Sequence diversity of hepatitis D virus in Mongolia

Introduction

The Hepatitis Delta Virus (HDV) is a defective, single-stranded RNA virusoid encoding for a single protein, the Hepatitis Delta Antigen (HDAg), which requires the hepatitis B virus (HBV) envelope protein (HBsAg) for its transmission. Currently, hepatitis D is the most aggressive form of viral hepatitis and treatment options are limited. Worldwide 12 million people are chronically infected with HDV being at high risk for progression to cirrhosis and development of liver cancer.

Objectives

Although it is well established that Mongolia is the country with the highest prevalence of HDV infections, the information on the molecular epidemiology and factors contributing to HDV sequence diversity are largely unclear. The aim of the study was to characterize the sequence diversity of HDV in rural areas from Mongolia and to determine the extent of HLA class I-associated selection pressure.

Patients and methods

From the HepMongolia cohort from rural areas in Mongolia, 451 HBsAg-positive individuals were selected and anti-HDV, HDV-RNA and the sequence of the large HDAg was determined. For all individuals the HLA class I locus was genotyped. Residues under selection pressure in the presence of individual HLA class I types were identified with the recently published analysis tool HAMdetector.

Results

Of 431 HBsAg positive patients, 281 were anti-HDV positive (65%), and HDV-RNA could be detected in 207 of 281 (74%) of patients. The complete large HDAg was successfully sequenced from 131 samples. Phylogenetic analysis revealed that all Mongolian HDV isolates belong to genotype 1, however, they separate into several different clusters without clear regional association. In turn, from phylogeny there is strong evidence for recent local transmission events. Importantly, we found multiple residues with strong support for HLA class I-associated selection pressure consistent with a functional CD8⁺ T cell response directed against HDV.

Conclusion

HDV isolates from Mongolia are highly diverse. The molecular epidemiology suggests circulation of multiple subtypes and provides evidence for ongoing recent transmissions.

Dissecting CD8+ T cell pathology of severe SARS-CoV-2 infection by single-cell immunoprofiling

Introduction

SARS-CoV-2 infection results in varying disease severity, ranging from asymptomatic infection to severe illness. A detailed understanding of the immune response to SARS-CoV-2 is critical to unravel the causative factors underlying differences in disease severity and to develop optimal vaccines against new SARS-CoV-2 variants.

Methods

We combined single-cell RNA and T cell receptor sequencing with CITE-seq antibodies to characterize the CD8⁺ T cell response to SARS-CoV-2 infection at high resolution and compared responses between mild and severe COVID-19.

Results

We observed increased CD8⁺ T cell exhaustion in severe SARS-CoV-2 infection and identified a population of NK-like, terminally differentiated CD8⁺ effector T cells characterized by expression of FCGR3A (encoding CD16). Further characterization of NK-like CD8⁺ T cells revealed heterogeneity among CD16⁺ NK-like CD8⁺ T cells and profound differences in cytotoxicity, exhaustion, and NK-like differentiation between mild and severe disease conditions.

Discussion

We propose a model in which differences in the surrounding inflammatory milieu lead to crucial differences in NK-like differentiation of CD8⁺ effector T cells, ultimately resulting in the appearance of NK-like CD8⁺ T cell populations of different functionality and pathogenicity. Our in-depth characterization of the CD8⁺ T cell-mediated response to SARS-CoV-2 infection provides a basis for further investigation of the importance of NK-like CD8⁺ T cells in COVID-19 severity.

Prognostic markers for the clinical course in the blood of patients with SARS-CoV-2 infection

BACKGROUND

The presentation of peptides and the subsequent immune response depend on the MHC characteristics and influence the specificity of the immune response. Several studies have found an association between HLA variants and differential COVID-19 outcomes and have shown that HLA genotypes are associated with differential immune responses against SARS-CoV-2, particularly in severely ill patients. Information, whether HLA haplotypes are associated with the severity or length of the disease in moderately diseased individuals is absent.

METHODS

Next-generation sequencing-based HLA typing was performed in 303 female and 231 male non-hospitalized North Rhine Westphalian patients infected with SARS-CoV2 during the first and second wave. For HLA-Class I, we obtained results from 528 patients, and for HLA-Class II from 531. In those patients, who became ill between March 2020 and January 2021, the 22 most common HLA-Class I (HLA-A, -B, -C) or HLA-Class II (HLA -DRB1/3/4, -DQA1, -DQB1) haplotypes were determined. The identified HLA haplotypes as well as the presence of a CCR5Δ32 mutation and number of O and A blood group alleles were associated to disease severity and duration of the disease.

RESULTS

The influence of the HLA haplotypes on disease severity and duration was more pronounced than the influence of age, sex, or ABO blood group. These associations were sex dependent. The presence of mutated CCR5 resulted in a longer recovery period in males.

CONCLUSION

The existence of certain HLA haplotypes is associated with more severe disease.

High-Throughput Next-Generation Sequencing of the Kidd Blood Group: Unexpected Antigen Expression Properties of Four Alleles and Detection of Novel Variants

Background

The blood supply for patients with foreign ethnic backgrounds can be challenging, as they often have blood group and HPA patterns that differ from the variants prevalent in the German population. In addition, hemoglobinopathies requiring regular blood transfusion may be more common in such populations. High-throughput genotyping tests can facilitate the identification of the most compatible blood products, thereby reducing the risk of transfusion reactions. The present study reports the results of a molecular study for the Kidd (JK) blood group. Allele frequencies and antigen prevalence data are presented for >8,000 individuals of various origins.

Material and Methods

More than 8,000 blood donors were genotyped for 22 blood group systems and 5 HPA genes using an amplicon-based next-generation sequencing (NGS) approach. As part of the test system, we focused on the JK system in more detail. Double-ARMS PCR analysis was performed for the haplotype phasing of the JK1/JK2 and two more common synonymous polymorphisms. We performed transcript analysis to detect potential alternative splice products. For a subset of samples, a comparison between serotype and red cell genotype was conducted. Allele frequencies were determined for geographically different panels of individuals.

Results

We successfully genotyped the JK blood group for 99.6% of the samples. Haplotype phasing revealed 96 different alleles. For several alleles that carry one of the synonymous SNVs c.588A>G and c.810G>A, we could not confirm the reported JK phenotypes. We found a higher frequency of JK:1 alleles for all populations except Iraqis. JK*01W.01 alleles were more common in the Asian groups and sub-Saharan Africans. A variant of the allele JK*02N.01 was present exclusively in Southeast Asians.

