Cyclin D1 degradation and p21 induction contribute to growth inhibition of colorectal cancer cells induced by epigallocatechin-3-gallate

Huangqin tang alleviates colitis-associated colorectal cancer via amino acids homeostasisand PI3K/AKT/mtor pathway modulation

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqin Tang (HQT), a traditional Chinese medicine formula, is commonly used in clinical practice for the treatment of inflammatory bowel diseases. It has been reported that HQT exerts antitumor effects on colitis-associated colorectal cancer (CAC). However, the mechanism by which HQT interferes with the inflammation-to-cancer transformation remains unclear.

AIMS OF THE STUDY

The purpose of this study was to dynamically evaluate the efficacy of HQT in alleviating or delaying CAC and to reveal the underlying mechanism.

METHODS

We established a mouse model of CAC using azoxymethane combined with 1.5% dextran sodium sulphate. The efficacy of HQT was evaluated based on pathological sections and serum biochemical indices. Subsequently, amino acids (AAs) metabolism analyses were performed using ultra-performance liquid chromatography-tandem mass spectrometry, and the phosphatidylinositol 3 kinase/protein kinase B/mechanistic target of rapamycin (PI3K/AKT/mTOR) pathway was detected by western blotting.

RESULTS

The data demonstrated that HQT could alleviate the development of CAC in the animal model. HQT effectively reduced the inflammatory response, particularly interleukin-6 (IL-6), in the inflammation induction stage, as well as in the stages of proliferation initiation and tumorigenesis. During the proliferation initiation and tumorigenesis stages, immunohistochemistry staining showed that the expression of the proliferation marker Ki67 was reduced, while apoptosis was increased in the HQT group. Accordingly, HQT substantially decreased the levels of specific AAs in the colon with CAC, including glutamic acid, glutamine, arginine, and isoleucine. Furthermore, HQT significantly inhibited the activated PI3K/AKT/mTOR pathway, which may contribute to suppression of cell proliferation and enhancement of apoptosis.

CONCLUSION

HQT is effective in alleviating and delaying the colon "inflammation-to-cancer". The mechanism of action may involve HQT maintained AAs metabolism homeostasis and regulated PI3K/AKT/mTOR pathway, so as to maintain the balance between proliferation and apoptosis, and then interfere in the occurrence and development of CAC.

RNA biomarkers in cancer therapeutics: The promise of personalized oncology

Cancer therapy is a rapidly evolving and constantly expanding field. Current approaches include surgery, conventional chemotherapy and novel biologic agents as in immunotherapy, that together compose a wide armamentarium. The plethora of choices can, however, be clinically challenging in prescribing the most suitable treatment for any given patient. Fortunately, biomarkers can greatly facilitate the most appropriate selection. In recent years, RNA-based biomarkers have proven most promising. These molecules that range from small noncoding RNAs to protein coding gene transcripts can be valuable in cancer management and especially in cancer therapeutics. Compared to their DNA counterparts which are stable throughout treatment, RNA-biomarkers are dynamic. This allows prediction of success prior to treatment start and can identify alterations in expression that could reflect response. Moreover, improved nucleic acid technology allows RNA to be extracted from practically every biofluid/matrix and evaluated with exceedingly high analytic sensitivity. In addition, samples are largely obtained by minimally invasive procedures and as such can be used serially to assess treatment response real-time. This chapter provides the reader insight on currently known RNA biomarkers, the latest research employing Artificial Intelligence in the identification of such molecules and in clinical decisions driving forward the era of personalized oncology.

Antitumor Effect of Epigallocatechin Gallate and Vincristine in Mice with L5178Y Lymphoma

The main objective of research into new therapies is the search for more efficacy and fewer toxic effects in cancer treatments. On one hand, vincristine (VCR) is a chemotherapeutic used in different kinds of tumors. On the other hand, epigallocatechin gallate (EGCG) is a green tea metabolite that has shown an antineoplastic effect in diverse investigations, so the objective of this work is to evaluate the antitumor effects of the EGCG/VCR combination on tumor volume and survival. To achieve this objective, the solid model of lymphoma L5178Y was used in BALB/c mice with different doses of VCR, EGCG, and their combination allowed tumor growth and survival time recording. After tumor collection, measurements, and immunohistochemistry for p53, Bcl2, and Cyclin D1 were performed. The results showed that the EGCG/vincristine combination had a greater antitumor effect than those effects of vincristine and EGCG. It can be attributed to the fact that the greatest inhibition of Bcl2 was present in gathering of EGCG harvest with vincristine. Therefore, the combination of EGCG with vincristine has a better antineoplastic effect by inhibiting tumor development and increasing survival on both substances independently.

