Genome-wide transcriptome analysis reveals inactivation of Wnt/β-catenin by 3,3′-diindolylmethane inhibiting proliferation of colon cancer cells

3,3'-Diindolylmethane Augments 5-Fluorouracil-InducedGrowth Suppression in Gastric Cancer Cells through Suppression of the Akt/GSK-3β and WNT/Beta-Catenin

Gastric cancer (GC) is one of the most lethal cancers in South Korea, and it is a cancer of concern worldwide. 5-fluorouracil (5-Fu) is commonly used as the first-line therapy for advanced GC; however, its side effects often limit the dosage range and impair patients' quality of life. Due to the limitations of current chemotherapy, new anticancer therapies are urgently needed. 3,3'-diindolylmethane (DIM) has been reported to have the ability to protect against various types of cancer. Our study aimed to elucidate the anticancer effect of DIM in GC when treated with the chemotherapeutic agent 5-Fu. In our results, combined treatment with DIM and 5-Fu resulted in higher apoptosis and lower cell proliferation than treatment with 5-Fu in SNU484 and SNU638 cell lines. Furthermore, when DIM and 5-Fu were administered together, cell invasion was diminished by mediated E-cadherin, MMP-9, and uPA; p-Akt and p-GSK-3β levels were reduced more significantly than when 5-Fu was administered alone. Moreover, in the Wnt signaling pathway, combined treatment of DIM and 5-Fu diminished β-catenin levels in the nucleus and inhibited cyclin D1and c-Myc protein levels. The Akt inhibitor, wortmannin, further inhibited the levels of β-catenin and c-Myc that were inhibited by DIM and 5-Fu. Furthermore, an animal xenograft model demonstrated that DIM combined with 5-Fu considerably reduced tumor growth without any toxic effects by regulating the Akt/GSK-3β and β-catenin levels. Our findings suggest that DIM significantly potentiates the anticancer effects of 5-Fu by targeting the Akt/GSK-3β and WNT/β-catenin because the combination therapy is more effective than 5-Fu alone, thereby offering an innovative potential therapy for patients with GC.

Therapeutic Potential of Naturally Occurring Small Molecules to Target the Wnt/β-Catenin Signaling Pathway in Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is an emerging public health problem and the second leading cause of death worldwide, with a significant socioeconomic impact in several countries. The 5-year survival rate is only 12% due to the lack of early diagnosis and resistance to available treatments, and the canonical Wnt signaling pathway is involved in this process. This review underlines the importance of understanding the fundamental roles of this pathway in physiological and pathological contexts and analyzes the use of naturally occurring small molecules that inhibits the Wnt/β-catenin pathway in experimental models of CRC. We also discuss the progress and challenges of moving these small molecules off the laboratory bench into the clinical platform.

Abstract

Colorectal cancer (CRC) ranks second in the number of cancer deaths worldwide, mainly due to late diagnoses, which restrict treatment in the potentially curable stages and decrease patient survival. The treatment of CRC involves surgery to remove the tumor tissue, in addition to radiotherapy and systemic chemotherapy sessions. However, almost half of patients are resistant to these treatments, especially in metastatic cases, where the 5-year survival rate is only 12%. This factor may be related to the intratumoral heterogeneity, tumor microenvironment (TME), and the presence of cancer stem cells (CSCs), which is impossible to resolve with the standard approaches currently available in clinical practice. CSCs are APC-deficient, and the search for alternative therapeutic agents such as small molecules from natural sources is a promising strategy, as these substances have several antitumor properties. Many of those interfere with the regulation of signaling pathways at the central core of CRC development, such as the Wnt/β-catenin, which plays a crucial role in the cell proliferation and stemness in the tumor. This review will discuss the use of naturally occurring small molecules inhibiting the Wnt/β-catenin pathway in experimental CRC models over the past decade, highlighting the molecular targets in the Wnt/β-catenin pathway and the mechanisms through which these molecules perform their antitumor activities.

