Immunohistology of the antigenic pattern of a continuous cell line from a human colon tumor.

The antigenic surface pattern of a continuous cell line (HT29) derived from a human primary carcinoma of the colon was studied by the immunofluorescence technique. Monovalent and polyvalent immune sera were used. The cells of this long-term culture kept the ability to synthesize the three principal colon tumor antigens: carcinoembryonic and nonspecific cross-reacting antigens, and the membrane-associated tissular autoantigen. On the HT29 cells, which still carry the original blood group of the tumor donor, no receptors for human Ig's were detected.

Promoting effect of biliverdin for liver cells initiated by aflatoxin B1.

In this paper we have studied the participation of biliverdin, a bile pigment produced from hemoglobin catabolism, in a two-stage carcinogenesis model using hepatic cells in culture. The initiation was realised by a short term exposure to low doses of aflatoxin B1. The cells were then cultivated in the presence of biliverdin in the medium. We observed that biliverdin increased the rate and the efficiency of neoplastic transformation of cells. These results suggest that biliverdin may act as a promoting substance.

Effects of PR toxin on liver cells in culture.

We studied the effects on liver cells in culture of PR toxin, a substance produced from Penicillium roqueforti. PR toxin displayed cytotoxicity which increased as a function of its concentration but the form of such toxicity differed, depending on the toxin's concentration. Thus, cells only underwent quick retraction and intensive vacuolization when treated with low drug concentrations, and they came away from the substrate easily under these conditions. By contrast, the major events observed in the case of high concentrations were loss of structure of the nuclei and strong adhesiveness of dead cells to the support. PR toxin already inhibited cell multiplication at low concentrations and became toxic when the concentration was raised; growth inhibition decreased but the toxic effect increased when cells passed from the exponential growth phase to a phase of slower growth. PR toxin inhibited tritiated precursor incorporation into DNA, RNA and proteins in a similar time and concentration-dependent manner. Inhibition of DNA synthesis persisted even after removal of the drug from the medium.

Cytostatic effects of T2 toxin on cultured human neoplastic cells of intestinal origin.

The cytostatic effects of T2 toxin, a sesquiterpenoid mycotoxin produced by some Fusarium strains, were studied on cultured human cells originating from rectal and colonic tumors (HRT18 and HT29). These cells were found to be sensitive to doses of the order of 0.1 to 1 ng/ml medium. Duration of treatment influences the reversibility of cytostatic effect. Brief treatments (1 to 6 hours) at a non toxic concentration of 10 ng/ml induce a cytostatic effect of 24 hours duration, which is reversible after this period. Longer treatments (24 hours or more) induce a cytostatic effect not reversed 3 days after removal of toxin. T2 toxin thus appears to have, in vitro, a powerful cytostatic effect.

[Relationship between the growth rate of the liver of young rats and the inhibitory effect of extracts of their liver on the multiplication of cultured cells]. / Relation entre la vitesse de croissance du foie de jeunes Rats et laction inhibitrice d'extraits de leur foir sur la multiplication de cellules en cultures

We have shown that extracts of liver from young Rats are less active, than extracts of liver from adult Rats, in inhibiting the multiplication of cells in culture. This inhibitory activity is at a minimum in livers taken from 10 to 15 days old Rats, which corresponds to the time of maximum increase in weight of the liver. The existence of an inverse relationship between the inhibitory activity of these extracts and the state of proliferation of the liver suggests that the inhibitory substance contained in the liver extracts may act as a regulator of growth of the organ.

Control of cell multiplication: preparation and immunological comparison of inhibitory factors in the homogenate and perfusate of the adult rat liver.

The control of organ cell multiplication by a negative feed-back mechanism implies that factors of the inhibitory mechanism are present in the blood and are produced by the target organ itself. We have examined the inhibitors which are present in the cytosol of adult rat liver as well as in efferent fluid from an isolated perfused organ. These two materials yielded predominantly protein molecules having in common a molecular weight of approximately 80 000 daltons and an isoelectric point between pH 8 and 9. They inhibit both the multiplication of LF hepatoma cells in vitro and the DNA synthesis in the remnant liver following partial hepatectomy in rats. The inhibitors were compared immunologically. When antibodies against the cytosol inhibitor were tested with the Ouchterlong technique against either the original antigen or the inhibitory fraction isolated from the perfusion effluent, a common precipitation line appeared. The inhibitory activity of both the cytosol and the perfusate was neutralized by prior incubation with anti-cytosol antibodies. These results, which strongly suggest a common inhibitor in the cytosol and the perfusate, strongly support the hypothesis of a feed-back mechanism for the control of liver cell proliferation.

An inhibitor of hepatoma cells multiplication in the efferent fluid from isolated perfused rat liver.

Efferent fluid from isolated rat livers perfused with a synthetic medium, when concentrated, inhibits the multiplication of hepatoma LF 20 cells "in vitro". The inhibitory factor is thermolabile, and is inactivated at a slow rate by proteolytic enzymes. Sephadex and Acrylamide-agarose chromatographic fractionation leads us to assume a molecular weight around 100,000 for the inhibitory factor. The release of the factor by the perfused liver depends on the temperature of the perfusing fluid. Potential role of this factor in the control of liver cell proliferation is discussed.

