Microbial transformation of azacarbazoles. IV. Conversion of chloro-substituted alpha-carbolines by Kitasatosporia setae strain

Biotransformation of alpha-carboline derivatives substituted at positions C-5, C-6, C-7 and C-8 with chlorine, carried out with Kitasatosporia setae strain yielded corresponding 1-methyl-alpha-iso-carbolines. The formation of products is dependent on the position of chlorine in substrate molecule. When chlorine is introduced at C-6, the yield of N-1 methylation is low, about 5%. Derivatives of alpha-carboline substituted with chlorine at C-7 and C-8 form corresponding alpha-iso-carbolines with yield up to 20% and 30%, respectively, whereas 5-chloro-alpha-carboline is converted into 5-chloro-1-methyl-alpha-iso-carboline with 60% yield. Apparently, additional pathway of microbial transformation of 2-chloro-alpha-carboline has been found. Primarily formed 2-chloro-1-methyl-alpha-iso-carboline subjected to complex enzymic conversion yields quantitatively 2-methoxy-1-methyl-alpha-iso-carboline-9-N-oxide. It has been found that 2-chloro-1-methyl-alpha-iso-carboline exhibit strong cytotoxic activity, against KB cells tissue culture, ID50 = 0.01 microM/ml and inhibits growth of Kitasatosporia setae strain, MIC = 0.5 microM/ml. Toxicity of formed 2-methoxy-1-methyl-alpha-iso-carboline-N-9-oxide is markedly lower, ID50 = 0.3 microM/ml and MIC = 3.5 microM/ml. The remaining C-5, C-6, C-7 and C-8 chloroderivatives of alpha-iso-carboline occur to be less active than 2-chloro-1-methyl-alpha-iso-carboline.     

Microbial transformation of azacarbazoles. II. Conversion of methyl-substituted alpha-carbolines to corresponding alpha-iso-carbolines by Kitasatosporia setae strain

alpha-Carboline derivatives substituted with methyl groups at C-2, C-4, C-2,4, C-6 and C-8 position were subjected to N-1 methylation performed by Kitasatosporia setae. The yield of formed corresponding alpha-iso-carbolines varied, depending on the position of methyl substituent. It has been observed that the methyl group introduced in position C-2 and C-6 of alpha-carboline molecule markedly diminishes the susceptibility of nitrogen for enzymic attack in comparison with methylation reaction performed with methyl iodide. On the contrary, derivatives possessing methyl groups in positions C-4 and C-8 are methylated by chemical and microbial means with approximately the same yield. The obtained alpha-iso-carbolines appeared to be toxic to the transforming Kitasatosporia setae strain at the concentration range of 0.2-2.5 microM/ml. Taking into account that the MIC values of parent alpha-carbolines estimated for Kitasatosporia setae were much higher than 2.5 microM/ml, this finding seems to be out of the accordance with the general belief that the microbial conversion of xenobiotics is only a detoxification process. Apparently, 4-methyl and 2 -dimethyl substituted alpha-iso-carbolines besides of their antimicrobial properties, displayed strong cytotoxic activity against KB cells line at the concentration range 0.03-0.05 microM/ml.     

Microbial transformation of azacarbazoles. V. Studies on N-1 methylation of 4-methyl-alpha-carboline by Kitasatosporia setae strain

N-1 methylation of an azacarbazole, 4-methyl-alpha-carboline by Kitasatosporia setae was associated with antifungal metabolite production. Incubation of 4-methyl-alpha-carboline with intact cells or homogenates of Kitasatosporia setae and L-/14CH3/-methionine or adenosyl-S-/14CH3/-L-methionine yielded radioactive products, 1,4-dimethyl-alpha-iso-carboline. The presence of 14C-labelled methyl groups in antifungal metabolite has been also observed. Mutants of Kitasatosporia setae with lost abilities to produce antifungal metabolite did not convert 4-methyl-alpha-carboline into its methyl derivative.     

