Abstract P2-01-08: Enumeration of heterogeneous circulating tumor cells (CTCs) using size-based method in early, and metastatic, breast cancer patients

Background

The detection of circulating tumor cells (CTCs) in peripheral blood is an independent predictor of the efficacy of systemic therapy, and also a prognostic marker for patients with metastatic breast cancer. One of the main methods to detect CTCs is CellSearch system, which uses immune-magnetic separation followed by immunocytochemistry. A microdevice (CTChip from ClearCell system) can capture and enumerate CTCs based on distinctive physiological differences (size and deformability) between cancer cells and blood cells. CTChip thus obtains a larger CTC yield than affinity-based separation, which enriches a particular subgroup of cells expressing EpCAM. In this study, we enumerate CTCs in peripheral blood from early and metastatic breast cancer patients using a size-based method.

Patients and methods

We examined blood samples from a total of 18 early and metastatic breast cancer patients, after obtaining written informed consent. Blood samples were taken in sodium EDTA tubes after discarding the first 1ml of blood from the syringe. Two ml blood samples were applied to CTChip (ClearCell system), and CTCs were eventually trapped in the microwells of the CTChip. Trapped cells were analyzed by immunocytochemistry with monoclonal antibodies specific for leukocytes (CD45) and epithelial cells (CK8/18), along with 4',6-diamidino-2-phenylindole (DAPI) for nuclei: CK8/18-positive, DAPI-positive and CD45-negative cells more than 10 μm in diameter were defined as CTCs. Eight patients were examined using both the CTChip and CellSearch system to compare the yield of CTCs.

Results

Of 18 patients, 6 were de novo stage IV, 6 were recurrent and 6 were early stage breast cancer patients. Of primary tumors, 8 were HER2- and ER and/or PR +, 6 were HER2-and ER- and PR-, 3 were HER2+ and ER and/or PR +, and one was HER2+ and ER- and PR-. Using CTChip, detected CTCs ranged from 3 - 107 cells/2 ml in all cases: 3 - 83 for early stage, 19 - 156 for stage IV and 21 - 146 for recurrent. The number of CTCs found in recurrent patients tended to be higher than in early stage patients. Size-based method using CTChip clearly showed high sensitivity compared with the CellSearch system, which detected CTCs in only 2 cases out of 8. In analysis by immunochemistry, we found CK-negative, CD45-negative and DAPI positive cells with larger diameter (>16 μm) than CK-positive CTCs in most patients, and the numbers were higher in stage IV (8.5 cells of median value) and recurrent (13 cells) patients than in early stage patients (1.5 cells). Our study suggested that CK-negative large cells might be CTCs with epithelial–mesenchymal transition (EMT).

Conclusion

This size-based technology enables us to capture CTCs regardless of EpCAM expression. Enumerated CTCs varied in size and positivity of CK8/18, suggesting the heterogeneity of CTCs. Further research, especially focusing on EMT will be crucial to understand the key mechanism of metastasis and drug resistance.

Citation Format: Tozuka K, Nagai SE, Kubo K, Komatsu K, Takai K, Inoue K, Matsumoto H, Hayashi Y, Tsuboi M, Yamada Y, Wang X, Suganuma M. Enumeration of heterogeneous circulating tumor cells (CTCs) using size-based method in early, and metastatic, breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-01-08.

Abstract P2-02-20: Enumeration of heterogeneous circulating tumor cells (CTCs) in metastatic breast cancer patients based on size and deformability

Background :

The detection of circulating tumor cells (CTCs) in peripheral blood is an independent predictor of the efficacy of systemic therapy and a prognostic marker for patients with metastatic breast cancer. One of the leading techniques to detect CTCs uses immune-magnetic separation followed by immunocytochemistry. A microdevice can capture and enumerate CTCs using distinctive physiological difference (size and deformability) between cancer cells and blood cells. This microdevice thus obtains a larger CTC yield than that of affinity based separation which enriches the samples from a particular subgroup of cells based on biomarker (EpCAM) used. In this study, we investigated CTCs in peripheral blood from metastatic breast cancer patients using this microdevice.

Patients and methods:

We examined blood samples of 9 patients with heavily treated locally recurrent or metastatic breast cancer. Informed consent from these patients was obtained before blood extraction. Blood samples were taken into sodium EDTA tubes after discarding the first 1ml of blood samples. Two ml whole blood were subjected to the microdevice (Clear cell system), and CTCs were trapped in the microwells: Trapped cells were analyzed by immunocytochemistry with monoclonal antibodies specific for leukocytes (CD45) and epithelial cells (CK8/18), along with 4,2-diamidino-2-phenylndole dihydrochloride (DAPI) for nuclei. CK8/18- positive, DAPI-positive and CD45-negative cells were defined as CTCs. Three patients were examined using both this microdevice and affinity-based separation with EpCAM, to compare the yield of CTCs.

Results:

Of the 9 patients: 7 had ER-positive primary tumors, and 6 had PgR-positive ones, HER2 overexpression was detected in 2 primary tumors. CTCs were detected in 8 patients. The single patient in whom CTCs were not detected suffered from local recurrence (axillary lymph node metastasis) only, with no distant metastases. We were also unable to detect CTCs using EpCAM affinity method for this patient. The number of detected CTCs in the other patients ranged from 19/2ml to 156/2ml (mean 90/2ml), and the sizes of CTCs varied from 5 to 16μm. CK8/18-negative and DAPI positive were detected in most patients, and these cells tended to be larger than CK8/18-positive cells, suggesting that epithelial–mesenchymal transition (EMT) might occur in CTCs. The total number of CTCs detected by the microdevice from 2 patients was larger than that of CTCs detected by EpCAM affinity method (107/2ml vs 1/7.5ml, and 19/2ml vs 39/7.5ml).

Conclusion:

CTCs detected by this microdevice varied in regard to the size of trapped cells and characteristics examined by immunochemistry, suggesting the heterogeneity of CTCs. Further research on this heterogeneity is vital in order to develop personalized treatment for patients with metastatic breast cancer.

Citation Format: Tozuka K, Nagai SE, Inoue K, Komatsu K, Matsumoto H, Hayashi Y, Kurozumi S, Suganuma M. Enumeration of heterogeneous circulating tumor cells (CTCs) in metastatic breast cancer patients based on size and deformability. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-20.

