Curcumin Inhibits Cell Viability and Increases Apoptosis of SW620 Human Colon Adenocarcinoma Cells via the Caudal Type Homeobox-2 (CDX2)/Wnt/β-Catenin Pathway

Greasing the Wheels of Pharmacotherapy for Colorectal Cancer: the Role of Natural Polyphenols

PURPOSE OF REVIEW

The main purpose of this review, mainly based on preclinical studies, is to summarize the pharmacological and biochemical evidence regarding natural polyphenols against colorectal cancer and highlight areas that require future research.

RECENT FINDINGS

Typically, colorectal cancer is a potentially preventable and curable cancer arising from benign precancerous polyps found in the colon's inner lining. Colorectal cancer is the third most common cancer, with a lifetime risk of approximately 4 to 5%. Genetic background and environmental factors play major roles in the pathogenesis of colorectal cancer. Theoretically, a multistep process of colorectal carcinogenesis provides enough time for anti-tumor pharmacotherapy of colorectal cancer. Chronic colonic inflammation, oxidative stress, and gut microbiota imbalance have been found to increase the risk for colorectal cancer development by creating genotoxic stress within the intestinal environment to generate genetic mutations and epigenetic modifications. Currently, numerous natural polyphenols have shown anti-tumor properties against colorectal cancer in preclinical research, especially in colorectal cancer cell lines. In this review, the current literature regarding the etiology and epidemiology of colorectal cancer is briefly outlined. We highlight the findings of natural polyphenols in colorectal cancer from in vitro and in vivo studies. The scarcity of human trials data undermines the clinical use of natural polyphenols as anti-colorectal cancer agents, which should be undertaken in the future.

Curcumin, calebin A and chemosensitization: How are they linked to colorectal cancer?

Colorectal cancer (CRC) is one of the leading malignant diseases worldwide with a high rate of metastasis and poor prognosis. Treatment options include surgery, which is usually followed by chemotherapy in advanced CRC. With treatment, cancer cells could become resistant to classical cytostatic drugs such as 5-fluorouracil (5-FU), oxaliplatin, cisplatin, and irinotecan, resulting in chemotherapeutic failure. For this reason, there is a high demand for health-preserving re-sensitization mechanisms including the complementary use of natural plant compounds. Calebin A and curcumin, two polyphenolic turmeric ingredients derived from the Asian Curcuma longa plant, demonstrate versatile anti-inflammatory and cancer-reducing abilities, including CRC-combating capacity. After an insight into their epigenetics-modifying holistic health-promoting effects, this review compares functional anti-CRC mechanisms of multi-targeting turmeric-derived compounds with mono-target classical chemotherapeutic agents. Furthermore, the reversal of resistance to chemotherapeutic drugs was presented by focusing on calebin A's and curcumin's capabilities to chemosensitize or re-sensitize CRC cells to 5-FU, oxaliplatin, cisplatin, and irinotecan. Both polyphenols enhance the receptiveness of CRC cells to standard cytostatic drugs converting them from chemoresistant into non-chemoresistant CRC cells by modulating inflammation, proliferation, cell cycle, cancer stem cells, and apoptotic signaling. Therefore, calebin A and curcumin can be tested for their ability to overcome cancer chemoresistance in preclinical and clinical trials. The future perspective of involving turmeric-ingredients curcumin or calebin A as an additive treatment to chemotherapy for patients with advanced metastasized CRC is explained.

Traditional Chinese medicine for colorectal cancer treatment: potential targets and mechanisms of action

Colorectal cancer (CRC) is a disease with complex pathogenesis, it is prone to metastasis, and its development involves abnormalities in multiple signaling pathways. Surgery, chemotherapy, radiotherapy, target therapy, and immunotherapy remain the main treatments for CRC, but improvement in the overall survival rate and quality of life is urgently needed. Traditional Chinese medicine (TCM) has a long history of preventing and treating CRC. It could affect CRC cell proliferation, apoptosis, cell cycle, migration, invasion, autophagy, epithelial-mesenchymal transition, angiogenesis, and chemoresistance by regulating multiple signaling pathways, such as PI3K/Akt, NF-κB, MAPK, Wnt/β-catenin, epidermal growth factor receptors, p53, TGF-β, mTOR, Hedgehog, and immunomodulatory signaling pathways. In this paper, the main signaling pathways and potential targets of TCM and its active ingredients in the treatment of CRC were systematically summarized, providing a theoretical basis for treating CRC with TCM and new ideas for further exploring the pathogenesis of CRC and developing new anti-CRC drugs.