Microbial transformation of azacarbazoles. VIII. Production of 14C-labelled benzo-alpha-iso-carbolines by permeabilized cells of Kitasatosporia setae strain

N-1 methylation of benzo-alpha-carbolines performed with Kitasatosporia setae strain yields corresponding benzo-alpha-iso-carbolines, compounds demonstrating relatively strong cytostatic and antitumor properties. To obtain radioactive benzo-alpha-iso-carbolines required for the further studies of their mode of antitumor action, a simple and useful method of the preparation of 14C-labelled compounds by microbial means has been elaborated.     

Microbial transformation of azacarbazoles. VII. Antitumor properties of benzo-alpha-iso-carbolines formed by Kitasatosporia setae strain from corresponding benzo-alpha-carbolines

2,3-Benzo-alpha-carboline, 7,8-benzo-alpha-carboline and their 4-methyl derivatives were subjected to microbial conversion yielding corresponding benzo-alpha-iso-carbolines. All obtained products showed significant antimicrobial and cytotoxic properties. ID50 values were found to be at range 0.01-0.001 microM/ml, regarding in vitro KB tumor cells system data. It has been found that introduction of methyl group at para-position to the nitrogen of pyridine nucleus strongly increases cytotoxic and microbial activity of benzo-alpha-iso-carbolines. Apparently it has been indicated that antitumor activity of benzo-alpha-iso-carbolines is strongly dependent on shape and size of the molecule. Of all the compounds tested only 2,3-benzo-1,4-dimethyl-alpha-iso-carboline increases life span of leukemia P388 bearing mice up to 160%.     

Microbial transformation of azacarbazoles. III. Conversion of methoxy- and phenyl- substituted alpha-carbolines to corresponding alpha-iso-carbolines by Kitasatosporia setae strain

Microbial N-1 methylation of alpha-carboline derivatives substituted at position C-2, C-6 and C-8 with methoxy- and at position C-2 and C-6 with phenyl groups conducted with Kitasatosporia setae resulted in corresponding alpha-iso-carboline formation. The yield of obtained products is significantly dependent on the position of substituent in alpha-carboline molecule. Compounds, as 2- and 6-methoxy-alpha-carboline undergo N-1 microbial methylation with strikingly low yields of 5%, whereas products of biotransformation of 8-methoxy-alpha-carboline was formed in markedly higher amount, about 50%. Similar correlations were observed for subjected to bioconversion C-2 and C-6 phenyl-alpha-carbolines. The yields of formed products were estimated as 3% and 5%, respectively. All obtained alpha-iso-carbolines were found to be toxic to the transforming strain of Kitasatosporia setae at the range of 1.2-2.5 microM/ml as well as against KB tumor culture cells (ID50 0.04-0.6 microM/ml).     

Kitasatosporia setae, an interesting actinomycete strain isolated from Spitsbergen soil

The phenotypic and genotypic properties as well as cell chemistry of an interesting actinomycete, which converted certain azacarbazoles into highly cytotoxic derivatives, were established. The strain was also compared with two similar Japanese actinomycetes of Kitasatosporia gen. nov. A great resemblance between the strains was observed. Apart from similar phenotypic properties they were characterized by contents of both L- and meso-DAP, glycine and galactose as the main cell wall components. They proved to have the same phospholipid, glycolipid and fatty acid patterns. The guanine-plus-cytosine contents of the deoxyribonucleic acids of the strains averaged 72.5 and there was a high degree of homology between the DNAs of the strains (approximately 80%). These data provide evidence that the Spitsbergen isolate and the Japanese actinomycetes belong to one genomic species.     

Microbial transformation of azacarbazoles. VI. Conversion of 6-hydroxy- and 6-amino-alpha-carbolines with copper oxidases

alpha-Carboline substituted at C-6 with hydroxy-group is oxidized by human ceruloplasmin and fungal laccase into reactive intermediate which dimerizes, while 6-amino-alpha-carboline subjected to action of both enzymes yields the polymeric products. To prepare sufficient quantities of compounds needed for structure elucidation studies, laccase, immobilised in polyacrylamide gel was employed as a convenient reagent. The resulting products are suggested to be metabolities of 6-hydroxy- and 6-amino-alpha-carbolines formed in vivo.     

