Antitumour activity of dopa, dopamine, noradrenalin or adrenalin and their reaction with nucleic acids

Synthesis and Characterization of 3-(1-((3,4-Dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione as a Potential Antitumor Agent

The newly synthesized coumarin derivative with dopamine, 3-(1-((3,4-dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione, was completely structurally characterized by X-ray crystallography. It was shown that several types of hydrogen bonds are present, which additionally stabilize the structure. The compound was tested in vitro against different cell lines, healthy human keratinocyte HaCaT, cervical squamous cell carcinoma SiHa, breast carcinoma MCF7, and hepatocellular carcinoma HepG2. Compared to control, the new derivate showed a stronger effect on both healthy and carcinoma cell lines, with the most prominent effect on the breast carcinoma MCF7 cell line. The molecular docking study, obtained for ten different conformations of the new compound, showed its inhibitory nature against CDK_S protein. Lower inhibition constant, relative to one of 4-OH-coumarine, proved stronger and more numerous interactions with CDK_S protein. These interactions were carefully examined for both parent molecule and derivative and explained from a structural point of view.

Schizophrenia and cancer: the adrenochrome balanced morphism

Cancer might be expected to be more common amongst schizophrenics than the general population. They frequently live in selenium deficient regions, have seriously compromised antioxidant defense systems and chain-smoke. The available literature on the cancer-schizoprenia relationship in patients from England, Wales, Ireland, Denmark, USA and Japan, however, strongly suggests that the reverse is true. One of the authors (Hoffer) has treated 4000 schizophrenics since 1952. Only four of these patients has developed cancer. Since low cancer incidence has been recorded amongst patients treated by both conventional physicians using pharmaceuticals and by orthomolecular doctors who emphasize vitamins and minerals, it follows that this depressed cancer incidence must be related to the biochemistry of the disorder itself. Taken as a whole, therefore, the evidence seems to suggest that schizophrenics, their siblings and parents are less susceptible to cancer than the general population. These relationships seem compatible with one or more genetic risk factors for schizophrenia that offer(s) a selective advantage against cancer. There is experimental evidence that appears to support this possibility. Matrix Pharmaceuticals Inc. has received a US patent covering the composition of IntraDose Injectable Gel. This gel contains cisplatin and epinephrine (adrenaline) and is designed to be injected directly into tumour masses. Cisplatin is a very powerful oxidant which will almost certainly rapidly convert the adrenaline to adrenochrome. While the manufacturers of IntraDose consider cisplatin to be the active cytotoxic agent in IntraDose, it seems more likely that adrenochrome and its derivatives may, in fact, be more effective. IntraDose gel has undergone or is undergoing a series of Phase III open-label clinical studies, being injected into patients' tumours that have been identified as the most troublesome by their physicians. The results have been impressive for breast cancer, malignant melanoma, esophageal cancer and cancer of the head, neck and liver. The evidence suggests that there are balanced morphisms in schizophrenia that result in above normal exposure to catecholamine derivatives. Since such catecholamines are both hallucinogenic and anticarcinogenic abnormally high exposure to them simultaneously increases susceptibility to schizophrenia and reduces the probability of developing cancer. These observations have significant implications for the treatment of both illnesses.

Potency, selectivity and cell cycle dependence of catechols in human tumour cells in vitro

Enhancement of the potency and melanoma-selectivity of redox agents was sought by two different approaches. In screening a series of catechols, derivatives of moderate half-life (dopa, dopamine, noradrenaline, 3,4-dihydroxybenzylamine, 3,4-dihydroxyphenylacetic acid; t1/2 12-33 hr) had significant toxicity (D37 20-30 microM) and selectivity for melanoma cells compared with HeLa. Less stable catechols (5-hydroxy- and 6-hydroxydopamine; t1/2 4 and 5 hr respectively) were toxic but lacked selectivity whereas more stable derivatives (4-hydroxyanisole, 2,3-dihydroxybenzoic acid; t1/2 greater than 72 hr) were less potent (D37 greater than 100 microM) and had poor selectivity. Gossypol, a complex catechol derivative, exhibited significant toxicity (D37 7.7 microM) but little selectivity. Enzymes capable of reacting with components of the culture medium and known to continuously generate hydrogen peroxide (glucose-6-oxidase) or superoxide ion (xanthine oxidase) exhibited a similar degree of selectivity as dopa, indicating that active oxygen species are more important mediators of catechol toxicity than quinones. Rhodamine 123, a cationic dye preferentially taken up by some tumour cells, was accumulated equally by melanoma and HeLa yet had a similar selectivity to that of dopa. In the second approach, the potency of dopa was found to be greatly enhanced during early S phase. This phenomenon, found with cells synchronised both by mitotic shake off and by 24 hr accumulation in G1S in the presence of 5 mM hydroxyurea, occurred during a period in which the proportion of cells in S phase cells was low. These results indicate that human cells are extremely sensitive to extracellular active oxygen species during a relatively short period in early S phase, and selective killing of asynchronous melanoma cells therefore requires agents capable of sustaining a redox effect for at least one cell cycle.