Blocking the Wnt/β‑catenin signaling pathway to treat colorectal cancer: Strategies to improve current therapies (Review)

Colorectal cancer (CRC) is one of the most common malignant tumor types occurring in the digestive system. The incidence of CRC has exhibits yearly increases and the mortality rate among patients with CRC is high. The Wnt/β‑catenin signaling pathway, which is associated with carcinogenesis, is abnormally activated in CRC. Most patients with CRC have adenomatous polyposis coli mutations, while half of the remaining patients have β‑catenin gene mutations. Therefore, targeting the Wnt/β‑catenin signaling pathway for the treatment of CRC is of clinical value. In recent years, with in‑depth research on the Wnt/β‑catenin signaling pathway, inhibitors have been developed that are able to suppress or hinder the development and progression of CRC. In the present review, the role of the Wnt/β‑catenin signaling pathway in CRC is summarized, the research status on Wnt/β‑catenin pathway inhibitors is outlined and potential targets for inhibition of this pathway are presented.

Curcumin Targeting Non-Coding RNAs in Colorectal Cancer: Therapeutic and Biomarker Implications

Colorectal cancer is one of the most common gastrointestinal malignancies, with high incidence rates, a low rate of early diagnosis, and complex pathogenesis. In recent years, there has been progress made in its diagnosis and treatment methods, but tumor malignant proliferation and metastasis after treatment still seriously affect the survival and prognosis of patients. Therefore, it is an extremely urgent task of current medicine to find new anti-tumor drugs with high efficiency and safety and low toxicity. Curcumin has shown potent anti-tumor and anti-inflammatory effects and is considered a hot spot in the research and development of anti-tumor drugs due to its advantages of precise efficacy, lower toxic side effects, and less drug resistance. Recent studies have revealed that curcumin has anti-tumor effects exerted on the epigenetic regulation of tumor-promoting/tumor-suppressing gene expression through the alteration of expression levels of non-coding RNAs (e.g., lncRNAs, miRNAs, and circRNAs). Herein, we summarize the interaction between curcumin and non-coding RNAs on the occurrence and development of colorectal cancer. The information complied in this review will serve as a scientific and reliable basis and viewpoint for the clinical application of non-coding RNAs in colorectal cancer.

Curcumin and Wnt/β‑catenin signaling in exudative age‑related macular degeneration (Review)

Curcumin is a natural product widely used due to its pharmacological effects. Nevertheless, only a limited number of studies concerning the effects of curcumin on exudative age‑related macular degeneration (AMD) is currently available. Since ophthalmic diseases, including exudative AMD, have a marked impact on public health, the prevention and therapy of ophthalmic disorders remain of increasing concern. Exudative AMD is characterized by choroidal neovascularization (CNV) invading the subretinal space, ultimately enhancing exudation and hemorrhaging. The exudative AMD subtype corresponds to 10 to 15% of cases of macular degeneration; however, the occurrence of this subtype has been reported as the major cause of vision loss and blindness, with the occurrence of CNV being responsible for 80% of the cases with vision loss. In CNV increased expression of VEGF has been observed, stimulated by the overactivation of Wnt/β‑catenin signaling pathway. The stimulation of the Wnt/β‑catenin signaling pathway is responsible for the activation of several cellular mechanisms, simultaneously enhancing inflammation, oxidative stress and angiogenesis in numerous diseases, including ophthalmic disorders. Some studies have previously demonstrated the possible advantage of the use of curcumin for the inhibition of Wnt/β‑catenin signaling. In the present review article, the different mechanisms of curcumin are described concerning its effects on oxidative stress, inflammation and angiogenesis in exudative AMD, by interacting with Wnt/β‑catenin signaling.

The mechanism of the cytotoxic effect of Panax notoginseng extracts on prostate cancer cells

INTRODUCTION

Panax notoginseng (Burkill) F.H. commonly referred to as Sanqi, is a Chinese herb that has long been used to treat various conditions including blood disorders and cardiovascular diseases. While Panax notoginseng has been used as an anti-cancer medicinal herb in recent years, how it achieves this therapeutic effect has not been thoroughly elucidated. The purpose of this study was to reveal more about the mechanism of the cytotoxic effect of Panax notoginseng on prostate cancer (PCa) cells.

