EMT-associated pathways, such as Notch-1 and TGF-beta signaling. As a result, phytoestrogens can inhibit or reverse the EMT process by upregulating the expression of epithelial phenotypes, including E-cadherin, and downregulating the expression of mesenchymal phenotypes, including N-cadherin, Snail, Slug, and vimentin. In this review, we focused on the important roles of phytoestrogens in inhibiting EMT in many types of cancer and suggested phytoestrogens as prominent alternative compounds to chemotherapy.

Computer-aided design, synthesis, and biological evaluation of new indole-2-carboxamide derivatives as PI3Kα/EGFR inhibitors

Structure-based drug design and molecular modeling were employed to identify a new series of indole-2-carboxamides as potential anticancer agents. These compounds were synthesized and characterized with the aid of several spectroscopic techniques, such as FT-IR, NMR, and mass spectrometry as well as by elemental analysis. Molecular docking studies confirmed that the newly synthesized compounds accommodate PI3Kα and EGFR kinase catalytic sites and form H-bonding with the key binding residues. The antitumor activity of these new compounds against an array of cancer cell lines (human colon carcinoma (HCT116), leukemia (K562), and breast cancer (MDA231) was evaluated. Results revealed that these compounds were selective against the kinase domain, and none of them showed any inhibitory activity against K562. In addition, results showed that compound 13 exhibited high potency in HCT116 and MDA231 with IC50 values of 19 and 15μM, respectively. Our findings recommend that further optimization of this series would be beneficial for colon and breast cancer treatment.

A synthetic 2,3-diarylindole induces cell death via apoptosis and autophagy in A549 lung cancer cells

A series of 2,3-diarylindoles were synthesized via the Larock heteroannulation, and evaluated for their anticancer activity against A549 lung cancer cells. The most potent compound, PCNT13 with IC50=5.17 μM, caused the induction of two modes of programmed cell death, apoptosis and autophagy.

The bounty of nature for changing the cancer landscape

The landscape of cancer has changed considerably in past several years, due mainly to aggressive screening, accumulation of data from basic and epidemiological studies, and the advances in translational research. Natural anticancer agents have always been a part and parcel of cancer research. The initial focus on natural anticancer agents was in context of their cancer chemopreventive properties but their ability to selectively target oncogenic signaling pathways has also been recognized. In light of the rapid advancements in our understanding of the role of microRNAs, cancer stem cells, and epigenetic events in cancer initiation and progression, a number of natural anticancer agents are showing promise in vitro, in vivo as well as in preclinical studies. Moreover, parent structures of natural agents are being extensively modified with the hope of improving efficacy, specificity, and bioavailability. In this article, we focus on two natural agents, 3,3'-diindolylmethane and garcinol, along with 3,4-difluorobenzo curcumin, a synthetic analog of natural agent curcumin. We showcase how these anticancer agents are changing cancer landscape by modulating novel microRNAs, epigenetic factors, and cancer stem cell markers. These activities are relevant and being appreciated for overcoming drug resistance and inhibition of metastases, the two overarching clinical challenges in modern medicine.

Anticancer effect of SZC017, a novel derivative of oleanolic acid, on human gastric cancer cells

Oleanolic acid (OA) and its several derivatives possess chemopreventive and chemotherapeutic functions against a series of cancer types. Many chemotherapeutic compounds are effective in improving the quality of life and prolonging the survival of patients with gastric cancer, therefore progress in the treatment of gastric cancer, especially the anticancer effects of OA derivatives must be achieved. The inhibitory effect of SZC017, a newly synthesized derivative of OA, on cell viability was determined by MTT assay. Furthermore, flow cytometry, transmission electron microscopy, and western blot analysis revealed that the inhibition of cell viability by OA was mediated by triggering the intrinsic apoptosis of gastric cancer cells, and inducing S phase arrest of SGC7901 cells. Mechanistically, SZC017 was effective against gastric cancer cells via inhibiting Akt/NF‑κB signaling and topoisomerase I and IIα proteins. Taken together, our data indicate that SZC017 may be a potential chemotherapeutic agent against gastric cancer cells.