Morin Sensitizes MDA-MB-231 Triple-Negative Breast Cancer Cells to Doxorubicin Cytotoxicity by Suppressing FOXM1 and Attenuating EGFR/STAT3 Signaling Pathways

Considerable emphasis is being placed on combinatorial chemotherapeutic/natural treatments for breast cancer. This study reveals the synergistic anti-tumor activity of morin and Doxorubicin (Dox) co-treatment on MDA-MB-231 triple-negative breast cancer (TNBC) cell proliferation. Morin/Dox treatment promoted Dox uptake and induced DNA damage and formation of nuclear foci of p-H2A.X. Furthermore, DNA repair proteins, RAD51 and survivin, and cell cycle proteins, cyclin B1 and forkhead Box M1 (FOXM1), were induced by Dox alone but attenuated by morin/Dox co-treatment. In addition, Annexin V/7-AAD analysis revealed that necrotic cell death after co-treatment and apoptotic cell death by Dox alone were associated with the induction of cleaved PARP and caspase-7 without Bcl-2 family involvement. FOXM1 inhibition by thiostrepton showed that co-treatment caused FOXM1-mediated cell death. Furthermore, co-treatment downregulated the phosphorylation of EGFR and STAT3. Flow cytometry showed that the accumulation of cells in the G2/M and S phases might be linked to cellular Dox uptake, p21 upregulation, and cyclin D1 downregulation. Taken together, our study shows that the anti-tumor effect of morin/Dox co-treatment is due to the suppression of FOXM1 and attenuation of EGFR/STAT3 signaling pathways in MDA-MB-231 TNBC cells, which suggests that morin offers a means of improving therapeutic efficacy in TNBC patients.

In vitro anti-gastrointestinal cancer activity of Toxocara canis-derived peptide: Analyzing the expression level of factors related to cell proliferation and tumor growth

Background: Recently, a hypothesis about the negative relationship between cancers and parasites has been proposed and investigated; some parasitic worms and their products can affect the cancer cell proliferation. Due to the potential anti-cancer effect of helminthic parasites, in the present study, the excretory–secretory protein of Toxocara canis (T. canis) parasite was used to evaluate the possible anti-cancer properties and their effect on gastrointestinal and liver cancer cell proliferation-related genes in laboratory conditions.

Methods and materials: The selected synthesized peptide fraction from the T. canis excretory–secretory Troponin protein peptide (ES TPP) was exposed at 32, 64, 128, and 256 μg/ml concentrations to three gastrointestinal cancer cell lines AGS, HT-29, and Caco 2, as well as HDF cells as normal cell lines. We used the MTT assay to evaluate cellular changes and cell viability (CV). Variations in gene (Bcl-2, APAF1, ZEB1, VEGF, cyclin-D1, and caspase-3) expression were analyzed by real-time RT-PCR.

Results: After 24 h of exposure to pept1ides and cell lines, a decrease in CV was observed at a concentration of 64 μg/ml and compared to the control group. Then, after 48 h, a significant decrease in the CV of Caco 2 cells was observed at a concentration of 32 μg/ml; in the other cancer cell lines, concentrations above 32 μg/ml were effective. The peptide was able to significantly alter the expression of the studied genes at a concentration of 100 μg/ml.

Conclusion: Although the studied peptide at high concentrations could have a statistically significant effect on cancer cells, it is still far from the standard drug and can be optimized and promising in future studies.

Inhibition and potential treatment of colorectal cancer by natural compounds via various signaling pathways

Colorectal cancer (CRC) is a common type of malignant digestive tract tumor with a high incidence rate worldwide. Currently, the clinical treatment of CRC predominantly include surgical resection, postoperative chemotherapy, and radiotherapy. However, these treatments contain severe limitations such as drug side effects, the risk of recurrence and drug resistance. Some natural compounds found in plants, fungi, marine animals, and bacteria have been shown to inhibit the occurrence and development of CRC. Although the explicit molecular mechanisms underlying the therapeutic effects of these compounds on CRC are not clear, classical signaling transduction pathways such as NF-kB and Wnt/β-catenin are extensively regulated. In this review, we have summarized the specific mechanisms regulating the inhibition and development of CRC by various types of natural compounds through nine signaling pathways, and explored the potential therapeutic values of these natural compounds in the clinical treatment of CRC.

