Mechanism-Driven and Clinically Focused Development of Botanical Foods as Multitarget Anticancer Medicine: Collective Perspectives and Insights from Preclinical Studies, IND Applications and Early-Phase Clinical Trials

Cancer progression and mortality remain challenging because of current obstacles and limitations in cancer treatment. Continuous efforts are being made to explore complementary and alternative approaches to alleviate the suffering of cancer patients. Epidemiological and nutritional studies have indicated that consuming botanical foods is linked to a lower risk of cancer incidence and/or improved cancer prognosis after diagnosis. From these observations, a variety of preclinical and clinical studies have been carried out to evaluate the potential of botanical food products as anticancer medicines. Unfortunately, many investigations have been poorly designed, and encouraging preclinical results have not been translated into clinical success. Botanical products contain a wide variety of chemicals, making them more difficult to study than traditional drugs. In this review, with the consideration of the regulatory framework of the USFDA, we share our collective experiences and lessons learned from 20 years of defining anticancer foods, focusing on the critical aspects of preclinical studies that are required for an IND application, as well as the checkpoints needed for early-phase clinical trials. We recommend a developmental pipeline that is based on mechanisms and clinical considerations.

Exploring the Biological Activity and Mechanism of Xenoestrogens and Phytoestrogens in Cancers: Emerging Methods and Concepts

Xenoestrogens and phytoestrogens are referred to as "foreign estrogens" that are produced outside of the human body and have been shown to exert estrogen-like activity. Xenoestrogens are synthetic industrial chemicals, whereas phytoestrogens are chemicals present in the plant. Considering that these environmental estrogen mimics potentially promote hormone-related cancers, an understanding of how they interact with estrogenic pathways in human cells is crucial to resolve their possible impacts in cancer. Here, we conducted an extensive literature evaluation on the origins of these chemicals, emerging research techniques, updated molecular mechanisms, and ongoing clinical studies of estrogen mimics in human cancers. In this review, we describe new applications of patient-derived xenograft (PDX) models and single-cell RNA sequencing (scRNA-seq) techniques in shaping the current knowledge. At the molecular and cellular levels, we provide comprehensive and up-to-date insights into the mechanism of xenoestrogens and phytoestrogens in modulating the hallmarks of cancer. At the systemic level, we bring the emerging concept of window of susceptibility (WOS) into focus. WOS is the critical timing during the female lifespan that includes the prenatal, pubertal, pregnancy, and menopausal transition periods, during which the mammary glands are more sensitive to environmental exposures. Lastly, we reviewed 18 clinical trials on the application of phytoestrogens in the prevention or treatment of different cancers, conducted from 2002 to the present, and provide evidence-based perspectives on the clinical applications of phytoestrogens in cancers. Further research with carefully thought-through concepts and advanced methods on environmental estrogens will help to improve understanding for the identification of environmental influences, as well as provide novel mechanisms to guide the development of prevention and therapeutic approaches for human cancers.

Abstract 183: Brassinolide, a plant steroid hormone, reverses drug resistance in human small-cell lung carcinoma cells