Conclusion

Genotyping for JK antigens with a targeted NGS assay can easily be performed in routine. The interpretation that c.588A>G leads to a weak phenotype and c.810G>A to a null phenotype is questionable. IDs as well as the descriptions of alleles carrying these SNVs should be revised in the ISBT JK table.

CD33 Delineates Two Functionally Distinct NK Cell Populations Divergent in Cytokine Production and Antibody-Mediated Cellular Cytotoxicity

The generation and expansion of functionally competent NK cells in vitro is of great interest for their application in immunotherapy of cancer. Since CD33 constitutes a promising target for immunotherapy of myeloid malignancies, NK cells expressing a CD33-specific chimeric antigen receptor (CAR) were generated. Unexpectedly, we noted that CD33-CAR NK cells could not be efficiently expanded in vitro due to a fratricide-like process in which CD33-CAR NK cells killed other CD33-CAR NK cells that had upregulated CD33 in culture. This upregulation was dependent on the stimulation protocol and encompassed up to 50% of NK cells including CD56^dim NK cells that do generally not express CD33 in vivo. RNAseq analysis revealed that upregulation of CD33⁺ NK cells was accompanied by a unique transcriptional signature combining features of canonical CD56^bright (CD117^high, CD16^low) and CD56^dim NK cells (high expression of granzyme B and perforin). CD33⁺ NK cells exhibited significantly higher mobilization of cytotoxic granula and comparable levels of cytotoxicity against different leukemic target cells compared to the CD33^- subset. Moreover, CD33⁺ NK cells showed superior production of IFNγ and TNFα, whereas CD33^- NK cells exerted increased antibody-dependent cellular cytotoxicity (ADCC). In summary, the study delineates a novel functional divergence between NK cell subsets upon in vitro stimulation that is marked by CD33 expression. By choosing suitable stimulation protocols, it is possible to preferentially generate CD33⁺ NK cells combining efficient target cell killing and cytokine production, or alternatively CD33^- NK cells, which produce less cytokines but are more efficient in antibody-dependent applications.

Next Generation Sequencing Identifies the HLA-DQA1*03:03 Allele in the Type 1 Diabetes Risk-Associated HLA-DQ8 Serotype

The highest genetic type 1 diabetes risk is conferred by HLA class II haplotypes defined by alleles at the HLA-DR and -DQ loci. The combination of HLA-DQA1*03:01 and DQB1*03:02 alleles (summarized as ‘HLA-DQ8′) is reported to be among the two most prevalent HLA class II haplotypes in Caucasian type 1 diabetes patients. This classification is based on conventional genotyping of exon 2 of the DQ gene locus and excludes exon 3. In this study, HLA genotyping on the type 1 diabetes susceptibility loci HLA-DRB1, DQA1 and DQB1 was performed using a high-resolution next generation sequencing method. In addition to the routinely examined exon 2, exon 3 was also sequenced. Samples from 229 children with type 1 diabetes were included and compared to a cohort of 9,786 controls. In addition to previously described HLA-DQ haplotypes in type 1 diabetes patients, we found that as well as HLA-DQA1*03:01,HLA-DQA1*03:03 also contributed to HLA-DQ8. HLA-DQA1*03:03 differs from HLA-DQA1*03:01 by one nucleotide substitution in exon 3 at position 160, leading to a single amino acid replacement. DRB1*04:05 was exclusively associated with DQA1*03:03 whereas the DRB1*04:01 haplotype comprised either DQA1*03:01 or DQA1*03:03. Significantly increased type 1 diabetes risk was confirmed for all these haplotypes with only minor differences between DQA1*03:01 and DQA1*03:03 alleles. This study identified the HLA-DQA1*03:03 allele as an addition to the already known type 1 diabetes risk haplotypes, and can contribute to more precise HLA genotyping approaches.

Interleukin-7-dependent nonclassical monocytes and CD40 expression are affected in children with type 1 diabetes

The important role of IL-7 in the generation of self-reactive T-cells in autoimmune diseases is well established. Recent studies on autoimmunity-associated genetic polymorphisms indicated that differential IL-7 receptor (IL-7R) expression of monocytes may play a role in the underlying pathogenesis. The relevance of IL-7-mediated monocyte functions in type 1 diabetes remains elusive. In the present study, we characterized monocyte phenotype and IL-7-mediated effects in children with type 1 diabetes and healthy controls with multicolor flow cytometry and t-distributed Stochastic Neighbor-Embedded (t-SNE)-analyses. IL-7R expression of monocytes rapidly increased in vitro and was boosted through LPS. In the presence of IL-7, we detected lower monocyte IL-7R expression in type 1 diabetes patients as compared to healthy controls. This difference was most evident for the subset of nonclassical monocytes, which increased after IL-7 stimulation. t-SNE analyses revealed IL-7-dependent differences in monocyte subset distribution and expression of activation and maturation markers (i.e., HLA-DR, CD80, CD86, CD40). Notably, monocyte CD40 expression increased considerably by IL-7 and CD40/IL-7R co-expression differed between patients and controls. This study shows the unique effects of IL-7 on monocyte phenotype and functions. Lower IL-7R expression on IL-7-induced CD40_high monocytes and impaired IL-7 response characterize monocytes from patients with type 1 diabetes.

Association of HLA genotypes, AB0 blood type and chemokine receptor 5 mutant CD195 with the clinical course of COVID-19

BACKGROUND

COVID-19, the pandemic disease caused by infection with SARS-CoV-2, may take highly variable clinical courses, ranging from symptom-free and pauci-symptomatic to fatal disease. The goal of the current study was to assess the association of COVID-19 clinical courses controlled by patients' adaptive immune responses without progression to severe disease with patients' Human Leukocyte Antigen (HLA) genetics, AB0 blood group antigens, and the presence or absence of near-loss-of-function delta 32 deletion mutant of the C-C chemokine receptor type 5 (CCR5).

PATIENT AND METHODS

An exploratory observational study including 157 adult COVID-19 convalescent patients was performed with a median follow-up of 250 days. The impact of different HLA genotypes, AB0 blood group antigens, and the CCR5 mutant CD195 were investigated for their role in the clinical course of COVID-19. In addition, this study addressed levels of severity and morbidity of COVID-19. The association of the immunogenetic background parameters were further related to patients' humoral antiviral immune response patterns by longitudinal observation.