Theabrownin Alleviates Colorectal Tumorigenesis in Murine AOM/DSS Model via PI3K/Akt/mTOR Pathway Suppression and Gut Microbiota Modulation

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide, yet therapeutic options for CRC often exhibit strong side effects which cause patients’ well-being to deteriorate. Theabrownin (TB), an antioxidant from Pu-erh tea, has previously been reported to have antitumor effects on non-small-cell lung cancer, osteosarcoma, hepatocellular carcinoma, gliomas, and melanoma. However, the potential antitumor effect of TB on CRC has not previously been investigated in vivo. The present study therefore aimed to investigate the antitumor effect of TB on CRC and the underlying mechanisms. Azoxymethane (AOM)/dextran sodium sulphate (DSS) was used to establish CRC tumorigenesis in a wild type mice model. TB was found to significantly reduce the total tumor count and improve crypt length and fibrosis of the colon when compared to the AOM/DSS group. Immunohistochemistry staining shows that the expression of the proliferation marker, Ki67 was reduced, while cleaved caspase 3 was increased in the TB group. Furthermore, TB significantly reduced phosphorylation of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), and the downstream mechanistic target of rapamycin (mTOR)and cyclin D1 protein expression, which might contribute to cell proliferation suppression and apoptosis enhancement. The 16s rRNA sequencing revealed that TB significantly modulated the gut microbiota composition in AOM/DSS mice. TB increased the abundance of short chain fatty acid as well as SCFA-producing Prevotellaceae and Alloprevotella, and it decreased CRC-related Bacteroidceae and Bacteroides. Taken together, our results suggest that TB could inhibit tumor formation and potentially be a promising candidate for CRC treatment.

Periplocymarin Induced Colorectal Cancer Cells Apoptosis Via Impairing PI3K/AKT Pathway

Colorectal cancer (CRC) is one of the most common cancers worldwide, and approximately one-third of CRC patients present with metastatic disease. Periplocymarin (PPM), a cardiac glycoside isolated from Periploca sepium, is a latent anticancer compound. The purpose of this study was to explore the effect of PPM on CRC cells. CRC cells were treated with PPM and cell viability was evaluated by CCK-8 assay. Flow cytometry and TUNEL staining were performed to assess cell cycle and apoptosis. Quantitative proteomics has been used to check the proteins differentially expressed by using tandem mass tag (TMT) labeling and liquid chromatography–tandem mass spectrometry. Bioinformatic analysis was undertaken to identify the biological processes that these differentially expressed proteins are involved in. Gene expression was analyzed by western blotting. The effect of PPM in vivo was primarily checked in a subcutaneous xenograft mouse model of CRC, and the gene expression of tumor was checked by histochemistry staining. PPM could inhibit the proliferation of CRC cells in a dose-dependent manner, induce cell apoptosis and promote G0/G1 cell cycle arrest. A total of 539 proteins were identified differentially expressed following PPM treatment, where among those there were 286 genes upregulated and 293 downregulated. PPM treatment caused a pro-apoptosis gene expression profile both in vivo and in vitro, and impaired PI3K/AKT signaling pathway might be involved. In addition, PPM treatment caused less detrimental effects on blood cell, hepatic and renal function in mice, and the anti-cancer effect was found exaggerated by PPM+5-FU combination treatment. PPM may perform anti-CRC effects by promoting cell apoptosis and this might be achieved by targeting PI3K/AKT pathway. PPM might be a safe and promising anti-cancer drug that needs to be further studied.

Plant Natural Products: Promising Resources for Cancer Chemoprevention

Cancer is a major factor threatening human health and life safety, and there is a lack of safe and effective therapeutic drugs. Intervention and prevention in premalignant process are effective ways to reverse carcinogenesis and prevent cancer from occurring. Plant natural products are rich in sources and are a promising source for cancer chemoprevention. This article reviews the chemopreventive effects of natural products, especially focused on polyphenols, flavonoids, monoterpene and triterpenoids, sulfur compounds, and cellulose. Meanwhile, the main mechanisms include induction of apoptosis, antiproliferation and inhibition of metastasis are briefly summarized. In conclusion, this article provides evidence for natural products remaining a prominent source of cancer chemoprevention.

Anti-proliferative activity of A. Oxyphylla and its bioactive constituent nootkatone in colorectal cancer cells

Background

A. oxyphylla extract is known to possess a wide range of pharmacological activites. However, the molecular mechanism of A. oxyphylla and its bioactive compound nootkatone in colorectal cancer is unknown.

Methods

Our study aims to examine the role of A. oxyphylla and its bioactive compound nootkatone, in tumor suppression using several in vitro assays.