SZC015, a synthetic oleanolic acid derivative, induces both apoptosis and autophagy in MCF-7 breast cancer cells

Breast cancer is one of the most common cancers among women with high mortality and morbidity. The present study was aimed to investigate the cytotoxic mechanism of SZC015, a synthetic oleanolic acid (OA) derivative, in MCF-7 human breast cancer cells. SZC015 reduced MCF-7 cell viability with an IC50 value of only 24.19 μM at 24 h by activating both apoptosis and autophagy pathways. More specifically, we found that SZC015 was able to activate intrinsic apoptosis, which was proved by activations of caspase3, caspase9, release of cytochrome C, cleavage of PARP and increasing ratio of Bax/Bcl-2. SZC015 induced autophagy in MCF-7 cells evidenced by the increase of LC3II/LC3I and up-regulation of Atg5 and beclin1. Moreover, these two cell death pathways were modulated by inhibiting phosphatidylinositide 3-kinase/protein kinase B/mammalian target of rapamycin/nuclear factor-κB (PI3K/Akt/mTOR/NF-κB), mitogen-activated protein kinase (MAPK) signaling pathways. SZC015 also induced S phase cell cycle arrest in MCF-7 cells. Furthermore, analysis of topoisomerase I (Top I) and topoisomerase IIα (Top IIα) proteins suggested that SZC015 may interfere the DNA topological phenomenon. The computer-assisted molecular docking study also showed SZC015 had lower interaction energy with Top I and Top IIα than that of OA. In conclusion, the current study revealed SZC015 played an important role in the regulation of autophagy and apoptosis in breast cancer cells.

Indole-3-Carbinol and Its Role in Chronic Diseases

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. Initially, these compounds were classified as blocking agents that increase drug-metabolizing enzyme activity. Now it is widely accepted that I3C and DIM affect multiple signaling pathways and target molecules controlling cell division, apoptosis, or angiogenesis deregulated in cancer cells. Although most of the current data support the role of I3C and DIM in prevention of hormone-dependent cancers, it seems that their application in prevention of the other cancer as well as cardiovascular disease, obesity, and diabetes reduction is also possible. This chapter summarizes the current experimental data on the I3C and DIM activity and the results of clinical studies indicating their role in prevention of chronic diseases.

Anti-cancer and cardioprotective effects of indol-3-carbinol in doxorubicin-treated mice

Doxorubicin (DOX) is a broad-spectrum antitumor antibiotic used in treatment of cancer. Its effect may be complicated by increased risk of cardiotoxicity. It was suggested that natural compounds with anticancer properties can be used in combination with DOX to decrease its dose and side effects. Indole-3-carbinol (I3C) is one of the phytochemicals that was shown to have anti-cancer effect. Our aim was to detect the possible chemosensitizing effects of I3C in DOX-induced cytotoxicity and the possible cardioprotective effects of I3C in DOX-induced cardiotoxicity. One hundred mice were divided into five equal groups: Control untreated group, solid Ehrlich carcinoma (SEC), SEC + DOX, SEC + I3C, SEC + DOX + I3C. Tumor volume, serum creatinine kinase and lactate dehydrogenase were measured. Also, tissue malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), sphingosine kinase-1 (SphK1) activity and interleukin-6 (IL-6) were determined. Parts of the tumor and cardiac tissues were subjected to histopathological examination. DOX or I3C alone or in combination induced significant increase in tumor CAT and SOD with significant decrease in tumor volume, tumor MDA, SphK1 activity and IL-6 and alleviated the histopathological changes with significant increase in the apoptotic index and significant decrease in tissue bcl2 compared to SEC group. Also, DOX induced cardiotoxicity which was ameliorated by I3C. In conclusion, DOX/I3C combination had a better effect than each of DOX or I3C alone against SEC in mice with marked improvement of the cardiotoxicity induced by DOX.