RESULTS

Univariate HLA analyses identified putatively protective HLA alleles (HLA class II DRB1*01:01 and HLA class I B*35:01, with a trend for DRB1*03:01). They were associated with reduced durations of disease instead decreased (rather than increased) total anti-S IgG levels. They had a higher virus neutralizing capacity compared to non-carriers. Conversely, analyses also identified HLA alleles (HLA class II DQB1*03:02 und HLA class I B*15:01) not associated with such benefit in the patient cohort of this study. Hierarchical testing by Cox regression analyses confirmed the significance of the protective effect of the HLA alleles identified (when assessed in composite) in terms of disease duration, whereas AB0 blood group antigen heterozygosity was found to be significantly associated with disease severity (rather than duration) in our cohort. A suggestive association of a heterozygous CCR5 delta 32 mutation status with prolonged disease duration was implied by univariate analyses but could not be confirmed by hierarchical multivariate testing.

CONCLUSION

The current study shows that the presence of HLA class II DRB1*01:01 and HLA class I B*35:01 is of even stronger association with reduced disease duration in mild and moderate COVID-19 than age or any other potential risk factor assessed. Prospective studies in larger patient populations also including novel SARS-CoV-2 variants will be required to assess the impact of HLA genetics on the capacity of mounting protective vaccination responses in the future.

Informed consent and informed intervention: SARS-CoV-2 vaccinations not just call for disclosure of newly emerging safety data but also for hypothesis generation and testing

Background

COVID-19 infection is a major threat to patients and health care providers around the world. One solution is the vaccination against SARS-CoV-2.

Methods

We performed a comprehensive query of the latest publications on the prevention of viral infections including the recent vaccination program and its side effects.

Results

The situation is evolving rapidly and there is no reasonable alternative to population-scale vaccination programs as currently enrolled.

Conclusion

Therefore, regulatory authorities should consider supplementing their conventional mandate of post-approval pharmacovigilance, which is based on the collection, assessment, and regulatory response to emerging safety findings.

High-Throughput Screening of Blood Donors for Twelve Human Platelet Antigen Systems Using Next-Generation Sequencing Reveals Detection of Rare Polymorphisms and Two Novel Protein-Changing Variants

Background

Exposure to non-matching human platelet alloantigens (HPA) may result in alloimmunization. Antibodies to HPA can be responsible for post-transfusion purpura, refractoriness to donor platelets, and fetal and neonatal alloimmune thrombocytopenia. For the supply of compatible apheresis platelet concentrates, the HPA genotypes are determined in a routine manner.

Methods

Here, we describe a novel method for genotyping twelve different HPA systems simultaneously, including HPA-1 to HPA-5, HPA-9w, HPA-10w, HPA-16w, HPA-19w, HPA-27w, and the novel HPA-34w by means of amplicon-based next-generation sequencing (NGS). Blood donor samples of 757 individuals with a migration background and 547 of Western European ancestry were genotyped in a mass-screening setup. An in-house software was developed for fast and automatic analysis. TaqMan assay and Sanger sequencing results served for validation of the NGS workflow. Finally, blood donors were divided in several groups based on their country of origin and the allele frequencies were compared.

Results

For 1,299 of 1,304 samples (99.6%) NGS was successfully performed. The concordance with TaqMan assay and Sanger sequencing results was 99.8%. Allele-calling dropouts that were observed for two samples with the TaqMan assay caused by rare single nucleotide polymorphisms were resolved by NGS. Additionally, twenty rare and two novel variants in the coding regions of the genes ITGB3, GPB1A, ITGBA2, and CD109 were detected. The determined allele frequencies were similar to those published in the gnomAD database.

Conclusions

No significant differences were observed in the distribution of allele frequencies of HPA-1 through HPA-5 and HPA-15 throughout the analyzed groups except for a lower allele frequency for the HPA-1b allele in the group of donors with Southern Asian ancestry. In contrast, other nucleotide variants that have not yet been phenotypically characterized occurred three times more often in blood donors with a migration background. High-throughput amplicon-based NGS is a reliable method for screening HPA genotypes in a large sample cohort simultaneously. It is easily upgradeable for genotyping additional targets without changing the setup or the analysis pipeline. Mass-screening methods will help building up blood donor registries to provide matched blood products.

A novel HLA-A null allele, HLA-A*30:130N, discovered by amplicon-based next-generation sequencing

A novel HLA-A allele, HLA-A*30:130N, carrying a two-nucleotide insertion in exon 4 is described.

A novel HLA-B variant, HLA-B*14:02:16, discovered by amplicon-based next-generation sequencing

HLA-B*14:02:16 differs from B*14:02:01:01 by a synonymous nucleotide substitution in codon 141.

Mutational and Functional Analysis of FANCB as a Candidate Gene for Sporadic Head and Neck Squamous Cell Carcinomas

BACKGROUND/AIM

Head and neck squamous cell carcinomas (HNSCCs) form a heterogeneous tumor entity located throughout the oral cavity, pharynx and larynx that is caused predominantly by chemically or virally induced carcinogenesis. Heterozygous germline mutations in cancer susceptibility genes might also lead to increased incidence of HNSCCs. As DNA stability is typically impaired in HNSCC cells and genes of the Fanconi anemia/BRCA DNA repair pathway can be mutated or down-regulated in HNSCCs, we investigated here whether germline mutations occur in the X-chromosomal FANCB as candidate gene.

MATERIALS AND METHODS

Germline DNA of 85 consecutive HNSCC patients was sequenced. Missense alterations in FANCB were functionally tested in reference cells.

RESULTS AND CONCLUSION

Four single nucleotide polymorphisms were identified, three of which were located in untranslated regions of FANCB (rs2188383, rs2375729, rs2905223) and predicted to be associated with normal function. One missense alteration, c.1004G>A resulting in p.G335E (rs41309679), in exon 4 was detected in five men in homozygous and in five women in heterozygous state. Four in silico prediction programs uniformally predicted p.G335E to be associated with loss-of-function of the protein. To clarify these predictions, we expressed the FANCB p.G335E protein in primary human FANCB deficient fibroblasts. Cell cycle analysis of these fibroblasts established that the FANCB p.G335E was functionally indistinguishable from the wildtype FANCB protein. Thus, functional studies in genetically defined cells showed that the p.G335E germline alteration in FANCB is not associated with impaired function.

RAD51C--a new human cancer susceptibility gene for sporadic squamous cell carcinoma of the head and neck (HNSCC)

INTRODUCTION

Head and neck squamous cell carcinomas (HNSSCs) are one of the leading causes of cancer-associated death worldwide. Although certain behavioral risk factors are well recognized as tumor promoting, there is very little known about the presence of predisposing germline mutations in HNSCC patients.

