Resistance to Apoptosis and Expansion of Regulatory T Cells in Relation to the Detection of Circulating Tumor Cells in Patients with Metastatic Epithelial Cancer

Regulatory T cells may be crucial in the development of T cell tolerance to malignancies and contribute to immune dysfunctions. We investigated the percentage, activity, and onset of apoptosis of T cell subpopulations by multicolor flow cytometry in metastatic epithelial cancer patients compared to normal controls. Furthermore, a possible relationship between the presence of circulating tumor cells detected by immunocytochemistry and immune cell abnormalities was evaluated. Our study demonstrated a significantly elevated proportion of regulatory T cells in cancer patients (p < 0.001). In contrast to all other T cell subpopulations, regulatory T cells showed comparable Annexin V-binding characteristics in patients and normal controls. No relationship between the detection of circulating tumor cells and immune dysfunction was observed. These results indicate that cancer patients have a higher number of regulatory T cells with resistance to apoptotic stimuli partly responsible for immune dysfunctions as often observed in cancer patients.     

Liver metastatic ability of human melanoma cell line is associated with losses of chromosomes 4, 9p21-pter and 10p

Genetic changes underlying the aggressive progression of human cutaneous melanoma are not completely understood. In order to characterise genetic alterations associated with the metastatic behaviour of this neoplasm we used comparative genomic hybridisation (CGH) in combination with fluorescence in situ hybridisation (FISH) on an experimental metastatic model of three related human melanoma cell lines. Tumour lines were selected based on their various metastatic capacity to liver in immunosuppressed mice. The parental cell line (A2058) was a human amelanotic melanoma cell line, adaptation of this line to in vivo growth as xenograft the HT168 tumour and its cell line was established. After intrasplenic transplantation of HT168 cells into immunosuppressed mice, a highly metastatic variant (HT168-M1) was selected. Several chromosomal aberrations common to all three lines indicating common clonal origin, as well as additional non-shared chromosomal changes were found. The original cell line (A2058) exhibited the highest number of genetic changes. Chromosomal alterations present only in the highly metastatic line (HT168-M1) involved losses on chromosome 4, 9p21.3-pter and 10p. Chromosome copy number patterns and the nature of chromosome 4 loss were further investigated by FISH using different centromeric probes and a chromosome 4 painting probe. According to our CGH and FISH results we assume that alterations present only in the aggressive metastatic subline are associated with the increased – metastatic potential. Our observations further support the hypothesis, based on some recently published data, that certain (so far unidentified) suppressor genes having an important role in tumour progression are located on these chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Differential Activities of CYP1A Isozymes in Hepatic and Intestinal Microsomes of Control and 3‐Methylcholanthrene‐Induced Rats

Abstract: Differences in expression of CYP1A isoforms (CYP1A1 and CYP1A2) in liver and small intestine of male Wistar rats and their inducibility by 3‐methylcholanthrene as well as the effect of different CYP1A1/1A2 expression on caffeine metabolism were investigated. In rat liver, CYP1A2 is the predominant isoform and CYP1A1 protein expression in liver is significantly increased after treatment by 3‐methylcholanthrene. In contrast, only CYP1A1 was detected in control and 3‐methylcholanthrene induced small intestine microsomes. Treatment with 3‐methylcholanthrene (40 mg/kg intraperitoneally daily during 1, 2, 3 or 4 days) demonstrated that liver CYP1A1 is more sensitive for the induction effects than CYP1A2 and also that significant induction of CYP1A1 in rat small intestine only occurred after 3 to 4 days pretreatment. Caffeine metabolism and inhibition studies by furafylline, CYP1A1 antiserum and ketoconazole revealed that the differences in the expression of CYP1A1 and CYP1A2 in the two tissues led to significant changes in the contribution of the various isoenzymes involved in the biotransformation of caffeine. Whereas in liver paraxanthine formation was almost exclusively catalyzed by CYP1A2, in rat proximal intestine it was formed by CYP1A1. In addition, other CYP enzymes (most probably CYP3A) play a significant role in theobromine and theophylline formation from caffeine in rat intestine. Overall, this study shows different expression and inducibility of CYP1A1/1A2 by 3‐methylcholanthrene in rat liver and small intestine. Furthermore in rat intestine cytochrome P450 isozymes such as CYP1A1 and CYP3A replace CYP1A2 in the caffeine metabolism.     

The Effects of Ketamine and Its Enantiomers on the Morphine- or Dexmedetomidine-induced Antinociception after Intrathecal Administration in Rats

Background: The spinal administration of some N-methyl-d-aspartate receptor antagonists results in antinociception and potentiates the effects of opioids and [alpha]2-adrenoceptor agonists, but ketamine and its enantiomers have not been examined. The present study investigated the interactions of racemic ketamine, R (-)-ketamine and S (+)-ketamine with morphine and with dexmedetomidine.

Methods: Intrathecal catheters were implanted into male Wistar rats. Three days later, the acute nociceptive sensitivity was assessed using the tail-flick test. Analgesic latencies were converted to the percentage maximum possible effect. The dose that yielded 50% of the maximum possible effect (ED50) and dose-response and time-course curves were determined for the ketamines (30-300 [mu]g), morphine (0.1-3.0 [mu]g), dexmedetomidine (0.3-10.0 [mu]g), and mixtures of two doses of ketamines (30 or 100 [mu]g) with different doses of morphine or dexmedetomidine for fixed-dose analysis.

