A Preliminary Study Indicating Improvement in the Median Survival Time of Glioblastoma Multiforme Patients by the Application of Deuterium Depletion in Combination with Conventional Therapy

Glioblastoma multiforme (GBM) and malignant gliomas are the most common primary malignant brain tumors. Temozolomide (TMZ) chemotherapy plus radiation therapy (RT), admi-mistered after debulking surgery, increased the median survival time (MST) from 12.1 months with RT alone merely to 14.6 months, respectively. In this study, the actions of deuterium-depleted water (DDW) on the survival of GBM patients who also received conventional therapies was investigated. Without changing the conventional treatment, the daily fluid intake of the patients was wholly replaced with DDW in 1.5-2 L per day volume to reduce the D concentration in their bodies. The primary endpoint was the MST. The 55 patients involved in this study, who received conventional treatment and consumed DDW, showed a longer MST (30 months) compared to the historical control (12.1-14.6 months). There was a massive difference between the two genders in the calculated MST values; it was 25 months in the male subgroup (n = 33) and 42 months in the female subgroup (n = 22), respectively. The MST was 27 months without TMZ treatment (38 patients) and 42 months in the TMZ-treated group (17 patients), respectively. For the selected 31 patients, who consumed DDW in the correct way in addition to their conventional treatments, their MST was calculated as 30 months. Within this group, the 20 subjects who had relapsed before DDW treatment had 30 months of MST, but in those 10 subjects who were in remission when DDW treatment started, their MST was 47 months. In the subgroup of patients who began their DDW treatment parallel with radiotherapy, their MST was again 47 months, and it was 25 months when their DDW treatment was started at 8 weeks or later after the completion of radiotherapy. Altogether, these survival times were substantially prolonged compared to the prospective clinical data of patients with primary GBM. Consequently, if conventional therapies are supplemented with D depletion, better survival can be achieved in the advanced stage of GBM than with the known targeted or combination therapies. Application of DDW is recommended in all stages of the disease before surgery and in parallel with radiotherapy, and repeated DDW courses are advised when remission has been achieved.

Blocking the Increase of Intracellular Deuterium Concentration Prevents the Expression of Cancer-Related Genes, Tumor Development, and Tumor Recurrence in Cancer Patients

The possible role of the naturally occurring deuterium in the regulation of cell division was first described in the 1990s. To investigate the mechanism of influence of deuterium (D) on cell growth, expression of 236 cancer-related and 536 kinase genes were tested in deuterium-depleted (40 and 80 ppm) and deuterium-enriched (300 ppm) media compared to natural D level (150 ppm). Among genes with expression changes exceeding 30% and copy numbers over 30 (124 and 135 genes, respectively) 97.3% of them was upregulated at 300 ppm D-concentration. In mice exposed to chemical carcinogen, one-year survival data showed that deuterium-depleted water (DDW) with 30 ppm D as drinking water prevented tumor development. One quarter of the treated male mice survived 344 days, the females 334 days, while one quarter of the control mice survived only 188 and 156 days, respectively. In our human retrospective study 204 previously treated cancer patients with disease in remission, who consumed DDW, were followed. Cumulative follow-up time was 1024 years, and average follow-up time per patient, 5 years (median: 3.6 years). One hundred and fifty-six patients out of 204 (77.9%) did not relapse during their 803 years cumulative follow-up time. Median survival time (MST) was not calculable due to the extremely low death rate (11 cancer-related deaths, 5.4% of the study population). Importantly, 8 out of 11 deaths occurred several years after stopping DDW consumption, confirming that regular consumption of DDW can prevent recurrence of cancer. These findings point to the likely mechanism in which consumption of DDW keeps D-concentration below natural levels, preventing the D/H ratio from increasing to the threshold required for cell division. This in turn can serve as a key to reduce the relapse rate of cancer patients and/or to reduce cancer incidence in healthy populations.