Microbial transformation of azacarbazoles. IX. Preliminary studies on hydroxylation of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline by Paecilomyces flavinosus

Microbial transformation of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline performed with several strains of fungi Beauveria bassiana, Verticillum lecani and Paecilomyces flavinosus yielded common products which were expected to be hydroxylated derivatives of starting compound. Among the microorganisms tested, strain Paecilomyces flavinosus P-5 was selected to perform quantitative bioconversion of 2,3-benzo-1,4-dimethyl-alpha-iso-carboline for preparative scale.     

Conservativity of three-dimensional structures of alpha-, beta- and gamma-interferons

Using the method of estimation of alpha-helical and beta-folded types of secondary structure from amino acid composition, it has been established that interferon-gamma (IFN-gamma) contains about 50-70% of alpha-helical and no more than 10-20% of beta-structure. The same result was obtained using empirical and stereochemical rules for the prediction of protein secondary structure from amino acid sequence. Packing of alpha-helical segments of IFN-gamma into 1 of the 2 three-dimensional structures previously suggested for IFN-alpha and IFN-beta, allowed to detect high conservativity of the hydrophobic core of the proteins compared. On this basis a tentative conclusion has been drawn that all interferons have, in general features, a similar globular alpha-helical conformation.     

Antineoplastic activity of azacarbazoles. I. Synthesis and antitumor properties of alpha-carboline and its selected derivatives

alpha-Carboline and its several derivatives have been synthesized and evaluated for their antitumor activity against L1210 lymphoid leukemia, P388 lymphocytic leukemia and Sarcoma 180. It was found that of these compounds only alpha-carboline and its derivatives substituted in C-4 position with a methyl group or in 6-C position with a methyl group and fluorine or chlorine atoms caused moderate inhibition of the tumor growth of Sarcoma 180. The introduction of bromide, iodide atoms, hydroxy-, amino-groups or some other substituents in C-6 position of alpha-carboline molecule reduced significantly the biological activity of the tested compounds against Sarcoma 180. Additionally, the introduction of an ethyl or ethoxycarbonyl group to the pyrrole ring at N-9 also obliterated antitumor properties of these analogues. None of the tested compounds displayed a significant activity against murine leukemias. In the cytotoxicity test of KB cells all the compounds were inactive.     

Expression of E-cadherin and alpha-, beta-, gamma-catenin proteins in endometrial carcinoma

Loss of the cell adhesion molecule E-cadherin is suggested to promote tumor invasion and distant metastasis in tumor development. Recently, it has been proposed that E-cadherin function requires its linkage to the cytoskeleton through catenins. We evaluated the expression of E-cadherin and alpha-, beta-, gamma-catenins in tissues of human endometrial carcinoma, analyzed the patterns of cell adhesion molecules' expression in endometrial carcinoma and investigated the relationship between the statuses of cell adhesion molecules and various clinicopathological factors. This study investigated the immunohistochemical expression of E-cadherin and alpha-, beta-, gamma-catenins in 33 paraffin embedded formalin fixed tissues of endometrial carcinomas. Aberrant E-cadherin, and alpha-, beta-, gamma-catenin expression was observed in 33.3 (11 of 33), 27.3 (9 of 33), 18.2 (6 of 33), and 51.5 (17 of 33) % of the specimens, respectively. Statistically significant correlation was found between aberrant expression of E-cadherin and lymph node metastasis and cell types other than endometrioid adenocarcinoma. Aberrant pattern of gamma-catenin expression was also correlated with deep myometrial invasion. However, alpha-, and beta-catenin expression was not correlated with any clinicopathological parameters. Using the Kaplan-Meier method and log-rank comparison test, abnormal expression of E-cadherin was correlated closely with poor survival (p < 0.05), but cases with loss of both E-cadherin and catenin expression predicted even poorer survival than cases with only one or no aberrant expression in E-cadherin and catenins. We revealed aberrant expression of these cell adhesion molecules among patients with endometrial carcinoma. Aberrant expression of E-cadherin was correlated with lymph node metastasis and cell types other than endometrioid adenocarcinoma, while aberrant expression of gamma-catenin was related with deep myometrial invasion. The expression of E-cadherin might be a possible prognostic factor for endometrial cancer while the expression of catenins may help predict patient's survival.     