METHODS

In this study, we analyzed 121 individuals with HNSCCs collected at our institution for germline alterations in the newly identified cancer susceptibility gene RAD51C.

RESULTS

Sequencing of all exons and the adjacent introns revealed five distinct heterozygous sequence deviations in RAD51C in seven patients (5.8%). A female patient without any other risk factors carried a germline mutation that disrupted the canonical splice acceptor site of exon 5 (c.706-2A>G).

CONCLUSIONS

As there are only a few publications in the literature identifying germline mutations in head and neck cancer patients, our results provide the first indication that paralogs of RAD51, recently described as mutated in breast and ovarian cancer patients, might also be candidates for genetic risk factors in sporadic squamous cell carcinomas of the head and neck.

Catalase activity prevents exercise-induced up-regulation of vasoprotective proteins in venous tissue

Physical activity induces favourable changes of arterial gene expression and protein activity, although little is known about its effect in venous tissue. Although our understanding of the initiating molecular signals is still incomplete, increased expression of endothelial nitric oxide synthase (eNOS) is considered a key event. This study sought to investigate the effects of two different training protocols on the expression of eNOS and extracellular superoxide dismutase (ecSOD) in venous and lung tissue and to evaluate the underlying molecular mechanisms. C57Bl/6 mice underwent voluntary exercise or forced physical activity. Changes of vascular mRNA and protein levels and activity of eNOS, ecSOD and catalase were determined in aorta, heart, lung and vena cava. Both training protocols similarly increased relative heart weight and resulted in up-regulation of aortic and myocardial eNOS. In striking contrast, eNOS expression in vena cava and lung remained unchanged. Likewise, exercise up-regulated ecSOD in the aorta and in left ventricular tissue but remained unchanged in lung tissue. Catalase expression in lung tissue and vena cava of exercised mice exceeded that in aorta by 6.9- and 10-fold, respectively, suggesting a lack of stimulatory effects of hydrogen peroxide. In accordance, treatment of mice with the catalase inhibitor aminotriazole for 6 weeks resulted in significant up-regulation of eNOS and ecSOD in vena cava. These data suggest that physiological venous catalase activity prevents exercise-induced up-regulation of eNOS and ecSOD. Furthermore, therapeutic inhibition of vascular catalase might improve pulmonary rehabilitation.

The checkpointkinase 2 (CHK2) 1100delC germ line mutation is not associated with the development of squamous cell carcinoma of the head and neck (SCCHN)

Background

The checkpointkinase 2 (CHK2) is part of the highly conserved ATM-CHK2 signaling pathway, which is activated in response to DNA damage, in particular after double strand breaks which can be caused by carcinogens like smoking. After induction of downstream targets, e.g. the tumor suppressor p53, its activation leads to cell cycle arrest and apoptosis. Recently, the presence of CHK2 germ line mutations, primarily the 1100delC variant, has been reported to be involved in carcinogenesis. The CHK2 1100delC variant results in a truncated protein which is instable and inactive. Carriers of this variant have been shown to have an increased risk to develop breast cancer and probably also other tumors. Our purpose was to investigate the role of CHK2 germ line mutations in patients with squamous cell carcinoma of the head and neck (SCCHN).

Materials and Methods

We investigated 91 patients suffering from SCCHN including all tumor sites (oropharynx, hypopharynx, larynx) for the presence of the germ line mutation 1100delC by direct sequence analysis. Patients were characterized by their tumor localization, tumor stage, age, the presence of additional malignant tumors and predisposing carcinogens (smoking, alcohol abuse).

Results

None of the patients, independently of the tumor site, age, the abuse of predisposing carcinogens, or the presence of other kinds of tumors, carried the CHK2 1100delC variant.

Conclusions

The germ line CHK2 1100delC variant does not seem to have a major impact on the development of SCCHN.

Potential genetic risk factors in angiotensin-converting enzyme-inhibitor-induced angio-oedema

AIMS

The pathophysiology of angiotensin-converting enzyme inhibitor (ACEi)-induced angio-oedema remains unclear. We have investigated the impact of ACE insertion/deletion (I/D) polymorphism in combination with serum ACE activity as well as the bradykinin B2 receptor 2/3 and c.C181T polymorphisms.

METHODS

We analysed the ACE I/D as well as bradykinin B2 (2/3 and C181T) receptor polymorphisms in 65 patients with documented episodes of ACEi-induced angio-oedema and 65 patients matched for age and sex being under ACEi treatment without history of angio-oedema. Furthermore, we determined serum ACE activity in 47 of the 65 angio-oedema patients 3 months after the angio-oedema attack and compared these values with 51 healthy individuals (control II).

RESULTS

No risk association was identified between ACE I/D (I-allele: 0.42 vs. 0.41, D-allele: 0.58 vs. 0.59; P= 0.095) or bradykinin B2 receptor polymorphisms and the development of angio-oedema during ACEi treatment. We found a trend of lower serum ACE activity in ACE I/I genotypes in comparison with control II (I/I: 28 +/- 4.5 vs. 33 +/- 1.8 U l(-1); ID: 39 +/- 3.3 vs. 41 +/- 1 U l(-1); DD: 56 +/- 6.7 vs. 52 +/- 1.8 U l(-1); P= 0.9).

CONCLUSIONS

Our data suggest that polymorphism of ACE I/D and the bradykinin B2 receptor polymorphisms are not involved in the development of ACEi-induced angio-oedema when considered individually. Further studies should be carried out to clarify whether a combination of these polymorphisms might be a risk factor for ACEi-induced angio-oedema.