Effects of hypocapnia on spontaneous burst activity in the piriform-amygdala complex of newborn rat brain preparations in vitro

We examined effects of hypocapnia on burst activity in the piriform-amygdala complex and C(4) inspiratory activity in limbic-brainstem-spinal cord preparations from 0- to 1-day-old rats. Hypocapnia (2% CO(2)) increased the burst rate in the piriform-amygdala complex but decreased the C(4) inspiratory burst rate. Since hyperventilation induces hypocapnia, and enhanced amygdala activity may be involved in induction of a sense of anxiety, our findings might explain the neuronal mechanism of a vicious circle between hyperventilation and an increased sense of anxiety.

DNA-binding activity of TNF-alpha inducing protein from Helicobacter pylori

Tumor necrosis factor-alpha (TNF-alpha) inducing protein (Tipalpha) is a carcinogenic factor secreted from Helicobacter pylori (H. pylori), mediated through both enhanced expression of TNF-alpha and chemokine genes and activation of nuclear factor-kappaB. Since Tipalpha enters gastric cancer cells, the Tipalpha binding molecules in the cells should be investigated. The direct DNA-binding activity of Tipalpha was observed by pull down assay using single- and double-stranded genomic DNA cellulose. The surface plasmon resonance assay, indicating an association between Tipalpha and DNA, revealed that the affinity of Tipalpha for (dGdC)10 is 2400 times stronger than that of del-Tipalpha, an inactive Tipalpha. This suggests a strong correlation between DNA-binding activity and carcinogenic activity of Tipalpha. And the DNA-binding activity of Tipalpha was first demonstrated with a molecule secreted from H. pylori.

Migration behaviour and pathogenesis of five ascarid nematode species in the Mongolian gerbilMeriones unguiculatus

To understand the characteristic features of the Mongolian gerbil,Meriones unguiculatus,as an animal model of ascarid infections, the migration behaviour and pathogenesis of larvae were investigated in experimentally infected gerbils. Embryonated eggs from each ofToxocara canis,Baylisascaris procyonis, B. transfuga, Ascaris suum, andA. lumbricoideswere orally inoculated into gerbils and larvae were recovered from various organs at designated periods. InT. canis-infected gerbils, larvae were present in the liver 3 days after infection and in the skeletal muscle and brain via the heart and lungs at a similar rate. InB. procyonis- andB. transfuga-infected gerbils, larvae were present in the lungs within 24 h after infection, with some having reached the brain by that time. After 24 h, larvae ofB. procyonistended to accumulate in the brain, while those ofB. transfugaaccumulated in skeletal muscles. InA. suum- andA. lumbricoides-infected gerbils, larvae remained in the liver on day 5 post-infection and elicited pulmonary haemorrhagic lesions, which disappeared 7 days after initial infection. Thereafter, no larvae of any type were recovered. Ocular manifestations were frequently observed inT. canis- andB. procyonisinfected gerbils, but were rare inB. transfuga-infected gerbils. In the cases ofA. suumandA. lumbricoides, migration to the central nervous system and eyes was extremely rare, and larvae had disappeared by 2 weeks post-infection. Fatal neurological disturbances were observed inB. procyonis-infected gerbils, whereas irreversible non-fatal neurological symptoms were observed in the case ofB. transfuga.

Carcinogenic potential of tobacco tar-resistant Staphylococcus aureus in buccal cavity

PURPOSE

The effects of cigarette smoking on the association between inflammation and cancer were studied, since some bacteria induce the production of tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine and endogenous tumor promoter, in cells.

METHODS

Bacteria from a gargled solution from the buccal cavity of 20 individuals were cultured in the presence of 4 mg/ml cigarette-smoke condensates. Although cigarette-smoke condensates inhibited growth of Staphylococcus aureus strongly and that of Staphylococcus warneri weakly, tobacco tar-resistant S. aureus and S. warneri were obtained.

RESULTS

One tobacco tar-resistant S. aureus strain (Sa-TA10) induced expression of the TNF-alpha gene in both Bhas 42 cells (v-Ha-ras transfected BALB/3T3 cells) and human lung cancer cell line H226B, while one tobacco tar-resistant S. warneri (Sw-TA75) did not induce it significantly. Moreover, Sa-TA10 induced formation of transformed foci and soft-agar colony in Bhas 42 cells in cooperation with the v-Ha-ras gene. The results suggested that Sa-TA10 has carcinogenic potential, whereas Sw-TA75 does not.

CONCLUSION

These data suggest that tobacco tar-resistant S. aureus, with carcinogenic potential, is present in the buccal cavity of some individuals, and that cigarette smoking simultaneously inhibits growth of most of the bacteria and selects carcinogenic bacteria.

Isolation and synthesis of TNF-alpha release inhibitors from Fijian kawa (Piper methysticum)

Two unique evidence that cancer incidence rates in Fiji were unusually low, compared with those of another Pacific islands and that green tea beverage is an acknowledged cancer preventive in Japan, allowed us to study a local beverage in Fiji, kawa (kava kava) or yangona (Piper methysticum) belonging to Piperaceae. We isolated five known kawapyrones (kavapyrones) (1-5) and a new additional kawapyrone, 7,8-epoxyyangonin (6), from kawa MeOH extract and subjected them to TNF-alpha (tumor necrosis factor-alpha) release assay from BALB/3T3 cells treated with okadaic acid, a tumor promoter. 5,6-Dehydrokawain (desmethoxyyangonin)(1) and yangonin (4) significantly inhibited TNF-alpha release with IC50 values of 17 microM and 40 microM; a potency as great as (-)-epigallocatechin gallate (EGCG) isolated from green tea extract. Among the experiments with 1-5, dihydrokawain (2) was unique in showing the strongest inhibitory activity against TNF-alpha release in mice, but the weakest activity in the cells. We synthesized 5,6-dehydrokawain (1) and yangonin (4) via three steps from the dianion of ethyl acetoacetate achieving a good yield and determined their conformations by high resolution NMR and x-ray crystallographic analysis.