Differential localization of alpha-, beta- and gamma-synucleins in the rat CNS

Alpha-synuclein is a presynaptic protein that normally participates in the homeostasis of synaptic vesicles. Missense mutations in its gene cause the protein to participate actively in the development of heritable forms of Parkinson's disease. Moreover, its metabolism is perturbed in all cases of Parkinson's disease where alpha-synuclein accumulates in a filamentous form in the Lewy body nerve cell lesion. Lewy bodies also develop in other common neurodegenerative disorders, like dementia with Lewy bodies and Lewy body variant of Alzheimer's disease. In the present study, we have studied the detailed distribution of alpha-, beta- and gamma-synuclein in the rat CNS. Alpha-synuclein was not observed in perikarya, but was distributed with high intensity in nerve terminals in the caudate and putamen and ventral pallidum, where beta-synuclein was much weaker and less densely distributed in the caudate and putamen. Gamma-synuclein was not found in the caudate and putamen. Alpha-synuclein was robustly distributed in the substantia nigra pars reticulata, but was very weak or virtually absent from the perikarya of the neurons in the pars compacta. In contrast, beta-synuclein was very weak or absent from the substantia nigra. gamma-Synuclein was absent from the terminals of substantia nigra pars reticulata, but sparsely distributed gamma-synuclein-containing neurons were detected in the substantia nigra pars compacta. In the brainstem, alpha-synuclein as well as gamma-synuclein were present in the locus coeruleus with high intensity, while beta-synuclein was very weak. In addition, alpha-synuclein was intense in the vagus nucleus, but weak in the oculomotor, facial, hypoglossal, accessory and ambiguous nuclei, where beta-synuclein was very intensely present. Furthermore, gamma-synuclein was localized in the terminals and in cell bodies of the Edinger-Westphal nucleus, the red nucleus, locus coeruleus, and most cranial nerve-related nuclei. In the spinal cord, alpha- and gamma-synucleins were intensely present in laminae I and II and in the preganglionic sympathetic nuclei, whereas beta-synuclein was very weak. These results indicate that alpha-synuclein is abundant in central catecholaminergic regions. Beta-synuclein is more localized in the somatic cholinergic components, while it is particularly weak or absent from catecholaminergic neurons. Gamma-synuclein appears to be present in both cholinergic and catecholaminergic regions, but very weak in the forebrain.     

Neurodegeneration with brain iron accumulation, type 1 is characterized by alpha-, beta-, and gamma-synuclein neuropathology

Neurodegeneration with brain iron accumulation, type 1 (NBIA 1), or Hallervorden-Spatz syndrome, is a rare neurodegenerative disorder characterized clinically by Parkinsonism, cognitive impairment, pseudobulbar features, as well as cerebellar ataxia, and neuropathologically by neuronal loss, gliosis, and iron deposition in the globus pallidus, red nucleus, and substantia nigra. The hallmark pathological lesions of NBIA 1 are axonal spheroids, but Lewy body (LB)-like intraneuronal inclusions, glial inclusions, and rare neurofibrillary tangles also occur. Here we show that there is an accumulation of alpha-synuclein (alphaS) in LB-like inclusions, glial inclusions, and spheroids in the brains of three NBIA 1 patients. Further, beta-synuclein (betaS) and gamma-synuclein (gammaS) immunoreactivity was detected in spheroids but not in LB-like or glial inclusions. Western blot analysis demonstrated high-molecular weight alphaS aggregates in the high-salt-soluble and Triton X-100-insoluble/sodium dodecyl sulfate-soluble fraction of the NBIA 1 brain. Significantly, the levels of alphaS were markedly reduced in the Triton X-100-soluble fractions compared to control brain, and unlike other synucleinopathies, insoluble alphaS did not accumulate in the formic acid-soluble fraction. These findings expand the concept of neurodegenerative synucleinopathies by implicating alphaS, betaS, and gammaS in the pathogenesis of NBIA 1.     