A novel mechanism for anti-EGFR antibody action involves chemokine-mediated leukocyte infiltration

Overexpression of the epidermal growth factor receptor (EGFR) is a hallmark of squamous cell carcinoma of the head and neck (SCCHN). Monoclonal antibodies (mAbs) against EGFR are currently used for therapy of recurrent or metastatic disease; however, their mode of action is not completely understood. To investigate the immunological effects of anti-EGFR mAb, we generated a three-dimensional spheroid model of EGFR-expressing SCCHN and used this model to study the effect of anti-EGFR mAb on leukocyte migration toward tumors. Pretreatment with the blocking anti-EGFR mAb EMD 72000, its F(ab')2 fragments or an EGFR tyrosine kinase inhibitor led to substantially increased leukocyte infiltration into EGFR overexpressing tumor spheroids, but not into those with low EGFR expression. Nonblocking anti-EGFR mAb or fibroblast-specific mAb did not affect leukocyte infiltration, suggesting that the observed increase in leukocyte infiltration depends on interference with EGFR activation. Using a human cytokine macroarray, we demonstrated that the blockade of EGFR by anti-EGFR mAb in EGFR-overexpressing SCCHN cells leads to differential expression of several cytokines and chemokines, including the chemokine MCP-1/CCL-2. The significant upregulation of MCP-1/CCL2 on exposure to anti-EGFR mAb was confirmed by quantitative PCR and enzyme-linked immunospot analyses. Moreover, blocking anti-MCP-1 antibody inhibited leukocyte migration toward tumor cells induced by anti-EGFR mAb, pointing to an important role of MCP-1/CCL2 in anti-EGFR mAb-induced leukocyte migration. Our findings demonstrate that anti-EGFR mAb induces leukocyte infiltration to tumor spheroids by upregulating chemokine expression. This novel mechanism for anti-EGFR mAb action may contribute to the antitumor effects of anti-EGFR mAb in vivo.

Pharmacological induction of vascular extracellular superoxide dismutase expression in vivo

Pentaerythritol tetranitrate (PETN) treatment reduces progression of atherosclerosis and endothelial dysfunction and decreases oxidation of low-density lipoprotein (LDL) in rabbits. These effects are associated with decreased vascular superoxide production, but the underlying molecular mechanisms remain unknown. Previous studies demonstrated that endogenous nitric oxide could regulate the expression of extracellular superoxide dismutase (ecSOD) in conductance vessels in vivo. We investigated the effect of PETN and overexpression of endothelial nitric oxide synthase (eNOS⁺⁺) on the expression and activity of ecSOD. C57BL/6 mice were randomized to receive placebo or increasing doses of PETN for 4 weeks and eNOS⁺⁺ mice with a several fold higher endothelial-specific eNOS expression were generated. The expression of ecSOD was determined in the lung and aortic tissue by real-time PCR and Western blot. The ecSOD activity was measured using inhibition of cytochrome C reduction. There was no effect of PETN treatment or eNOS overexpression on ecSOD mRNA in the lung tissue, whereas ecSOD protein expression increased from 2.5-fold to 3.6-fold (P < 0.05) by 6 mg PETN/kg body weight (BW)/day and 60 mg PETN/kg BW/day, respectively. A similar increase was found in aortic homogenates. eNOS⁺⁺ lung cytosols showed an increase of ecSOD protein level of 142 ± 10.5% as compared with transgene-negative littermates (P < 0.05), which was abolished by N^ω-nitro-L-arginine treatment. In each animal group, the increase of ecSOD expression was paralleled by an increase of ecSOD activity. Increased expression and activity of microvascular ecSOD are likely induced by increased bioavailability of vascular nitric oxide. Up-regulation of vascular ecSOD may contribute to the reported antioxidative and anti-atherosclerotic effects of PETN.

An intronic alteration of the fibroblast growth factor 10 gene causing ALSG-(aplasia of lacrimal and salivary glands) syndrome

Background

A combined aplasia, hypoplasia or atresia of lacrimal points and salivary glands is rarely diagnosed. Those patients suffer from epiphora, xerostomia and severe dental caries. This phenotype represents the autosomal-dominant aplasia of lacrimal and salivary glands syndrome (ALSG). Recently, aberrations of the Fibroblast Growth Factor 10 (FGF10) gene have been identified to be causative for this disorder.

Methods

We performed a sequence analysis of the FGF10 gene of a patient with ALSG-syndrome and his also affected brother as well as 193 controls. The FGF10 transcript was analyzed using RNA extracted from primary fibroblasts of the patient's mucosa.

Results

We detected a novel heterozygous sequence variation in intron 2 (c.430-1, G > A) causing the ALSG syndrome. The alteration derogates the regular splice acceptor site and leads to the use of a new splice acceptor site 127 bp upstream of exon 3. The aberration was detected in the genomic DNA derived from two affected brothers, but not in 193 control individuals. Furthermore, no diseased member of the family displayed additional abnormalities that are indicative for the clinically overlapping lacrimo-auriculo-dento-digital syndrome (LADD).

Conclusion

This family-based approach revealed an intronic variation of the FGF10 gene causing ALSG-syndrome. Our results expand the mutational and clinical spectrum of the ALSG syndrome.

Is there a role for the Fas-/Fas-Ligand pathway in chemoresistance of human squamous cell carcinomas of the head and neck (SCCHN)?

The aim of the present investigation was to determine the expression of the Fas-receptor/ligand system in established cell lines of squamous cell carcinomas of the head and neck (SCCHN), and to study it's functional impact on chemotherapy-induced apoptosis in these SCCHN cell lines. We observed constitutive expression of Fas and FasL in 13 SCCHN cell lines by RT-PCR, Southern-blotting and immunocytochemistry, respectively. Administration of the agonistic Fas-antibody CH-11 led to a significant reduction of viable cells in the colorimetric MTT-assay in 5 out of 13 (38%) cell lines tested and preincubation with Interferon-gamma (IFN-gamma) rendered 3 (23%) primarily resistant cell lines sensitive. Cisplatin (cDDP) and bleomycin (BLM) caused dose-dependent cytotoxicity in all cell lines as determined by the 50% inhibitory concentration (IC(50)) and induction of apoptosis. Furthermore, both antineoplastic agents led to an enhanced surface expression of Fas and FasL in all cell lines, and this effect was independent of the respective p53-status. This upregulation of Fas/FasL surface expression increased preexisting Fas-sensitivity only, but failed to make primarily resistant cell lines undergo Fas-mediated growth reduction or apoptosis. Vice versa, blockade of Fas-receptor-ligand-interactions by monoclonal antibodies directed against FasL was able to attenuate the cytotoxic effect of cDDP and BLM in 2 out of 5 (40%) cell lines tested only. In conclusion, in contrast to many other solid tumors, the Fas/FasL-system does not seem to play an exclusive role in anticancer drug mediated apoptosis in SCCHN.