Results

Both A. oxyphylla extract and nootkatone exhibited antiproliferative activity in colorectal cancer cells. A. oxyphylla displayed antioxidant activity in colorectal cancer cells, likely mediated via induction of HO-1. Furthermore, expression of pro-apoptotic protein NAG-1 and cell proliferative protein cyclin D1 were increased and decreased respectively in the presence of A. oxyphylla. When examined for anticancer activity, nootkatone treatment resulted in the reduction of colony and spheroid formation. Correspondingly, nootkatone also led to increased NAG-1 expression and decreased cyclin D1 expression. The mechanism by which nootkatone suppresses cyclin D1 involves protein level regulation, whereas nootkatone increases NAG-1 expression at the transcriptional level. In addition to having PPARγ binding activity, nootkatone also increases EGR-1 expression which ultimately results in enhanced NAG-1 promoter activity.

Conclusion

In summary, our findings suggest that nootkatone is an anti-tumorigenic compound harboring antiproliferative and pro-apoptotic activity.

Epigallocatechin gallate induces chemopreventive effects on rats with diethylnitrosamine‑induced liver cancer via inhibition of cell division cycle 25A

Epigallocatechin gallate (EGCG), the most active monomer in green tea (GT), has demonstrated potential therapeutic and preventive effects on various tumors, including liver cancer. However, the anticancer mechanisms of EGCG in liver cancer remain to be elucidated. The abnormal expression of cell division cycle 25A (CDC25A) has been identified in liver cancer and is closely associated with malignancy and poor prognosis in patients with hepatocellular carcinoma (HCC). The present study used human hepatoma cell lines and rats with diethylnitrosamine (DEN)-induced HCC as models to investigate the association between the effect of EGCG on liver cancer and regulation of the p21waf1/Cip1/CDC25A axis. The results demonstrated that EGCG can inhibit the proliferation of HepG2 and Huh7 cells, reduce the expression of CDC25A and increase the expression of p21waf1/Cip1 in HepG2. In vivo, HCC was induced by DEN in Sprague-Dawley rats. EGCG significantly reduced tumor volume and improved the survival rates of rats with HCC. The expression levels of CDC25A mRNA and protein in liver tissues and the level of serum γ glutamyl transpeptidase in rats treated with EGCG were significantly decreased, while p21waf1/Cip1 mRNA and protein expression levels were increased compared with the HCC group, in the process of DEN-induced HCC. No significant difference in the chemopreventive effects on liver cancer was observed between GT extract and EGCG under an EGCG equivalence condition. Thus, EGCG can suppress human hepatoma cell proliferation and prolong the survival of rats with HCC, and the potential mechanism may be involved in EGCG-induced upregulation of p21waf1/Cip1 and downregulation of CDC25A.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

Numerous natural products originated from Chinese herbal medicine exhibit anti-cancer activities, including anti-proliferative, pro-apoptotic, anti-metastatic, anti-angiogenic effects, as well as regulate autophagy, reverse multidrug resistance, balance immunity, and enhance chemotherapy in vitro and in vivo. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2011) on the key compounds with anti-cancer effects derived from Chinese herbal medicine (curcumin, epigallocatechin gallate, berberine, artemisinin, ginsenoside Rg3, ursolic acid, silibinin, emodin, triptolide, cucurbitacin B, tanshinone I, oridonin, shikonin, gambogic acid, artesunate, wogonin, β-elemene, and cepharanthine) in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we focused on their recently discovered and/or investigated pharmacological effects, novel mechanism of action, relevant clinical studies, and their innovative applications in combined therapy and immunomodulation. In addition, the present review has extended to describe other promising compounds including dihydroartemisinin, ginsenoside Rh2, compound K, cucurbitacins D, E, I, tanshinone IIA and cryptotanshinone in view of their potentials in cancer therapy. Up to now, the evidence about the immunomodulatory effects and clinical trials of natural anti-cancer compounds from Chinese herbal medicine is very limited, and further research is needed to monitor their immunoregulatory effects and explore their mechanisms of action as modulators of immune checkpoints.