SZC017, a novel oleanolic acid derivative, induces apoptosis and autophagy in human breast cancer cells

Oleanolic acid (OA) and its derivatives such as 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), CDDO-Me, and CDDO-Im show potent anticancer function. In this study, we elucidated the anticancer effect of SZC017, a novel OA derivative and identified the mechanisms by which SZC017 induces MCF-7 cell death. We found that SZC017 effectively decreased the cell viability of these breast cancer cells, but was less toxic to MCF10A mammary epithelial cells. Mechanisms underlying the inhibition of cell viability are apoptosis, autophagy induction, and G0/G1 phase arrest. SZC017 treatment suppressed the levels of Akt, phosphorylated-Akt (p-Akt), p-IκBα, total p65, and total p-p65, in addition to p-p65 in both the cytoplasm and nucleus. Furthermore, the inhibition of p65 nuclear translocation was confirmed by immunofluorescence staining. Cell viability was increased after pretreatment with chloroquine, an inhibitor of autophagy, whereas the level of procaspase-3 was significantly decreased. A concentration-dependent increase in the intracellular reactive oxygen species (ROS) level was observed in both MCF-7 and MDA-MB-231 cells. Additionally, pretreatment with N-acetyl-L-cysteine (NAC), a ROS scavenger, increased cell viability and the expression of Akt and procaspase-3, but decreased the ratio of LC3-II/I. These data show that SZC017 is an effectively selective anticancer agent against breast cancer cells, highlighting the potential use of this derivative as a breast cancer therapeutic agent.

Reciprocal activation between IL-6/STAT3 and NOX4/Akt signalings promotes proliferation and survival of non-small cell lung cancer cells

Inflammatory cytokines and oxidative stress are two critical mediators in inflammation-associated cancer. Interleukin-6 (IL-6) is one of the most critical tumor-promoting cytokines in non-small cell lung cancer (NSCLC). In our recent study, we confirmed that NADPH oxidase 4 (NOX4), an important source of reactive oxygen species (ROS) production in NSCLC cells, promotes malignant progression of NSCLC. However, whether the crosstalk of NOX4 and IL-6 signalings exists in NSCLC remains undentified. In this study, we show that NOX4 expression is positively correlated with IL-6 expression in NSCLC tissues. Exogenous IL-6 treatment significantly enhances NOX4/ROS/Akt signaling in NSCLC cells. NOX4 also enhances IL-6 production and activates IL-6/STAT3 signaling in NSCLC cells. Specifically, NOX4 is confirmed to functionally interplay with IL-6 to promote NSCLC cell proliferation and survival. The in vivo results were similar to those obtained in vitro. These data indicate a novel NOX4-dependent link among IL-6 in the NSCLC microenvironment, oxidative stress in NSCLC cells and autocrined IL-6 in NSCLC cells. NOX4/Akt and IL-6/STAT3 signalings can reciprocally and positively regulate each other, leading to enhanced NSCLC cell proliferation and survival. Therefore, NOX4 may serve as a promising target against NSCLC alone with IL-6 signaling.

Estrogen upregulates inflammatory signals through NF-κB, IFN-γ, and nitric oxide via Akt/mTOR pathway in the lymph node lymphocytes of middle-aged female rats

The alterations in the secretion of sex steroids, especially estrogen, in females throughout reproductive life and its decline with age alters the functions of the neuroendocrine-immune network and renders them susceptible to age-related diseases and cancers. This study investigates the mechanisms of estrogen-induced alterations in cell-mediated immune and inflammatory responses in the lymphocytes from lymph nodes (axillary and inguinal) of ovariectomized (OVX) middle-aged female rats. Ovariectomized middle-aged (MA) Sprague-Dawley female rats (n=8) were implanted with 17β-estradiol (E2) 30-day release pellets (0.6 and 300μg). At the end of the treatment period, lymph nodes (axillary and inguinal) were isolated and examined for serum 17β-estradiol, lymphoproliferation, cytokine production, expression of p-Akt, p-mTOR, p-IκB-α and p-NF-κB (p50 and p65), extent of lipid peroxidation, nitric oxide (NO) production, cytochrome c oxidase activity and reactive oxygen species (ROS) production. There was an OVX-related decline in serum 17β-estradiol level, Con A-induced lymphoproliferation, p-Akt and p-mTOR expression, and cytochrome c oxidase (COX) activity. E2 supplementation increased serum 17β-estradiol level, lymphoproliferation, expression of p-Akt, p-mTOR, p-IκB-α and p-NF-κB (p50 and p65), lipid peroxidation, IFN-γ, TNF-α, ROS and NO production, while it decreased IL-6 production. E2 mediates inflammatory responses by increasing the levels of NO and TNF-α by up regulating IFN-γ and simultaneously promotes aging through the generation of free radicals as reflected by increased lipid peroxidation and ROS production in lymph nodes. These findings may have wide implications to immunity and inflammatory disorders including autoimmune diseases predominantly prevalent in females.