Use of a permanent cell line extracts to study the tumor associated immune reactions in colorectal cancer patients by leucocyte migration inhibition test.

Crude extracts of colorectal surgical tumors, either individual or pooled, and HT29 line cells were compared in leucocyte migration inhibition test. HT29 cell extract gave more positive reactions with leucocytes of colorectal cancer patients than the other ones, and less with control leucocytes. It was thus used for all the subsequent experiments. As a whole, we obtained 44% (30/68) of positive inhibitions in patients afflicted with a colorectal carcinoma, against 9% (3/31e in normal controls and 20% (8/40) in patients bearing a carcinoma from another organ. Among the latest patients, those having a gynecological carcinoma were rarely positive, contrasting with those suffering from a carcinoma from the aerodigestive organs. It seemed that the antigen(s) involved in the reaction had no organ specificity, but rather a broad tissue specificity.

[Inhibiting effects of protein fractions isolated from the rat liver in compensating hypertrophy after partial hepatectomy]. / Activité inhibitrice de fractions protéiques isolées du foie de rat sur l'hypertrophie compensatrice après hépatectomie partielle

We have purified from adult rat liver proteic fractions, which inhibit the cellular growth of cell cultures. These fractions, when they are injected into hepatectomised rats, were able to inhibit the entry of hepatic cells into phase S. Therefore we consider that these substances participate actively in homeostatic control in adult liver.

Leucocyte-migration-inhibition test in patients with colorectal cancer: clinicopathological correlations.

Leucocyte-migration-inhibition test was used to study the immune reactions of leucocytes from 136 colorectal cancer patients, 43 patients with non-cancerous chronic colorectal diseases and 82 controls, with saline extracts of HT29 line. A positive inhibition was found in only 43% of colorectal cancer patients. It was higher in carcinomas of limited extension than in invasive ones (64% against 39%). Furthermore, operation by itself had a depressive effect on the reaction, as the positivity in 25 patients tested twice was 64% before operation and 32% after. Leucocytes from patients with non-cancerous chronic colorectal diseases gave many positive reactions (65%). The percentage of positivity was about the same for diseases with high, low or no risk of cancerization. Hence the antigen(s) of tumour extracts that react with patient's leucocytes are, at least partially, unrelated to cancer.

Progression of spontaneous malignant transformation of epithelial rat liver cell lines.

Cultured epithelial cell lines from normal rat livers were shown to undergo gradual transformation and malignancy which increased with time. Morphological changes appeared both before and after cells had attained a malignant state, as detected by agar tests. The progression of the degree of malignancy was determined by the morphological appearance of the cells, the increase in the number and size of cell colonies in soft agar, the expression of gamma glutamyl transferase (gamma GT) and the shortening of the latency period necessary for tumor formation after transplantation to syngeneic rats of cells from sequential passages.

Cytotoxic and cytostatic effect of T2-toxin on epithelial cell lines derived from rat liver.

Cytotoxic and cytostatic effects of T2-toxin (Fusarium mycotoxin) on cells in culture derived from rat hepatomas and rat livers were investigated. Results showed that these effects appeared to be dependent on both drug concentration and duration of drug exposure. Non-transformed, as well as spontaneous neoplastic transformed liver cells and hepatoma cells were sensitive to its effect. T2-toxin had no selective action on cancer cells; however, a progression appeared in sensitivity to the toxic effect as a function of the degree of tumorigenicity of the cell line. This progression dis not exist for the cytostatic effect, which remained only in relation to the degree of proliferation of the cells in culture.

Effects of retinoic acid on the transformation and metabolic cooperation of rat liver cells in vitro, and on the growth of hepatoma cells in vivo.

By different experimental approaches in culture, we obtained convergent responses to 13 cis-retinoic acid (RA) in rat liver epithelial cell lines. We showed that the degree of transformation of the cells which had already been spontaneously transformed in culture, could be enhanced, since the capacity of these cells both to grow in soft agar and to express gamma-glutamyl transpeptidase increased markedly. We also showed that RA acted synergistically with a promoter, 12-tetradecanoyl-phorbol-13-acetate (TPA), as regards the promoter's property of blocking the metabolic cooperation between cells. RA did not, however, trigger cell transformation in the lines which had not yet been transformed, and unlike TPA, did not by itself inhibit intercellular communications. On the other hand, in our in vivo experiments, it appeared that RA, by slowing down the growth of a transplanted rat hepatoma, might have a slightly protective effect against tumour development.

Maintenance and reversibility of active albumin secretion by adult rat hepatocytes co-cultured with another liver epithelial cell type.

When adult rat hepatocytes were co-cultured with another liver epithelial cell type in a medium supplemented or not with fetal calf serum (FCS), it was found that 1. They survived for more than 2 months 2. Albumin secretion levels remained high over the whole culture period 3. Decreased secretion might be reversed 4. This protein secretion activity appeared to be dependent upon both the presence of cell-cell contacts and the production of an extracellular material. The results demonstrate for the first time long-term stabilization and reversibility of a specific function (albumin secretion) at high levels by adult hepatocytes cultured in serum-free medium and suggest that both the presence of other liver cell type(s) and the production of an extracellular matrix are needed for the maintenance of specific functions in cultured hepatocytes.