Expression of E-cadherin-associated molecules (alpha-, beta-, and gamma-catenins and p120) in colorectal polyps.

E-cadherin and its associated cytoplasmic proteins alpha-, beta-, and gamma-catenin and p120 protein play a crucial role in the maintenance of normal tissue architecture. Perturbation in any of these molecules results in loss of intercellular adhesion and cell transformation. In this study, we have used immunohistochemistry to localize E-cadherin, alpha-, beta-, and gamma-catenin, and p120 in paraffin-embedded tissues from 60 patients with colonic polyps. Specimens consisted of 20 samples each from hyperplastic, inflammatory, and sporadic adenomatous polyps. Ten histologically normal colonic samples were also studied. Normal colonic epithelial cells showed strong E-cadherin/ catenin/p120 immunostaining at the cell-cell junction. In 65% (13/20) of adenomatous polyps, beta-catenin showed abnormal nuclear localization with increased expression and loss of membranous staining compared with the adjacent normal mucosa. In two cases (10%), gamma-catenin was seen in the nuclei. Heterogeneous p120 immunoreactivity was observed in four cases (20%), of which two also showed beta-catenin nuclear localization. Preserved membranous alpha-catenin staining was seen in all cases. E-cadherin was down-regulated in 6 of 20 (30%) adenomas with loss of cell surface staining in 3 cases. All hyperplastic and 40% (8/20) of inflammatory polyps showed weak E-cadherin expression on the surface epithelium. Similar changes in p120 expression were seen in all hyperplastic and 20% (4/20) of inflammatory polyps. There were no concomitant changes in alpha-, beta-, or gamma-catenin expression. These results indicate that changes in catenin expression and cellular localization occur early in dysplastic colonic lesions.     

Varicella-zoster virus isolates,but not the vaccine strain OKA,induce sensitivity to alpha-1 and beta-1 adrenergic stimulation of sensory neurones in culture

The reactivation of varicella-zoster virus (VZV) from its persistent state in sensory neurones causes shingles and induces severe, long-lasting pain and hyperalgesia that often lead to postherpetic neuralgia. To investigate the VZV-induced neuropathic changes, we established conditions for the active infection of sensory neurones from rat dorsal root ganglia in vitro. After 2 days of culture, up to 50% of the cells expressed viral antigens of the immediate-early and late replication phase. The intracellular calcium ion concentration was monitored in individual cells by microfluorimetry. Whereas the calcium response to capsaicin was preserved, the VZV-infected neurones gained an unusual sensitivity to noradrenaline stimulation in contrast to non-infected cells. The adrenergic agonists phenylephrine and isoproterenol had a similar efficacy demonstrating that both alpha(1)- and beta(1)-adrenoreceptors were involved. The sensitivity to adrenergic stimulation was observed after infection with different wildtype isolates, but not with the attenuated vaccine strain OKA. The lack of noradrenaline sensitivity of vaccine-infected neurones demands a structural comparison of wildtype and vaccine viruses with and without phenotype. A partial sequence evaluation (26 kb) of the European OKA vaccine strain surprisingly revealed a series of nucleotide exchanges in comparison to presumably identical OKA strains from other sources, although VZV is generally considered genetically stable. In summary, we report that the infection with wildtype VZV isolates, but not with the vaccine strain, induces noradrenaline sensitivity in sensory neurones, which correlates with clinical and experimental observations of adrenergic effects involved in VZV-induced neuralgia.     