Small-cell lung carcinoma (SCLC) has a dismal prognosis in part because of multidrug resistance (MDR). Epibrassinolide (EB) is a steroid hormone present in higher plants, where it has numerous physiological effects and acts via a LRR-RLK membrane receptor and GSK3/SHAGGY pathway, resulting in stabilization of a transcription factor. The parallels to the Wnt signaling pathway, which is activated in SCLC and results in increased β-catenin, prompted investigations of the effects of EB on SCLC cells, particularly showing MDR. SCLC cells were NCI-H69 and a derived line, VPA17, showing resistance to etoposide (9-fold), doxorubicin (20-fold) and vincristine (10-fold). EB was cytotoxic to both cell lines (IC50 = 2 uM), indicating a lack of cross-resistance. EB was pro-apoptotic after 24 h as measured by ELISA of BUdR-labeled DNA fragments. Apoptosis was also indicated by an increase in caspase-3 specific activity (to 2.5 enzyme units/mg protein vs. 0.01 for untreated controls). Matrigel assays showed that EB reduced the SCLC cell invasion phenotype by 80% in a time-dependent fashion. Pre-incubation of VPA17 cells in 1 µM EB for 96 h reduced the IC50 for etoposide (6.0 uM to 1.8 µM) and doxorubicin (0.37 µM to 0.09 µM). Synergism between EB and chemotherapy drugs was determined by exposure of VPA17 cells to 1:1 ratios at the appropriate IC50 values of EB: etoposide or EB: doxorubicin. After 4 days, the combination index (CI) was determined using CalcuSyn software. EB and etoposide showed modest synergism (CI = 0.80 at ED50 and CI = 0.90 at ED95); EB and doxorubicin also showed synergism (CI = 0.65 at ED50 and CI = 0.90 at ED95). The Wnt - β-catenin signaling pathway was investigated as a possible explanation for the pharmacological effects of EB. In the presence of EB, SCLC cells showed a time- and dose dependent reduction of β-catenin (maximum 80% reduction). Cell fractionation studies showed that the reduction was primarily in nuclear β-catenin. Transcription analyses of SCLC cells showed EB led to significant reduction in expression of β-catenin-dependent genes that are anti-apoptotic (e.g., c-Jun, survivin), cell division-related (e.g., CCND1 cyclin, sox9), and metastasis-related (e.g., MMP7, uPAR). Down-regulation of the β-catenin promoter was confirmed by transfection of SCLC cells with a construct containing the promoter coupled to a luciferase reporter (reduced by 85%). WIKI4, a known inhibitor of Wnt signaling, was cytotoxic to SCLC cells (IC50 = 0.02 uM). Synergism between EB and WIKI4 was determined by exposure of VPA17 cells to 1:1 ratios at the appropriate IC50 values of EB: WIKI4, as above. EB and WIKI4 showed antagonism (CI = 1.09 at ED50 and CI = 1.35 at ED95), suggesting that EB and WIKI4 act on the same pathway. Taken together, these data indicate that EB, a natural product with widespread occurrence in plants, is pharmacologically active in both drug-sensitive and drug-resistant SCLC cells and acts through the Wnt signaling pathway.

Citation Format: David Sadava, Susan E. Kane. Brassinolide, a plant steroid hormone, reverses drug resistance in human small-cell lung carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 183. doi:10.1158/1538-7445.AM2017-183

Abstract 982: Silibinin reverses drug resistance in human small-call lung carcinoma cells

Small-cell lung carcinoma (SCLC) has a dismal prognosis in part because of multidrug resistance (MDR). Silibinin is a flavonolignan extracted from milk thistle (Silybum marianum), extracts of which are used in traditional medicine. Recently, silibinin has shown anti-cancer activity in cell and animal models, in particular prostate cancer where a clinical trial is underway. Here, we report the effects of silibinin on SCLC, particularly cells showing MDR. SCLC cells studied were NCI-H69 and a derived cell line VPA17 showing resistance to etoposide (9-fold), doxorubicin (15-fold) and vincristine (10-fold). VPA17 cells did not show resistance to silibinin (IC50 = 60μM for H69 and VPA17). Flow cytometry analysis after incubation in 30 μM silibinin showed no changes in cell cycle phases in VPA17 or H69 cells (G1 = 49%, S = 29%, G2/M = 18%) compared with untreated cells (p>0.05). Silibinin (30 μM) incubation was pro-apoptotic in VPA17 cells after >3 days, as measured by ELISA of BUdR labeled DNA fragments. Apoptosis was also indicated by an increase in caspase-3 specific activity (to 16 enzyme units/104 cells vs. 5 units/104 cells for untreated controls (p < 0.05). The anti-apoptotic protein survivin was elevated as measured by ELISA in VPA17 compared to H69 cells (11.8 vs.1.8 pg/μg protein, p < 0.01). Incubation for 96 h in 30μM silibinin significantly reduced survivin in VPA17 cells (3.4 pg/μg protein, p < 0.01 compared with untreated cells) but not in H69 cells. VPA17 cells incubated in 30 μM silibinin for 5 days showed an inhibition of pgp-mediated efflux of calcein acetoxymethyl ester (calcein AM): Compared with drug-sensitive H69 cells, VPA17 drug-resistant cells had significantly reduced calcein AM retention (21 vs. 59 fluorescence units, p<0.01). However, silibinin incubation reversed this drug efflux, with increased retention of calcein AM only in VPA17 cells (88 fluorescence units, p<0.001 compared with untreated cells). Silibinin did not inhibit pgp-mediated efflux directly, since there was no effect on calcein AM efflux after 45 min. incubation of untreated VPA17 cells. Pre-incubation of VPA17 cells in 30 μM silibinin for 5 days reduced the IC50 for etoposide (5.50 uM to 0.65 μM, p < 0.05) and doxorubicin (0.620 μM to 0.035 μM, p < 0.05). Synergism between silibinin and chemotherapy drugs was determined by exposure of VPA17 cells to 1:1 ratios at the appropriate IC50 values of silibinin: etoposide or silibinin: doxorubicin at 0.25 x IC50, 0.5 x IC50, 2 x IC50 and 4 x IC50. After 4 days, the combination index (CI) was determined using CalcuSyn software. Silibinin and etoposide showed synergism (CI = 0.46 at ED50 and CI = 0.95 at ED95); silibinin and doxorubicin also showed synergism (CI = 0.24 at ED50 and CI = 0.96 at ED95). These data indicate that in SCLC, silibinin is pro-apoptotic, reverses MDR and acts synergistically with chemotherapy drugs. Silibinin, a non-toxic natural product may be useful in treatment of drug-resistant SCLC.