HS-133, a novel fluorescent phosphatidylinositol 3-kinase inhibitor as a potential imaging and anticancer agent for targeted therapy

As PI3K/Akt signaling is frequently deregulated in a wide variety of human tumors, PI3K inhibitors are an emerging class of drugs for cancer treatment. The monitoring of the drug behavior and distribution in the biological system can play an important role for targeted therapy and provide information regarding the response or resistance to available therapies. In this study, therefore, we have developed a family of xanthine derivatives, serving as a dual function exhibiting fluorescence, as well as inhibiting PI3K. Among them, HS-133 showed anti-proliferative effects and was monitored for its subcellular localization by a fluorescence microscopy. HS-133 suppressed the PI3K/Akt pathway and induced cell cycle arrest at the G0/G1 phase. The induction of apoptosis by HS-133 was confirmed by the increases of the cleaved PARP, caspase-3, and caspase-8. Furthermore, HS-133 decreased the protein expression of HIF-1α and VEGF, as well inhibited the tube formation and migration of the human umbilical vein endothelial cells. In vivo imaging also showed that tumors were visualized fluorescent with HS-133, and its oral administration significantly inhibited the growth of tumor in SkBr3 mouse xenograft models. Thus, we suggest that HS-133 may be used as a fluorescent anticancer agent against human breast cancer.

Dihydromethysticin kavalactone induces apoptosis in osteosarcoma cells through modulation of PI3K/Akt pathway, disruption of mitochondrial membrane potential and inducing cell cycle arrest

The objective of the present study was to evaluate the tumor and apoptotic effects of dihydromethysticin kavalactone against human osteosarcoma (MG-63) cells. Antiproliferative activity was measured with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction by dihydromethysticin was demonstrated by fluorescence microscopy, quantitative videomicroscopy and Annexin V-FITC apoptosis detection kit. Mitochondrial membrane potential disruption was demonstrated by rhodamine-123 dye using flow cytometry. We also evaluated the effect of dihydromethysticin on PI3K/Akt pathway with an immunoblotting analysis. The results showed that the compound induced dose-dependent as well as time-dependent antiproliferative effects against MG-63 cell growth. Cell death and apoptotic body formation was noticed followed dihydromethysticin treatment at various doses. The percentage of apoptotic cells (early apoptosis+late apoptosis) increased from 6.63% in untreated control to 23.92%, 23.81% and 93.9% in 25 µM, 75 µM and 100 µ Mdihydromethysticin-treated cells respectively. Flow cytometric analysis showed dihydromethysticin induced an increase in G0/G1 cells (apoptotic cells). Furthermore, we observed mitochondrial transmembrane depolarization along with decreased phosphorylation levels for PI3K, AKT (Ser 473), AKT (Thr 308), GSK-3β, and BAD. These reductions were associated with down regulation of AKT and upregulation of both GSK-3β and BAD.

Camptothecin suppresses expression of matrix metalloproteinase-9 and vascular endothelial growth factor in DU145 cells through PI3K/Akt-mediated inhibition of NF-κB activity and Nrf2-dependent induction of HO-1 expression

Though camptothecin (CPT) possesses potent anti-inflammatory, immunomodulatory, anticancerous, and antiproliferative effects, little is known about the mechanism by which CPT regulates the expression of matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF). Therefore, the current study aimed to investigate the effects of CPT on the expression of MMP-9 and VEGF, which are important factors for the invasion of tumors. In vitro application of CPT resulted in a slight inhibition of cell proliferation and a significant reduction in the matrigel invasion of DU145 cells. Treatment with CPT also downregulated phorbol-12-myristate-13-acetate (PMA)- and tumor necrosis factor-α (TNF-α)-induced MMP-9 and VEGF expression by inhibiting nuclear factor-κB (NF-κB) activity. Downregulation of phosphoinositide 3-kinase (PI3K)/Akt phosphorylation in response to CPT was revealed as an upstream pathway regulating the expression of MMP-9 and VEGF accompanying the inhibition of NF-κB activity. We further confirmed that CPT inhibits PMA-induced MMP-9 and VEGF expression by upregulating nuclear factor-erythroid related factor-2 (Nrf2)-mediated heme oxygenase-1 (HO-1) induction. Taken together, these data indicate that CPT inhibits the invasion of cancer cells accompanied by suppression of MMP-9 and VEGF production by suppressing the PI3K/Akt-mediated NF-κB pathway and enhancing the Nrf2-dependent HO-1 pathway, suggesting that CPT may be a good candidate to inhibit MMP-9 and VEGF expression.