METHODS

Ethanol extract of Panax notoginseng root was authenticated using high-performance liquid chromatography (HPLC). The cytotoxic activity of this herb against PCa cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The assessment of cellular metabolic activity demonstrated that Panax notoginseng reduces the viability of LNCaP and 22Rv1 cells in a dose-dependent manner. Annexin-V binding flow cytometry assay showed that Panax notoginseng induces apoptosis in PCa cells. Cell cycle analysis by quantification of DNA content using flow cytometry showed that Panax notoginseng arrests the cell cycle at the G2/M phase in both LNCaP and 22Rv1 cells. Moreover, ELISA demonstrated that Panax notoginseng-treated PCa cells secrete significantly less tumor-promoting cytokine interleukin-4 (IL-4) to the supernatant compared with controls.

CONCLUSIONS

These results provide evidence for the cytotoxic effects of Panax notoginseng on PCa cell lines. This botanical is a promising candidate for the complementary and integrative medicine treatment of PCa and further studies are indicated to determine the anti-cancer mechanism of Panax notoginseng.

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.

Revealing the role of miRNA-489 as a new onco-suppressor factor in different cancers based on pre-clinical and clinical evidence

Recently, microRNAs (miRNAs) have shown to be potential therapeutic, diagnostic and prognostic targets in disease therapy. These endogenous non-coding RNAs contribute to regulation of different cellular events that are necessary for maintaining physiological condition. Dysregulation of miRNAs is correlated with development of various pathological events such as neurological disorders, cardiovascular diseases, and cancer. miRNA-489 is a new emerging miRNA and studies are extensively investigating its role in pathological conditions. Herein, potential function of miRNA-489 as tumor-suppressor in various cancers is described. miRNA-489 is able to sensitize cancer cells into chemotherapy by disrupting molecular pathways involved in cancer growth such as PI3K/Akt, and induction of apoptosis. The PROX1 and SUZ12 as oncogenic pathways, are affected by miRNA-489 in suppressing metastasis of cancer cells. Wnt/β-catenin as an oncogenic factor ensuring growth and malignancy of tumors is inhibited via miRNA-489 function. For enhancing drug sensitivity of tumors, restoring miRNA-489 expression is a promising strategy. The lncRNAs can modulate miRNA-489 expression in tumors and studies about circRNA role in miRNA-489 modulation should be performed. The expression level of miRNA-489 is a diagnostic tool for tumor detection. Besides, down-regulation of miRNA-489 in tumors provides unfavorable prognosis.

Therapeutic Effects of Polyphenols on the Treatment of Colorectal Cancer by Regulating Wnt β-Catenin Signaling Pathway

Colorectal cancer (CRC) is the third most common cause of cancer-related death worldwide in terms of both its rates of incidence and mortality. Due to serious side effects associated with conventional chemotherapeutic treatments, many natural products with fewer adverse side effects have been considered as potential treatment options. In fact, many natural products have widely been used in various phases of clinical trials for CRC, as well as in in vitro and in vivo preclinical studies. Curcumin (CUR) and resveratrol (RES) are classified as natural polyphenolic compounds that have been demonstrated to have anticancer activity against CRC and are associated with minimal side effects. By regulating select target genes involved in several key signaling pathways in CRC, in particular, the Wnt β-catenin signaling cascade, the course of CRC may be positively altered. In the current review, we focused on the therapeutic effects of CUR and RES in CRC as they pertain to modulation of the Wnt β-catenin signaling pathway.

Gallic acid for cancer therapy: Molecular mechanisms and boosting efficacy by nanoscopical delivery

Cancer is the second leading cause of death worldwide. Majority of recent research efforts in the field aim to address why cancer resistance to therapy develops and how to overcome or prevent it. In line with this, novel anti-cancer compounds are desperately needed for chemoresistant cancer cells. Phytochemicals, in view of their pharmacological activities and capacity to target various molecular pathways, are of great interest in the development of therapeutics against cancer. Plant-derived-natural products have poor bioavailability which restricts their anti-tumor activity. Gallic acid (GA) is a phenolic acid exclusively found in natural sources such as gallnut, sumac, tea leaves, and oak bark. In this review, we report on the most recent research related to anti-tumor activities of GA in various cancers with a focus on its underlying molecular mechanisms and cellular pathwaysthat that lead to apoptosis and migration of cancer cells. GA down-regulates the expression of molecular pathways involved in cancer progression such as PI3K/Akt. The co-administration of GA with chemotherapeutic agents shows improvements in suppressing cancer malignancy. Various nano-vehicles such as organic- and inorganic nano-materials have been developed for targeted delivery of GA at the tumor site. Here, we suggest that nano-vehicles improve GA bioavailability and its ability for tumor suppression.