Discrete roles of cytokines, TNF-alpha, IL-1, IL-6 in tumor promotion and cell transformation

Based on our previous results, which pointed to tumor necrosis factor-alpha (TNF-alpha) as the essential cytokine in tumor promotion in mouse skin, we present here three principal findings related to the specific roles of TNF-alpha, interleukin-1 (IL-1) and IL-6 in tumor promotion (using TNF-alpha- and IL-6-deficient mice) and in BALB/3T3 cell transformation: i) The previously reported residual tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) in TNF-/- mice was confirmed by experiments with TNF+/+ and TNF-/- 129/Svj mice of the same strain, using two-stage carcinogenesis experiments. TPA produced tumors in 100% of TNF+/+ and 78% of TNF-/- mice at 20 weeks, and the average number of tumors per mouse was 11.1 in the former group and 2.1 in the latter. Judging from the expression of various inflammatory cytokine genes in TNF+/+ and TNF-/- mice, the residual tumor promoting activity of TPA in TNF-/- mice may be dependent on expression of IL-1alpha and IL-1beta genes. ii) Tumor promotion by TPA and okadaic acid in IL-6+/+ and IL-6-/- C57/BL6 mice was studied, with TPA producing tumors in 57.1% of IL-6+/+ and 40.0% of IL-6-/- mice at 20 weeks, and okadaic acid in 40.0% of IL-6+/+ and 53.3% of IL-6-/- mice. Thus, there was no significant difference between TPA or okadaic acid tumor promotion in either group. In addition, expression of IL-6 gene in skin of both types of mice suggested that IL-6 is not the essential cytokine in tumor promotion, since it can be replaced by other cytokines. iii) In transformed clones of BALB/3T3 cells induced by TNF-alpha alone, IL-1alpha gene expression was induced after transformation by TNF-alpha had occurred, which did not occur in parental cells. Expression patterns of TNF-alpha, IL-1beta, IL-6 and IL-10, along with TGF-beta, were similar in both parental and transformed cells. Considering all these results, we conclude that various cytokines have discrete roles in tumor promotion and cell transformation.

[Three-dimensional curve tracing]

The time required in judging if two probes are on the same curve increased monotonically with the separation of the probes along that curve. This process is called "curve tracing" (Jolicoeur, Ullman & Mackay, 1986). In this study we examined whether curve tracing would occur on a three-dimensionally presented curve with depth variation. By comparing the performance on depth varying and no depth varying stimuli, we examined the properties of three-dimensional curve tracing. The mean RT on three-dimensional stimuli increased monotonically as the distance between two probes increased, which indicates that curve tracing also occurs on three-dimensional stimuli. The mean RT on three-dimensional stimuli was longer than that on two-dimensional stimuli. Our results suggest that three-dimensional structure of the stimuli caused additional costs on curve tracing.

New TNF-alpha releasing inhibitors, geraniin and corilagin, in leaves of Acer nikoense, Megusurino-ki

The success of green tea as a cancer preventive is based on evidence that green tea contains tannins and antioxidants, does not show toxicity in humans and has long traditional use in Asia. In the light of this, herbal medicines are now also attracting attention as potential sources of cancer preventive agents. Using the inhibition of TNF-alpha release assay, we studied Acer nikoense (Megusurino-ki in Japanese), one of the herbal medicines. The inhibitory activity of TNF-alpha release was found in the leaf extract rather than the bark extract, and the main active constituents were identified as geraniin and corilagin, which are present in another Japanese traditional herb, Geranium thunbergii (Genno-shoko). The IC50 values of TNF-alpha release inhibition were 43 microM for geraniin and 76 microM for corilagin, whereas that for (-)-epigallocatechin gallate (EGCG) was 26 microM. Treatment with geraniin prior to application of okadaic acid, a tumor promoter on mouse skin initiated with 7,12-dimethylbenz(a)anthracene, reduced the percentage of tumor-bearing mice from 80.0 to 40.0% and the average numbers of tumor per mouse from 3.8 to 1.1 in week 20. Thus, geraniin has slightly weaker inhibitory activity than EGCG. Since geraniin and corilagin have been well investigated as representative tannins, we discuss here the new possibility of classical herbal medicine in the development of preventive agents for cancer and other life-style related diseases.

Helicobacter pylori membrane protein 1: a new carcinogenic factor of Helicobacter pylori

Considering a suspected link between Helicobacter pylori infection and human stomach cancer, a new H. pylori gene for membrane protein 1 (HP-MP1) was recently cloned. Because HP-MP1 induces release of inflammatory cytokines and tumor necrosis factor-alpha acts as both initiator and tumor promoter, we studied the possible involvement of HP-MP1 in carcinogenesis of H. pylori. Two cell lines, BALB/3T3 cells as control and v-Ha-ras-transfected BALB/3T3 cells (Bhas 42 cells) as putative initiated cells, were each transfected with HP-MP1, urease B genes, or vector alone. All of the Bhas/mpl clones showed strong expression of tumor necrosis factor-alpha gene and produced tumors in 100% of nude mice. Two Bhas/ure clones showed weak tumorigenicity; the other Bhas and BALB clones showed none. Results indicate strong carcinogenic activity of HP-MP1 in cooperation with viral Ras protein and weak activity of urease B.

Cancer prevention with green tea and monitoring by a new biomarker, hnRNP B1

The study of green tea polyphenols as a cancer preventative is approaching a new era, with significant results accumulating rapidly. This paper briefly reviews four topics related to mechanisms of action of tea polyphenols: (I) identification of the genes commonly affected by EGCG, as demonstrated by Clontech's Atlas cDNA Expression Array; (II) the significance of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1) as a new biomarker for early detection of lung cancer, and inhibition of its expression by EGCG; (III) the synergistic or additive effects of EGCG with the cancer preventive agents, sulindac and tamoxifen, on induction of apoptosis in PC-9 cells and on inhibition of intestinal tumor development in multiple intestinal neoplasia (Min) mice; (IV) the results of a 10 year prospective cohort study demonstrating the effectiveness of daily consumption of green tea in preventing cancer, and a prototype study for developing green tea beverage as cancer preventive.