Indoles Derived From Glucobrassicin: Cancer Chemoprevention by Indole-3-Carbinol and 3,3'-Diindolylmethane

Hydrolysis of glucobrassicin by plant or bacterial myrosinase produces multiple indoles predominantly indole-3-carbinol (I3C). I3C and its major in vivo product, 3,3'-diindolylmethane (DIM), are effective cancer chemopreventive agents in pre-clinical models and show promise in clinical trials. The pharmacokinetics/pharmacodynamics of DIM have been studied in both rodents and humans and urinary DIM is a proposed biomarker of dietary intake of cruciferous vegetables. Recent clinical studies at Oregon State University show surprisingly robust metabolism of DIM in vivo with mono- and di-hydroxylation followed by conjugation with sulfate or glucuronic acid. DIM has multiple mechanisms of action, the most well-characterized is modulation of aryl hydrocarbon receptor (AHR) signaling. In rainbow trout dose-dependent cancer chemoprevention by dietary I3C is achieved when given prior to or concurrent with aflatoxin B1, polycyclic aromatic hydrocarbons, nitrosamines or direct acting carcinogens such as N-methyl-N'-nitro-nitrosoguanidine. Feeding pregnant mice I3C inhibits transplacental carcinogenesis. In humans much of the focus has been on chemoprevention of breast and prostate cancer. Alteration of cytochrome P450-dependent estrogen metabolism is hypothesized to be an important driver of DIM-dependent breast cancer prevention. The few studies done to date comparing glucobrassicin-rich crucifers such as Brussels sprouts with I3C/DIM supplements have shown the greater impact of the latter is due to dose. Daily ingestion of kg quantities of Brussels sprouts is required to produce in vivo levels of DIM achievable by supplementation. In clinical trials these supplement doses have elicited few if any adverse effects. Sulforaphane from glucoraphanin can act synergistically with glucobrassicin-derived DIM and this may lead to opportunities for combinatorial approaches (supplement and food-based) in the clinic.

Regulation of carcinogenesis and mediation through Wnt/β-catenin signaling by 3,3'-diindolylmethane in an enzalutamide-resistant prostate cancer cell line

Enzalutamide (ENZ) is an important drug used to treat castration-resistant prostate cancer (CRPC), which inhibits androgen receptor (AR) signaling. Previous study showed that 3,3′-diindolylmethane (DIM) is an AR antagonist that also inhibits Wnt signaling and epithelial-mesenchymal transition (EMT). To investigate whether combined treatment with ENZ and DIM can overcome ENZ resistance by regulating Wnt signaling to inhibit AR signaling and EMT in ENZ-resistant prostate cancer cells, 22Rv1 cells were cultured in normal medium and treated with ENZ, DIM, and DIM with ENZ. Exposure of ENZ-resistant cells to both DIM and ENZ significantly inhibited cell proliferation without cytotoxicity and invasion in comparison with the control. DIM significantly increased the E-cadherin expression and inhibited the expressions of Vimentin and Fibronectin, subsequently inhibiting EMT. Co-treatment with ENZ and DIM significantly increased the expressions of GSK3β and APC and decreased the β-catenin protein expression, causing inhibition of Wnt signaling and AR expression, it also significantly decreased the AR-v7 expression and down-regulated AR signaling. Via suppression of Wnt and AR signaling, co-treatment increased the E-cadherin and decreased the Vimentin and Fibronectin RNA and protein expressions, then inhibited EMT. Co-treatment with DIM and ENZ regulated Wnt signaling to reduce not only the AR expression, but also the AR-v7 expression, indicating suppression of EMT that inhibits cancer cell proliferation, invasion and migration to ameliorate ENZ resistance.

Colon Cancer Risk of a Westernized Diet Is Reduced in Mice by Feeding Cruciferous or Apiaceous Vegetables at a Lower Dose of Carcinogen but Not a Higher Dose