Role of E-cadherin, alpha-, beta-, and gamma-catenins, and p120 (cell adhesion molecules) in prolactinoma behavior.

E-cadherin/catenin complex regulates cellular adhesion and motility and is believed to function as an invasion suppressor system. In a number of cancers, abnormal and reduced expression of E-cadherin/catenin complex is associated with tumor invasion and metastasis. Prolactinomas show frequent invasion on the surrounding structures, despite their histologically benign nature. Furthermore, gender-based differences in endocrine and surgical findings are found in patients with prolactinoma. To understand biological factors governing prolactinoma behavior, this study analyzed the expression of E-cadherin; alpha-, beta-, and gamma-catenins; p120; and cell proliferation marker MIB-1 labeling index in 13 invasive tumors (9 in men, 4 in women), 26 noninvasive tumors (4 in men, 22 in women), and 8 normal anterior pituitaries by immunohistochemistry. Immunostaining of E-cadherin; alpha-, beta-, and gamma-catenins; and p120 showed a membranous pattern of reactivity and generally stronger in normal pituitaries than in prolactinomas. Expression of E-cadherin and beta-catenin was significantly lower in invasive than in noninvasive prolactinomas (P <.002 and P <.005, respectively), and reduced expression of E-cadherin and beta-catenin was more frequent in invasive than in noninvasive prolactinomas (P <.001 and P <.05, respectively); in contrast, gamma-catenin expression showed higher in invasive than in noninvasive prolactinomas (P <.05). Expression of E-cadherin was significantly lower in macroprolactinomas than in microprolactinomas (P <.01), and decreased expression of E-cadherin and beta-catenin predicted high MIB-1 expression (P <.05). Moreover, the expression of E-cadherin and beta-catenin was significantly lower in macroprolactinomas in men than in those in women (P <.01 and P <.02, respectively). No statistical correlations were observed between expression of alpha-catenin, p120, and clinicopathologic features. In conclusion, the reduction of E-cadherin and beta-catenin expression was related to invasiveness and proliferative status of prolactinomas and correlated with the more aggressive behavior of prolactinomas in men compared with in women.     

Coordinate synthesis and degradation of the alpha-, beta- and gamma-subunits of the receptor for immunoglobulin E

The surface receptor for immunoglobulin E (IgE) on rat basophilic leukemia cells and their normal counterparts has been postulated to consist of four polypeptide chains: a 45-kDa alpha-chain which binds IgE, a 33-kDa beta-component and two disulfide-linked, 9-10-kDa gamma-polypeptides. The instability of this complex in mild detergents makes it possible that, in vivo also, the structure may not be stable and that there is an independent assembly or exchange of the chains. We studied this question using surface-labeling and biosynthetic labeling techniques and found that the chains turn over coordinately and do not independently exchange. The results provide further support for the proposal that the alpha beta gamma 2 complex is the unit receptor for IgE.     

Analysis of beta-catenin mutations and alpha-, beta-, and gamma-catenin expression in normal and neoplastic human pituitary tissues