Psoas abscess and cellulitis of the right gluteal region resulting from carcinoma of the cecum

Although retroperitoneal or psoas abscess is an unusual clinical problem, the insidious and occult characteristics of this abscess sometimes cause diagnostic delays, resulting in considerably high morbidity and mortality. In particular, psoas abscess caused by perforated colon carcinoma is uncommon. We report a case of psoas abscess caused by a carcinoma of the cecum. A 72-year-old Japanese woman was admitted to our hospital, with pain in the right groin and buttock. The pain had appeared 6 months before admission, and the symptoms had then been relieved by oral antibiotics. On March 25, 1999, inflammatory signs in the right buttock indicated localized cellulitis, and incision and drainage was performed at a local hospital. The patient was referred to our hospital on the same day. On admission to our hospital, computed tomography (CT) scan revealed a thick right-sided colonic wall and enlargement of the right ileopsoas muscle. Barium enema and colonofiberscopy revealed an ulcerated tumor occupying the entire circumference of the cecum. A retroperitoneal abscess and fistula had been formed by the retroperitoneal perforation of cecum carcinoma: surgical resection was performed after remission of the local inflammatory signs. Operative findings indicated that the cancerous lesion and its surrounding tissues were firmly attached to the right iliopsoas and major psoas muscle, and en-bloc resection, including adjacent muscular tissue, was performed. The fact that carcinoma of the colon could be a cause of psoas abscess and cellulitis in the gluteal region should be considered when an unexplained psoas abscess is diagnosed.

Spontaneous necrosis of gallbladder carcinoma in patient with pancreaticobiliary maljunction

While gallbladder carcinoma is occasionally associated with pancreaticobiliary maljunction, spontaneous necrosis of carcinoma is extremely rare. We herein present a case of spontaneous necrosis of gallbladder carcinoma associated with direct invasion of viable cancer cell nests to the muscularis propria and subserosal layer located beneath the primary nodules. A 65-year-old Japanese man was admitted to a local hospital, complaining of repeated discomfort in the right hypochondrium. Ultrasonography and computed tomography scanning revealed cholecystitis associated with gallstones. Cholecystectomy was performed, and operative cholangiography demonstrated pancreaticobiliary maljunction. The resected gallbladder showed multiple mixed stones filled with necrotic debris and bile sludge. Scrutiny of the mucosal surface revealed multiple small necrotic nodules in the fundus, which were histologically confirmed to be necrotic remnants of a cancerous glandular structure. Small nests of papillary adenocarcinoma were found beneath the nodules in the muscularis propria and in the venous structure located in the connective tissues next to the divided margin of the gallbladder bed. Resection of S4a and S5 of the liver and resection of the extrahepatic bile duct was then performed to remove the remaining cancerous tissues and/or micrometastasis in the liver and bile duct. The biliary tree was reconstructed with a hepaticoduodenostomy. No cancer nests or any precancerous lesions were found in the additionally resected specimens. This case indicates a unique morphological feature of gallbladder carcinoma associated with pancreaticobiliary maljunction, which provides some insight into the pathogenesis of spontaneous necrosis of gallbladder carcinoma.

Modulation of gene expression by (-)-epigallocatechin gallate in PC-9 cells using a cDNA expression array

Green tea is the most effective cancer preventive beverage. In the light of this, the mechanisms of action of tea polyphenols were investigated on the molecular levels. We present here the effects of (-)-epigallocatechin gallate (EGCG) on expression of 588 genes in human lung cancer cell line PC-9 cells, using a human cancer cDNA expression array. The levels of gene expression in non-treated control cells, and cells treated with EGCG alone, with the tumor promoter okadaic acid alone, and with EGCG plus okadaic acid, were studied, and their expression levels were classified into down-regulation (under 0.5 fold) and up-regulation (over 2.0 fold) by comparing with the levels of control. Non-treated PC-9 cells expressed 163 genes out of 588, and EGCG-treated cells induced down-regulated expression of 12 genes and up-regulated expression of 4 other genes. From a comparison of gene expression in the cells treated with EGCG and in cells treated with EGCG plus okadaic acid, we found the following genes commonly affected by EGCG: down-regulation of four genes, NF-kappaB inducing kinase (NIK), death-associated protein kinase 1 (DAPK 1), rhoB and tyrosine-protein kinase (SKY); up-regulation of one gene, retinoic acid receptor alpha1. Among them, we think down-regulation of NIK gene expression is significant for cancer prevention, based on evidence that inhibition of NF-kappaB activation is a result of inhibition of NIK/IKK signalling complex.

A new function of green tea: prevention of lifestyle-related diseases

In the normal human life span, there occur lifestyle-related diseases that may be preventable with nontoxic agents. This paper deals with the preventive activity of green tea in some lifestyle-related diseases. Green tea is one of the most practical cancer preventives, as we have shown in various in vitro and in vivo experiments, along with epidemiological studies. Among various biological effects of green tea, we have focused on its inhibitory effect on TNF-alpha gene expression mediated through inhibition of NF-kappaB and AP-1 activation. Based on our recent results with TNF-alpha-deficient mice, TNF-alpha is an endogenous tumor promoter. TNF-alpha is also known to be a central mediator in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. We therefore hypothesized that green tea might be a preventive agent for chronic inflammatory diseases. To test this hypothesis, TNF-alpha transgenic mice, which overexpress TNF-alpha only in the lungs, were examined. The TNF-alpha transgenic mouse is an animal model of human idiopathic pulmonary fibrosis which also frequently develops lung cancer. Expressions of TNF-alpha and IL-6 were inhibited in the lungs of these mice after treatment with green tea in drinking water for 4 months. In addition, judging from the results of a prospective cohort study in Saitama Prefecture, Japan, green tea helps to prevent cardiovascular disease. In this study, a decreased relative risk of death from cardiovascular disease was found for people consuming over 10 cups of green tea a day, and green tea also had life-prolonging effects on cumulative survival. These data suggest that green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases (including cardiovascular disease and cancer), resulting in prolongation of life span.