Nitro aspirin (NCX4040) induces apoptosis in PC3 metastatic prostate cancer cells via hydrogen peroxide (H2O2)-mediated oxidative stress

Non-steroidal anti-inflammatory drugs (NSAID) have shown promise as anticancer agents by inducing cell death apart from their antipyretic, anti-inflammatory and anti-thrombogenic effects. In our current study, we investigated the oxidative stress mediated cell death mechanism of a NSAID derivative NCX4040 (a nitric oxide (NO) releasing form of aspirin) in castration-resistant prostate cancer (CRPC) PC3 cell line. Our data revealed that NCX4040 is more potent than its parent compound aspirin or NO releasing compound DETA NONOate. NCX4040 significantly induced hydrogen peroxide formation with ensuing oxidative stress and mitochondrial depolarization resulting in lipid peroxidation, cell cycle arrest, inhibition of colony growth and induction of apoptosis in PC3 cells. Moreover, NCX4040 inhibited migration potential of PC3 cells by depolymerizing F-actin and promoting anoikis. Interestingly, elevated levels of NADPH oxidase 1 (NOX1), superoxide dismutase (SOD) 1 and 2 were observed upon NCX4040 treatment. However, down regulation of anti-apoptotic markers B-cell lymphoma 2 (Bcl2) and anti-oxidant thioredoxin reductase 1 (TXNRD1) expression were observed. In addition, NCX4040 down regulated cyclin D1 expression in PC3 cells further supporting the anticancer effect of NCX4040. Western blot analysis revealed that significant down regulation of key anti-apoptotic markers such as cellular inhibitor of apoptosis protein-1 (cIAP1), X-linked inhibitor of apoptosis (XIAP), survivin, and Cellular-Myc (c-Myc). On the other hand, NCX4040-treated cells showed upregulation of phosho histone H2AX (pH2AX), cleaved caspase3 and cleaved Poly [ADP-ribose] polymerase 1 (PARP1). Taken together, our data demonstrate that NCX4040 treatment enhances free radical formation which in turn induces oxidative stress leading to mitochondrial mediated cell death in metastatic PC3 cells.

Advances in the Antagonism of Epigallocatechin-3-gallate in the Treatment of Digestive Tract Tumors

Due to changes in the dietary structure of individuals, the incidence of digestive tract tumors has increased significantly in recent years, causing a serious threat to the life and health of patients. This has in turn led to an increase in cancer prevention research. Many studies have shown that epigallocatechin-3-gallate (EGCG), an active ingredient in green tea, is in direct contact with the digestive tract upon ingestion, which allows it to elicit a significant antagonizing effect on digestive tract tumors. The main results of EGCG treatment include the prevention of tumor development in the digestive tract and the induction of cell cycle arrest and apoptosis. EGCG can be orally administered, is safe, and combats other resistances. The synergistic use of cancer drugs can promote the efficacy and reduce the anti-allergic properties of drugs, and is thus, favored in medical research. EGCG, however, currently possesses several shortcomings such as poor stability and low bioavailability, and its clinical application prospects need further development. In this paper, we have systematically summarized the research progress on the ability of EGCG to antagonize the activity and mechanism of action of digestive tract tumors, to achieve prevention, alleviation, delay, and even treat human gastrointestinal tract tumors via exogenous dietary EGCG supplementation or the development of new drugs containing EGCG.

Anti-proliferative and anti-apoptotic potential effects of epigallocatechin-3-gallate and/or metformin on hepatocellular carcinoma cells: in vitro study

The effects of epigallocatechin-3-gallate (EGCG) and metformin single treatment have been tested against hepatocellular carcinoma (HCC). This study aimed to assess the combination effects of EGCG and metformin on proliferation and apoptosis of HepG2cells and identified new potential molecular targets. The effect of EGCG and metformin against cell proliferation in HepG2 was determined using MTT assay. Reverse transcription polymerase chain reaction was applied to examine the gene expression of cyclin D1, lncRNA-AF085935, caspase-3, survivin and VEGF. The level of protein expression of glypican-3 was assessed by western blot. In HepG2 cells, EGCG and metformin combination treatment exhibited high significant effect against tumor proliferation. It significantly reduced cyclin D1, lncRNA-AF085935, glypican-3 and promoted apoptosis through increasing caspase3 and decreasing survivin compared to control cells. Moreover, EGCG and metformin treated cells showed decreased expression levels of VEGF. Our study provided new insights of the anticarcinogenic effects of EGCG and metformin on HCC through their effects on glypican-3 and lncRNA-AF085935.

Epigallocatechin-3-Gallate Promotes the Growth of Mink Hair Follicles Through Sonic Hedgehog and Protein Kinase B Signaling Pathways

Background: Hair follicles play an essential role in the growth of hair. Epigallocatechin-3-gallate (EGCG), a catechin polyphenol in green tea, has various bioactivities. The present study aims to evaluate the effect of EGCG on the growth of mink hair follicles and investigate the possible molecular mechanisms.

