Antigenic heterogeneity of human lung cancers.

Antigenic reactivity of 35 perchloric acid (PCA) extracts of different histologic human lung cancer tissues was studied--in comparison with the reactivity of the carcinoembryonic antigen (CEA), the nonspecific cross-reacting antigen (NCA), and alpha-1-antichymotrypsin--with the use of specific immune sera against PCA extracts of lung squamous cell carcinoma, and anti-CEA, anti-NCA, and anti-alpha-1-antichymotrypsin sera. The following antigenic systems were found in lung cancers: a) antigens specific for most squamous cell cancers and adenocarcinomas, which are undetectable in small cell cancers; b) NCA-type antigens; c) CEA-like antigens; and d) the antigen responsible for alpha-1-antichymotrypsin reactivity. A considerable antigenic heterogeneity among lung cancers indicates the necessity for precise histopathologic verification of individual lung cancer cases before commencement of immunologic studies and purification of antigens specific for lung cancers.

Regulation and molecular characterization of dopamine D2 receptors in a prolactin-secreting 7315a anterior pituitary tumor.

The regulation and molecular properties of the dopamine (DA) D2 receptors were compared in the prolactin-secreting 7315a anterior pituitary tumor with those in the striatum of rats. Chronic treatment with haloperidol increases the maximal binding for [3H]spiroperidol in tumor and striatum, but the percent increase is much higher in tumor than in striatum. Photoaffinity labelling of DA D2 receptors with N-(p-azido-m-[125I]iodophenethyl)spiperone ([125I]N3-NAPS) yielded a major specifically labeled peptide with the Mr of 32-34 kDa in tumor, and two specifically labeled peptides with Mr of 32-34 and 92-94 kDa in striatum. The analysis of DA D2 receptor mRNA shows that the size is similar in tumor and striatum. The DA D2 receptor mRNA in tumor is very low and chronic treatment with haloperidol produces a considerable increase of the specific mRNA. It is postulated that the reported defect in regulation of prolactin release by DA agonists might be due to posttranslational changes in the tumor DA D2 receptor.

Preliminary immunologic characterization of glycoprotein antigens (CEA) of tumors of gastrointestinal tract in humans.

Using the method of double diffusion in agar and precipitation, inhibition test and specific antitumor immune sera, perchloric extracts of carcinomas of the stomach and lower parts of the gastrointestinal tract were found to contain a carcinoembryonic antigen with electrophoretic mobility of gamma-globulins. Antigens from carcinomas of all studied parts of the gastrointestinal tract (stomach, sigmoid, colon and rectum) gave lines of identity in the test of double diffusion in agar. This antigen was not demonstrable in the mucous membranes surrounding the carcinomas of the gastrointestinal tract or in normal organs (gastrointestinal mucosa, liver, kidneys, spleen, plasma), or in perchloric extracts of gastrointestinal tissues of human fetuses.

Differences in the purification effect of carcinoembryonic antigen (CEA) from the three different hepatic metastases of rectum carcinoma.

Carcinoembryonic actigen (CEA) was purified from three liver metastases of carcinoma recti by a conventional procedure involving perchloric acid extraction of tumor tissue and fractionation of the extract by gel filtrations on Sepharose 4B and Sephadex G-200. The preparations obtained showed a different degree of heterogeneity in SDS-polyacrylamide gel electrophoresis and crossed immunoelectrophoresis, and also a different antigenic activity. One of preparations obtained was a homogeneous CEA by all these criteria, and two others showed heterogeneity and lower antigenic activity. The most heterogeneous CEA preparation was further purified by the affinity chromatography on Concanavalin A-Sepharose 4B and by DEAE-Sephadex A-50 chromatography and the usefulness of these procedures for purification of CEA is compared.

Conformation of d(CpG) modified by the carcinogen 4-aminobiphenyl: a combined experimental and theoretical analysis.

The change in DNA conformation produced by the attachment of a reactive substance is likely to be a vital factor in determining the biological consequences of the reaction. We have prepared a deoxydinucleoside monophosphate containing the major adduct derived from the carcinogenic amine 4-aminobiphenyl and analyzed its conformation by theoretical and experimental methods. Reaction of d(CpG) with N-acetoxy-N-(trifluoroacetyl)-4-aminobiphenyl afforded the product modified at C-8 of guanine with 4-aminobiphenyl. After purification by reverse-phase high-performance liquid chromatography, milligram amounts of product were obtained. It was analyzed by circular dichroism, proton magnetic resonance, and minimized potential-energy calculations. A flexible molecule with a mixture of conformers is indicated. Both carcinogen-base-stacked states and base-base-stacked states, with guanine both syn anti, contribute to the population mixture on the dimer level. The global minimum-energy conformation has syn-guanine and carcinogen-base stacking. Forms of this type are calculated to represent roughly 58% of the conformer population. Because of the twisted nature of the biphenyl moiety, carcinogen-base stacking inherently involves less overlap than that in the planar and rigid three-ringed aminofluorene analogue. This difference might relate to the diminished effectiveness of the aminobiphenyl vs. the aminofluorene adduct as a frameshift mutagen in Salmonella typhimurium 1538.

Tyrosine hydroxylase mRNA expression by dopaminergic neurons in culture: effect of 1-methyl-4-phenylpyridinium treatment.

To enable us to study expression of tyrosine hydroxylase [TH; tyrosine 3-monooxygenase; L-tyrosine tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] as a measure of dopaminergic neuron function in future experiments, methods were developed to quantify TH mRNA levels in cultures of dopaminergic mesencephalic cells. The model of selective dopaminergic toxicity of 1-methyl-4-phenylpyridinium (MPP+) was used to verify the specificity of our methods. Fetal (embryonic day 15) rat ventral mesencephalic cell cultures were treated with 15 microM MPP+ for 48 h, conditions previously shown to reduce the number of TH-immunoreactive neurons, TH activity, and dopamine uptake to 5-10% of control values. This treatment decreased the number of neurons labeled by TH in situ hybridization to 9% of untreated controls and caused a strong reduction of the abundance of TH mRNA in Northern blots. Our findings establish TH mRNA expression as a parameter for future studies of toxic and trophic effects on cultured dopaminergic neurons, and they support the view that MPP+ destroys dopaminergic neurons.