Citation Format: David Sadava, Susan Kane. Silibinin reverses drug resistance in human small-call lung carcinoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 982. doi:10.1158/1538-7445.AM2013-982

The green tea polyphenol, epigallocatechin-3-gallate inhibits telomerase and induces apoptosis in drug-resistant lung cancer cells

Epidemiological studies on humans and investigations in animal models suggest that consumption of green tea has anti-cancer effects. Small-cell lung carcinoma (SCLC) has a poor prognosis, particularly due to the development of drug resistance. We investigated the effects of the green tea polyphenol, epigallocatechin-3-gallate (EGCG) on human SCLC cells. EGCG had similar effects (IC(50) of approximately 70 microM) on drug-sensitive (H69) and drug-resistant (H69VP) SCLC cells, indicating that it is not part of the drug resistance phenotype expressed in these cells. In both cell lines, incubation in EGCG at 1 x IC(50) for 24h resulted in 50-60% reduced telomerase activity as measured by a PCR-based assay for telomeric repeats. Colorimetric assays of cells treated for 36 h with EGCG demonstrated a reduction in activities of caspases 3 (50%) and 9 (70%) but not caspase 8, indicating initiation of apoptosis. DNA fragmentation as measured by ELISA occurred within cells treated with EGCG and this was confirmed by TUNEL staining. Flow cytometric analysis of SCLC cells incubated for 36 h in EGCG indicated a cell-cycle block in S phase. These data indicate the potential use of EGCG, and possibly green tea, in treating SCLC.

Contaminants of PC-SPES are not responsible for cytotoxicity in human small-cell lung carcinoma cells

PC-SPES is a mixture of herbs used in the treatment of prostate cancer. Batches of this product were found to contain traces of synthetic drugs, and the product was removed from the market. On the basis of a correlation between contaminant levels and cytotoxicity in prostate carcinoma cell lines, Sovak et al. [M. Sovak, A. Seligson, M. Konas, M. Hajduch, M. Dolezal, M. Machala, R. Nagourney, Herbal composition PC-SPES for management of prostate cancer: identification of active principles, J. Natl Cancer Inst. 94 (2002) 1275-1281] concluded that the contaminants were responsible for cytotoxicity of this preparation. Previously, we showed that extracts of PC-SPES are cytotoxic and pro-apoptotic in both drug-sensitive (H69) and drug resistant (H69V) human small-cell lung carcinoma (SCLC) cell lines. Here, we investigated whether the contaminants might be responsible for these effects. In contrast to the data reported for prostate carcinoma cells, extracts of batches of PC-SPES from the year 1998 (reportedly contaminated) and 2001 (much less contaminated) were equally cytotoxic in both SCLC cell lines. Tests of individual contaminants gave IC50 values far in excess of the amounts reported to be present in the IC50 level for the PC-SPES extracts: diethlystilbesterol: actual IC50 in H69 cells, >1000 microM; concentration present in herbal extract at IC50, 0.05-0.2 microM; indomethacin: actual IC50 in H69 cells, 800 microM; concentration in herbal extract, 1.5-20 microM; warfarin: actual IC50 in H69 cells, 950 microM; concentration in herbal extract, 0.57-0.93 microM. Adding the calculated maximum concentration of the contaminants, singly or in combination, to extracts of the less contaminated batch (2001) of PC-SPES did not alter the cytotoxicity of the extract in H69 or H69V cells. At the contaminated concentrations, as well as 5 x those concentrations, none of the contaminants was pro-apoptotic, as indicated by a DNA fragmentation kinetics assay. However, extracts of both early and late batches of PC-SPES were pro-apoptotic in SCLC cells. We conclude that the traces of pharmaceuticals found in PC-SPES were not responsible for its cytotoxic and pro-apoptotic activities of this herbal mixture on SCLC cells.