Western-style diets (WD) are associated with greater risk of colon cancer. Exposure to 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), a food-borne carcinogen, is linked to increased colon cancer risk. In contrast, intake of apiaceous and cruciferous vegetables (APIs and CRUs) is associated with reduced risk. Here we evaluated effects of a WD alone or a WD containing API or CRU, relative to a purified diet (basal), on colon cancer risk in mice. All diets were fed at one of two concentrations of PhIP (100 or 400 ppm). The activity of the hepatic PhIP-activating enzyme, cytochrome P450 (CYP) 1A2, was examined at week 4 and colonic precancerous lesions (aberrant crypt foci, ACF) were enumerated at week 12. In low PhIP-fed groups, CYP1A2 activity was greater for CRU than all other groups, which did not differ from one another. WD had a significantly greater effect on the formation of ACF than the basal diet. In groups fed API or CRU, the ACF number was reduced to the level observed in the basal diet-fed group. In high PhIP-fed groups, all WD-based diets had greater CYP1A2 activity than the basal diet-fed group. Surprisingly, the basal diet group had more ACF than the WD group, and API and CRU groups did not differ from the WD alone group. Thus, at the lower dose of PhIP, the WD increased colon cancer risk in mice, compared to a purified diet, and APIs and CRUs reduced the risk of the WD. However, at the higher dose of PhIP, the enhancement of colon cancer risk by the WD was not evident, nor was the chemopreventive effect of these vegetables.

Age-related transcriptome changes in melanoma patients with tumor-positive sentinel lymph nodes

Age is an important factor for determining the outcome of melanoma patients. Sentinel lymph node (SLN) status is also a strong predictor of survival for melanoma. Paradoxically, older melanoma patients have a lower incidence of SLN metastasis but a higher mortality rate when compared with their younger counterparts. The mechanisms that underlie this phenomenon remain unknown. This study uses three independent datasets of RNA samples from patients with melanoma metastatic to the SLN to identify age-related transcriptome changes in SLNs and their association with outcome. Microarray was applied to the first dataset of 97 melanoma patients. NanoString was performed in the second dataset to identify the specific immune genes and pathways that are associated with recurrence in younger versus older patients. qRT-PCR analysis was used in the third dataset of 36 samples to validate the differentially expressed genes (DEGs) from microarray and NanoString. These analyses show that FOS, NR4A, and ITGB1 genes were significantly higher in older melanoma patients with positive SLNs. IRAK3- and Wnt10b-related genes are the major pathways associated with recurrent melanoma in younger and older patients with tumor-positive SLNs, respectively. This study aims to elucidate age-related differences in SLNs in the presence of nodal metastasis.

Reactive Oxygen Species-Mediated Autophagy by Ursolic Acid Inhibits Growth and Metastasis of Esophageal Cancer Cells

Ursolic acid (UA) possesses various pharmacological activities, such as antitumorigenic and anti-inflammatory effects. In the present study, we investigated the mechanisms underlying the effects of UA against esophageal squamous cell carcinoma (ESCC) (TE-8 cells and TE-12 cells). The cell viability assay showed that UA decreased the viability of ESCC in a dose-dependent manner. In the soft agar colony formation assay, the colony numbers and size were reduced in a dose-dependent manner after UA treatment. UA caused the accumulation of vacuoles and LC3 puncta, a marker of autophagosome, in a dose-dependent manner. Autophagy induction was confirmed by measuring the expression levels of LC3 and p62 protein in ESCC cells. UA increased LC3-II protein levels and decreased p62 levels in ESCC cells. When autophagy was hampered using 3-methyladenine (3-MA), the effect of UA on cell viability was reversed. UA also significantly inhibited protein kinase B (Akt) activation and increased p-Akt expression in a dose-dependent manner in ESCC cells. Accumulated LC3 puncta by UA was reversed after wortmannin treatment. LC3-II protein levels were also decreased after treatment with Akt inhibitor and wortmannin. Moreover, UA treatment increased cellular reactive oxygen species (ROS) levels in ESCC in a time- and dose-dependent manner. Diphenyleneiodonium (an ROS production inhibitor) blocked the ROS and UA induced accumulation of LC3-II levels in ESCC cells, suggesting that UA-induced cell death and autophagy are mediated by ROS. Therefore, our data indicate that UA inhibits the growth of ESCC cells by inducing ROS-dependent autophagy.