Deuterium-depleted water stimulates GLUT4 translocation in the presence of insulin, which leads to decreased blood glucose concentration

Deuterium (D) is a stable isotope of hydrogen (H) with a mass number of 2. It is present in natural waters in the form of HDO, at a concentration of 16.8 mmol/L, equivalent to 150 ppm. In a phase II clinical study, deuterium depletion reduced fasting glucose concentration and insulin resistance. In this study, we tested the effect of subnormal D-concentration on glucose metabolism in a streptozotocin (STZ)-induced diabetic rat model. Animals were randomly distributed into nine groups to test the effect of D2O (in a range of 25-150 ppm) on glucose metabolism in diabetic animals with or without insulin treatment. Serum glucose, fructose amine-, HbA1c, insulin and urine glucose levels were monitored, respectively. After the 8-week treatment, membrane-associated GLUT4 fractions from the soleus muscle were estimated by Western blot technique. Our results indicate that, in the presence of insulin, deuterium depletion markedly reduced serum levels of glucose, -fructose amine, and -HbA1c, in a dose-dependent manner. The optimal concentration of deuterium was between 125 and 140 ppm. After a 4-week period of deuterium depletion, the highest membrane-associated GLUT4 content was detected at 125 ppm. These data suggest that deuterium depletion dose-dependently enhances the effect of insulin on GLUT4 translocation and potentiates glucose uptake in diabetic rats, which explains the lower serum glucose, -fructose amine, and -HbA1c concentrations. Based on our experimental data, deuterium-depleted water could be used to treat patients with metabolic syndrome (MS) by increasing insulin sensitivity. These experiments indicate that naturally occurring deuterium has an impact on metabolic regulations.

Deuterium-depletion has no significant impact on the mutation rate of Escherichia coli, deuterium abundance therefore has a probabilistic, not deterministic effect on spontaneous mutagenesis

Deuterium (D), the second most abundant isotope of hydrogen is present in natural waters at an approximate concentration of 145-155 ppm (ca. 1.5E-4 atom/atom). D is known to influence various biological processes due to its physical and chemical properties, which significantly differ from those of hydrogen. For example, increasing D-concentration to >1000-fold above its natural abundance has been shown to increase the frequency of genetic mutations in several species. An interesting deterministic hypothesis, formulated with the intent of explaining the mechanism of D-mutagenicity is based on the calculation that the theoretical probability of base pairs to comprise two adjacent D-bridges instead of H-bridges is 2.3E-8, which is equal to the mutation rate of certain species. To experimentally challenge this hypothesis, and to infer the mutagenicity of D present at natural concentrations, we investigated the effect of a nearly 100-fold reduction of D concentration on the bacterial mutation rate. Using fluctuation tests, we measured the mutation rate of three Escherichia coli genes (cycA, ackA and galK) in media containing D at either <2 ppm or 150 ppm concentrations. Out of 15 pair-wise fluctuation analyses, nine indicated a significant decrease, while three marked the significant increase of the mutation/culture value upon D-depletion. Overall, growth in D-depleted minimal medium led to a geometric mean of 0.663-fold (95% confidence interval: 0.483-0.911) change in the mutation rate. This falls nowhere near the expected 10,000-fold reduction, indicating that in our bacterial systems, the effect of D abundance on the formation of point mutations is not deterministic. In addition, the combined results did not display a statistically significant change in the mutation/culture value, the mutation rate or the mutant frequency upon D-depletion. The potential mutagenic effect of D present at natural concentrations on E. coli is therefore below the limit of detection using the indicated methods.

Deuterium Depletion Inhibits Cell Proliferation, RNA and Nuclear Membrane Turnover to Enhance Survival in Pancreatic Cancer

The effects of deuterium-depleted water (DDW) containing deuterium (D) at a concentration of 25 parts per million (ppm), 50 ppm, 105 ppm and the control at 150 ppm were monitored in MIA-PaCa-2 pancreatic cancer cells by the real-time cell impedance detection xCELLigence method. The data revealed that lower deuterium concentrations corresponded to lower MiA PaCa-2 growth rate. Nuclear membrane turnover and nucleic acid synthesis rate at different D-concentrations were determined by targeted [1,2-13C2]-D-glucose fate associations. The data showed severely decreased oxidative pentose cycling, RNA ribose 13C labeling from [1,2-13C2]-D-glucose and nuclear membrane lignoceric (C24:0) acid turnover. Here, we treated advanced pancreatic cancer patients with DDW as an extra-mitochondrial deuterium-depleting strategy and evaluated overall patient survival. Eighty-six (36 male and 50 female) pancreatic adenocarcinoma patients were treated with conventional chemotherapy and natural water (control, 30 patients) or 85 ppm DDW (56 patients), which was gradually decreased to preparations with 65 ppm and 45 ppm deuterium content for each 1 to 3 months treatment period. Patient survival curves were calculated by the Kaplan-Meier method and Pearson correlation was taken between medial survival time (MST) and DDW treatment in pancreatic cancer patients. The MST for patients consuming DDW treatment (n = 56) was 19.6 months in comparison with the 6.36 months' MST achieved with chemotherapy alone (n = 30). There was a strong, statistically significant Pearson correlation (r = 0.504, p < 0.001) between survival time and length and frequency of DDW treatment.

