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Results for “Liver Neoplasms, Experimental”

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[Features of the biosynthesis of immunoglobulin G peculiar to the growth process].

It is established that with partial hepatectomy, Shvets leukosis and hepatoma RS-1 the biosynthesis intensity of rat blood serum proteins producing aggregates in the acid medium is considerably higher than that of other serum proteins, the incorporation of the radioactive precursor into immunoglobulin G peculiar to intensive normal and malignant growth being particularly intensive. During liver regeneration as well as in malignant growth specific radioactivity of immunoglobulin G peculiar to the growth processes is three and five times, respectively, as high as this value for blood serum soluble proteins and proteins of alpha-globulin fractions.

Alpha-Globulins↗
PubMed1983

Characterization and analysis of oncofetal tRNA and its possible application for cancer diagnosis and therapy.

We determined the primary structures of various tumor-specific tRNAs as well as of their normal counterparts by postlabeling RNA-sequencing procedures. The results clearly indicated that tumor-specific tRNAs are mostly formed by undermodification of hypermodified nucleosides located in the anticodon loop: no new tRNA transcripts have so far been found in tumor cells. Among the modified nucleosides affected by tumorigenesis, queuosine and Y base are the most interesting. In various tumor tRNAPhe species, hydroxy Y base located next to the anticodon is undermodified to form hypomodified hydroxy Y base lacking methyl and carboxymethyl groups. This Y base analog should be a good marker for analyzing the state of cancer cells. Queuosine, located in the first position of the anticodon, is partly or completely replaced by guanosine in all tumor cells tested so far. The amount of G-tRNA decreased markedly when the cells differentiated into mature erythroid cells, with concomitant increase of Q-tRNA. This indicates that the presence of G-tRNA is closely related to the state of the cells, not merely to the fast growth rate of tumor cells. The enzyme tRNA-guanine transglycosylase, which is a key enzyme in biosynthesis of queuosine in tRNA (inserting Q base into tRNA by a transglycosylase reaction), is active in both tumor cells and normal cells. Administration of chemically synthesized Q base to tumor-bearing mice resulted in complete conversion of G-tRNA to Q-tRNA in tumor cells, indicating that exogenously added Q base is effectively incorporated into G-tRNA. Various Q base analogs that can be used as substrates for tRNA-guanine transglycosylase were synthesized chemically. These compounds may be used for clinical cancer diagnosis, since they should be incorporated selectively into tRNA in tumor cells. In addition to use as cancer chemotherapeutic reagents, it should be possible to develop new Q base analogs that induce miscoding or blocking of protein synthesis after insertion into G-tRNA.

Animals↗
PubMed1983

The role of partial hepatectomy and of promoters in the formation of tumors in non-target tissues of trans-4-acetylaminostilbene in rats.

After repeated administration of trans-4-acetylaminostilbene to rats, DNA-bound metabolites accumulate to the greatest extent in liver and kidney, which are considered to be nontarget tissues for this carcinogen. To test whether the persistent DNA adducts represent procarcinogenic lesions, an initiation-promotion experiment was carried out using trans-4-acetylaminostilbene as an initiator and phenobarbital, DDT and diethylstilbestrol as promoters. In addition, partial hepatectomy was performed in some groups. Partial hepatectomy alone or in combination with promoters led to the formation of preneoplastic enzyme deficient foci, hyperplastic nodules and hepatoma in great yields. In addition, mammary tumors were observed with diethylstilbestrol promotion. The results support our proposal that aminostilbene derivatives produce procarcinogenic DNA-lesions in many, if not all, tissues and that secondary factors determine when and where tumors arise.

Adenoma, Bile Duct↗