Results: Neither racemic ketamine nor its enantiomers alone had a significant effect on the tail-flick test, with the exception of the highest dose of racemic ketamine, which caused motor impairment. Morphine and dexmedetomidine each produced dose-dependent antinociception, with ED50 of 1.7 [mu]g (95% confidence interval: 1.04-2.32) and 4.85 [mu]g (3.96-5.79), respectively. A low dose (30 [mu]g) of racemic ketamine or its enantiomers did not influence the ED50 of morphine significantly. Coadministration of 100 [mu]g racemic ketamine or S (+)-ketamine, but not R (-)-ketamine, significantly enhanced and prolonged the antinociceptive effect of morphine. Both doses of racemic ketamine or its isomers significantly decreased the ED50 value for dexmedetomidine, although the higher dose of racemic or S (+)-ketamine had the highest potency. One-hundred micrograms of racemic ketamine or S (+)-ketamine also prolonged the effects of dexmedetomidine.     

Organization, administration, and performance of clinical studies

This contribution deals with all important organizational and administrative aspects of clinical studies in German speaking countries. All trials are to be executed in accordance with the Good Clinical Practice (GCP) Guidelines. GCP applies to the process of designing, conducting, recording, and reporting of clinical studies. Compliance with GCP facilitates the mutual acceptance of resulting clinical data by the respective regulatory authorities worldwide. Before initiating a clinical study the investigator has to obtain written and dated approval from the responsible ethics committee, the competent authorities, and the hospital administration. The investigator's study file contains all essential study documents. One of the most important tasks of an investigator is to properly inform the prospective subjects and to obtain their informed consent. All relevant treatment-related information has to be recorded in the patient files. These source data are transferred to case report forms. During monitoring visits, audits, and inspections, source data verification will be performed routinely. Any adverse events (AEs) must be documented according to the CTCAE, the Common Terminology Criteria for Adverse Events. All serious adverse events (SAEs) have to be reported to the sponsor immediately. At the end of the study a termination visit is performed, and all authorities are officially informed about the termination of the trial.     

Enhanced activation of epidermal growth factor receptor caused by tumor-derived E-cadherin mutations

Mutations of the tumor suppressor E-cadherin and overexpression of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) are among the most frequent genetic alterations associated with diffuse-type gastric carcinoma. Accumulating evidence suggests a functional relationship between E-cadherin and EGFR that regulates both proteins. We report that somatic mutation of E-cadherin is associated with increased activation of EGFR followed by enhanced recruitment of the downstream acting signaling components growth factor receptor binding protein 2 and Shc, and activation of Ras. Reduced complex formation of mutant E-cadherin - with an in frame deletion of exon 8 in the extracellular domain resulting in reduced adhesion and increased motility - with EGFR was observed compared with wild-type E-cadherin. We conclude that reduced binding of mutant E-cadherin to EGFR in a multicomponent complex or reduced stability of the complex may enhance EGFR surface motility, thereby facilitating EGFR dimerization and activation. Furthermore, reduced surface localization due to enhanced internalization of mutant E-cadherin compared with the wild-type protein was observed. The internalization of EGFR was decreased in response to epidermal growth factor stimulation in cells expressing mutant E-cadherin, suggesting that mutation of E-cadherin also influences the endocytosis of EGFR. Moreover, we show increased activation of EGFR in gastric carcinoma samples with mutant E-cadherin lacking exons 8 or 9. In summary, we describe activation of EGFR by mutant E-cadherin as a novel mechanism in tumor cells that explains the enhanced motility of tumor cells in the presence of an extracellular mutation of E-cadherin.     

Increased numbers of endothelial progenitor cells in peripheral blood and tumor specimens in non-small cell lung cancer: a methodological challenge and an ongoing debate on the clinical relevance

Bone marrow-derived endothelial progenitor cells (EPC) play an important role in neovascularisation and tumor growth. However, the clinical relevance of EPCs on blood vessel formation in non-small cell lung cancer (NSCLC) is unclear. EPC numbers in circulation are very low and therefore their detection is technically challenging. In the present study, 10 NSCLC patients and 5 healthy controls were included. Patients underwent blood analyses before and after surgery. EPCs were isolated from whole blood by magnetic cell sorting to CD34 (MACS). Afterwards, FACS analyses using antibodies against CD133, CD34, VEGFR2 and CD45 and and immunocytological staining to CD133 on cytospins (MCA) were performed. Cryostat sections of tumor samples were stained for CD133, CD31 and cytokeratin A7. Serum levels of the vascular endothelial growth factor (VEGF) were quantified by sandwich ELISA. Compared to the control group NSCLC patients showed significantly elevated EPC counts and VEGF levels in peripheral blood before and after surgery. From a methodological point of view, the tested procedure (MCA) was validated as compared to the standard FACS analyses (CD34+/VEGFR2+). MCA proved to have a very high sensitivity and even allowed the identification of singular positive EPCs.