Combination cancer chemoprevention with green tea extract and sulindac shown in intestinal tumor formation in Min mice

Green tea is the most effective beverage for cancer prevention in humans. Looking at the concept of combination cancer chemoprevention, we previously reported the synergistic effects of (-)-epigallocatechin gallate (EGCG) with sulindac, and the additive effects of EGCG with tamoxifen, on cancer-preventive activity in human lung cancer cell line PC-9. This paper reports confirmation of the synergistic effects of EGCG with sulindac on the inhibition of intestinal tumors in multiple intestinal neoplasia (Min) mice. Treatment with both green tea extract and sulindac significantly reduced the number of tumors from 72.3 +/- 28.3 to 32.0 +/- 18.7 tumors per mouse, a decrease of 44.3%, whereas treatment with green tea extract alone or with sulindac alone reduced it to 56.7 +/- 3.5 and 49.0 +/- 12.7, respectively. The results also indicated that green tea extract inhibited tumor growth in Min mice almost as potently as sulindac itself did. The three treated groups did not show any adenocarcinomas, whereas 10.8% of the control group did. Since cancer-preventive agents like sulindac and tamoxifen are associated with adverse effects, we discuss the possibility of non-toxic, combination cancer chemoprevention with green tea, looking at the goal of truly effective cancer prevention.

A new concept of tumor promotion by tumor necrosis factor-alpha, and cancer preventive agents (-)-epigallocatechin gallate and green tea--a review

The study of tumor promotion in rodent carcinogenesis using chemical tumor promoters has revealed various tumor promotion pathways, such as the 12-O-tetradecanoylphorbol-13-acetate (TPA) pathway mediated through activation of protein kinase C, and the okadaic acid pathway mediated through inhibition of protein phosphatases 1 and 2A (PP-1 and PP-2A). We previously demonstrated that application of TPA and okadaic acid induced tumor necrosis factor-alpha (TNF-alpha) gene expression in mouse skin, but that tautomycin, which is an inhibitor of PP-1 and PP-2A and not a tumor promoter on mouse skin, did not. Moreover, we found that TNF-alpha stimulated transformation of BALB/3T3 cells initiated with 3-methylcholanthrene 1,000 times stronger than did TPA (Cancer Res. 53, 1982-1985, 1993). This evidence demonstrates a link between the okadaic acid pathway and the endogenous tumor promotion pathway of TNF-alpha. Recently we presented the first evidence that tumor promotion in TNF-alpha(-/-) mice was significantly depressed compared with TNF-alpha(+/+) mice. Thus, in human carcinogenesis, we think that TNF-alpha and other inflammatory cytokines in preneoplastic lesion stimulate tumor promotion and progression of initiated cells as well as premalignant cells. The first part of this paper reports on this TNF-alpha tumor promotion pathway. In the second part, we report a promising screening method for cancer preventive agents, based on evidence that pretreatment with agents such as tamoxifen, sulindac, 1alpha, 25-(OH)2 vitamin D3, quercetin, caffeic acid phenethyl ester, and (-)-epigallocatechin gallate (EGCG) commonly inhibited TNF-alpha release from BALB/3T3 cells induced by okadaic acid. EGCG, the main constituent of Japanese green tea, and green tea itself are acknowledged cancer preventives in Japan, and this paper presents evidence of their effectiveness in both a high-risk group and the general population.

Evidence that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB

The transcription factor NF-kappaB is a positive transcription factor for a number of genes and has been recognized as an anti-apoptotic regulator. However, the mechanism by which NF-kappaB blocks apoptosis is still controversial. Here, we demonstrate the evidence that NF-kappaB could attenuate the TNF-alpha-induced apoptosis without de novo protein synthesis using human pancreatic cancer cell lines, MIA PaCa-2 and Capan-2. The TNF-alpha-induced apoptosis was blocked by IL-1beta, a potent inducer of NF-kappaB activation. This inhibitory effect of IL-1beta was evident when cells were treated with protein synthesis inhibitors such as cycloheximide (CHX). Moreover, NF-kappaB decoy oligonucleotides could not block the anti-apoptotic effect of IL-1beta at doses sufficient to block the NF-kappaB-dependent transcription induced by IL-1beta. To confirm the role of NF-kappaB in blocking apoptosis, we generated stable cell lines expressing IkappaBdeltaN, a highly stable form of IkappaBalpha, a cytoplasmic inhibitor of NF-kappaB. In these stable transfectants, the antiapoptotic effect of IL-1beta was totally abolished, indicating that the anti-apoptotic action of IL-1beta could be ascribed to the NF-kappaB action. These findings show that de novo protein synthesis is dispensable for anti-apoptotic effects of NF-kappaB and support the possibility that NF-kappaB could exert its anti-apoptotic action through protein-protein interaction.

Mechanisms of cancer prevention by tea polyphenols based on inhibition of TNF-alpha expression

Among various biochemical and biological activities of tea polyphenols, we believe inhibition of the expression and release of tumor necrosis factor-alpha (TNF-alpha) is crucial, since our study with TNF-alpha-deficient mice has revealed that TNF-alpha is an essential factor in tumor promotion. We found that EGCG dose-dependently inhibited AP-1 and NF-kappaB activation in BALB/3T3 cells treated with okadaic acid, resulting in inhibition of TNF-alpha gene expression. Furthermore, treatment with 0.1% green tea extract in drinking water reduced TNF-alpha gene expression as well as TNF-alpha protein level in the lung of TNF-alpha transgenic mice; and IL-1beta and IL-10 gene expression in the lung was also inhibited by treatment with green tea extract, indicating that green tea inhibits both TNF-alpha and the cytokines induced by TNF-alpha in organs. We recently found synergistic effects of EGCG and cancer preventive agents such as tamoxifen and sulindac, on cancer preventive activity. Taken together, the results show that green tea is efficacious as a non-toxic cancer preventive for humans.

The role of interleukin-6 in inhibition of lung metastasis in subcutaneous tumor-bearing mice

Metastasis is the most important factor for prognosis in cancer patients, and its occurrence is largely associated with host immune response. We found that the presence of a growing tumor of colon 26, a mouse colon cancer cell line, completely inhibited lung colony formation in a mouse injected with colon 26 intravenously, whereas depletion of effector cells, such as natural killer and T cell subsets, did not affect antimetastasis of colon 26. Since colon 26 releases large amounts of interleukin-6 (IL-6) spontaneously, we studied the association of IL-6 with lung metastasis. Serum IL-6 level increased gradually and reached 12.6 pg/ml five days after inoculation of colon 26 in the back of mice, while at the same time, lung colony formation was inhibited. Moreover, expression of IL-6 mRNA in lung was observed to be associated with elevated serum IL-6 level. We show the first evidence that inhibition of lung metastases in tumor-bearing mice by colon 26 is closely associated with an increase in serum IL-6, but not in cellular immunity.

