The concept of cancer and inflammation has a long history. Virchow's irritation theory based on human cancer engendered the essential role of inflammation in carcinogenesis. Drs. Yamagiwa and ...Ichikawa first published a comprehensive paper entitled “Experimental study on the pathogenesis of epithelial tumors” (I report) in 1915 in German, and went on to publish five more reports (1915–1924) under the same title. They succeeded in demonstrating that inflammation is an important carcinogenic factor, and the mechanisms are now being investigated by numerous scientists all over the world. In order to introduce Yamagiwa's work to modern cancer researchers, the essentials of their six reports have been translated into English as a short review. Scientists' comments on Yamagiwa's contribution are attached by way of introduction.
Drs. Yamagiwa and Ichikawa first published a comprehensive paper entitled “Experimental study on the pathogenesis of epithelial tumors” in 1915 in German. The essentials of their six reports under the same title have been translated into English as a short review. Scientists' comments on Yamagiwa's contribution are attached by way of introduction.
Green tea is now recognized as the most effective cancer preventive beverage. In one study, 10 Japanese‐size cups of green tea daily supplemented with tablets of green tea extract limited the ...recurrence of colorectal polyps in humans to 50%. Thus, cancer patients who consume green tea and take anticancer drugs will have double prevention. We studied the effects of combining (−)‐epigallocatechin gallate (EGCG) and anticancer drugs, focusing on inhibition of cell growth and induction of apoptosis. Numerous anticancer drugs, such as tamoxifen, COX‐2 inhibitors, and retinoids were used for the experiments, and the combination of EGCG and COX‐2 inhibitors consistently induced the enhancement of apoptosis. To study the mechanism of the enhancement, we paid special attention to the enhanced expressions of DDIT3 (growth arrest and DNA damage‐inducible 153, GADD153), GADD45A, and CDKN1A (p21/WAF1/CIP1) genes, based on our previous evidence that a combination of EGCG and sulindac specifically induced upregulated expression of GADD153 and p21 genes in PC‐9 lung cancer cells. The synergistic enhancements of apoptosis and GADD153 gene expression in human non‐small cell lung cancer cells by the combination of EGCG and celecoxib were mediated through the activation of the MAPK signaling pathway. This article reviews the synergistic enhancement of apoptosis, gene expression, and anticancer effects using various combinations of EGCG and anticancer drugs, including the combination of (−)‐epicatechin (EC) and curcumin. Based on the evidence, we present a new concept: green tea catechins as synergists with anticancer drugs. (Cancer Sci 2011; 102: 317–323)
Cancer preventive activities of green tea and its main constituent, (-)-epigallocatechin gallate (EGCG) have been extensively studied by scientists all over the world. Since 1983, we have studied the ...cancer chemopreventive effects of EGCG as well as green tea extract and underlying molecular mechanisms. The first part of this review summarizes ground-breaking topics with EGCG and green tea extract: 1) Delayed cancer onset as revealed by a 10-year prospective cohort study, 2) Prevention of colorectal adenoma recurrence by a double-blind randomized clinical phase II trial, 3) Inhibition of metastasis of B16 melanoma cells to the lungs of mice, 4) Increase in the average value of Young's moduli, i.e., cell stiffness, for human lung cancer cell lines and inhibition of cell motility and 5) Synergistic enhancement of anticancer activity against human cancer cell lines with the combination of EGCG and anticancer compounds. In the second part, we became interested in cancer stem cells (CSCs). 1) Cancer stem cells in mouse skin carcinogenesis by way of introduction, after which we discuss two subjects from our review on human CSCs reported by other investigators gathered from a search of PubMed, 2) Expression of stemness markers of human CSCs compared with their parental cells, and 3) EGCG decreases or increases the expression of mRNA and protein in human CSCs. On this point, EGCG inhibited self-renewal and expression of pluripotency-maintaining transcription factors in human CSCs. Human CSCs are thus a target for cancer prevention and treatment with EGCG and green tea catechins.
Purpose
Our previous experiments show that the main constituent of green-tea catechins, (−)-epigallocatechin gallate (EGCG), completely prevents tumor promotion on mouse skin initiated with ...7,12-dimethylbenz(a)anthracene followed by okadaic acid and that EGCG and green tea extract prevent cancer development in a wide range of target organs in rodents. Therefore, we focused our attention on human cancer stem cells (CSCs) as targets of cancer prevention and treatment with EGCG.
Methods
The numerous reports concerning anticancer activity of EGCG against human CSCs enriched from cancer cell lines were gathered from a search of PubMed, and we hope our review of the literatures will provide a broad selection for the effects of EGCG on various human CSCs.