Methods: The length of hair follicles was recorded up to 6 days in presence of 0.1–5 μM EGCG. Primary dermal papilla cells (DPCs) and outer root sheath cells (ORSCs) were treated with 0.25–4 μM EGCG, and their growth was evaluated by MTT assay and cell cycle detection. The levels of key molecules in sonic hedgehog (Shh) and protein kinase B (AKT) signaling pathways were further assessed by quantitative real-time PCR, western blot and immunofluorescence. To determine the involvement of Shh and AKT pathways in EGCG-mediated growth-promotion of ORSCs and DPCs, Shh pathway inhibitors cyclopamine and GANT61 or AKT pathway inhibitor LY294002 were employed, and then cell proliferation and cell cycle were analyzed.

Results: Data from ex vivo culture showed that, in presence of 0.5–2.5 μM EGCG, the growth of mink hair follicles was promoted. In vitro, the proliferation of DPCs and ORSCs was enhanced by 0.5–4 μM EGCG treatment. More cells entered S phase upon treatment of EGCG, accompanied with upregulation of cyclin D1 and cyclin E1. Furthermore, when exposed to EGCG, the Shh and AKT signaling pathways were activated in both hair follicles and primary DPCs and ORSCs. Inhibiting either of these two pathways partly reversed the effect of EGCG on proliferation and cell cycle of DPCs and ORSCs.

Conclusion: EGCG promotes the growth of mink hair follicles at concentrations of 0.5–2.5 μM. This growth-promoting effect of EGCG may be associated with the increased proliferation of DPCs and ORSCs through activating Shh and AKT signaling pathways.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

The cytotoxic mechanism of epigallocatechin gallate on proliferative HaCaT keratinocytes

BACKGROUND

Epigallocatechin gallate (EGCG) is the major ingredient of sinecatechins ointment, approved for the treatment of external genital and perianal warts. However, the molecular mechanism for EGCG's effect on warts resulting from the human papillomavirus (HPV) infection of keratinocytes is not well understood. HPV may survive in proliferative keratinocytes and may be involved in cell cycle regulation and progression. The objective of this study was to investigate the mechanism underlying EGCG's treatment on external genital warts of HPV infection through the cultured keratinocyte cells from the HaCaT cell line.

METHODS

MTT and flow cytometry assays were used to measure cell viability and the cell cycle profile, with and without EGCG treatment, for HaCaT keratinocyte cells cultured in a calcium-free medium and 1.8 mM calcium which induced proliferative and differentiated keratinocytes, respectively, for 24 h. The expression levels of cytotoxic proteins and factors were evaluated with the RT-PCR and western blotting analysis.

RESULTS

EGCG influenced the proliferation stage but not the differentiation stage of keratinocytes. We suggest that apoptosis and autophagy might be the possible mechanism for the EGCG's effect on the proliferative HaCaT cells. Furthermore, we found that EGCG reduced the protein levels of cyclin D1 and Zac1 (a zinc-finger protein which regulates apoptosis and cell cycle arrest 1) dose-dependently in proliferative as compared to differentiated keratinocytes. It also induced the expression of p21 and DEC1 (differentiated embryo-chondrocyte expressed gene 1), and promoted G1 arrest of cell cycle in proliferative keratinocytes.

CONCLUSIONS

These results help clarify the mechanisms of EGCG treatment of HPV-infected keratinocytes and may contribute to new targets, such as Zac1 and DEC1 for external genital and perianal warts.

Absorption, metabolism, anti-cancer effect and molecular targets of epigallocatechin gallate (EGCG): An updated review

Green tea is one of the most popular beverages in the world, especially in Asian countries. Consumption of green tea has been demonstrated to possess many health benefits, which mainly attributed to the main bioactive compound epigallocatechin gallate (EGCG), a flavone-3-ol polyphenol, in green tea. EGCG is mainly absorbed in the intestine, and gut microbiota play a critical role in its metabolism prior to absorption. EGCG exhibits versatile bioactivities, with its anti-cancer effect most attracting due to the cancer preventive effect of green tea consumption, and a great number of studies intensively investigated its anti-cancer effect. In this review, we therefore, first stated the absorption and metabolism process of EGCG, and then summarized its anti-cancer effect in vitro and in vivo, including its manifold anti-cancer actions and mechanisms, especially its anti-cancer stem cell effect, and next highlighted its various molecular targets involved in cancer inhibition. Finally, the anti-cancer effect of EGCG analogs and nanoparticles, as well as the potential cancer promoting effect of EGCG were also discussed. Understanding of the absorption, metabolism, anti-cancer effect and molecular targets of EGCG can be of importance to better utilize it as a chemopreventive and chemotherapeutic agent.