Potential Role of Traditional Chinese Medicines by Wnt/β-Catenin Pathway Compared With Targeted Small Molecules in Colorectal Cancer Therapy

Colorectal cancer (CRC) has become a global public health problem because of its high incidence and mortality rate worldwide. The previous clinical treatment for CRC mainly involves conventional surgery, chemotherapy, and radiotherapy. With the development of tumor molecular targeted therapy, small molecule inhibitors present a great advantage in improving the survival of patients with advanced CRC. However, various side effects and drug resistance induced by chemotherapy are still the major obstacles to improve the clinical benefit. Thus, it is crucial to find new and alternative drugs for CRC treatment. Traditional Chinese medicines (TCMs) have been proved to have low toxicity and multi-target characteristics. In the last few decades, an increasing number of studies have demonstrated that TCMs exhibit strong anticancer effects in both experimental and clinical models and may serve as alternative chemotherapy agents for CRC treatment. Notably, Wnt/β-catenin signaling pathway plays a vital role in the initiation and progression of CRC by modulating the stability of β-catenin in the cytoplasm. Targeting Wnt/β-catenin pathway is a novel direction for developing therapies for CRC. In this review, we outlined the anti-tumor effects of small molecular inhibitors on CRC through Wnt/β-catenin pathway. More importantly, we focused on the potential role of TCMs against tumors by targeting Wnt/β-catenin signaling at different stages of CRC, including precancerous lesions, early stage of CRC and advanced CRC. Furthermore, we also discussed perspectives to develop potential new drugs from TCMs via Wnt/β-catenin pathway for the treatment of CRC.

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

Progress in Natural Compounds/siRNA Co-delivery Employing Nanovehicles for Cancer Therapy

Chemotherapy using natural compounds, such as resveratrol, curcumin, paclitaxel, docetaxel, etoposide, doxorubicin, and camptothecin, is of importance in cancer therapy because of the outstanding therapeutic activity and multitargeting capability of these compounds. However, poor solubility and bioavailability of natural compounds have limited their efficacy in cancer therapy. To circumvent this hurdle, nanocarriers have been designed to improve the antitumor activity of the aforementioned compounds. Nevertheless, cancer treatment is still a challenge, demanding novel strategies. It is well-known that a combination of natural products and gene therapy is advantageous over monotherapy. Delivery of multiple therapeutic agents/small interfering RNA (siRNA) as a potent gene-editing tool in cancer therapy can maximize the synergistic effects against tumor cells. In the present review, co-delivery of natural compounds/siRNA using nanovehicles are highlighted to provide a backdrop for future research.

Angiogenesis-Related Functions of Wnt Signaling in Colorectal Carcinogenesis

Simple Summary

Angiogenesis belongs to the most clinical characteristics of colorectal cancer (CRC) and is strongly linked to the activation of Wnt/β-catenin signaling. The most prominent factors stimulating constitutive activation of this pathway, and in consequence angiogenesis, are genetic alterations (mainly mutations) concerning APC and the β-catenin encoding gene (CTNNB1), detected in a large majority of CRC patients. Wnt/β-catenin signaling is involved in the basic types of vascularization (sprouting and nonsprouting angiogenesis), vasculogenic mimicry as well as the formation of mosaic vessels. The number of known Wnt/β-catenin signaling components and other pathways interacting with Wnt signaling, regulating angiogenesis, and enabling CRC progression continuously increases. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