Effect of Systemic Subnormal Deuterium Level on Metabolic Syndrome Related and other Blood Parameters in Humans: A Preliminary Study

The effects of deuterium depletion on the human organism have been, except for the antitumor action, seldom investigated by now and the available data are scarce. In oncological patients who also suffered from diabetes and were treated with deuterium-depleted water (DDW), an improvement of glucose metabolism was observed, and rat studies also proved the efficacy of DDW to reduce blood sugar level. In the present work, 30 volunteers with pre- or manifest diabetes were enrolled to a clinical study. The patients received 1.5 L of water with reduced deuterium content (104 ppm instead of 145 ppm, equivalent 12 mmol/L in human) daily for 90 days. The effects on fasting glucose and insulin level, on peripheral glucose disposal, and other metabolic parameters were investigated. Fasting insulin and glucose decreased, and insulin reaction on glucose load improved, in 15 subjects, while in the other 15 the changes were opposite. Peripheral glucose disposal was improved in 11 of the subjects. In the majority of the subjects, substantial increase of serum high-density lipoprotein (HDL) cholesterol and significant decrease of serum Na+ concentration were also seen-the latter possibly due to activation of a Na+/H+ antiporter by the decreased intracellular deuterium level. The results support the possible beneficial role of DDW in disorders of glucose metabolism but leave questions open, requiring further studies.

Structural homologies between phenformin, lipitor and gleevec aim the same metabolic oncotarget in leukemia and melanoma

Phenformin's recently demonstrated efficacy in melanoma and Gleevec's demonstrated anti-proliferative action in chronic myeloid leukemia may lie within these drugs' significant pharmacokinetics, pharmacodynamics and structural homologies, which are reviewed herein. Gleevec's success in turning a fatal leukemia into a manageable chronic disease has been trumpeted in medical, economic, political and social circles because it is considered the first successful targeted therapy. Investments have been immense in omics analyses and while in some cases they greatly helped the management of patients, in others targeted therapies failed to achieve clinically stable recurrence-free disease course or to substantially extend survival. Nevertheless protein kinase controlling approaches have persisted despite early warnings that the targeted genomics narrative is overblown. Experimental and clinical observations with Phenformin suggest an alternative explanation for Gleevec's mode of action. Using ¹³C-guided precise flux measurements, a comparative multiple cell line study demonstrated the drug's downstream impact on submolecular fatty acid processing metabolic events that occurred independent of Gleevec's molecular target. Clinical observations that hyperlipidemia and diabetes are both reversed in mice and in patients taking Gleevec support the drugs' primary metabolic targets by biguanides and statins. This is evident by structural data demonstrating that Gleevec shows pyridine- and phenyl-guanidine homology with Phenformin and identical phenylcarbamoyl structural and ligand binding homology with Lipitor. The misunderstood mechanism of action of Gleevec is emblematic of the pervasive flawed reasoning that genomic analysis will lead to targeted, personalized diagnosis and therapy. The alternative perspective for Gleevec's mode of action may turn oncotargets towards metabolic channel reaction architectures in leukemia and melanoma, as well as in other cancers.

Submolecular regulation of cell transformation by deuterium depleting water exchange reactions in the tricarboxylic acid substrate cycle

The naturally occurring isotope of hydrogen ((1)H), deuterium ((2)H), could have an important biological role. Deuterium depleted water delays tumor progression in mice, dogs, cats and humans. Hydratase enzymes of the tricarboxylic acid (TCA) cycle control cell growth and deplete deuterium from redox cofactors, fatty acids and DNA, which undergo hydride ion and hydrogen atom transfer reactions. A model is proposed that emphasizes the terminal complex of mitochondrial electron transport chain reducing molecular oxygen to deuterium depleted water (DDW); this affects gluconeogenesis as well as fatty acid oxidation. In the former, the DDW is thought to diminish the deuteration of sugar-phosphates in the DNA backbone, helping to preserve stability of hydrogen bond networks, possibly protecting against aneuploidy and resisting strand breaks, occurring upon exposure to radiation and certain anticancer chemotherapeutics. DDW is proposed here to link cancer prevention and treatment using natural ketogenic diets, low deuterium drinking water, as well as DDW production as the mitochondrial downstream mechanism of targeted anti-cancer drugs such as Avastin and Glivec. The role of (2)H in biology is a potential missing link to the elusive cancer puzzle seemingly correlated with cancer epidemiology in western populations as a result of excessive (2)H loading from processed carbohydrate intake in place of natural fat consumption.

