Increased hepatic nicotinamide N-methyltransferase activity as a marker of cancer cachexia in mice bearing colon 26 adenocarcinoma.

When a cachexigenic subclone (clone 20) of murine colon 26 adenocarcinoma was transplanted into female BALB/c mice, hepatic NNMT activity continued to increase until death in proportion to progressive carcass weight loss, a marker of cancer cachexia. On the other hand, noncachexigenic subclone (clone 5)-transplanted mice showed neither increase of NNMT activity nor carcass weight loss. Among cytostatic fluorinated pyrimidines, 5'-dFUrd could inhibit the increase of NNMT activity and prevent weight loss in mice bearing clone 20. On the other hand, 2'-dFUrd did not show these effects. 5-FUra and Tegafur inhibited the increase of NNMT activity at higher concentrations. These findings suggest that the levels of hepatic NNMT activity are closely associated with the degree of weight loss, and they appear to be a useful marker of cancer cachexia.

Drug resistance to ganciclovir observed in suicide gene therapy is due to the loss of integrated herpes simplex virus-thymidine kinase gene.

Human pancreatic cancer cells (AsPC-1) expressing the herpes simplex virus-thymidine kinase (HSV-TK) gene were inoculated into nude mice and ganciclovir (GCV) was administrated for the treatment. At the initial course of treatment we observed a notable reduction of tumor masses. However, therapeutic effect of GCV to the recurrent tumors decreased significantly. This reduced sensitivity of the AsPC-1/HSV-TK cells to GCV was also confirmed by an in vitro test. Examination of HSV-TK gene in the drug resistant cells showed a loss of the integrated gene. These data indicate that repeated GCV administration results in the loss of integrated HSV-TK gene and confers GCV resistance.

Antitumor effect induced by the expression of granulocyte macrophage-colony stimulating factor gene in murine colon carcinoma cells.

Murine colon carcinoma cells which secrete several kinds of cytokine after retroviral transduction with corresponding genes, were examined for their antitumor effects in syngeneic mice. The mice inoculated with granulocyte macrophage-colony stimulating factor (GM-CSF) producer cells showed not only prolonged survival but also reduced tumorigenicity. The antitumor effect caused by the expression of interleukin-4 was less than that of GM-CSF, and interleukin-6 producer cells did not show any effects on the survival of the host animals. Histological examination of the GM-CSF-producing tumor revealed predominant infiltration of neutrophils and necrotic change of the tumor. The present study indicates the feasibility of cancer gene therapy with the expression of GM-CSF gene in tumor cells.

Characterization of nicotinamide methyltransferase in livers of mice bearing Ehrlich ascites tumors: preferential increase of activity.

There was a 2- to 7-fold increase in nicotinamide methyltransferase activity in the livers of mice and rats bearing seven different kinds of tumors compared with the respective control normal livers, while activity in the tumors themselves was hardly detectable. The activity in the liver started to increase markedly 3-7 days after i.p. transplantation of Ehrlich ascites tumors into the mice, maintaining a plateau up to death. Metabolic conversion of 14C-nicotinamide to 14C-N1-methylnicotinamide was 3-fold higher in the slices of the ascites tumor host liver than in the normal liver, but the conversion to other radioactive metabolites was not significantly different. Nicotinamide methyltransferase was finally purified 20,000-fold with a yield of 4% from the cytosolic fraction of the ascites tumor host liver by means of five purification steps. At every purification step, only one enzyme fraction was detected. The enzyme finally isolated exhibited a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with a molecular weight of 26,000. As for the compounds investigated, including the substrates for methyltransferases other than nicotinamide methyltransferase, only quinoline could be the substrate for enzyme activity. It is suggested that the increase in enzyme activity in the tumor host liver probably derived from the endogenous enzyme preexisting in the liver before tumor transplantation.

Resonance Raman study on intact pea phytochrome and its model compounds: evidence for proton migration during the phototransformation.

Resonance Raman (RR) scattering from intact pea phytochrome was observed in resonance with the blue band at ambient temperature. The relative populations of the red-light-absorbing form (Pr) and far-red-light-absorbing form (Pfr) under laser illumination were estimated from the absorption spectra. The most prominent RR band of Pr obtained by 364-nm excitation under 740-nm pumping exhibited a frequency shift between H2O and D2O solutions, but that of Pfr obtained by 407-nm excitation under 633-nm pumping did not, indicating a distinct difference in a protonation state of their chromophores. Since the protonation level of a whole molecule of intact phytochrome remains unchanged between Pr and Pfr, this observation indicates migration of a proton from the chromophore of Pr to the protein moiety of Pfr. As model compounds, octaethylbiliverdin (OEBV-h3), its deuterated and 15N derivatives, and their protonated forms were also studied with both RR and 1H and 15N NMR spectroscopies. The RR spectrum of the protonated form, for which the protonation site was determined to be C-ring pyrrole nitrogen by NMR, displayed a deuteration shift corresponding to that of Pr, suggesting a similar protonated structure for the pyrrolic rings of Pr. The RR spectral difference between OEBV-h3 and OEBV-d3 and that between H2O and D2O solutions of Pfr suggested that the N-H protons of the A-, B-, and D-rings of intact phytochrome are replaced with deuterons in D2O. A role of the 7-kDa segment of phytochrome is discussed on the basis of RR spectral differences between the intact and large phytochromes.

Calcium binding proteins: purification of hepatocalcin-55 from bovine liver.

1. Bovine liver was homogenized and the proteins were fractionated by two DEAE-Sephadex steps and a gel filtration. 2. All 150 fractions collected from the DEAE-Sephadex column were electrophoresed and combined to give ten groups of proteins with different SDS-electrophoresis patterns. 3. Fractions G and H, showing fast migrating proteins, were transblotted to a polyvinylidenedifluoride membrane. By incubation with 45CaCl2 and subsequent autoradiography one protein revealed strong calcium binding. 4. This protein, named hepatocalcin-55, was obtained in a pure form from the gel filtration through Sephadex G-75. The molecular weight (55,000) was determined by gel filtration. Since SDS electrophoresis shows one protein band at Mr = 27,000 the native hepatocalcin must be a dimer. Its isoelectric point was found to be at 4.9. 5. Gamma-carboxyglutamate could not be detected in alkaline hydrolyzates of the protein under study. No carbohydrates were found in the hepatocalcin.