Repression of Human Hepatocellular Carcinoma Growth by Regulating Met/EGFR/VEGFR-Akt/NF-κB Pathways with Theanine and Its Derivative, (R)-2-(6,8-Dibromo-2-oxo-2H-chromene-3-carboxamido)-5-(ethylamino)-5-oxopentanoic Ethyl Ester (DTBrC)

L-Theanine and Immunity: A Review

L-theanine (N-ethyl-γ-glutamine) is the main amino acid in tea leaves. It not only contributes to tea flavor but also possesses several health benefits. Compared with its sedative and calming activities, the immunomodulatory effects of L-theanine have received less attention. Clinical and epidemiological studies have shown that L-theanine reduces immunosuppression caused by strenuous exercise and prevents colds and influenza by improving immunity. Numerous cell and animal studies have proven that theanine plays an immunoregulatory role in inflammation, nerve damage, the intestinal tract, and tumors by regulating γδT lymphocyte function, glutathione (GSH) synthesis, and the secretion of cytokines and neurotransmitters. In addition, theanine can be used as an immunomodulator in animal production. This article reviews the research progress of L-theanine on immunoregulation and related mechanisms, as well as its application in poultry and animal husbandry. It is hoped that this work will be beneficial to future related research.

L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications

Tea (Camellia sinensis L.) is a very popular health drink and has attracted increasing attention in recent years due to its various bioactive substances. Among them, L-theanine, a unique free amino acid, is one of the most important substances in tea and endows tea with a special flavor. Moreover, L-theanine is also a bioactive compound with plenty of health benefits, including antioxidant, anti-inflammatory, neuroprotective, anticancer, metabolic regulatory, cardiovascular protective, liver and kidney protective, immune regulatory, and anti-obesity effects. Due to the unique characteristics and beneficial functions, L-theanine has potential applications in the development of functional foods. This review summarized the influencing factors of L-theanine content in teas, the main health benefits and related molecular mechanisms of L-theanine, and its applications in food, understanding of which can provide updated information for the further research of L-theanine.

Chemoprotective effect of theanine in 1,2-dimethylhydrazine-induced colorectal cancer in rats via suppression of inflammatory parameters

Colorectal cancer is considered as a major cancer among all types of cancers, especially in developed countries. The colorectal cancer has few to no symptoms and mostly the tumor is often diagnosed in the later stage of cancer. Oxidative stress and inflammatory reaction play an important role in the expansion and the progression of colorectal cancer. Theanine exhibits antioxidant and anti-inflammatory potential against various diseases. As a result of its antioxidant and anti-inflammatory nature, in this study, we estimated the protective effect of theanine against 1,2-dimethylhydrazine (DMH)-induced colorectal cancer and explored the possible mechanism. Subcutaneous injection (35 mg/kg) of DMH was used to induce colorectal cancer in rats. Rats were divided into different groups and were orally administrated with theanine (5, 10, and 20 mg/kg) for 16 weeks. Body weight, tumor size, and average tumor weight were determined at the end of the experimental study. Biochemical tests, antioxidant properties, phase I and phase II enzymes, and inflammatory mediators were estimated. The mRNA expression of p38 mitogen-activated protein kinase (p38MAPK), p53, and apoptosis was also estimated at the end of the experimental study. Theanine significantly (p < .001) increases the body weight and suppressed the average tumor size in DMH-induced colorectal cancer. Similarly, it significantly (p < .001) reduces the level of prostaglandin (PGE₂ ), cyclooxygenase-2 (COX-2), and myeloperoxidase (MPO). It also decreases the oxidative stress by suppressing the level of malonaldehyde (MDA) and enhancing the level of SOD, GPx, CAT, and GR. Theanine considerably reduced tumor markers, such as lactate dehydrogenase (LDH) and carcinoembryonic antigen (CEA) and phase I and phase II enzymes in a dose-dependent manner. It also significantly (p < .001) suppressed the expression of p38-MAPK, p-53, caspase-3, caspase-8, and caspase-9 in a dose-dependent manner. Collectively, we can say that theanine exhibited the chemoprotective effect against the colorectal cancer by inhibiting the oxidative stress and inflammatory reaction. PRACTICAL APPLICATIONS: Theanine is the major amino acid phytoconstituent of green tea. It has a potent antioxidant activity and is also able to protect against various oxidative damage. In this experimental study, theanine exhibits a protective effect against colorectal cancer by suppressing the oxidative stress and inflammatory reaction. The results suggest that theanine may be used for colorectal cancer prevention and treatment.