Pancreatic cancer in vitro toxicity mediated by Chinese herbs SPES and PC-SPES: implications for monotherapy and combination treatment

One of the greatest challenges in the treatment of pancreatic cancer remains its inherent lack of beneficial response to cytotoxic chemotherapy. Chinese herbal extracts have been widely used for the treatment of various cancers, but objective information on their efficacy in pancreatic cancer is lacking. Eight human pancreatic cancer cell lines (MIA, Panc-1, BxPC, ASPC, HS-766T, CaPan-2, CFPAC, and HTB-147) were studied for in vitro susceptibility to ethanol extracts of SPES and PC-SPES, two quality-controlled, dried, encapsulated supplements of 15 and eight Chinese herbs, respectively. Resulting toxicities, alone and in combination with doxorubicin or gemcitabine, were analyzed by [(3)H]thymidine incorporation or sulforhodamine B staining, colony formation, and TUNEL flow cytometry assays. Combination toxicity mechanisms were calculated by the combination index method of Chou and Talalay. In all cell lines, there was dose-dependent inhibition of proliferation. By [(3)H]thymidine incorporation assay, 50% growth inhibition after 48 h continuous exposure (IC(50)) occurred at concentrations of 0.2-0.8 microl/ml SPES and 0.4-1.3 microl/ml PC-SPES. Growth inhibition was accompanied by a significant enhancement of the TUNEL-positive apoptotic fraction of all cell lines after treatment with either extract. After treatment with PC-SPES, the cell lines consistently displayed a G2 cell cycle block; SPES induced an increase in S phase, with a smaller impact on G2. When added at a concentration of 0.2 microl/ml (approximately IC(20)), both extracts enhanced Panc-1 cell killing mediated by doxorubicin, with an average decrease in the corresponding IC(50) of 33% (range 11-62%). Combination effects with either extract appeared to be antagonistic in the case of gemcitabine and additive to mildly synergistic in the case of doxorubicin. Both SPES and PC-SPES exhibited significant toxicity in pancreatic cancer cells, mediated via induction of apoptosis. Both mixtures should be evaluated for their in vivo and clinical therapeutic utility as monotherapy agents against pancreatic cancer. SPES could possibly be combined with cell cycle-independent cytotoxic drugs. Due to a consistent G2 blocking pattern, PC-SPES may prove useful as a radiation sensitizer.

Liposomal daunorubicin overcomes drug resistance in human breast, ovarian and lung carcinoma cells

Multi-drug resistance due in part to membrane pumps such as P-glycoprotein (Pgp) is a major clinical problem in human cancers. We tested the ability of liposomally-encapsulated daunorubicin (DR) to overcome resistance to this drug. A widely used breast carcinoma cell line originally selected for resistance in doxorubicin (MCF7ADR) was 4-fold resistant to DR compared to the parent MCF7 cells (IC50 79 nM vs. 20 nM). Ovarian carcinoma cells (SKOV3) were made resistant by retroviral transduction of MDR1 cDNA and selection in vinblastine. The resulting SKOV3MGP1 cells were 130-fold resistant to DR compared to parent cells (IC50 5700 nM vs. 44 nM). Small-cell lung carcinoma cells (H69VP) originally selected for resistance to etoposide were 6-fold resistant to DR compared to H69 parent cells (IC50 180 nM vs. 30 nM). In all three cases, encapsulation of DR in liposomes as Daunoxome (Gilead) did not change the IC50 of parent cells relative to free DR. However, liposomal DR overcame resistance in MCF7ADR breast carcinoma cells (IC50 20 nM), SKOV3MGP1 ovarian carcinoma cells (IC50 237 nM) and H69VP small-cell lung carcinoma cells (IC50 27 nM). Empty liposomes did not affect the IC50 for free DR in the three resistant cell lines, nor did empty liposomes affect the IC50 for other drugs that are part of the multi-drug resistance phenotype (etoposide, vincristine) in lung carcinoma cells. These data indicate the possible value of liposomal DR in overcoming Pgp-mediated drug resistance in human cancer.