Modification of dopa toxicity in human tumour cells

A variety of factors were found to modify the toxicity of L-dopa in HeLa cells (D37 16 microM) and in dopa-sensitive, nonpigmented human melanoma cells (MM96) (D37 5 microM) having a similar size and doubling time. Dopa toxicity was decreased by concurrent treatment with superoxide dismutase, peroxidase or catalase, by erythrocytes, or by hypoxia. Toxicity could be increased by the enzyme inhibitors L- and D-penicillamine, sodium diethyldithiocarbamate or 3-amino-1,2,4-triazole. The two cell lines had similar levels of superoxide dismutase and peroxidase; in 6 human melanoma lines, no correlation was found between dopa killing and tyrosinase activity as determined either by formation of dopa from tyrosine or by formation of melanin from dopa. Uptake of L-dopa was similar in HeLa and MM96 cells, and the toxicity of D-dopa was the same in both lines as that of the L-isomer. Dopa decomposed within 12 hr in culture medium, the rate and products being influenced by addition of the above enzymes and by the cell density. Dopa-melanin and medium containing decomposed dopa were also selectively toxic to MM96 cells. Adenovirus 5 was used in two different ways to assess the relative importance of DNA damage and inhibition of DNA synthesis by dopa. Viral replication was found to be unaffected in cells being treated with dopa but was strongly inhibited in cells treated with the DNA polymerase inhibitor cytosine arabinoside. Secondly, the virus was itself inactivated by treatment with dopa for 24 hr (D37 1.3 mM); similar dose response curves were obtained for replication of dopa-treated virus in untreated HeLa or MM96 cells. These results show that the initial events of dopa toxicity occur outside the cell and lead to the formation of a stable, toxic product (probably melanin) which does not strongly inhibit DNA polymerase activity. Melanoma hypersensitivity was not due to differences in oxygen-metabolizing enzymes, dopa uptake, or DNA repair.

Catecholamine analogs as potential antitumor agents

The structural requirements for murine P-388 leukemia activity in the dopamine series were investigated. Eight of the 31 analogs evaluated possessed reproducible antitumor activity. The ortho-aromatic hydroxyl groups were required for activity, but the aminoethyl side chain was not crucial since this group could be replaced by methyl or aminomethyl groups with the retention of activity. The lack of activity of O-alkylated and monosubstituted analogs suggests that o-quinone formation may be important for activity, a possibility supported by the observed P-388 activity of 5-hydroxydopamine compared with the inactivity of the 6-hydroxy isomer.

Changes in mouse skin cyclic nucleotides during chemical carcinogenesis and tumor response to treatment with BCG, L-Dopa and cyclic DBAMP

During chemical carcinogenesis by 9, 10-dimethyl 1,2-benzanthracene the cyclic AMP and GMP content was measured in the skin of mice. The tissue of the developing skin tumor is characterized by an elevated cyclic GMP- and a lowered cyclic AMP level. Consequently the quotient of cyclic AMP and GMP is greatly lowered and is discussed as a crucial factor of cell derangement. Complete regression of the tumor is to be achieved by increasing the cyclic AMP levels by means of cyclic DBAMP and L-Dopa in 20% of the experimental animals. Additional stimulation by BCG of the unspecific immune defence has a favourable effect on tumor regression (about 50%). In a different type of tumor (solid Ehrlich carcinoma) it was possible after pretreatment of the mice with L-Dopa, cyclic DBAMP and BCG and after treatment following tumor injection to prevent tumor development in 67% of the animals.