Preventive effects of drinking green tea on cancer and cardiovascular disease: epidemiological evidence for multiple targeting prevention

The significance of drinking green tea in prevention of two of the main lifestyle-related diseases, cancer and cardiovascular disease, was demonstrated in terms of a prospective cohort study on a total of 8,552 general residents in Saitama Prefecture, Japan. On the basis of the follow-up study, we revealed decreased relative risk of cancer incidence for those consuming over 10 cups a day, compared with those consuming below 3 cups: 0.54 (95% confidence interval, 0.22-1.34) for men, 0.57 (0.34-0.98) for women, and 0.59 (0.35-0.98) for both sexes. Furthermore, a significant delay in cancer onset was associated with increased consumption of green tea. Next, decreased relative risk of death from cardiovascular disease was 0.58 (0.34-0.99) for men, 0.82 (0.49-1.38) for women, and 0.72 (0.60-1.04) for members of both sexes consuming over 10 cups a day. Finally, we evaluated the life-prolonging effects of drinking green tea on cumulative survival, using the life table.

Sensitization of cancer cells to DNA damage-induced cell death by specific cell cycle G2 checkpoint abrogation

We devised two short peptides corresponding to amino acids 211-221 of human Cdc25C fused with a part of HIV1-TAT. These peptides inhibited hChk1 and Chk2/HuCds1 kinase activity in vitro and specifically abrogated the G2 checkpoint in vivo. These peptides sensitized p53-defective cancer cell lines to DNA-damaging agent to death without obvious cytotoxic effect on normal cells. Our results clearly indicate that the specific abrogation of the cell cycle G2 checkpoint is a feasible strategy for cancer therapy, and hChk1 and Chk2/HuCds1 are proper targets for that purpose.

Essential role of tumor necrosis factor alpha (TNF-alpha) in tumor promotion as revealed by TNF-alpha-deficient mice

To examine the hypothesis that tumor necrosis factor (TNF) alpha is an essential cytokine in carcinogenesis, we conducted two-stage carcinogenesis experiments with an initiator, 7,12-dimethylbenz(a)anthracene (DMBA), plus either of two tumor promoters, okadaic acid and 12-O-tetradecanoylphorbol-13-acetate (TPA), on the skin of TNF-alpha-deficient (TNF-/-) mice. TNF-/- mice treated with DMBA plus okadaic acid developed no tumors for up to 19 weeks, and at 20 weeks, the percentage of tumor-bearing TNF-/- mice was 10%, whereas the percentage of tumor-bearing TNF+/+ mice was 100%. In TNF-/- mice treated with DMBA plus TPA, tumor onset was delayed 4 weeks, and the time to development of small tumors in 100% of mice was 9 weeks later than that seen in TNF+/+ CD-1 mice. The average number of tumors in TPA-treated TNF-/- mice was 2.8, compared with 11.8 for TNF+/+ CD-1 mice. To understand the residual tumor-promoting activity in TNF-/- mice, we also investigated the possible significance of interleukin (IL) 1 as an additional cytokine in tumor promotion. A single application of TPA and okadaic acid increased IL-1alpha and IL-1beta gene expression in TNF-/- mice. All of our results demonstrate that TNF-alpha is the key cytokine for tumor promotion in mouse skin and, very possibly, for carcinogenesis in humans as well.

Green tea and cancer chemoprevention

Worldwide interest in green tea as a cancer preventive agent for humans has increased, because it is non-toxic and it is effective in a wide range of organs. (-)-Epigallocatechin gallate (EGCG) is the main constituent of green tea; the others are (-)-epicatechin gallate, (-)-epigallocatechin and (-)-epicatechin (EC). This paper reports the results of our latest pharmacological and biochemical studies with 3H-EGCG, along with studies on human subjects. The study on bioavailability of 3H-EGCG in mice revealed the wide distribution of radioactivity in multiple organs. Specifically, radioactivity was found in all reported target organs of EGCG and green tea extract (digestive tract, liver, lung, pancreas, mammary gland and skin) as well as other organs (brain, kidney, uterus and ovary or testes) in mice. Recently, we demonstrated that EC enhanced incorporation of 3H-EGCG into human lung cancer cell line PC-9 cells. EC along with another cancer preventive agent sulindac also synergistically enhanced apoptosis in PC-9 cells induced by EGCG. Moreover, a case-control study on breast cancer patients revealed that high daily consumption of green tea was associated with a lower recurrence rate among Stages I and II patients. All the results suggest that consumption of green tea is a practical and effective cancer preventive both before cancer onset and after cancer treatment.

Mechanistic aspects of green tea as a cancer preventive: effect of components on human stomach cancer cell lines

It is now well accepted that (-)-epigallocatechin gallate (EGCG) inhibits carcinogenesis in the digestive tract in rodents. To understand the mechanisms of anticarcinogenesis, we first studied growth inhibition by EGCG in human stomach cancer cell lines established at Seoul National University (SNU cell lines). Inhibition by EGCG of [3H]thymidine incorporation into eight SNU cell lines was examined, in relation to transforming growth factor-beta (TGF-beta) responsiveness. Various tea polyphenols derived from green tea and black tea induced growth inhibition and apoptosis of human stomach cancer cell line KATO III, and inhibition of tumor necrosis factor-alpha (TNF-alpha) release from the cells, in the order of (-)-epicatechin gallate (ECG), EGCG, (-)-epigallocatechin (EGC), teaflavins (TF) and (-)-epicatechin (EC). In addition, we demonstrated that EGCG inhibited TNF-alpha gene expression in KATO III cells, as well as okadaic acid-induced AP-1 and NF-kappa B activation. The inhibitory potencies of EGCG for AP-1 and NF-kappa B binding to DNA were different between KATO III cells and mouse fibroblast cell line BALB/3T3. Thus, EGCG and other tea polyphenols may interact with various transcription factors, in addition to AP-1 and NF-kappa B, in nuclei of various cells, resulting in inhibition of TNF-alpha gene expression and TNF-alpha release.