Transcriptomic analysis of the mode of action of the candidate anti-fouling compound di(1H-indol-3-yl)methane (DIM) on a marine biofouling species, the bryozoan Bugula neritina

Di(1H-indol-3-yl)methane (DIM) was previously suggested to be an environmentally friendly antifouling compound, but it was also reported that the compound was highly stable in natural seawater. The present study reported that 3 h DIM treatments at 4 μg mL^-1 or higher concentration and 12 h DIM treatments at 2 μg mL^-1 or higher concentration induced significant larval mortality and metamorphic abnormality in the bryozoan Bugula neritina. The bioassay results correlated with the dose-dependent up-regulation of HSP family proteins, pro-apoptotic proteins, ubiquitination protein, and the dose-dependent down-regulation of anti-apoptotic genes and developmental genes. Unexpectedly, genes involved in fatty acid biosynthesis and protein synthesis were up-regulated in response to DIM treatment, but, in general, the effects of DIM on B. neritina larvae were comparable to that reported in human cancer cell lines. DIM also induced changes in steroid hormone biosynthesis genes in B. neritina larvae, leading to the concern that DIM might have long-term effects on marine lives. Overall, the present study suggested that application of DIM to the bryozoan larvae would trigger a major transcriptomic response, which might be linked to the observed larval mortality and abnormality. We suggest that application of DIM as an antifouling ingredient should be proceeded with great cautions.

Dependence and Guidance Receptors-DCC and Neogenin-In Partial EMT and the Actions of Serine Proteases

The Epithelial-Mesenchymal Transition (EMT) is an important concept in understanding the processes of oncogenesis, especially with respect to the relationship between cell proliferation and metastatic properties such as spontaneous cell motility, chemotaxic migration and tissue invasion. EMT is now recognized as a more complex phenomenon than an all-or-nothing event, in which different components of the EMT may have distinct roles in the physio-pathological regulation of cell function and which may in turn depend on differential interactions with cell constituents and metabolic products. This mini-review summarizes recent work on the induction of cancer properties in parallel with the presence of EMT activities in the presence of serine proteases, with the focus on those tumor suppressors known as "dependence" receptors such as neogenin and Deleted in Colorectal Cancer (DCC). It is concluded that various forms of partial EMT should be given more detailed investigation and consideration as the results could have valuable implications for the development of disease-specific and patient-specific therapies.

3,3'-Diindolylmethane Improves Intestinal Permeability Dysfunction in Cultured Human Intestinal Cells and the Model Animal Caenorhabditis elegans

3,3'-Diindolylmethane (DIM), a digestive metabolite originating from cruciferous vegetables, has dietary potential for the treatment of various human intestinal diseases. Although intestinal permeability dysfunction is closely related to the initiation and progression of human intestinal inflammatory diseases (IBDs), the effect of DIM on intestinal permeability is unclear. We evaluated the effect of DIM on the intestinal permeability of human intestinal cell monolayers and the animal model Caenorhabditis elegans, which were treated with IL-1β and Pseudomonas aeruginosa, respectively, to mimic IBD conditions. DIM substantially restored the intestinal permeability of differentiated Caco-2 cells by enhancing the expression of tight junction proteins (including occludin and ZO-1). Compared to the IL-1β single treatment (551.0 ± 49.0 Ω·cm²), DIM (10 μM) significantly increased the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers (919.0 ± 66.4 Ω·cm², p < 0.001). DIM also ameliorated the impaired intestinal permeability and extended the lifespan of C. elegans fed P. aeruginosa. The mean lifespan of DIM-treated worms (10.8 ± 1.3 days) was higher than that of control-treated worms (9.7 ± 1.1 days, p < 0.01). Thus, DIM is a potential nutraceutical candidate for the treatment of leaky gut syndrome by improving intestinal permeability.

A Novel Phytochemical, DIM, Inhibits Proliferation, Migration, Invasion and TNF-α Induced Inflammatory Cytokine Production of Synovial Fibroblasts From Rheumatoid Arthritis Patients by Targeting MAPK and AKT/mTOR Signal Pathway