Transferrin overcomes drug resistance to artemisinin in human small-cell lung carcinoma cells

Multiple drug resistance is a significant problem in small-cell lung cancer (SCLC). Artemisinin (ART) is a natural product used to treat drug-resistant malaria. The drug is effective because the Fe2+ present in infected erythrocytes acts non-enzymatically to convert ART to toxic products. We tested the effects of ART on drug-sensitive (H69) and multi-drug-resistant (H69VP) SCLC cells, pretreated with transferrin (TF) to increase the intracellular Fe2+ level. Antibody staining followed by flow cytometry analysis showed twice the level of TF receptors on the H69VP as compared to the H69 cells. Low doses of ART were cytotoxic to SCLC cells. The cytotoxicity of ART for H69VP cells (IC50=24 nM) was ten-fold lower than for H69 cells (IC50=2.3 nM), indicating that ART is part of the drug resistance phenotype. Pretreatment of H69 cells with 220-880 nM TF did not alter the IC50 for ART. However, in the ART-resistant H69VP cells, pretreatment with TF lowered the ART IC50 to near drug-sensitive levels (IC50=5.4 nM after 4 h pretreatment with 880 nM TF). Desferrioxamine (5 microM) inhibited the effect of TF on the IC50 for ART in drug-resistant cells but did not have an effect on ART cytotoxicity in drug-sensitive cells. DNA fragmentation as measured by ELISA occurred within ART-treated cells, with kinetics indicating apoptosis rather than necrosis. This was confirmed by TUNEL staining. These data indicate the potential use of ART and TF in drug-resistant SCLC.

Effects of four Chinese herbal extracts on drug-sensitive and multidrug-resistant small-cell lung carcinoma cells

PURPOSE

We examined the pharmacology, cell biology and molecular biology of small-cell lung carcinoma cells treated with four extracts of Chinese herbal medicines. Many cancer patients take these medicines, but their effects at the cellular level are largely unknown. We were especially interested in the effects on drug-resistant cells, as resistance is a significant clinical problem in lung cancer.

METHODS

Drug-sensitive (H69), multidrug-resistant (H69VP) and normal lung epithelial cells (BEAS-2) were exposed to extracts from two plants used in Chinese herbal medicine for lung cancer: Glycorrhiza glabra (GLYC) and Olenandria diffusa (OLEN), and to extracts of two commercially available combinations of Chinese herbal medicines, SPES (15 herbs) and PC-SPES (8 herbs). Cytotoxicity was measured in terms of cell growth inhibition (IC(50)). The kinetics of DNA fragmentation after exposure to the herbal extracts was measured by BudR labeling followed by ELISA. Apoptosis was measured by the TUNEL assay followed by flow cytometry. Expression of apoptosis- and cell cycle-related genes was measured by reverse transcription of mRNA followed by filter hybridization to arrays of probes and detection by chemiluminescence.

RESULTS

In each case, the four herbal extracts were equally cytotoxic to H69 and H69VP and less cytotoxic to BEAS-2. All four extracts induced DNA fragmentation in the lung carcinoma cells. The kinetics showed DNA fragments released to the medium (an indication of necrosis) in GLYC-exposed cultures, but inside the cells (an indication of apoptosis) in OLEN-, SPES- and PC-SPES-exposed cultures. TUNEL analysis confirmed that exposure to the latter three extracts, but not to GLYC, led to apoptosis. Compared to untreated and GLYC-treated cells, H69 and H69VP cells treated with OLEN, SPES and PC-SPES showed elevated expression of a number of genes involved in the apoptotic cascade, similar to cells treated with etoposide and vincristine.

CONCLUSION

The Chinese herbal medicine extracts OLEN, SPES and PC-SPES are cytotoxic to both drug-resistant and drug-sensitive lung cancer cells, show some tumor cell specificity compared to their effect on normal cells, and are proapoptotic as measured by DNA breaks and gene expression. The reaction of the tumor cells to these extracts was similar to their reaction to conventional chemotherapeutic drugs.

Hyperplasia, hyperproliferation and decreased migration rate of colonic epithelial cells in mice fed a diet deficient in vitamin D

Low serum levels of vitamin D metabolites have been associated with an increased risk for colon cancer. To investigate the effects of vitamin D deficiency on the colon, 4-week-old mice were fed a diet either containing (100,000 IU/kg diet) or lacking this vitamin for 3 weeks. Food consumption and body weight gain were similar in both groups. Following injection with 3H-thymidine to label dividing cells, cellular proliferation and migration up the colonic crypt were determined autoradiographically. Although overall crypt lengths were similar in both groups, there was hyperplasia and hyperproliferation in crypts of the deficient animals. Also, their epithelial cells migrated up the crypt at a significantly slower rate (maximum 0.78 micron/h) than did those from control mice (1.42 microns/h). There was no difference in cellularity, proliferation or migration in duodenal epithelium. These results indicate that vitamin D deficiency significantly alters colonic but not duodenal epithelial cells.