Abstract

Aberrant activation of the Wnt/Fzd/β-catenin signaling pathway is one of the major molecular mechanisms of colorectal cancer (CRC) development and progression. On the other hand, one of the most common clinical CRC characteristics include high levels of angiogenesis, which is a key event in cancer cell dissemination and distant metastasis. The canonical Wnt/β-catenin downstream signaling regulates the most important pro-angiogenic molecules including vascular endothelial growth factor (VEGF) family members, matrix metalloproteinases (MMPs), and chemokines. Furthermore, mutations of the β-catenin gene associated with nuclear localization of the protein have been mainly detected in microsatellite unstable CRC. Elevated nuclear β-catenin increases the expression of many genes involved in tumor angiogenesis. Factors regulating angiogenesis with the participation of Wnt/β-catenin signaling include different groups of biologically active molecules including Wnt pathway components (e.g., Wnt2, DKK, BCL9 proteins), and non-Wnt pathway factors (e.g., chemoattractant cytokines, enzymatic proteins, and bioactive compounds of plants). Several lines of evidence argue for the use of angiogenesis inhibition in the treatment of CRC. In the context of this paper, components of the Wnt pathway are among the most promising targets for CRC therapy. This review summarizes the current knowledge about the role of the Wnt/Fzd/β-catenin signaling pathway in the process of CRC angiogenesis, aiming to improve the understanding of the mechanisms of metastasis as well as improvements in the management of this cancer.

Reduced Caudal Type Homeobox 2 (CDX2) Promoter Methylation Is Associated with Curcumin's Suppressive Effects on Epithelial-Mesenchymal Transition in Colorectal Cancer Cells

Background

Curcumin is a component of Curcuma longa with various biological activities. The present study aimed to investigate curcumin’s inhibitory effects on epithelial-mesenchymal transition (EMT) in colorectal cancer (CRC) cells and possible mechanisms of action underlying these effects.

Material/Methods

Human SW480 CRC cells were incubated with curcumin at 0.1, 0.2, 0.4, 0.8, or 1.6 μmol/L. The 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay was utilized to evaluate cell viabilities. The DNA methylation levels of the cdx2 promoter were assessed by bisulfite sequencing polymerase chain reaction (BSP). Real-time quantitative PCR was used to measure the mRNA expression levels. Protein expression levels were evaluated with western blotting. Immunofluorescence staining was used to evaluate the nuclear translocation of β-catenin.

Results

Curcumin concentrations of 0.1, 0.2, and 0.4 μmol/L showed no significant association with the viability of SW480 cells, which were chosen for subsequent experiments. Curcumin incubation significantly downregulated expression levels of DNA methyltransferase1 (DNMT1), DNMT3a, and the methylation levels of the cdx2 promoter in a concentration-dependent manner. The expression levels of N-cadherin, Vimentin, Wnt3a, Snail1, and Twist, as well as the nuclear translocation levels of β-catenin, were reduced in a curcumin concentration-dependent manner. The expression levels of E-cadherin were increased in a curcumin concentration-dependent manner.

Conclusions

Curcumin negatively regulated transcription factors promoting EMT in CRC cells by decreasing cdx2 promoter DNA methylation and consequently suppressing the CDX2/Wnt3a/β-catenin signaling pathway.

Curcumin Suppresses Apoptosis and Inflammation in Hypoxia/Reperfusion-Exposed Neurons via Wnt Signaling Pathway

BACKGROUND Cerebral ischemia/reperfusion (I/R) injury contributes to mortality and morbidity in preterm infants. Curcumin has been shown to exert neuro-protective effects in the central nervous system (CNS). The aim of this study was to investigate the neuro-protective activity of curcumin and the possible underlying molecular mechanisms. MATERIAL AND METHODS A hypoxia/reoxygenation (H/R) protocol was used to simulate I/R injury in vitro. Isolated neonatal neurons were pre-treated with curcumin at serially diluted concentrations and exposed to H/R injury. Cell viability and apoptosis were assessed by MTT and flow cytometry, respectively. Contents of TNFa and IL6 in supernatant of cell culture medium were detected by ELISA. Protein expression, phosphorylation, and nuclear translocation levels were studied by Western blotting. RESULTS H/R reduced cell viability and increased apoptosis of neurons. H/R significantly increased Wnt5a expression, JNK1 phosphorylation, and NF-kappaB nuclear translocation. Moreover, expression levels of cleaved caspase3, TNFalpha, and IL6 were elevated in H/R-exposed neurons. Curcumin pre-treatment significantly increased cell viability and inhibited apoptosis of neurons exposed to H/R, in a concentration-dependent manner. Moreover, curcumin pre-treatment significantly decreased expression levels of Wnt5a, IL6, TNFalpha, and phosphorylation level of JNK1, as well as the nuclear translocation level of NF-kappaB in H/R-exposed neurons, in a concentration-dependent manner. CONCLUSIONS Curcumin exerted neuro-protective effects against H/R-induced neuron apoptosis and inflammation by inhibiting activation of the Wnt/JNK1 signaling pathway.