Results
Based on our theoretical study, we discuss the findings as follows: (1) Compared with the parental cells, human CSCs express increased levels of the stemness markers Nanog, Oct4, Sox2, CD44, CD133, as well as the EMT markers, Twist, Snail, vimentin, and also aldehyde dehydrogenase. They showed decreased levels of E-cadherin and cyclin D1. (2) EGCG inhibits the transcription and translation of genes encoding stemness markers, indicating that EGCG generally inhibits the self-renewal of CSCs. (3) EGCG inhibits the expression of the epithelial-mesenchymal transition phenotypes of human CSCs. (4) The inhibition of EGCG of the stemness of CSCs was weaker compared with parental cells. (5) The weak inhibitory activity of EGCG increased synergistically in combination with anticancer drugs.
Conclusions
Green tea prevents human cancer, and the combination of EGCG and anticancer drugs confers cancer treatment with tissue-agnostic efficacy.
The anticancer activity of immune checkpoint inhibitors is attracting attention in various clinical sites. Since green tea catechin has cancer-preventive activity in humans, whether green tea ...catechin supports the role of immune checkpoint inhibitors was studied. We here report that (-)-epigallocatechin gallate (EGCG) inhibited programmed cell death ligand 1 (PD-L1) expression in non⁻small-cell lung cancer cells, induced by both interferon (IFN)-γ and epidermal growth factor (EGF). The mRNA and protein levels of IFN-γ⁻induced PD-L1 were reduced 40⁻80% after pretreatment with EGCG and green tea extract (GTE) in A549 cells, via inhibition of JAK2/STAT1 signaling. Similarly, EGF-induced PD-L1 expression was reduced about 37⁻50% in EGCG-pretreated Lu99 cells through inhibition of EGF receptor/Akt signaling. Furthermore, 0.3% GTE in drinking water reduced the average number of tumors per mouse from 4.1 ± 0.5 to 2.6 ± 0.4 and the percentage of PD-L1 positive cells from 9.6% to 2.9%, a decrease of 70%, in lung tumors of A/J mice given a single intraperitoneal injection of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In co-culture experiments using F10-OVA melanoma cells and tumor-specific CD3+ T cells, EGCG reduced
mRNA expression about 30% in F10-OVA cells and restored
mRNA expression in tumor-specific CD3+ T cells. The results show that green tea catechin is an immune checkpoint inhibitor.
The concept of cancer and inflammation has a long history.
V
irchow's irritation theory based on human cancer engendered the essential role of inflammation in carcinogenesis.
D
rs.
Y
amagiwa and
I
...chikawa first published a comprehensive paper entitled “
E
xperimental study on the pathogenesis of epithelial tumors” (
I
report) in 1915 in
G
erman, and went on to publish five more reports (1915–1924) under the same title. They succeeded in demonstrating that inflammation is an important carcinogenic factor, and the mechanisms are now being investigated by numerous scientists all over the world. In order to introduce
Y
amagiwa's work to modern cancer researchers, the essentials of their six reports have been translated into
E
nglish as a short review.
S
cientists' comments on
Y
amagiwa's contribution are attached by way of introduction.
Purpose
The okadaic acid class of tumor promoters, which are inhibitors of protein phosphatases 1 and 2A (PP1 and PP2A), induced tumor promotion in mouse skin, rat glandular stomach, and rat liver. ...Endogenous protein inhibitors of PP2A, SET and CIP2A, were up-regulated in various human cancers, so it is vital to review the essential mechanisms of tumor promotion by the okadaic acid class compounds, together with cancer progression by SET and CIP2A in humans.
Results and discussion
The first part of this review introduces the okadaic acid class compounds and the mechanism of tumor promotion: (1) inhibition of PP1 and PP2A activities of the okadaic acid class compounds; (2) some topics of tumor promotion; (3)
TNF-α
gene expression as a central mediator in tumor promotion; (4) exposure to the okadaic acid class of tumor promoters in relation to human cancer. The second part emphasizes the overexpression of SET and CIP2A in cancer progression, and the anticancer activity of SET antagonists as follows: (5) isolation and characterization of SET; (6) isolation and characterization of CIP2A; (7) progression of leukemia with SET; (8) progression of breast cancer with SET and CIP2A; (9) progression of lung cancer with SET; (10) anti-carcinogenic effects of SET antagonists OP449 and FTY720; and also (11) TNF-α-inducing protein of
Helicobacter pylori
, which is a clinical example of the okadaic acid pathway.
Conclusions
The overexpression of endogenous protein inhibitors of PP2A, SET and CIP2A, is tightly linked to the progression of various human cancers, as well as Alzheimer’s disease.
Purpose
Okadaic acid class of tumor promoters are transformed into endogenous protein inhibitors of PP2A, SET, and CIP2A in human cancers. This indicates that inhibition of PP2A activity is a common ...mechanism of cancer progression in humans. It is important to study the roles of SET and CIP2A vis-à-vis their clinical significance on the basis of new information gathered from a search of PubMed.