Insights into Growth Factors in Liver Carcinogenesis and Regeneration: An Ongoing Debate on Minimizing Cancer Recurrence after Liver Resection

Hepatocellular carcinoma has become a leading cause of cancer-associated mortality throughout the world, and is of great concern. Currently used chemotherapeutic drugs in the treatment of hepatocellular carcinoma lead to severe side effects, thus underscoring the need for further research to develop novel and safer therapies. Liver resection in cancer patients is routinely performed. After partial resection, liver regeneration is a perfectly calibrated response apparently sensed by the body's required liver function. This process hinges on the effect of several growth factors, among other molecules. However, dysregulation of growth factor signals also leads to growth signaling autonomy and tumor progression, so control of growth factor expression may prevent tumor progression. This review describes the role of some of the main growth factors whose dysregulation promotes liver tumor progression, and are also key in regenerating the remaining liver following resection. We herein summarize and discuss studies focused on partial hepatectomy and liver carcinogenesis, referring to hepatocyte growth factor, insulin-like growth factor, and epidermal growth factor, as well as their suitability as targets in the treatment of hepatocellular carcinoma. Finally, and given that drugs remain one of the mainstay treatment options in liver carcinogenesis, we have reviewed the current pharmacological approaches approved for clinical use or research targeting these factors.

miRNA-1246 in extracellular vesicles secreted from metastatic tumor induces drug resistance in tumor endothelial cells

Tumor endothelial cells (TECs) reportedly exhibit altered phenotypes. We have demonstrated that TECs acquire drug resistance with the upregulation of P-glycoprotein (P-gp, ABCB1), contrary to traditional assumptions. Furthermore, P-gp expression was higher in TECs of highly metastatic tumors than in those of low metastatic tumors. However, the detailed mechanism of differential P-gp expression in TECs remains unclear. miRNA was identified in highly metastatic tumor extracellular vesicles (EVs) and the roles of miRNA in endothelial cell resistance were analyzed in vitro and in vivo. In the present study, we found that treatment of highly metastatic tumor-conditioned medium induced resistance to 5-fluorouracil (5-FU) with interleukin-6 (IL-6) upregulation in endothelial cells (ECs). Among the soluble factors secreted from highly metastatic tumors, we focused on EVs and determined that miR-1246 was contained at a higher level in highly metastatic tumor EVs than in low metastatic tumor EVs. Furthermore, miR-1246 was transported via the EVs into ECs and induced IL-6 expression. Upregulated IL-6 induced resistance to 5-FU with STAT3 and Akt activation in ECs in an autocrine manner. These results suggested that highly metastatic tumors induce drug resistance in ECs by transporting miR-1246 through EVs.

Theanine and cancer: A systematic review of the literature

A growing literature indicates several health benefits of theanine, a major nonprotein derivative amino acid special to tea, and a nonedible mushroom. This study aimed to systematically review the scientific evidence regarding the anticarcinogen and anticancer effects of natural theanine. A systematic search for the relevant articles published until January 2021 on MEDLINE, Scopus, and Web of Knowledge was conducted. Out of 377 initial records, 14 in vitro, ex vivo, and in vivo studies met our inclusion criteria. Most of the included in vitro and ex vivo studies reported beneficial effects of theanine on the proliferation, apoptosis, metastasis, migration, and invasion in various cancer cell lines. The in vivo studies also supported the potential impacts of theanine on cancer incidence or progression. Theanine exerted its anticancer function by inhibiting EGFR, VEGFR, Met, and Akt/mTOR, JAK2/STAT3, and ERK/NFκB pathways, as well as activating the intrinsic apoptosis pathway and caspase-independent programmed cell death. In conclusion, the results indicated moderate apoptotic, antimetastatic, antimigration, and anti-invasion effects, along with the mild antiproliferative influence of theanine on cancer. Further studies are necessary to ascertain the effectiveness of theanine on the prevention and suppression of cancer and shed light upon the attributable mechanisms in the in vivo condition.

Oncopreventive effects of theanine and theobromine on dimethylhydrazine-induced colon cancer model

Theanine and theobromine are abundantly present in tea and cocoa, respectively. This study was performed to assess the chemopreventive effects of these phytochemicals, alone or together, on dimethylhydrazine (DMH)-induced colon cancer. Thirty male Wistar rats were divided into five groups and subcutaneously injected with saline (negative control group) or 30 mg/kg DMH (the other groups) two times/week for 12 weeks. The negative and positive control animals were orally treated with drinking water, and the other groups were gavaged with theanine (400 mg/kg), theobromine (100 mg/kg), or their mixture for two weeks before and throughout the injection period. At the end of the study, the morphological and histopathological features, Ki-67 proliferation marker, and the expression of Akt/mTOR, JAK2/STAT3, MAPK/ERK, and TGF-β/Smad pathways were investigated. Theanine and theobromine, alone or together, reduced the number of cancerous and precancerous lesions, the volume of tumors, the Ki-67 immunostaining, and the expression of Akt/mTOR and JAK2/STAT3 oncogenic pathways. The simultaneous treatment was more effective in the down-regulation of Akt and mTOR compared to either theanine or theobromine alone. Theobromine administration also caused more inhibitory effects on the Ki-67 and Akt/mTOR expression than theanine. Besides, all dietary interventions increased the mRNA and protein expression of Smad2. In conclusion, theanine and theobromine, alone and in combination, inhibited tumorigenesis through down-regulation of the Akt/mTOR and JAK2/STAT3 pathways and an increment of the Smad2 tumor suppressor. The inhibition of the Akt/mTOR pathway was more pronounced by simultaneous treatment.

