Tumours, experimentally-induced

Lettre and Fernholz have tested a series of colchicine derivatives, including a group of alkylcolchiceines, on experimentally induced tumours all proved to be less potent than the parent alkaloid. A -Acetyl-j3-p-anisyl-y-(3 4 5-trimethoxyphenyl)-propylamine,... 

L-Asparaginase, an enzyme derived from E. coli or Erwinia carotovora, has been employed in cancer chemotherapy where its selectivity depends upon the essential requirement of some tumours for the amino acid L-asparagine. Normal tissues do not require this amino acid and thus the enzyme is administered with the intention of depleting tumour cells of asparagine by converting it to aspartic acid and ammonia. Whilst L-asparaginase showed promise in a variety of experimentally induced tumours, it is only useful in humans for the treatment of acute lymphoblastic leukaemia, although it is sometimes used for myeloid leukaemia. 

Up to now only incomplete and provisional data have been obtained on the modification of host resistance against tumours and infections. Nevertheless, we shall report some examples illustrating the usefulness of the two lines of mice for the study of the mechanisms of host resistance The dissociation of humoral and cell mediated immunity characterizing the two lines would permit evaluation of the relative importance of each type of response in the resistance against experimentally induced diseases. 

Levicar N, Dewey RA, Daley E, Bates TE, Davies D, Kos J, Pilkington GJ, Lah TT (2003) Selective suppression of cathepsin L by antisense cDNA impairs human brain tumor ceU invasion in vitro and promotes apoptosis. Cancer Gene Ther 10 141-151 Levicar N, Strojnik T, Kos J, Dewey RA, Pilkington GJ, Lah TT (2002) Lysosomal enzymes, cathepsins in brain tumour invasion. J Neurooncol 58 21-32 Li F, Ackermann EJ, Bennett CF (1999) Pleiotropic cell-division defects and apoptosis induced by interference with survivin function. Nat Cell Biol 1 461 66 Lopes MBS, VandenBerg SR, Scheithauer BW (1993) The World Health Organization classification of nervous system tumors in experimental neuro-oncology. In AJ Levine and HH Schmidek, eds Molecular Genetics of Nervous System Tumors. Wiley-Liss, New York, NY, pp 1-36... 

The term carcinogen denotes a chemical substance or a mixture of chemical substances which induce cancer or increase its incidence. Substances which have induced benign and malignant tumours in well performed experimental studies on animals are considered also to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans. 

There are some experimental evidences that the control of iron ameliorates the outcome of a grave inflammatory process. For instance, in a model system of sepsis induced in mice by the injection of lethal doses of lipopolysaccharide (LPS), the pre-treatment with desferal caused the reduction of tumour necrosis factor alpha (TNF-a) serum levels and an increase in the rate of survival [ 17], Nonetheless there are very few studies in this area. 

Experimental infection of animals has shown that certain viruses can induce cancer. This oncogenic activity can also be demonstrated in vitro in cell cultures. Cells surviving viral infection can change dramatically, acquiring the characteristics of tumour cells. These transformed cells exhibit frequent mitosis. They also lose the property of cell contact inhibition, so they tend to pile up on top of each other rather than remaining as organized monolayers. 

McClain, R.M. ( 990). Mouse liver tumours and microsomal enzyme inducing drugs. Experimental and Clinical perspectives with phenobarhital. In Mouse Liver Carcinogenesis. Mechanisms ond Species Comparison, pp, 345-365. 

Group III includes moderate carcinogens. These are many substances inducing tumours in a smaller fraction of experimental animals (up to 20%) and during their long-term action, i.e. in the second half of the life of these animals. Their carcinogenic effects on the man are still a matter of debate. 

The specific effect of beryllium in DNA metabolism may be highly relevant in the elucidation of its experimentally demonstrated carcinogenic action. Primary tumours of the lung in rats typically occur 8 months after intratracheal application. Either a single tumour or multiple tumours may be formed. Histologically those are adenomas, less frequently epitheliomas. By the action on beryllium, certain enzymes were affected, as in other experiments on animals, where the cancer disease was induced by different... 

Simpson KJ, Lukacs NW, McGregor AH, Harrison DJ, Strieter RM, Kimkel SL (2000) Inhibition of tumour necrosis factor alpha does not prevent experimental paracetamol-induced hepatic necrosis. J Pathol 190 489-494... 

Substance P also plays a role in neurogenic inflammation of experimental arthritis and can induce the release of IL-1, tumour necrosis factor, and IL-6 from monocytes [72]. Enkephalinase has been detected in the synovial fluid from arthritic joints [54] suggesting that it may play a balancing role in the pro-inflammatory process of various neuropeptides and cytokines in the joint. 

Tanaka S, Akaike T, Fang J, Beppu T, Ogawa M, Tamura F, Miyamoto Y, Maeda H. Antiapoptotic effect of haem oxygenase-1 induced by nitric oxide in experimental solid tumour. Br J Cancer 2003 88 902-909. 

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