3,3'-diindolylmethane downregulates cyclin D1 through triggering endoplasmic reticulum stress in colorectal cancer cells

As a major in vivo condensation product of indole-3-carbinol, which is mostly present in cruciferous vegetables, 3,3'-diindolylmethane (DIM) has been previously reported with anti-proliferative action in different types of cancer by our group and others. To further elucidate these underlying mechanisms, we examined the effect of DIM on cyclin D1, which was aberrantly overexpressed in various cancer cells and tumors. Herein, we found that DIM downregulated cyclin D1 expression in colorectal cancer cells (CRC), which was independent of PPARγ expression and protease activity. Furthermore, DIM did not affect cyclin D1 mRNA expression, suggesting DIM modulated cyclin D1 expression at the translational level. Subsequently, blocking eIF2α phosphorylation resulted from endoplasmic reticulum (ER) stress restored cyclin D1 in the presence of DIM. Thus, the present study demonstrates that DIM downregulates cyclin D1 through triggering ER stress in human colorectal cancer cells.

Berry anthocyanins reduce proliferation of human colorectal carcinoma cells by inducing caspase-3 activation and p21 upregulation

Colorectal cancer is the fourth most common type of cancer worldwide, and adenocarcinoma cells that form the majority of colorectal tumors are markedly resistant to antineoplastic agents. Epidemiological studies have demonstrated that consumption of fruits and vegetables that are rich in polyphenols, is linked to reduced risk of colorectal cancer. In the present study, the effect of a standardized anthocyanin (ACN)‑rich extract on proliferation, apoptosis and cell cycle in the Caco-2 human colorectal cancer cell line was evaluated by trypan blue and clonogenic assays and western blot analysis of cleaved caspase‑3 and p21Waf/Cif1. The results of the current study demonstrated that the ACN extract markedly decreased Caco‑2 cell proliferation, induced apoptosis by activating caspase‑3 cleavage, and upregulated cyclin‑dependent kinase inhibitor 1 (p21Waf/Cif1) expression in a dose dependent manner. Furthermore, ACN extract was able to produce a dose‑dependent increase of intracellular reactive oxygen species (ROS) in Caco‑2 cells, together with a light increase of the cell total antioxidant status. In conclusion, the present study demonstrated that a standardized berry anthocyanin rich extract inhibited proliferation of Caco‑2 cells by promoting ROS accumulation, inducing caspase‑3 activation, and upregulating the expression of p21Waf/Cif1.

Damnacanthal and its nanoformulation exhibit anti-cancer activity via cyclin D1 down-regulation

AIMS

Damnacanthal is an anthraquinone isolated from the root of Morinda citrifolia L. (noni), and it exhibits many pharmacological properties, including anti-cancer activity. Damnacanthal targets several signal transduction proteins related to cell growth inhibition or apoptosis. However, the molecular mechanisms by which damnacanthal affects cell cycle regulation have not been elucidated in detail.

MAIN METHODS

Cyclin D1 is an important regulatory protein in cell cycle progression and is overexpressed in many cancer cells. In this study, we investigated the molecular mechanism of damnacanthal on cyclin D1 expression.

KEY FINDINGS

We found that damnacanthal inhibited growth of several cancer cell lines (HCT-116, HT-29, MCF-7 and PC-3) in a dose- and time-dependent manner with a decrease in cyclin D1 protein expression. Damnacanthal did not change mRNA of cyclin D1; rather it suppressed cyclin D1 expression at the post-translational level. Subsequent experiments with several mutant cyclin D1 constructs suggest that the lysine sites of cyclin D1 play a pivotal role in damnacanthal-mediated cyclin D1 degradation. Furthermore, damnacanthal was encapsulated in self-assembled chitosan nanoparticles to improve both physicochemical and biological activities.

SIGNIFICANCE

Our results suggest that encapsulated damnacanthal exhibits better activity in cell growth inhibition, compared to non-encapsulated damnacanthal. Thus, damnacanthal has potential to be a candidate for the development of chemoprevention or therapeutic agents for cancers.

Anti-inflammatory activity of mushroom-derived hispidin through blocking of NF-κB activation

BACKGROUND

Hispidin, a polyphenol compound mainly derived from the valuable medicinal mushroom Phellinus species, has been found to possess distinct biological effects. However, the anti-inflammatory potential of hispidin still remains uncharacterized.