Effect of methadone addiction on glucose metabolism in rats

Female albino rats were exposed to methadone over a 35-day period by addition of the drug in their drinking water. The final dose of the drug was 1.8 mg/kg body weight per day. After this period, the drug was withdrawn from some animals for 30 days (postexposure). Compared to unexposed controls, serum glucose levels rose during exposure and returned to control levels postexposure. Oral glucose tolerance tests showed impairment in 35-day drug-exposed animals compared to controls and postexposure. The activities of three key enzymes of glycolysis and three key enzymes of gluconeogenesis were measured in liver during and at the end of the exposure period, as well as postexposure. Compared to unexposed controls and postexposure, specific activities of two glycolytic enzymes in livers of exposed animals-hexokinase and phosphofructokinase 1-were significantly reduced, whereas the activity of a third glycolytic enzyme-pyruvate kinase-was unchanged. The specific activities of two gluconeogenic enzymes-glucose-6-phosphatase and fructose-1,6-biphosphatase-were significantly elevated in the drug-exposed animals compared to controls, whereas the activity of a third enzyme-phosphoenolpyruvate carboxykinase-was unchanged. These data indicate that methadone addiction produces a metabolic state similar to insulin-resistant diabetes.

Development of enzymes of glycolysis and gluconeogenesis in human fetal liver

The activities of two key enzymes of glycolysis and two key enzymes of gluconeogenesis were measured in liver samples from 44 human fetuses ranging in gestational age from 20 weeks to term, from infants to 10 years and from adults from 21 to 58 years. Specific activities of both gluconeogenic enzymes, fructose-1,6-biphosphatase and phosphoenolpyruvate carboxykinase, increased throughout the period of fetal development examined, and rose to near adult levels after birth. The activities of both glycolytic enzymes, phosphofructokinase 1 and pyruvate kinase, were lower in fetal than in pediatric and adult samples. For both of these enzymes, there was a significant reduction in activity of livers from fetuses of 34-37 weeks' gestation. Both enzymes showed hyperbolic kinetics at 24 weeks' gestation, but this changed to sigmoid kinetics during the 34-37 weeks' period of low activity. The data indicate that during the last weeks of gestation, inhibition of the activities of these two glycolytic enzymes, coupled with the rise in the two gluconeogenic enzymes, may reflect a change in liver from a primarily glycolytic role in the first two trimesters to a gluconeogenic role shortly before birth.

Transition from cytosolic to mitochondrial thymidine kinase during development in human fetal tissues

The transition from cytosolic ("fetal") to mitochondrial ("adult") thymidine kinase, as detected by electrophoresis, was examined in six human fetal tissues of gestational ages 11-40 weeks. In all tissues there was an early period during development in which only the fetal form was detected, followed by a transitional period in which both fetal and adults forms were present, followed by a later period in which only the adult enzyme occurred. Transitional periods were 23-25 wk. gestational age for colon, 13-15 wk. for kidney, 18-20 wk. for liver, 14-18 wk. for lung, 34-36 wk. for serum, and 25-28 wk. for thyroid. In all cases, only the adult form was present by the time of birth and persisted during the first 18 months of extrauterine life. The adult form, but not the fetal form, was inhibited by dCTP.

The effects of maternal hyperphenylalaninemia on learning in mature rats

Pregnant rats were given a diet supplemented with 0.5% alpha-methyl-phenylalanine and 3% phenylalanine from the 12th day of gestation to term. Compared to unsupplemented controls, maternal serum phenylalanine was elevated 8-10-fold. Experimental litters did not differ from controls in number of offspring, birth weight, or subsequent growth on an unsupplemented diet. At 8 weeks of age, animals were tested for latent learning on a 4-arm maze, and at 10 weeks, they were tested for observational learning with littermates in a food preference paradigm. In both tests, experimental animals did learn, but significantly less than controls. The data suggest that maternal hyperphenylalaninemia, induced as a model for the inborn error, phenylketonuria, can lead to learning deficits later in the lives of offspring.