Abstract 1426: Fumarate hydratase and deuterium depletion control oncogenesis via NADPH-dependent reductive synthesis: mitochondrial matrix water, DNA deuteration and epigenetic events

Clear cell kidney tumors become exclusively oxidative pentose cycle, hence cytoplasmic free water dependent by fumarate hydratase mutations, which disrupts the use of low deuterium containing metabolic water of the mitochondrial matrix and consumes pentose cycle-derived NADPH for reductive carboxylation [Yang Y., et al. PLoS One 8: e72179 (2013); Mullen AR, et al. Nature 481: 385-8, (2011)]. Metabolic water by complete fat oxidation, coupled with cytochrome-c, contains low average ∼115 ppm (parts per million) deuterium due to deuterium discrimination by plant lipogenic enzymes during photosynthesis. We herein report that mono-deuterated, 100 ppm, 50 ppm and 25 ppm extracellular (free) water treatment significantly decrease nucleotide and nuclear membrane behenic- and lignoceric acid synthesis in comparison with natural 150 ppm deuterium containing water via the oxidative branch of the pentose cycle in breast (MCF7) and lung (H441) cancer cell cultures, which recapitulates metabolism after genetically restored mitochondrial fumarate hydratase function in clear cell kidney tumors. Targeted [1,2-13C2]-D-glucose to [1-13C1]-D-ribose and 13C-glutamate fate associations indicate that the serine synthesis, one-carbon (folate) metabolism and the glycine cleavage (SOGC) pathway [Tedeschi PM, et al. Cell Death Dis 4: e877, (2013)] also mediates the metabolic control of deuterium depletion in MIA-PaCa pancreatic adenocarcinoma cells. We conclude that impaired mitochondria are involved in cell transformation by limiting the low natural deuterium containing complete fatty acid oxidation product, metabolic water, to enter nuclear membranes and nucleotides via reductive synthesis. In turn, “heavy” natural water and sugar dependent NADPH production taken over by the oxidative branch of the pentose cycle, as well as the SOGC-pathway, are deuterium loading “ticking time bombs” with a strong isotope effect and thus oncogenic epigenetic events that include unstable hydrogen bonds, aneuploidy in DNA structures and chemically altered methylation sites with severely disrupted gene expression patterns. Nevertheless, extra-mitochondrial NADPH synthesis opens a therapeutic window for deuterium depleted water to maintain and/or restore normal cellular functions. Our study provides a novel mechanism regarding lipid based ketogenic diets in the presence of hyperbaric oxygen treatment to decrease metastasis formation by producing low deuterium metabolic water via complete oxidation to prevent DNA, histone and nuclear membrane deuteration during NADPH dependent reductive synthesis.

Citation Format: László G. Boros, Emmanuelle J. Meuillet, Ildikó Somlyai, Gábor Jancsó, György Jákli, Krisztina Krempels, László G. Puskás, István L. Nagy, Miklós Molnár, Keith R. Laderoute, Patricia A. Thompson, Gábor Somlyai. Fumarate hydratase and deuterium depletion control oncogenesis via NADPH-dependent reductive synthesis: mitochondrial matrix water, DNA deuteration and epigenetic events. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1426. doi:10.1158/1538-7445.AM2014-1426

Deuterium depleted water effects on survival of lung cancer patients and expression of Kras, Bcl2, and Myc genes in mouse lung

Although advances in cancer therapies continue to develop, the shortness of the survival of lung cancer patients is still disappointing. Therefore, finding new adjuvant strategies is within the focus of cancer cure. Based on observations that deuterium depletion inhibits the growth of cancer cell lines and suppresses certain proto-oncogenes, we have conducted a clinical study in 129 patients with small cell and nonsmall cell lung cancers who consumed deuterium-depleted drinking water (DDW) as a nontoxic agent in addition to conventional chemotherapy and radiotherapy. Median survival time (MST) was 25.9 mo in males and 74.1 mo in female patients; the difference between genders was statistically significant (p < 0.05). Median survival of subjects with brain metastasis was 27.1 mo. Cumulative 5-yr survival probabilities were 19%, 52%, and 33% in males, females, and all patients with brain metastasis, respectively. Gene expression analysis in mouse lung indicated that DDW attenuates 7,12-dimethylbenz(a)anthracene (DMBA)-induced expression of Bcl2, Kras, and Myc in females. In conclusion, DDW counteracts the DMBA-induced overexpression of Bcl2, Kras and Myc genes in mouse lung, and it may extend survival of lung cancer patients as a nontoxic anticancer dietary supplement, especially for women with tumors overexpressing cancer-related genes, because MST of DDW-consuming group was 2-4 times longer than it is generally observed in lung cancer patients.