Study on the function and mechanism of atorvastatin in regulating leukemic cell apoptosis by the PI3K/Akt pathway

OBJECTIVE

To investigate the effects of atorvastatin on the proliferation and apoptosis of leukemic cell lines (Jurkat, K562 and HL-60), and expore the function of TLR4/MYD88/NF-κB and PI3K/AKT signal pathway in this process.

METHODS

Cells in logarithmic growth phase were divided into negative control group and experimental group (cells were treated with atorvastatin with intervention concentrations of 1, 5 and 10 μmol/L respectively) and cultured for 24 hours. Changes in apoptosis and cell cycle of leukemic cells were detected utilizing the Flow Cytometry. Changes in the expression of TLR4/MYD88/NF-κB and PI3K/AKT signal pathway related genes were detected utilizing Real-time PCR and Western Blot method.

RESULTS

Atorvastatin inhibit proliferation and induce apoptosis in K562, HL-60 and Jurkat cells in a dose-dependent manner. K562, HL-60 and Jurkat cells in G0/G1 phase increased and that in S phase decreased after being treated with atorvastatin for 24 hours compared with that in control group, suggesting that the atorvastatin can retard the three cells in the G0/G1 phase. The study find that the basal expressions of TLR4, MYD88 and NF-κB gene in K562, HL-60 and Jurkat cells are obviously down-regulated in a dose-dependent manner after being treated with atorvastatin with different concentrations. This down-regulation action of atorvastatin to the expression of the TLR4, MYD88 and NF-κB gene becomes more obvious with the increase of the drug level. In addition, the PI3K, AKT and their phosphorylation levels in the above cells down-regulate obviously in a dose-dependent manner after being treated with atorvastatin. This down-regulation action of atorvastatin to the PI3K, AKT and their phosphorylation levels become more obvious with the increase of the drug level.

CONCLUSIONS

Atorvastatin can inhibit proliferation and induce apoptosis in leukemia cells, which may be associated with the regulation of atorvastatin to the TLR4/MYD88/PI3K/AKT/NF-κB signaling pathway.

PI3K/Akt signaling in osteosarcoma

Osteosarcoma (OS) is the most common nonhematologic bone malignancy in children and adolescents. Despite the advances of adjuvant chemotherapy and significant improvement of survival, the prognosis remains generally poor. As such, the search for more effective anti-OS agents is urgent. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is thought to be one of the most important oncogenic pathways in human cancer. An increasing body of evidence has shown that this pathway is frequently hyperactivated in OS and contributes to disease initiation and development, including tumorigenesis, proliferation, invasion, cell cycle progression, inhibition of apoptosis, angiogenesis, metastasis and chemoresistance. Inhibition of this pathway through small molecule compounds represents an attractive potential therapeutic approach for OS. The aim of this review is to summarize the roles of the PI3K/Akt pathway in the development and progression of OS, and to highlight the therapeutic potential of targeting this signaling pathway. Knowledge obtained from the application of these compounds will help in further understanding the pathogenesis of OS and designing subsequent treatment strategies.