RESULTS

In this study, the effects of hispidin on activation of nuclear factor kappa B (NF-κB) and the subsequent production of inducible nitric oxide synthase (iNOS) were determined in the lipopolysaccharide (LPS)-induced macrophage RAW 264.7 cells. Our data indicated that hispidin inhibits transcriptional activity of NF-κB in a dose-dependent manner. Hispidin also attenuated LPS-induced NF-κB nuclear translocation and associated inhibitor of kappa B (IκB-α) degradation. Furthermore, hispidin deceased iNOS protein expression and the generation of reactive oxygen species (ROS) in the LPS-induced cells, but did not affect phosphorylation of mitogen-activated protein kinases.

CONCLUSION

These findings suggest that hispidin exhibits anti-inflammatory activity through suppressing ROS mediated NF-κB pathway in mouse macrophage cells.

Therapeutic targeting of replicative immortality

One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed “senescence,” can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells’ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy.

Epigallocatechin 3-O-gallate induces 67 kDa laminin receptor-mediated cell death accompanied by downregulation of ErbB proteins and altered lipid raft clustering in mammary and epidermoid carcinoma cells

Since the administration of synthetic medicines is associated with drug resistance and undesired side effects, utilization of natural compounds could be an alternative and complementary modality to inhibit or prevent the development of tumors. Epigallocatechin 3-O-gallate (EGCG, 1), the major flavan component of green tea, and genistein (2), a soy isoflavonoid, are known to have chemopreventive and chemotherapeutic effects against cancer. This study demonstrated that both flavonoids inhibit cell proliferation, an effect enhanced under serum-free conditions. Compound 1, but not 2, induced downregulation of ErbB1 and ErbB2 in mammary and epidermoid carcinoma cells, and its inhibitory effect on cell viability was mediated by the 67 kDa laminin receptor (67LR). While 1 was superior in inducing cell death, 2 was more efficient in arresting the tumor cells in the G2/M phase. Furthermore, number and brightness analysis revealed that 1 decreased the homoclustering of a lipid raft marker, glycosylphosphatidylinositol-anchored GFP, and it also reduced the co-localization between lipid rafts and 67LR. The main conclusion made is that the primary target of 1 may be the lipid raft component of the plasma membrane followed by secondary changes in the expression of ErbB proteins. Compound 2, on the other hand, must have other unidentified targets.

Green tea polyphenol epigallocatechin 3-gallate, contributes to the degradation of DNMT3A and HDAC3 in HCT 116 human colon cancer cells

BACKGROUND

Colon cancer is still the second leading cause of cancer deaths in the United States. Epigenetic gene silencing involving DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) plays an important role in the progression of colon cancer.

MATERIALS AND METHODS

In the present study we found that the sensitivity of colon cancer cells to methylation plays a role in its response to alternative therapy involving the green tea polyphenol, epigallocatechin 3-gallate. HDAC and DNMT protein expression were reduced when methylation-sensitive HCT 116 human colon cancer cells was treated with EGCG, but was relatively stable in the HT-29 cell line. This decrease in expression may be partially explained by our finding that DNMT3A and HDAC3 are degraded in the methylation-sensitive colon cancer cells in part by inhibiting their association with the E3 ubiquitin ligase, UHRF1.

CONCLUSION

These findings provide a rationale for the development of a targeted therapy for methylation-sensitive colon cancer that can include EGCG in combination with other DNMT and HDAC inhibitors.

ERK1/2 inhibition enhances apoptosis induced by JAK2 silencing in human gastric cancer SGC7901 cells

Recent studies suggest JAK2 signaling may be a therapeutic target for treatment of gastric cancer (GC). However, the exact roles of JAK2 in gastric carcinogenesis are not very clear. Here, we have targeted JAK2 to be silenced by shRNA and investigated the biological functions and related mechanisms of JAK2 in GC cell SGC7901. In this study, JAK2 is commonly highly expressed in GC tissues as compared to their adjacent normal tissues (n = 75, p < 0.01). Specific down-regulation of JAK2 suppressed cell proliferation and colony-forming units, induced G2/M arrest in SGC7901 cells, but had no significant effect on cell apoptosis in vitro or tumor growth inhibition in vivo. Interestingly, JAK2 silencing-induced activation of ERK1/2, and inactivation of ERK1/2 using the specific ERK inhibitor PD98059 markedly enhanced JAK2 shRNA-induced cell proliferation inhibition, cell cycle arrest and apoptosis. Ultimately, combination of PD98059 and JAK2 shRNA significantly inhibited tumor growth in nude mice. Our results implicate JAK2 silencing-induced cell proliferation inhibition, cell cycle arrest, and ERK1/2 inhibition could enhance apoptosis induced by JAK2 silencing in SGC7901 cells.