Alterations in the p53 pathway and their association with radio- and chemosensitivity in head and neck squamous cell carcinoma

Chemotherapy and/or radiotherapy are established measures in treatment protocols of head and neck squamous cell carcinoma (HNSCC). However, we still lack reliable predictive markers for the response to radio- and chemotherapy. The p53 pathway is involved in stress response and thus might influence chemo-/radiosensitivity. Using 29 HNSCC cell lines previously characterized for p53 mutations, we simultaneously analyzed several key players in the p53 pathway by RT-PCR, transcript sequencing and immunohistochemistry, and investigated their association with chemosensitivity and radiosensitivity. Cell lines with p53 mutations were slightly more sensitive to cisplatin than those with wild-type p53. The type of mutation did not influence radio- or chemosensitivity. p14(ARF), an activator of p53, was lost or mutated in all cell lines. Three cell lines showed overexpression of HDM-2, a major negative regulator of p53; however, HDM-2 levels did not correlate with radio- or chemosensitivity. HPV-16 oncoproteins were detected in one highly chemoresistant cell line. Our findings suggest that molecular events resulting in the inactivation of the p53 pathway occur in all HNSCC cell lines. However, single alterations in the p53 pathway are not reliable predictors for the response to radio- or chemotherapy in HNSCC.

Immunological characterization of missense mutations occurring within cytotoxic T cell-defined p53 epitopes in HLA-A*0201+ squamous cell carcinomas of the head and neck

Previous analyses of p53 in 40 HLA-A*0201(HLA-A2)(+) squamous cell carcinomas of the head and neck (SCCHN) indicated that 6/13 p53 missense mutations that were detected, S149C, T150R, V157F, Y220C, Y220H and E271K, occurred within HLA-A2-restricted cytotoxic T lymphocyte (CTL)-defined p53 epitopes. Of the 6, the p53 S149C, Y220C and Y220H peptides were immunogenic. Anti-p53 mutant S149C and Y220H effector cells cross-reacted against the parental wild type sequence (wt) p53 peptides, whereas anti-p53 Y220C effector cells were specific for the mutant peptide, p53 Y220C cDNA-transfected HLA-A2(+) SaOS cells, and an HLA-A2(+) SCCHN cell line naturally expressing the mutation. These results indicate that the p53 Y220C mutation can be processed and presented for CD8(+) T cell recognition. Furthermore, using an autologous PBMC/tumor system, anti-p53 Y220C peptide-effector cells recognizing the autologous tumor could also be generated. Our analysis of p53 in 10 additional HLA-A2(+) SCCHN tumors detected the p53 Y220C in 2/10 tumors raising the overall frequency of the p53 Y220C mutation to 6/50 (12%) HLA-A2(+) SCCHN tumors. In contrast, independent of their HLA class I genotypes, the p53 Y220C mutation frequency for all human tumors analyzed to date is approximately 1.5%. This unexpectedly high frequency of the p53 Y220C mutation in HLA-A2(+) SCCHN suggests that vaccines targeting this mutation would not only be expected to induce robust anti-tumor immune responses in HLA-A2(+) subjects, but also be more widely applicable than previously envisioned for any given p53 missense mutation.

Gamma-delta T-cells in patients with squamous cell carcinoma of the head and neck

In our attempt to characterize a general immune-suppression found in patients with squamous cell carcinoma of the head and neck (SCCHN) we now focused on a subset of CD3 lymphocytes described as gamma/delta-T-cells, a cell type with potential relevance in non-MHC restricted anti-tumor immune responses. Peripheral blood of 33 SCCHN patients and 33 age-matched controls (CON) was evaluated for the frequency of gamma/delta-T-cells among CD3+ T-cells and their onset of apoptosis (Annexin V binding) by multicolor flow cytometry. Results were correlated with clinical parameters. Patients with SCCHN had a significantly higher proportion of gamma/delta-T-cells compared to healthy controls (4.4+/-0.4% for SCCHN vs. 3.0+/-0.3% for CON, p=0.01). However, this increase was not paralleled with a difference in the onset of apoptosis if compared to CON. There was also no correlation between the proportion of gamma/delta-T-cells and tumor stage. However, a significantly higher proportion of gamma/delta-T-cells was found in patients with recurrent or metachronous second primary SCCHN (6.0+/-1.0%) if compared to the other SCCHN (3.8+/-0.4%, p=0.02). In a follow up 3-6 months post-treatment patients showed a decrease of gamma/delta-T-cells among CD3+cells (2.7+/-0.4%, n=4) if they were operated only and an increase if primary radio-chemotherapy (6.7+/-1.7%, n=8) or a combination of operation plus radio-chemotherapy (6.8+/-2.3%, n=3) was applied. Furthermore, patients receiving palliative treatment including radio-chemotherapy had highest values of gamma/delta-T-cells (9.1+/-2.7%, n=4) overall implicating that the treatment modality significantly influences the proportion of gamma/delta-T-cells. Since patients with SCCHN, particularly those with recurrent or second primary disease after treatment, had a higher proportion of gamma/delta-T-cells without signs of a reduced onset of apoptosis this could be due to an increased de novo generation. The current study implies that increased frequencies of gamma/delta-T-cells in patients with SCCHN may not only be the result of tumor-host interactions but the consequence of applied treatment modalities.

T cells specific for HPV16 E7 epitopes in patients with squamous cell carcinoma of the oropharynx

Squamous cell carcinomas of the oropharynx (SCCO) are often infected with oncogenic human papilloma virus (HPV) subtype 16. To determine the frequency of T cells specific for human leukocyte antigen (HLA)-A2.1 restricted HPV16 E7 protein-derived epitopes, tetramer analysis was performed using peripheral blood lymphocytes of 20 HLA-A2.1+ patients and 20 HLA-A2.1+ healthy individuals. Tetramers specific for 3 HPV16 peptides (E711-20, E782-90 and E786-93), an influenza matrix peptide (a model recall antigen) or an HIV reverse transcriptase peptide (a model novel antigen) were used in multicolor flow analysis. The HPV-specific T-cell frequencies were correlated with the HPV16 E7 and p16 status in tumor sections. In vitro stimulation (IVS) with autologous dendritic cells (DC) pulsed with HPV16 E7 epitopes was performed to demonstrate proliferation and antitumor activity of the HPV-responsive T cells. Frequencies of CD8+ T cells specific for HPV16 E7 peptides were not significantly different in patients with SCCO relative to normal donors. However, patients with tumors expressing HPV16 E7 (60%) and p16 (50%) had an increased frequency (p<0.05) of T cells specific for the E711-20 epitope compared to those with tumors negative for both markers. HPV16 E711-20 and HPV16 E786-93 specific T cells were expandable upon IVS with cognate peptide-pulsed DC and were reactive against peptide-pulsed targets or, in case of the E711-20 epitope-specific T cells, against HPV16 E7 expressing CaSki cell line. Thus, in patients with HPV16+ SCCO, precursor T cells specific for E711-20 epitope are present (1/3,947) in the circulation, are responsive to stimulation with the cognate viral peptide and recognize in vitro HPV16 E7+ tumor cells. Further studies have to elucidate why those T cells are unable to eliminate the tumor in vivo and this might also allow for finding potential strategies that will increase the chances of developing a future HPV-based vaccine in patients with SCCO.