L-theanine suppresses the metastasis of prostate cancer by downregulating MMP9 and Snail

Prostate cancer (PCa) is a very prevalent male-specific malignancy; most PCa patients eventually die as a result of metastasis. L-theanine (C7H14N2O3), a nonprotein amino acid derivative from green tea leaves, has been demonstrated to act as an anticarcinogen through proapoptotic and antiproliferative effects. However, the antimetastatic effect of L-theanine in tumor cells and its underlying mechanism are still unclear. Here, we found that L-theanine could suppress invasion, migration, and increase cell-cell adhesion of prostate cancer cells in vitro and in vivo. We also found that L-theanine could inhibit the epithelial-mesenchymal transition process in PCa. Our study revealed that L-theanine could downregulate MMP9, N-cadherin, Vimentin, Snail, and upregulate E-cadherin. Furthermore, L-theanine suppressed the transcription of MMP9 and Snail by significantly inhibiting the ERK/NF-κB signaling pathway and the binding activity of p65 to the promoter regions of MMP9 and Snail. All of these findings suggest that L-theanine has therapeutic potential for metastatic PCa and may be considered a promising candidate for antimetastatic therapy of prostate cancer.

Extract Derived from Cedrus atlantica Acts as an Antitumor Agent on Hepatocellular Carcinoma Growth In Vitro and In Vivo

Cedrus atlantica is widely used in herbal medicine. However, the anti-cancer activity of C. atlantica extract (CAt extract) has not been clarified in hepatocellular carcinoma. In the study, we elucidated the anti-hepatoma capacity of CAt extract on HCC in vitro and in vivo. To explore the anti-hepatoma mechanisms of the CAt extract in vitro, HCC and normal cells were treated with the CAt extract, which showed marked inhibitory effects on HCC cells in a dose-dependent manner; in contrast, the CAt extract treatment was less cytotoxic to normal cells. In addition, our results indicate that the CAt extract induced apoptosis via caspase-dependent and independent apoptosis pathways. Furthermore, the CAt extract inhibited HCC tumor cell growth by restraining cell cycle progression, and it reduced the signaling of the AKT, ERK1/2, and p38 pathways. In the xenograft model, the CAt extract suppressed HCC tumor cell growth and prolonged lifespan by inhibiting PCNA protein expression, repressing part of the VEGF-induced autocrine pathway, and triggering strong expression of cleaved caspase-3, which contributed to cell apoptosis. Moreover, the CAt extract did not induce any obvious changes in pathological morphology or body weight, suggesting it had no toxicity. CAt extract exerted anti-tumor effects on HCC in vitro and in vivo. Thus, CAt extract could be used as a potential anti-cancer therapeutic agent against HCC.

Sporamin suppresses growth of human esophageal squamous cell carcinoma cells by inhibition of NF‑κB via an AKT‑independent pathway

The aim of the present study was to determine whether sporamin, a trypsin inhibitor, suppresses the growth of human esophageal squamous cell carcinoma (ESCC) cells in vitro. Sporamin treatment led to the suppression of viability and proliferation of human ESCC cell lines, EC9706 and EC109, as determined by MTT and [3H] thymidine incorporation assays, respectively. Flow cytometry and fluorescence microscopy demonstrated that sporamin significantly induced apoptosis in EC9706 and EC109 cells. Western blotting demonstrated that sporamin downregulated the expression of Bcl‑2 and Bcl‑2 like 1, and upregulated the expression of Bcl‑2‑associated X in EC9706 and EC109 cells. In addition, marked inhibition of nuclear factor (NF)‑κB activation was observed in sporamin‑treated EC9706 and EC109 cells by an electrophoretic mobility shift assay. Sporamin treatment also resulted in reduced expression levels of phosphorylated (p)‑NF‑κB inhibitor α and nuclear NF‑κB p65. However, the expression levels of p‑protein inase (AKT) and its downstream target, p‑p70 S6 kinase, were not markedly altered following sporamin treatment. In conclusion, sporamin may suppress the growth of human ESCC cells via NF‑κB‑dependent and AKT‑independent mechanisms and may act as a promising natural therapeutic agent for the treatment of human ESCC.

Sporamin induces apoptosis and inhibits NF-κB activation in human pancreatic cancer cells

Sporamin, a Kunitz-type trypsin inhibitor (TI) from sweet potato tuberous roots, has demonstrated anti-tumor activity through poorly defined mechanisms. Furthermore, the effects of sporamin on pancreatic cancer have not been explored. Herein, we studied the effects of sporamin on two human pancreatic cancer cell lines, PANC-1 and BxPC-3. Sporamin significantly inhibited the cell viability and proliferation activity and induced apoptosis in PANC-1 and BxPC-3 cells. Consistently, in sporamin-treated PANC-1 and BxPC-3 cells, the anti-apoptotic proteins Bcl-2 and Bcl-XL were downregulated and the pro-apoptotic protein Bax was upregulated. Moreover, nuclear factor kappa B activation and IκBα phosphorylation were inhibited, and total IκBα expression was increased in sporamin-treated PANC-1 and BxPC-3 cells. Thus, our results suggest that the anti-tumor effects of sporamin in pancreatic cancer cells might result partly from induction of apoptosis by downregulating nuclear factor kappa B pathway.