Anti-aging effects of deuterium depletion on Mn-induced toxicity in a C. elegans model

Work with sub-natural levels of deuterium (D) in animals has demonstrated an anti-cancer effect of low D-concentration in water. Our objective was to investigate whether deuterium-depleted water (DDW) can overturn reverse manganese (Mn)-induced reduction in life span, using the Caenorhabditis elegans (C. elegans) as a model system. DDW per se had no effect on worm's life span 48 h after treatment; however, it reversed the Mn-induced decrease in C. elegans life span. Mn reduced DAF-16 levels, a transcription factor strongly associated with life-span regulation. Low D-concentration (90 ppm) restored the Mn-induced changes in DAF-16 to levels indistinguishable from controls, suggesting DDW can regulate the DAF-16 pathway. We further show that insulin-like receptor DAF-2 levels were unaltered by Mn exposure, tAKT levels increased, whilst superoxide dismutase (SOD-3) levels were decreased by Mn. DDW (90 ppm) restored the levels of tAKT and superoxide dismutase (SOD) to control values without changing DAF-2 levels. Treatment of Mn exposed worms with DDW (90 ppm) restored life-span, DAF-16 and SOD-3 levels to control levels, strongly suggesting that low D concentrations can protect against Mn toxic effects.

Biological significance of naturally occurring deuterium: the antitumor effect of deuterium depletion

A felszíni vizekben a deutérium (D) koncentrációja több mint 16 mmol/l (150 ppm), az élő szervezetekben 10 mmol/l fölötti. A csökkentett deutériumtartalmú (30±5 ppm) vízzel folyó kutatások során korábban azt tapasztalták, hogy a deutériummegvonás gátolta a sejtosztódást in vitro különböző tumoros sejtvonalakban (PC-3, humán prosztatatumor; MDA, humán emlőtumor; HT-29, humán vastagbéltumor; M14, humán melanoma). A csökkentett deutériumtartalmú víz tumorregressziót idézett elő humán eredetű tumorral xenotranszplantált, immunszuppresszált egerekben (MDA és MCF-7 humán emlőtumor, PC-3 prosztatatumor), és apoptózist indukált in vitro és in vivo . A csökkentett deutériumtartalmú víz (25±5 ppm) részleges vagy teljes tumorregressziót idézett elő spontán tumoros kutyákban és macskákban. A készítményt 1999-ben daganatellenes állatgyógyszerként törzskönyvezték (Vetera-DDW-25 A.U.V., 13/99 FVM). Injekciós változatát klinikai vizsgálatban sikeresen tesztelték. Az Országos Gyógyszerészeti Intézet 5621/40/95 számú engedélye alapján, a GCP-elvek betartásával lefolytatott randomizált, kettős vak elrendezésű humán fázis II klinikai vizsgálat szignifikáns különbséget igazolt a kontroll- és a kezelt csoport között a vizsgált paraméterek vonatkozásában. Egyéves utánkövetés során a csökkentett deutériumtartalmú víz szignifikánsan csökkentette a prosztatatumoros betegek halálozási arányát, miközben a túlélés hosszát szignifikánsan növelte. Az eredmények azt igazolják, hogy a sejtek képesek szabályozni a deutérium/hidrogén (D/H) arányát és ennek változtatásával elindítani bizonyos molekuláris folyamatokat, amelyeknek kulcsszerepük van a sejtciklus szabályozásában. Feltételezzük, hogy nem az intracelluláris pH változása, hanem az azt kísérő D/H arány változása adja meg a sejteknek a jelet az S-fázisba lépéshez. A D-koncentráció csökkenése beavatkozik a szignáltranszdukciós folyamatokba, így idézve elő a tumor regresszióját. A D szerepének felismerése a sejtosztódás szabályozásában új lehetőségeket nyit meg a daganatterápia és a megelőzés területén, hozzájárulva ezzel a jelenlegi daganatellenes terápiák hatékonyságának növeléséhez.