Comprehensive analysis of the p53 status in mucosal and cutaneous melanomas

The abrogation of the function of the "gatekeeper of the genome", p53, is the most prevalent molecular alteration in solid human tumors. Regarding melanomas the involvement of p53 alterations is discussed controversially to date. In order to evaluate the status of p53 in detail, primary tumors and metastases of 63 sporadic cutaneous (CM) and mucosal (MuM) melanomas were examined by immunohistochemistry and sequence analysis of the entire coding region of the p53 transcript, i.e., exons 2 to 11. In addition, loss of heterozygosity (LOH) and loss of allele-specific transcription (LOT) were determined. Accumulation of the p53 protein occurred in most of the CM and MuM specimens (71% and 58%, respectively). In contrast, protein stabilizing p53 mutations were observed in 14% of the CM and no mutation was found in MuM specimens. Two of the aberrations located outside the core domain. LOH was detected in 22% CM and 58% MuM, and LOT in 25% of the CM specimens. The genotype distribution at the polymorphic p53 codon 72 in melanoma patients differed significantly from control subjects. The calculation of odds ratios (OR) and 95% confidence intervals (CI) indicated an increased risk for developing cutaneous melanomas in individuals carrying the Pro-coding allele. Altogether, aberrant p53 expression appears to be a common event in both CM and MuM.

Homozygous deletions of CDKN2A caused by alternative mechanisms in various human cancer cell lines

The CDKN2A tumor-suppressor locus on chromosome band 9p21, which encodes p16(INK4A), a negative regulator of cyclin-dependent kinases, and p14(ARF1), an activator of TP53, is inactivated in many human cancers by point mutation, promoter hypermethylation, and, often, deletion. Homozygous deletions are unusually prevalent at this locus in very different human cancers. In the present study, we compared deletions in squamous cell carcinoma of the head and neck (SCCHN) cell lines to those in T-cell acute lymphatic leukemia (T-ALL), glioma, and bladder carcinoma (TCC) cell lines. Of 14 SCCHN lines, 10 showed homozygous deletions of CDKN2A, one displayed promoter hypermethylation with gene silencing, and one had a frameshift deletion in exon 2. Many deletion ends were in or proximal to the repetitive sequence clusters flanking the locus. Breakpoint junctions displayed variable microhomologies or insertions characteristic of DNA repair by nonhomologous end-joining. In general, deletions were much smaller in SCCHN than in TCC and glioma. In T-ALL, breakpoints were near consensus sites for recombination mediated by RAG (recombination activating genes) enzymes, and the structure of the junctions was consistent with this mechanism. We suggest that different mechanisms of CDKN2A deletion prevail in different human cancers. Aberrant RAG-mediated recombination may be responsible in T-ALL, and exuberant DNA repair by nonhomologous end-joining is the likely prevailing mechanism in SCCHN, but a distinct mechanism in TCC and glioma remains to be elucidated.

p53, p63 and p73 expression in squamous cell carcinomas of the head and neck and their response to cisplatin exposure

p63 and p73 share significant structural and functional homologies with the tumour suppressor p53. Unlike the p53 gene, both encode for several isoforms which vary in their NH2 and COOH termini with variable and, in part, opposed biological functions. The objective of the present study was to analyse the expression profiles of p53 family members in squamous cell carcinomas of the head and neck (HNSCC) and their alterations caused by exposure to the clinically active drug cisplatin. Using multiplex RT-PCR combined with the Southern technique, we determined transcription of p53 family members in 10 established HNSCC cell lines. In the majority of HNSCC, p53 and different p63/p73 isoforms were expressed with cell-line-specific patterns for composition and intensity of transcript expression. Exposure to cisplatin caused multiple alterations in the p63 and p73 profiles suggesting a complex regulation which may influence the sensitivity to chemotherapy.

p53 codon 72 polymorphic variants, loss of allele-specific transcription, and human papilloma virus 16 and/or 18 E6 messenger RNA expression in squamous cell carcinomas of the head and neck

A polymorphism at codon 72 of the human tumor suppressor p53 determines translation into either arginine or proline. Yet, the impact of this amino acid variability on the risk to develop malignant tumors, particularly carcinomas associated with human papilloma virus (HPV) infections, remains unresolved because of contradictory results. To address a potential correlation between the different genotypes and the manifestation of squamous cell carcinomas of the head and neck (SCCHN), we determined the p53 codon 72 in 193 healthy subjects and 122 unselected SCCHN with known HPV status. Furthermore, loss of allele-specific transcription was analyzed in p53 codon 72 heterozygous (Arg/Pro) SCCHN and correlated with HPV 16 and/or 18 E6 transcript expression. We found a moderately increased risk (odds ratio, 1.86; 95% confidence interval, 1.0-3.3) for individuals with germ line heterozygosity to develop SCC of the pharynx. On the other hand, p53 codon 72 polymorphic variants, most notably the Arg/Arg genotype, showed no association with the presence of HPV 16 and/or 18 E6 transcript. Moreover, there was no evidence for HPV-driven selection in SCCHN with allele-specific loss of transcription. Our data suggest that the p53 codon 72 polymorphism has a minor impact on the development of SCCHN.

p53 Codon 72 Polymorphic Variants, Loss of Allele-Specific Transcription, and Human Papilloma Virus 16 and/or 18 E6 Messenger RNA Expression in Squamous Cell Carcinomas of the Head and Neck

A polymorphism at codon 72 of the human tumor suppressor p53 determines translation into either arginine or proline. Yet, the impact of this amino acid variability on the risk to develop malignant tumors, particularly carcinomas associated with human papilloma virus (HPV) infections, remains unresolved because of contradictory results. To address a potential correlation between the different genotypes and the manifestation of squamous cell carcinomas of the head and neck (SCCHN), we determined the p53 codon 72 in 193 healthy subjects and 122 unselected SCCHN with known HPV status. Furthermore, loss of allele-specific transcription was analyzed in p53 codon 72 heterozygous (Arg/Pro) SCCHN and correlated with HPV 16 and/or 18 E6 transcript expression. We found a moderately increased risk (odds ratio, 1.86; 95% confidence interval, 1.0-3.3) for individuals with germ line heterozygosity to develop SCC of the pharynx. On the other hand, p53 codon 72 polymorphic variants, most notably the Arg/Arg genotype, showed no association with the presence of HPV 16 and/or 18 E6 transcript. Moreover, there was no evidence for HPV-driven selection in SCCHN with allele-specific loss of transcription. Our data suggest that the p53 codon 72 polymorphism has a minor impact on the development of SCCHN.