Disaccharide esters screened for inhibition of tumor necrosis factor-alpha release are new anti-cancer agents

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine playing a part in various pathological states. Non-toxic inhibitors of TNF-alpha release are thought to be promising agents for cancer prevention. We found that the acetone fraction of the tobacco leaf surface lipid containing glucose esters and sucrose esters inhibited both TNF-alpha release from BALB/3T3 and KATO III cells induced by okadaic acid and tumor promotion by okadaic acid on mouse skin initiated with 7,12-dimethylbenz(a)anthracene (DMBA). Next, we investigated the inhibition of TNF-alpha release with synthetic disaccharide esters, such as 6,6'-di-O-alkanoyl-alpha, alpha-trehaloses (6,6'-diester-trehaloses), 4,4'-di-O-alkanoyl-alpha, alpha-trehaloses (4,4'-diester-trehaloses) and 6,6'-diamino-6,6'-dideoxy-N,N'-dialkanoyl-alpha, alpha-trehaloses (6,6'-diamide-trehaloses) bearing fatty acids of various chain lengths, and n-dodecyl-beta-D-maltoside as a disaccharide monoester. 6,6'-Diester-trehaloses and 4,4'-diester-trehaloses of C8 to C12 fatty acids, 6,6'-diamide-trehaloses of C8 to C14 fatty acids, and n-dodecyl-beta-D-maltoside all inhibited TNF-alpha release in a dose-dependent manner. The IC50 values are 7.4-14.8 microM for 6,6'-diester-trehaloses (C8 to C12), 14.6-21.6 microM 4,4'-diester-trehaloses (C8 to C12), 2.9-15.0 microM for 6,6'-diamide-trehaloses (C8 to C14) and 23 microM for dodecyl-beta-D-maltoside. Both 6,6'-di-O-octanoyl-alpha, alpha-trehalose (C8, designated as SS555) and n-dodecyl-beta-D-maltoside (C12) inhibited tumor promotion by okadaic acid on mouse skin initiated with DMBA. Percentages of tumor-bearing mice in week 15 of tumor promotion were reduced from 60.0 to 13.3 with SS555, and to 46.7 with n-dodecyl-beta-D-maltoside. Moreover, SS555 inhibited TNF-alpha gene expression mediated through inhibition of AP-1 activation, but not NF-kappa B activation. This paper reports that diester-trehaloses of C8 to C12 fatty acids and mimics of disaccharide monoesters such as n-dodecyl-beta-D-maltoside appear to be potential cancer-preventive agents of a new type.

Unique features of the okadaic acid activity class of tumor promoters

Following the first report of tumor promotion by okadaic acid in 1988, we further identified additional tumor promoters of the okadaic acid activity class, such as calyculin A and microcystin-LR. However, tautomycin, which is also an inhibitor of protein phosphatases-1 and -2A (PP-1 and PP-2A), as are okadaic acid, calyculin A and microcystin-LR, is not a tumor promoter on mouse skin or in rat glandular stomach. This paper presents unique features of the okadaic acid activity class of tumor promoters with regards to three significant findings: 1) the okadaic acid pathway, mediated through inhibition of PP-1 and PP-2A, is a general tumor promotion pathway in various organs; 2) simultaneous treatment of okadaic acid with teleocidin, one of the 12-O-tetradecanoylphorbol-13-acetate (TPA) activity type of tumor promoters, did not show any synergistic effects on tumor promotion; and 3) two different types of tumor promoters, okadaic acid and TPA, commonly induced tumor necrosis factor-alpha (TNF-alpha) gene expression on mouse skin. The results also strongly suggest that TNF-alpha, now known to be an endogenous tumor promoter and a mediator of cancer development, plays an important role in tumor promotion and progression in humans. In the light of this, we discuss a practical method of screening for chemical tumor promoters based on their induction of TNF-alpha release from HL-60 cells.

Mechanistic findings of green tea as cancer preventive for humans

Based on our initial work with green tea, in which repeated topical applications of (-)-epigallocatechin gallate (EGCG), the main green tea polyphenol, inhibited tumor promotion in a two-stage carcinogenesis experiment on mouse skin (Phytother Res 1, 44-47, 1987), numerous scientists have since provided so much additional evidence of the benefits of drinking green tea that it is now an acknowledged cancer preventive in Japan, and will possibly soon be recognized as such in other countries. Our work has so far produced several important results with EGCG and green tea: a wide range of target organs in animal experiments for cancer prevention, wide bioavailability of 3H-EGCG in various organs of mice, delayed cancer onset of patients with a history of consuming over 10 cups of green tea per day, and absence of any severe adverse effects among volunteers who took 15 green tea tablets per day (2.25 g green tea extracts, 337.5 mg EGCG, and 135 mg caffeine) for 6 months. This paper introduces three new findings: 1) EGCG interacted with the phospholipid bilayer membrane resulting in confirmation of the sealing effect of EGCG; 2) EGCG inhibited TNF-alpha gene expression in the cells and TNF-alpha release from the cells; 3) high consumption of green tea was closely associated with decreased numbers of axillary lymph node metastases among premenopausal Stage I and II breast cancer patients, and with increased expression of progesterone and estrogen receptors among postmenopausal ones. These results provide new insights into our understanding of the mechanisms of action of tea polyphenols and green tea extract as a cancer preventive.

Growth inhibition of leukemic cells by (-)-epigallocatechin gallate, the main constituent of green tea

In this report, we presented the results that EGCG, the main constituent of the polyphenols present in Japanese green tea inhibited growth of leukemic cell lines of both human and mice. The proliferation of human leukemic cell lines and mouse NFS60 cell line was inhibited by EGCG. Sensitivity of each line to EGCG was different, and more than 50% of DNA synthesis was reduced in all the cell lines in the presence of 50 microM EGCG. On the other hand, normal hematopoietic progenitor cells retained their natural function of supplying mature cells of various lineages in the presence of less than 10 microM EGCG in vitro. Even in the presence of 100 microM EGCG, half the colonies containing all the lineages of cells were developed. All the dead cells of each line showed characteristics of apoptosis, which might be due to inhibition by EGCG of growth factors' signaling. Besides anticarcinogenic activity, EGCG is expected to have a new function for leukemia therapy without side effects.