Glycerol metabolism in higher plants: glycerol kinase

Glycerol kinase activity was identified in extracts of higher plant seeds and seedlings, and was partially purified and characterized from cucumber radicle tissue. The enzyme was localized in the post-mitochondrial supernatant of the cell, and catalyzed the formation of glycerol-3-phosphate. The pH optiumum was 9.0. ATP, CTP, GTP or UTP could be used as the phosphoryl group donor. The Km for glycerol was 55 microM and Km values for the nucleoside triphosphates were 145-620 microM. The Vmax for the reaction was 40-78 pmol product per min. Kinetic data indicate that the enzyme has a sequential mechanism.

Development of enzymes of glycerol metabolism in human fetal liver

The activities of three key enzymes of glycerol metabolism were measured in liver samples from 37 human fetuses ranging in gestational age from 18 weeks to term, from neonates (1-3 days) and from infants to 2 years. Glycerol kinase specific activity was constant throughout the period of fetal development examined, and was comparable to that measured in neonates and infants. However, the subcellular distribution of the activity changed markedly, being predominantly particulate in fetal samples and cytoplasmic in postnatal samples. The particulate activity had an elevated Km for glycerol. Cytoplasmic glycerol-3-phosphate dehydrogenase activity was very low in the fetal period, and then rose to adult levels during infancy. There were no kinetic differences between the fetal and postnatal activities. Mitochondrial glycerol-3-phosphate dehydrogenase activity rose somewhat after birth to near adult levels. The data indicate that glycerol can be metabolized by human fetal, neonatal and infant liver.

The effect of methadone addiction on cyclic nucleotide levels in regions of rat brain

Studies of tissue culture cells and tissue slices have implicated the nucleotides, cyclic AMP and cyclic GMP, in the mechanism of action of opiates. However, there are little in vivo data to corroborate this hypothesis. We addicted rats to the synthetic opiate, methadone, by providing the drug in their drinking water (dosage 2.1 mg./kg./day). The two cyclic nucleotides were measured in four brain areas which contain a high concentration of opiate receptors: amygdala, neostriatum, periventricular grey, and thalamus. Data were obtained after acute exposure of the drug (1 day), tolerance (35 days), withdrawal (35 days on drug then 1 day off drug), and readjustment (35 days on drug then 21 days off drug). Cyclic GMP levels were low (0.03 pmol./mg. tissue) in the four regions and did not differ significantly during the experiment. Cyclic AMP levels were higher (1-3 pmol./mg.) and fluctuated consistently in the four regions. After acute methadone treatment, there was a reduction in cyclic AMP, which continued at lower levels after tolerance. One day of withdrawal led to increased cAMP, which rose to near control levels. After readjustment, the levels were reduced. These data indicate an involvement of cyclic AMP in the addiction and withdrawal processes in the intact animal.

Tricyclic antidepressant drugs affect histamine receptors in human leukocytes

Tricyclic antidepressant drugs bind to histamine receptors in rodent and other mammalian tissues. However, a readily accessible, normal human tissue for studies of these drugs has not been available. We showed that freshly isolated human leukocytes can be used for this purpose. Following isolation by dextran sedimentation, leukocytes were incubated for 30 sec. in histamine concentrations from 1.0 nM to 1.0 mM. A dose-related increase in intracellular cyclic AMP was observed. When the cells were preincubated for 10 min. in the tricyclic, nortriptyline, and then challenged with histamine, the concentration of histamine needed for a comparable cyclic AMP increase was elevated 100-fold over non-preincubated cells. These results indicate that the tricyclic drug interacts with histamine receptors on leukocytes, and that these cells may be used for biochemical and clinical studies of these drugs.

The effect of vitamin C on the rapid induction of aortic changes in rabbits

Male rabbits were injected intraperitoneally for five consecutive days with one of the following: (A) 0.3 ml/kg dimethyl ethylene glycol (solvent); (B) 40 mg/kg cholesterol and 8 mg/kg ergocalciferol in solvent; (C) same regimen as B with the addition of 150 mg/kg ascorbic acid in water. Daily blood samples were taken for determination of cholesterol and triglycerides, and for lipoprotein electrophoresis. After 5 days of injections, histological sections were made of the aorta at the arch. After 5 days, group B, as compared with group A, had higher serum cholesterol (150 ng/dl vs. 50 mg/dl, p less than 0.005), higher serum triglycerides (650 mg/dl vs. 150 mg/dl, p less than 0.01), and lower high-density lipoprotein (16% vs. 35%, p less than 0.05). On autopsy, discontinuous elastic fibers and intimal damage were seen in sections of the aortas from group B, but not from group A. After 5 days, group C had control levels of cholesterol (55 mg/dl) and triglycerides (160 mg/dl), and no significant difference from the control lipoprotein profile. Injections of cholesterol alone showed a slight induction of aortic lesions and blood chemistry changes. No alterations in these parameters were induced by ergocalciferol alone. The data indicate a prophylactic effect of vitamin C on the biochemical and histological changes rapidly induced by cholesterol and ergocalciferol.