Dietary Glucosinolates Sulforaphane, Phenethyl Isothiocyanate, Indole-3-Carbinol/3,3'-Diindolylmethane: Anti-Oxidative Stress/Inflammation, Nrf2, Epigenetics/Epigenomics and In Vivo Cancer Chemopreventive Efficacy

Glucosinolates are a group of sulfur-containing glycosides found in many plant species, including cruciferous vegetables such as broccoli, cabbage, brussels sprouts, and cauliflower. Accumulating evidence increasingly supports the beneficial effects of dietary glucosinolates on overall health, including as potential anti-cancer agents, because of their role in the prevention of the initiation of carcinogenesis via the induction of cellular defense detoxifying/antioxidant enzymes and their epigenetic mechanisms, including modification of the CpG methylation of cancer-related genes, histone modification regulation and changes in the expression of miRNAs. In this context, the defense mechanism mediated by Nrf2-antioxidative stress and anti-inflammatory signaling pathways can contribute to cellular protection against oxidative stress and reactive metabolites of carcinogens. In this review, we summarize the cancer chemopreventive role of naturally occurring glucosinolate derivatives as inhibitors of carcinogenesis, with particular emphasis on specific molecular targets and epigenetic alterations in in vitro and in vivo human cancer animal models.

3,3'-Diindolylmethane potentiates paclitaxel-induced antitumor effects on gastric cancer cells through the Akt/FOXM1 signaling cascade

Gastric cancer is the fourth most common cancer and is one of the leading causes of cancer-related mortality worldwide. Forkhead box M1 (FOXM1) is overexpressed in gastric cancer, suggesting that it is important in gastric cancer oncogenesis. However, no studies have investigated the role of 3,3'-diindolylmethane (DIM), a component of cruciferous vegetables, in the regulation of FOXM1 and its signaling pathway in gastric cancer. Here, we report for the first time that DIM effectively downregulated Akt/FOXM1 in gastric cancer cells. Combination treatment with DIM and paclitaxel significantly and dose-dependently inhibited the proliferation of SNU638 cells when compared to treatment with DIM or paclitaxel alone. Colony formation of SNU638 cells was significantly attenuated by treatment with DIM and paclitaxel, and DIM potentiated the inhibition of colony formation in SNU638 cells by paclitaxel when compared to treatment with a single agent. Treatment with DIM plus paclitaxel substantially increased apoptosis as indicated by increased levels of cleaved polyADP-ribose polymerase (PARP) and cleaved caspase-9 protein. DIM dose-dependently sensitized gastric cancer cells through downregulation of FOXM1 and potentiated the effects of paclitaxel. FOXM1 effector genes such as CDK4, p53 and cyclin D1 were downregulated in gastric cancer cells by combination treatment with DIM and paclitaxel. In addition, DIM significantly and dose-dependently inhibited phosphorylation of Akt and potentiated paclitaxel-induced inhibition of Akt function in gastric cancer cells. Therefore, our results indicate that DIM effectively potentiates the efficacy of chemotherapeutic agents such as paclitaxel by downregulation of the Akt/FOXM1 signaling cascade in gastric cancer cells. Our findings suggest that DIM enhances the therapeutic efficacy of paclitaxel in gastric cancer and is a potential clinical anticancer agent for the prevention and/or treatment of gastric cancer.

Molecular targets of naturopathy in cancer research: bridge to modern medicine

The relevance of naturopathy (defined as the practice of medicine for the treatment of human diseases with natural agents) in human cancer is beginning to be appreciated, as documented by renewed interest in nutraceutical research, the natural anticancer agents of dietary origin. Because of their pleiotropic effects and the ability to modulate multiple signaling pathways, which is a good attribute of natural agents, nutraceuticals have frequently been demonstrated to re-sensitize drug-resistant cancers. The effectiveness of nutraceuticals can be further enhanced if the tools for the relative assessment of their molecular targets are readily available. Such information can be critical for determining their most effective uses. Here, we discuss the anticancer potential of nutraceuticals and the associated challenges that have interfered with their translational potential as a naturopathic approach for the management of cancers. In the years to come, an efficient screening and assessment of molecular targets will be the key to make rapid progress in the area of drug design and discovery, especially focusing on evidence-based development of naturopathy for the treatment of human malignancies.

Mechanistic insight into conjugated N–N bond cleavage by Rh(iii)-catalyzed redox-neutral C–H activation of pyrazolones

DFT calculations are performed to understand the conjugated N–N bond cleavage by Rh(iii)-catalyzed redox-neutral C–H activation of pyrazolones with PhCCPh.