Results and discussion
The first part of this review introduces the carcinogenic roles of TNF-α and IL-1, which are induced by the okadaic acid class of compounds. The second part describes unique features of SET and CIP2A in cancer progression for several types of human cancer: (1) SET-expressing circulating tumor cells (SET-CTCs) in breast cancer, (2) knockdown of CIP2A and increased PP2A activity in chronic myeloid leukemia, (3) CIP2A and epidermal growth factor receptor (EGFR) activity in erlotinib sensitive- and resistant-non-small cell lung cancer, (4) SET antagonist EMQA plus radiation therapy against hepatocellular carcinoma, (5) PP2A inactivation as a common event in colorectal cancer, (6) prostate cancer susceptibility variants, homeobox transcription factor (
HOXB13
T) and
CIP2A
T, and (7) SET inhibitor OP449 for pre-clinical investigation of pancreatic cancer. In the Discussion, the binding complex of SET is briefly introduced, and overexpression of SET and CIP2A proteins is discussed in relation to age-associated chronic inflammation (inflammaging).
Conclusion
This review establishes the concept that inhibition of PP2A activity is a common mechanism of human cancer progression and activation of PP2A activity leads to effective anticancer therapy.
Microcystin-LR and nodularin, along with okadaic acid, are potent inhibitors of protein phosphatases 1 and 2A (PP1 and PP2A). The mechanisms of action of microcystin-LR and nodularin in the liver and ...that of okadaic acid, a potent tumor promoter on mouse skin, have attracted the attention of the scientists. This paper reviews several topics: new inhibitors of PP1 and PP2A with new chemical structures, structure-function relationships for both receptor binding and inhibition of protein phosphatases, the crystal structure of PP1 or PP2A-toxin complex, induction of gene expression and apoptosis. These subjects were studied by using in vitro and in vivo experimental systems. Two-stage carcinogenesis experiments with microcystin-LR and nodularin for the first time demonstrated that microcystin-LR is a new tumor promoter in rat liver initiated with diethylnitrosamine (DEN), and that nodularin is a potent tumor promoter associated with weak initiating activity in rat liver initiated with DEN. A working group of WHO (IARC) concluded that microcystin-LR is "possibly carcinogenic to humans" and that nodularin is "not classifiable as to carcinogenicity". Our studies revealed that chemical tumor promoters are inducers of TNF-α in the cells of target tissues and that TNF-α is an endogenous tumor promoter. This advance in carcinogenesis made it possible to look for the link between chemical tumor promoters and endogenous tumor promoters, such as TNF-α and IL-1. The carcinogenic features of TNF-α are described in this review, and the TNF-α inducing protein (Tipα) of Helicobacter pylori genome is presented as an example of a tumor promoter of human stomach cancer development.
Purpose
Cell-surface nucleolin in human gastric cancer cell lines is a receptor for TNF-α-inducing protein (Tipα) of
Helicobacter pylori
. The binding complex of nucleolin and Tipα is internalized ...into the cells and then induces tumor progression of human gastric cancer. Surface nucleolin is also a receptor of human immunodeficiency virus-1, and the anti-HIV pseudopeptide (HB-19) showed anti-carcinogenic activity in vivo. Surface nucleolin has dual functions depending on the ligands: In order to understand the mechanisms of surface nucleolin, it is necessary to review surface nucleolin and its relation to carcinogenic ligands and anti-carcinogenic ligands. Other ligands can be grouped among disease-related ligands, which is an important new topic for the prevention of various ailments.
Results and discussion
This paper mainly deals with two ligands of surface nucleolin, Tipα and pseudopeptide HB-19. The binding complex of nucleolin and Tipα induces expression of
TNF
-
α
and
chemokine
genes and activates NF-κB in gastric cancer cells of humans and mice. However, when human gastric cancer cell line MKN-1 was transfected with nucleolin-targeted siRNA, the result was inhibition of cell migration and elongation induced by Tipα. The amount of surface nucleolin was reduced in membrane fraction of the nucleolin knockdown MKN-1 cells, but the amount of nucleolin in the cytosol or nuclear fractions of the cells did not change. The results indicate that surface nucleolin acts as a carcinogenic mediator for Tipα of
H. pylori.
In contrast, both the viral external envelop glycoprotein gp120 of HIV and the anti-HIV pseudopeptide HB-19 bind to surface nucleolin. Through this binding, treatment with HB-19 inhibited tumor development in human breast cancer cell line MDA-MB-231 and rhabdoid tumor cell line derived from Wilms’s tumor in xenograft nude mouse models. The results show that surface nucleolin acts as an anti-carcinogenic mediator for HB-19.
Conclusion
Based on these discrete functions of surface nucleolin, the binding complex of carcinogenic ligands and surface nucleolin seems to be competing with that of anti-carcinogenic ligands and surface nucleolin. Moreover, carcinogenic ligands derived from endogenous sources play a significant role in human cancer development, and the interaction of surface nucleolin with disease-related ligands will be a new research subject for the prevention and treatment of various ailments.
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