28-deacetylbelamcandal, a tumor-promoting triterpenoid from Iris tectorum

A spiroiridal-type triterpenoid, 28-deacetylbelamcandal (1), was isolated from the rhizomes of Iris tectorum as an active principle that stimulated differentiation of human promyelocytic leukemia (HL-60) cells, a short-term screening method for 12-O-tetradecanoylphorbol 13-acetate (TPA)-type tumor promoters. In the same manner as TPA, compound 1 bound to protein kinase C (PKC) and activated PKC, and induced tumor necrosis factor-alpha release from HL-60 cells. In an in vivo study, groups treated with 100 microg 7, 12-dimethylbenz[a]anthracene plus 400 nmol of 1 showed 64.3% tumor incidence by week 20. It has thus been demonstrated that 1 represents a new structural class of mouse skin-tumor promoters.

Synergistic effects of (--)-epigallocatechin gallate with (--)-epicatechin, sulindac, or tamoxifen on cancer-preventive activity in the human lung cancer cell line PC-9

The study on incorporation of [3H](-)-epigallocatechin gallate (EGCG) into human lung cancer cell line PC-9 indicated that the [3H]EGCG incorporation was significantly enhanced by (-)-epicatechin, an inert tea polyphenol without a galloyl moiety. (-)-Epicatechin enhanced apoptosis, growth inhibition of PC-9 cells, and inhibition of tumor necrosis factor-alpha release from BALB/c-3T3 cells by EGCG and other tea polyphenols with a galloyl moiety in a dose-dependent manner. Moreover, the effects of EGCG on induction of apoptosis were also synergistically enhanced by other cancer-preventive agents, such as sulindac and tamoxifen. This paper reports significant evidence that whole green tea is a more reasonable mixture of tea polyphenols for cancer prevention in humans than EGCG alone and that it is even more effective when it is used in combination with other cancer preventives.

Anticancer activity of morphine and its synthetic derivative, KT-90, mediated through apoptosis and inhibition of NF-kappaB activation

We recently reported that morphine inhibits growth of various human cancer cell lines (IC50/2.7-8.8 mM). We then extended the study using newly synthesized morphine derivatives, such as KT-90 and KT-87, which are analgesics 5 times more potent than morphine. KT-90 was found to inhibit growth of human cancer cell lines (IC50/42-70 microM) up to 80 times more potently than morphine. As for mechanisms of action, KT-90 and morphine induced apoptosis, and inhibited tumor necrosis factor alpha (TNF-alpha) gene expression induced by tumor promoters, okadaic acid and 12-O-tetradecanoylphorbol-13-acetate, associated with reduction of NF-kappaB DNA binding activity. This paper provides evidence that KT compounds confirmed the presence of anticancer activity of morphine in addition to its analgesic action.

Wide distribution of [3H](-)-epigallocatechin gallate, a cancer preventive tea polyphenol, in mouse tissue

The increasing recognition of green tea and tea polyphenols as cancer preventives has created a need for a study of their bioavailability. For this purpose, we synthesized [3H] (-)-epigallocatechin gallate ([3H]EGCG) with a specific activity of 48.1 GBq/mmol and directly administered the solution into the stomachs of CD-1 female or male mice. Radioactivity in the digestive tract, various organs, blood, urine and feces was measured with an oxidizer at various times after administration and significant radioactivity was found in the previously reported target organs of EGCG and green tea extract (digestive tract, liver, lung, pancreas, mammary gland and skin), as well as other organs (brain, kidney, uterus and ovary and testes) in both sexes. Incorporation of radioactivity in the cells was confirmed by microautoradiography. Within 24 h, 6.6 (females) and 6.4% (males) of total administered radioactivity was excreted in the urine and 37.7 and 33.1% in feces. HPLC analysis of urine from both sexes revealed that 0.03-0.59% of administered [3H]EGCG, along with at least five metabolites, was excreted. In addition, we found that a second, equal administration to female mice after a 6 h interval enhanced tissue levels of radioactivity in blood, brain, liver, pancreas, bladder and bone 4-6 times above those after a single administration. These results suggest that frequent consumption of green tea enables the body to maintain a high level of tea polyphenols and this paper is the first pharmacological evidence of a wide distribution of [3H]EGCG in mouse organs, indicating a similar wide range of target organs for cancer prevention in humans.

Cancer inhibition by green tea

Green tea is now an acknowledged cancer preventive in Japan. This paper discusses several important features of (-)-epigallocatechin gallate (EGCG), the main constituent of green tea and tea polyphenols. EGCG and other tea polyphenols inhibited growth of human lung cancer cell line, PC-9 cells with G2/M arrest. 3H-EGCG administered by p.o. intubation into mouse stomach revealed that small amounts of 3H-activity were found in various organs where EGCG and green tea extract had previously demonstrated their anticarcinogenic effects, such as skin, stomach, duodenum, colon, liver, lung and pancreas. Cancer onset of patients who had consumed over 10 cups of green tea per day was 8.7 years later among females and 3.0 years later among males, compared with patients who had consumed under three cups per day. The mechanisms of action of EGCG were briefly discussed with regard to inhibition of tumor necrosis factor-alpha (TNF-alpha) release.

Tumourigenicity of MTG8, a leukaemia-related gene, in concert with v-Ha-ras gene in BALB/3T3 cells

The MTG8 (ETO) gene has been identified as the translocation partner of AML1 (PEBP2alphaB or CBFalpha2) gene in the AML1/MTG8 (ETO) fused gene caused by t(8;21) translocation in human acute myeloid leukaemia, M2 type. Although AML1/MTG8 chimaeric protein is known to inhibit the functioning of AML1 protein, the precise function of MTG8 gene itself is not known yet. We studied the significance of MTG8 gene in the oncogenicity of AML1/MTG8 fused gene, by introducing full-length MTG8 cDNA into both BALB/3T3 cells containing v-Ha-ras gene (Bhas 42 cells) and BALB/3T3 cells without v-Ha-ras gene. Irrespective of the overexpression of MTG8 gene in both groups of cells, Bhas-MTG8 clones which contained v-Ha-ras gene and expressed the MTG8 gene at a level more than twice that of parental Bhas 42 cells induced cell transformation, whereas BALB-MTG8 clones without v-Ha-ras gene did not. Furthermore, injection of the transformed Bhas-MTG8 clones into the subcutaneous tissue of nude mice induced tumours, whereas that of BALB-MTG8 clones did not. These results suggest that MTG8 gene product, in cooperation with viral Ras protein, resulted in tumour formation. We provide the first evidence that MTG8 gene by itself has a carcinogenic property within the AML1/MTG8 (ETO) fused gene.