The cadherin-catenin system mediates Ca²⁺-dependent cell-cell adhesion, and genetic alterations in these molecules play a significant role in multistage carcinogenesis. Mutations in the β-catenin gene, mostly affecting exon 3, have been detected in malignant cell lines and in primary tumors. Immunohistochemical abnormalities in α-, β-, and γ-catenin have been reported in malignant and benign tumors, and nuclear localization of β-catenin has been associated with mutations in exon 3 of this gene. Mutational analysis of exon 3 of the β-catenin gene was undertaken by polymerase chain reaction (PCR) and sequencing using genomic DNA extracted from frozen tissues, including 4 normal pituitaries, 22 pituitary adenomas, and one pituitary carcinoma. Frozen sections from these cases were used for immunohistochemical detection of β-catenin. We also analyzed immunohistochemical expression of α-, β-, and γ-catenin by paraffin sections from 154 pituitary tumors, including 148 adenomas and 6 carcinomas. Genomic DNA was extracted from paraffin sections of 2 gonadotroph tumors showing nuclear staining for β-catenin and was used for PCR and sequencing of exon 3 of the β-catenin gene. No mutations in exon 3 of the β-catenin gene were found in any of the 23 cases analyzed by PCR and sequencing. In addition, the 2 cases studied by paraffin section immunohistochemistry, with nuclear staining for β-catenin, were negative for mutations in this exon. Normal pituitary expressed all three catenin proteins. Immunostaining usually showed a membranous pattern of reactivity and was generally stronger in normal pituitary than in the adjacent adenomas. Stains for α-catenin were positive in fewer tumors than for β-catenin. The lowest frequency immunopositive tumors and the weakest immunostaining was for γ-catenin. All medically treated prolactinomas were negative for γ-catenin, whereas treated growth hormone adenomas were less often positive for both α- and γ-catenin than for untreated tumors. The percentage of positive cases for β-catenin was the same in these two groups. Most pituitary carcinomas were negative for both α- and γ-catenin but were β-catenin positive. These results indicate that (i) mutations in exon 3 of the β-catenin gene are uncommon in pituitary tumors, and (ii) expression of α-, β-, and γ-catenin is decreased in pituitary adenomas compared to normal pituitary tissues.     

Abnormal immunoreactivity of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex in premalignant and malignant non-melanocytic skin tumours.

E-cadherin/catenin (alpha-, beta-, and gamma-) complex plays a critical role in the control of epithelial differentiation. The aim of this study was to examine the immunoreactivity of E-cadherin and alpha-, beta-, and gamma-catenins in premalignant and malignant non-melanocytic skin tumours (NMST) and to correlate their expression with the grade of tumour differentiation, as assessed by the established histopathological criteria and by the Ki-67 index. Benign NMSTs were also studied. To investigate any possible influence of immunosuppression in the expression of E-cadherin and catenins, the study compared tumours obtained from renal transplant recipients (RTRs) and immunocompetent patients. Immunoperoxidase staining of E-cadherin and alpha-, beta-, and gamma-catenins was performed in 42 squamous cell carcinomas (SCCs) (26 from RTRs and 16 from non-RTRs), 30 lesions of Bowen's disease (11 from RTRs and 19 from non-RTRs), 11 atypical squamoproliferative lesions from RTRs, 19 actinic keratoses (9 from RTRs and 10 from non-RTRs), and 20 viral warts from RTRs. The findings of this study were as follows. Firstly, the probability of abnormal expression of E-cadherin and alpha-, beta-, and gamma-catenins increased from benign to premalignant and malignant NMSTs (p<0.001 for all). Secondly, there was agreement in abnormal expression between most of the molecules measured in malignant and premalignant NMSTs (p<0.05). Thirdly, in SCC, abnormal expression of E-cadherin and catenins was more frequent in lesions with a high (>40%) Ki-67 index than in those with a low Ki-67 index (<40%) (p=0.003). However, only the abnormal expression of gamma-catenin increased with the grade of SCC differentiation (p=0.008). Fourthly, abnormal expression of gamma-catenin predicted a high proliferation index (Ki-67 index 40%) in NMSTs (p<0.01, OR=6.19). Finally, there was no difference in the abnormal expression of E-cadherin and catenins between NMSTs from immunosuppressed and immunocompetent patients. Thus, abnormal expression of the E-cadherin/catenin complex was quite common in SCC and Bowen's disease and also in a proportion of intraepithelial dysplastic lesions, such as atypical squamoproliferative lesions and actinic keratosis, suggesting that these changes may be early indicators of the neoplastic process. Abnormal expression of gamma-catenin was the sole predictor of high proliferation in NMST and was also correlated with the tumour grade, suggesting a possible important role for gamma-catenin in tumourigenesis.