Human glycerol kinase deficiency: enzyme kinetics and fibroblast hybridization

Glycerol kinase deficiency has been associated with neuromuscular, skeletal and adrenal abnormalities and has also been seen in individuals without these clinical findings. Examination of residual enzyme activity in patients' liver, kidney, leukocytes and fibroblasts showed a generalized, heritable defect: the apparent Km for glycerol was increased 5-200-fold over control values, whereas the apparent Km for ATP was not significantly altered. This kinetic defect was similar in fibroblasts from clinically different individuals with this inborn error of metabolism. Hybridization of fibroblasts from these individuals showed no evidence of complementation for glycerol kinase activity.

Effect of prematurity on the developmental progression from fetal to adult thymidine kinase in human serum

The developmental progression of thymidine kinase from the electrophoretically slow-migrating 'fetal' forms to the fast-migrating 'adult' form was examined weekly in the serum of 5 premature infants. Only the fetal forms were present up to 32 weeks after conception. The adult form appeared along with the fetal forms until 39 weeks post-conception; thereafter, only the adult form was detected. With respect to post-conceptional age, the timing of the changeover from fetal to adult serum, thymidine kinase was the same in the prematurely born infants as in stillborn infants at an equivalent gestational age.

Studies on the biochemistry and fine structure of silica shell formation in diatoms : Formation of hydroxyproline and dihydroxyproline in Nitzschia angularis

In diatoms, the siliceous cell walls are enveloped by an organic component which includes 4-hydroxyproline and 3,4-dihydroxy-L-proline. The formation of these two amino acids were studied in Nitzschia angularis in Si-starvation synchrony. Both appear to arise from peptidyl proline. Its conversion to peptidyl hydroxyproline was shown in cell-free extracts and in kinetic studies using [(14)C]proline. Two lines of evidence indicate that dihydroxyproline does not arise from the further hydroxylation of peptidyl hydroxyproline: First, there was a lag of several minutes between the incorporation of [(14)C]proline into protein and the appearance therein of [(14)C]hydroxyproline but no such lag for the appearance of dihydroxyproline. Second, α,α'-dipyridyl blocked the formation of hydroxyproline, but not of dihydroxypyroline, from peptidyl proline. Cell walls made in the presence of dipyridyl differed little in overall chemical composition from walls made in its absence and were morphologically identical. [(14)C]dehydroproline was rapidly metabolized in the cells, with [(14)C]dihydroxyproline a prominent product. Studies of the conversion of [(14)C]proline to [(14)C]hydroxyproline at various stages of wall formation showed an increased synthesis of [(14)C]dihydroxyproline at the end of cell separation.

Multiple forms of thymidine kinase during human development

The developmental progression of thymidine kinase from the electrophoretically slow-migrating 'fetal' forms to the fast-migrating 'adult' form was examined in human serum and fetal liver. In fetal liver, only the fetal forms of the enzyme were present at 17 weeks' gestation. A transitional period followed in that both enzyme forms were identified and by 24 weeks only the adult form was detected in fetal liver. This same enzyme changeover pattern--fetal to transitional to adult--occurred at a later time in human serum as it took place between 30 and 40 weeks' gestation.

Effect of methadone addiction on N-demethylation activity of rat liver microsomes

Adult male rats were addicted to methadone via small dosages in their drinking water. The N-demethylation activity of microsomal mixed function oxidase in liver was determined for partially addicted (25 days of drug consumption) and fully addicted (38 days of drug consumption) rats. Compared to controls which did not receive the drug, enzyme activity expressed on a microsmal protein basis was increased in partially addicted, but not increased in fully addicted animals. Enzyme activity expressed on a liver weight basis was decreased in partially addicted animals but unchanged from contro levels in fully addicted animals. Brief (three-day) exposures to phenobarbital or high dosages of methadone led to an increase in N-demethylation activity.

Cell wall protein in plants: autoradiographic evidence

Autoradiography of phloem-parenchyma tissue from carrots, which was allowed to incorporate radioactive proline and then plasmolyzed, indicates that a stable protein moiety is associated with the cell wall.