In rheumatoid arthritis(RA) pathogenesis, activated RA fibroblast-like synoviocytes (RA-FLSs) exhibit similar proliferative features as tumor cells and subsequent erosion to cartilage will eventually lead to joint destruction. Therefore, it is imperative to search for compounds, which can effectively inhibit the abnormal activation of RA-FLSs, and retard RA progression.3′3-Diindolylmethane (DIM), the major product of the acid-catalyzed oligomerization of indole-3-carbinol from cruciferous vegetables, has been reported to be functionally relevant to inhibition of migration, invasion and carcinogenesis in some solid tumors. In this study, we explored the anti-proliferation, anti-metastasis and anti-inflammation effects of DIM on RA-FLSs as well as the underlying molecular mechanisms. To do this, primary RA-FLSs were isolated from RA patients and an animal model. Cell proliferation, migration and invasion were measured using CCK-8, scratch, and Transwell assays, respectively. The effects of DIM on Matrix metalloproteinases (MMPs) and some inflammatory factors mRNA and key molecules such as some inflammatory factors and those involved in aberrantly-activated signaling pathway in response to tumor necrosis factor α(TNF-α), a typical characteristic mediator in RA-FLS, were quantitatively measured by real-time PCR and western blotting. Moreover, the effect of DIM on adjuvant induced arthritis(AIA) models was evaluated with C57BL/6 mice in vivo. The results showed that DIM inhibited proliferation, migration and invasion of RA-FLS in vitro. Meanwhile, DIM dramatically suppressed TNF-α–induced increases in the mRNA levels of MMP-2, MMP-3, MMP-8, and MMP-9; as well as the proinflammatory factors IL-6, IL-8, and IL-1β. Mechanistic studies revealed that DIM is able to suppress phosphorylated activation not only of p38, JNK in MAPK pathway but of AKT, mTOR and downstream molecules in the AKT/mTOR pathway. Moreover, DIM treatment decreased expression levels of proinflammatory cytokines in the serum and alleviated arthritis severity in the knee joints of AIA mice. Taken together, our findings demonstrate that DIM could inhibit proliferation, migration and invasion of RA-FLSs and reduce proinflammatory factors induced by TNF-α in vitro by blocking MAPK and AKT/mTOR pathway and prevent inflammation and knee joint destruction in vivo, which suggests that DIM might have therapeutic potential for RA.

Therapeutic potential of targeting the Wnt/β-catenin signaling pathway in colorectal cancer

Aberrant Wnt/β-catenin signaling has often been reported in different cancers, particularly colorectal cancer (CRC), and this signaling cascade is central to carcinogenesis. Approximately 80% of CRC cases harbor mutations in the adenomatous polyposis coli gene, and half of the remaining cases feature mutations in the β-catenin gene that affect the Wnt/β-catenin signaling pathway. Unsurprisingly, the Wnt/β-catenin signaling pathway has potential value as a therapeutic target in the treatment of CRC. Several inhibitors of the Wnt/β-catenin signaling pathway have been developed for CRC treatment, but so far no molecular therapeutic targeting this pathway has been incorporated into oncological practice. In this review, we discuss the role of Wnt/β-catenin signaling in CRC and its potential as a target of innovative therapeutic approaches for CRC.

Serine protease modulation of Dependence Receptors and EMT protein expression

Expression of the tumour suppressor Deleted in Colorectal Cancer (DCC) and the related protein neogenin is reduced by the mammalian serine protease chymotrypsin or the bacterial serine protease subtilisin, with increased cell migration. The present work examines whether these actions are associated with changes in the expression of cadherins, β-catenin and vimentin, established markers of the Epithelial-Mesenchymal Transition (EMT) which has been linked with cell migration and tumour metastasis. The results confirm the depletion of DCC and neogenin and show that chymotrypsin and subtilisin also reduce expression of β-catenin in acutely prepared tissue sections but not in human mammary adenocarcinoma MCF-7 or MDA-MB-231 cells cultured in normal media, or primary normal human breast cells. A loss of β-catenin was also seen in low serum media but transfecting cells with a dcc-containing plasmid induced resistance. E-cadherin was not consistently affected but vimentin was induced by low serum-containing media and was increased by serine proteases in MCF-7 and MDA-MB-231 cells in parallel with increased wound closure. Vimentin might contribute to the promotion of cell migration. The results suggest that changes in EMT proteins depend on the cells or tissues concerned and do not parallel the expression of DCC and neogenin. The increased cell migration induced by serine proteases is not consistently associated with the expression of the EMT proteins implying either that the increased migration may be independent of EMT or supporting the view that EMT is not itself consistently related to migration. (241).