Indole and synthetic derivative activate chaperone expression to reduce polyQ aggregation in SCA17 neuronal cell and slice culture models

In spinocerebellar ataxia type 17 (SCA17), the expansion of a translated CAG repeat in the TATA box binding protein (TBP) gene results in a long polyglutamine (polyQ) tract in the TBP protein, leading to intracellular accumulation of aggregated TBP and cell death. The molecular chaperones act in preventing protein aggregation to ameliorate downstream harmful events. In this study, we used Tet-On SH-SY5Y cells with inducible SCA17 TBP/Q₇₉-green fluorescent protein (GFP) expression to test indole and synthetic derivative NC001-8 for neuroprotection. We found that indole and NC001-8 up-regulated chaperone expression to reduce polyQ aggregation in neuronal differentiated TBP/Q₇₉ cells. The effects on promoting neurite outgrowth and on reduction of aggregation on Purkinje cells were also confirmed with cerebellar primary and slice cultures of SCA17 transgenic mice. Our results demonstrate how indole and derivative NC001-8 reduce polyQ aggregation to support their therapeutic potentials in SCA17 treatment.

The potential of indole and a synthetic derivative for polyQ aggregation reduction by enhancement of the chaperone and autophagy systems

In polyglutamine (polyQ)-mediated disorders, the expansion of translated CAG repeats in the disease genes result in long polyQ tracts in their respective proteins, leading to intracellular accumulation of aggregated polyQ proteins, production of reactive oxygen species, and cell death. The molecular chaperones act in preventing protein misfolding and aggregation, thus inhibiting a wide range of harmful downstream events. In the circumstance of accumulation of aggregated polyQ proteins, the autophagic pathway is induced to degrade the misfolded or aggregated proteins. In this study, we used Flp-In 293/SH-SY5Y cells with inducible SCA3 ATXN3/Q75-GFP expression to test the effect of indole and synthetic derivatives for neuroprotection. We found that ATXN3/Q75 aggregation can be significantly prohibited in Flp-In 293 cells by indole and derivative NC001-8. Meanwhile, indole and NC001-8 up-regulated chaperones and autophagy in the same cell models. Both of them further promote neurite outgrowth in neuronal differentiated SH-SY5Y ATXN3/Q75-GFP cells. Our results demonstrate how indole and derivative NC001-8 are likely to work in reduction of polyQ-aggregation and provide insight into the possible effectual mechanism of indole compounds in polyQ spinocerebellar ataxia (SCA) patients. These findings may have therapeutic applications in a broad range of clinical situations.

The therapeutic potential of targeting the epithelial-mesenchymal transition in cancer

INTRODUCTION

The process of epithelial-to-mesenchymal transition (EMT) has long been advocated as a process during tumor progression and the acquisition of metastatic potential of human cancers. EMT has also been linked with resistance to cancer therapies.

AREAS COVERED

Basic research has provided evidence connecting EMT to increased invasion, angiogenesis and metastasis of cancer cells. A number of signaling pathways such as notch, wnt, hedgehog and PI3K-AKT, and various other individual factors therein, have been intricately connected to the onset of EMT. Here, we provide latest updates on the evidences that further highlight an association between various signaling pathways and EMT, with a focus on therapeutic targets that may have the potential to reverse EMT.

EXPERT OPINION

Our understanding of EMT and its underlying causes is rapidly evolving and a number of putative targets have been identified. It is crucial, now than ever before, to design novel translational and clinical studies for the benefit of advanced stage cancer patients with metastatic disease.

Multiple therapeutic and preventive effects of 3,3'-diindolylmethane on cancers including prostate cancer and high grade prostatic intraepithelial neoplasia

Cruciferous vegetables belong to the plant family that has flowers with four equal-sized petals in the pattern of a crucifer cross. These vegetables are an abundant source of dietary phytochemicals, including glucosinolates and their hydrolysis products such as indole-3-carbinol (I3C) and 3,3′-diindolylmethane (DIM). By 2013, the total number of natural glucosinolates that have been documented is estimated to be 132. Recently, cruciferous vegetable intake has garnered great interest for its multiple health benefits such as anticancer, antiviral infections, human sex hormone regulation, and its therapeutic and preventive effects on prostate cancer and high grade prostatic intraepithelial neoplasia (HGPIN). DIM is a hydrolysis product of glucosinolates and has been used in various trials. This review is to provide an insight into the latest developments of DIM in treating or preventing both prostate cancer and HGPIN.