A retrospective evaluation of the effects of deuterium depleted water consumption on 4 patients with brain metastases from lung cancer

HYPOTHESES

Because of the number of sufferers and high mortality rate, the standard care and new therapeutic options in the treatment of brain metastasis from lung cancer are the subject of intense research. A new concept based on the different chemical and physical behavior of protium and deuterium affecting cell signaling and tumor growth has been introduced in the treatment of cancer patients. The aim of this study was to investigate the impact of deuterium depleted water (DDW) consumption in addition to conventional forms of therapy on the survival of lung cancer patients with brain metastasis.

STUDY DESIGN

A series of 4 case histories was retrospectively evaluated. The patients were diagnosed with brain metastasis deriving from a primary lung tumor and started consuming DDW at the time of or after the diagnosis of the brain metastasis, which was inoperable or the surgical intervention did not result in complete regression. The primary objective was survival.

METHODS

The daily water intake of the patients was replaced with DDW, which complemented the conventional forms of treatment. Patients were consuming DDW for at least 3 months. The treatment was continued with DDW of 10 to 15 to 20 ppm lower deuterium (D) content every 1 to 2 months and thus a gradual decrease was maintained in the D-concentration in the patient's body.

RESULTS

DDW consumption integrated into conventional treatments resulted in a survival time of 26.6, 54.6, 21.9, and 33.4 months in the 4 patients, respectively. The brain metastasis of 2 patients showed complete response (CR), whereas partial response (PR) was detected in 1 patient, and the tumor growth was halted (no change or NC) in 1 case. The primary tumor of 2 patients indicated CR, and the lung tumor in 2 patients showed PR.

CONCLUSIONS

DDW was administered as an oral anticancer agent in addition to conventional therapy, and noticeably prolonged the survival time of all 4 lung cancer patients with brain metastasis. We suggest that DDW treatment, when integrated into other forms of cancer treatment, might provide a new therapeutic option.

Deuterium depletion can decrease the expression of C-myc Ha-ras and p53 gene in carcinogen-treated mice

In spite of the fact that the deuterium concentration is over 10 mmol/l in all living organisms, its possible role has been ignored for six decades. Recent studies have shown that the depletion of the naturally occurring deuterium can result in tumour regression in mice, dogs, cats and humans. The effect of deuterium depletion on gene expression plays a key part in tumour development. The carcinogen, 7,12-dimethylbenz(alpha)anthracene (DMBA), was used to increase gene expression in "short term" investigations. The expression of c-myc, Ha-ras and p53 gene was followed in CBA/Ca sensitive inbred mice drinking tap water or deuterium-depleted water (DDW) after induction. By detecting the RNA expression 48 hours after exposure to the carcinogen it was found that the expression of all genes investigated was inhibited in six different organs (spleen, lung, thymus, kidney, liver and lymph node) in the DDW-treated group. It is suggested that genes playing a key role in the cell cycle regulation and tumour development are sensitive to deuterium depletion.

Naturally occurring deuterium is essential for the normal growth rate of cells

The role of naturally occurring D in living organisms has been examined by using deuterium-depleted water (30-40 ppm D) instead of water containing the natural abundance of D (150 ppm). The deuterium-depleted water significantly decreased the growth rate of the L929 fibroblast cell line, and also inhibited the tumor growth in xenotransplanted mice. Eighty days after transplantation in 10 (59%) out of 17 tumorous mice the tumor, after having grown, regressed and then disappeared. We suggest that the naturally occurring D has a central role in signal transduction involved in cell cycle regulation.

Cloning of the promoters of an Escherichia coli rRNA gene. New experimental system to study the regulation of rRNA transcription

The promoters of the rrnB gene of Escherichia coli have been cloned on a multicopy, pBR322-derived plasmid by deleting most of the structural part of rrnB and fusing the terminators of the gene immediately to the promoters. Several further deletions were constructed to vary the promoter-terminator distance, destroy or damage selectively any of the promoters or terminators, and vary the distance between the two pairs of P1 P2 and P3 P4 promoters. All these transcription signals were shown to function on the plasmids in vitro and in vivo. The truncated in vivo transcription products initiated at the P1 and P2 promoters of the recombinant plasmids were found to be stable, and the accumulated transcripts could be easily distinguished from the chromosome-coded rRNA. This provides a convenient experimental system to study the regulation of rRNA biosynthesis.