Radix Tetrastigma hemsleyani flavone exhibits antitumor activity in colorectal cancer via Wnt/β-catenin signaling pathway

Background

Radix Tetrastigma hemsleyani flavone (RTHF) is extracted from a traditional Chinese medicinal herb T. hemsleyani, which is conventionally used as a folk medicine for its anti-inflammation activity and antiviral activity. In this study, the effects of RTHF on inhibiting malignant biological properties in colorectal cancer (CRC) were evaluated by conducting both in vitro and in vivo experiments, and the underlying mechanism was investigated.

Materials and methods

Cell Counting Kit-8, colony formation, and flow cytometry assays were performed to evaluate the proliferation of RTHF-treated colon tumor cells. Migration and invasion capacities were also tested by cell wound scratch assay and Transwell invasion assay. Moreover, the antitumor effects of RTHF on azoxymethane/dextran sulfate sodium-induced colitis-related CRC were investigated in C57BL/6 mice. In addition, Western blot and/or quantitative reverse transcription polymerase chain reaction analysis were used to evaluate the expressions of Lgr5, Cyclin D1, c-Myc, and E-cadherin.

Results

These experiments showed that RTHF could decrease the cell growth kinetics and clone-forming capacity. RTHF could also dose dependently induce cell cycle arrest at G0/G1 phase and inhibit epithelial-mesenchymal transition process. Furthermore, downregulation of β-catenin activation and downstream protein expression were detected in CRC cells after being treated with RTHF. RTHF daily gavage suppressed the number and size of CRC in mice and inhibited Lgr5 and Cyclin D1 expressions in tumor tissue.

Conclusion

In conclusion, RTHF treatment inhibits colorectal tumor growth, decreases Wnt/β-catenin pathway activity, and downregulates target genes’ expression.

Recombinant human bone morphogenetic protein-2 inhibits gastric cancer cell proliferation by inactivating Wnt signaling pathway via c-Myc with aurora kinases

The detailed molecular mechanisms and safety issues of recombinant human bone morphogenetic protein-2 (rhBMP-2) usage in bone graft substitution remain poorly understood. To investigate the molecular mechanisms underlying the function of rhBMP-2 in gastric cancer cells, we used microarrays to determine the gene expression patterns related to the effects of rhBMP-2. Based on a gene ontology analysis, several genes were upregulated during the regulation of the cell cycle and BMP signaling pathway. MYC was found to be significantly decreased along with its downstream target genes, the aurora kinases (AURKs), by rhBMP-2 in the network analysis. We further confirmed this finding with western blot data that rhBMP-2 inhibited c-Myc, AURKs, and β-catenin in SNU484 and SNU638 cells. An AURK inhibitor significantly decreased c-Myc expression in gastric cancer cells. Combination treatment with rhBMP-2 and AURK inhibitor resulted in significantly decreased c-Myc expression compared with gastric cancer cells treated with an rhBMP-2 or AURK inhibitor, respectively. Similar effects for decreased c-Myc expression were observed when we silenced β-catenin in gastric cancer cells. These results indicate that rhBMP-2 attenuated the growth of gastric cancer cells via the inactivation of β-catenin via c-Myc and AURKs. Therefore, our findings suggest that rhBMP-2 could be safely used with patients who undergo gastric or gastroesophageal cancer surgery.

Cellular and Molecular Mechanisms of 3,3'-Diindolylmethane in Gastrointestinal Cancer

Studies in humans have shown that 3,3′-diindolylmethane (DIM), which is found in cruciferous vegetables, such as cabbage and broccoli, is effective in the attenuation of gastrointestinal cancers. This review presents the latest findings on the use, targets, and modes of action of DIM for the treatment of human gastrointestinal cancers. DIM acts upon several cellular and molecular processes in gastrointestinal cancer cells, including apoptosis, autophagy, invasion, cell cycle regulation, metastasis, angiogenesis, and endoplasmic reticulum (ER) stress. In addition, DIM increases the efficacy of other drugs or therapeutic chemicals when used in combinatorial treatment for gastrointestinal cancer. The studies to date offer strong evidence to support the use of DIM as an anticancer and therapeutic agent for gastrointestinal cancer. Therefore, this review provides a comprehensive understanding of the preventive and therapeutic properties of DIM in addition to its different perspective on the safety of DIM in clinical applications for the treatment of gastrointestinal cancers.