Is the p53 inactivation frequency in squamous cell carcinomas of the head and neck underestimated? Analysis of p53 exons 2-11 and human papillomavirus 16/18 E6 transcripts in 123 unselected tumor specimens

Mutations and interaction with high-risk human papillomavirus (HPV) E6 oncoprotein are well-established mechanisms of p53 inactivation. In a series of 123 unselected squamous cell carcinomas of the head and neck (SCCHN), we performed sequence analysis of the entire coding region of p53 transcript and determined the presence of the E6 transcripts of HPV 16 and 18. Aberrant p53 transcripts were identified in 97 (79%) SCCHN. HPV 16 and/or 18 E6 transcripts were detected in 37 (30%) tumor specimens, including 20 (77%) of the 26 p53 wild-type tumors. The likely inactivation of p53 in 117 (95%) of the 123 SCCHN suggests that this event could be obligatory in the multistep process of carcinogenesis.

Analysis of BRCA1, TP53, and TSG101 germline mutations in German breast and/or ovarian cancer families

About 5%-10% of breast cancers are considered to be hereditary and associated with germline mutations of specific genes. As yet, the most frequently affected genes identified are BRCA1 and BRCA2, but also other genes such as TP53 are supposed to influence the predisposition toward breast cancer. In the present study, we analyzed patients of 19 German families with early onset breast cancer and/or a family history of breast and/or ovarian cancer for the presence of mutations in BRCA1 and TP53. In addition, we screened for germline mutations in the putative tumor suppressor gene TSG101. For this purpose we used direct sequence analysis of the entire coding regions for all three genes and, in the case of BRCA1, single-strand conformation polymorphism analysis and protein transcription-translation assays. We identified eight previously described polymorphisms and several aberrations in BRCA1: 1 unclassified missense mutation, 3 small protein truncating mutations, 1 novel pseudoexon, and 5 splicing variants. No mutation was detected in TP53. Analysis of TSG101 transcripts revealed an aberrant transcript in two breast cancer patients belonging to the same family, suggesting TSG101 as a predisposing gene in hereditary breast cancer.

Reliable detection of p53 aberrations in squamous cell carcinomas of the head and neck requires transcript analysis of the entire coding region

BACKGROUND

Aberrations of the p53 tumor suppressor gene are common events in squamous cell carcinomas of the head and neck (SCCHN). However, reported frequencies range considerably, and the predictive value of aberrant p53 is continuing to be an issue of controversy. These inconsistencies are possibly caused by methodical limitations.

METHODS

In cell lines established from 23 SCCHN, we performed sequence analysis of p53 mRNA and genomic DNA, as well as protein detection using immunohistochemistry and Western blotting.

RESULTS

Of the 23 SCCHN, 21 (91%) tumors have aberrant or no p53, including four aberrations (19%) located outside the usually examined exons 5 to 9. A second allele is present in 11, and the respective transcript in 4 tumors. Expression of protein could be detected in only 12 of the 21 p53 aberrant tumors (57%).

CONCLUSIONS

Depending on the methodical approach applied, a considerable number of SCCHN may be misclassified regarding their p53 status.

Mpv37 mouse strain--a model for the relationship between the kidney and the inner ear

Using the Mpv17-negative mouse strain, which developed inner ear and kidney dysfunction, we confirm a strong relationship between the kidney and the inner ear. Both organs have specialized epithelia involved in active ion transport, which are separated from the vessels by a basement membrane of similar composition. Our recent results indicate that the glomerular and the stria vascularis basement membrane are simultaneously affected in early stages. Concomitant deposits of IgG during the progressive development of the disease support the idea of a shared antigen. Understanding the pattern of the development of the degeneration will provide a basis towards understanding the essential role of the Mpv17 protein in the structures of both organs and may provide a basis for future therapeutic intervention.

Effects of tamoxifen on human squamous cell carcinoma lines of the head and neck

Tamoxifen (TAM) is a well-tolerated compound in the treatment of breast cancer and is primarily considered to act by competition with estrogen receptors (ER). Here we investigated the in vitro efficacy and potentially underlying mechanisms of TAM in established cell lines of squamous cell carcinomas of the head and neck (SCCHN). Using proliferation and apoptosis assays the antitumor activity of TAM in five SCCHN and the breast carcinoma line MCF-7 (positive control) was determined. MCF-7 was more sensitive to low-dose TAM (below 1 microM), whereas SCCHN showed significant growth inhibition at higher TAM concentrations (5-10 microM). Growth curve analysis and apoptosis assays were indicative for a cytostatic effect of low-dose TAM and high-dose TAM led to cell loss by apoptosis in sensitive SCCHN. In order to further characterize the observed antitumor effects we determined the amount of steroid hormone receptors with the dextran-coated charcoal method and immunocytochemistry. In addition, production of transforming growth factor (TGF-)-alpha, -beta1 and -beta2 was measured by ELISA, and protein kinase C (PKC) activity was assessed with a radioligand assay. Except MCF-7, none of the SCCHN lines was positive for ER. TAM caused decreased TGF-alpha and increased TGF-beta levels in MCF-7, but not in SCCHN supernatants. Furthermore, the antiestrogen reduced PKC activity in MCF-7, but not in SCCHN. In the present in vitro system, the observed antitumor activity of high-dose TAM in SCCHN cannot be explained by estrogen antagonism, alterations of TGF-alpha/beta levels or decreased PKC activity.

Antitumor activity of protein kinase C inhibitors and cisplatin in human head and neck squamous cell carcinoma lines

Protein kinase C (PKC) plays a pivotal role in signal transduction involved in the control of cell proliferation, differentiation and apoptosis. Interference with such signaling pathways may result in altered tumor cell response to antineoplastic drugs. We investigated the effects of two selective PKC inhibitors as single agents and in combination with cisplatin in cell lines derived from squamous cell carcinomas of the head and neck (SCCHN). Safingol (Saf) is directed against the regulatory domain, whereas chelerythrine (Che) interacts with the catalytic domain of PKC. In six SCCHN cell lines (UM-SCC 11B, 14A, 14C and 22B, 8029NA, and a 5-fold cisplatin-resistant subline 8029DDP). PKC activities ranged between 1 and 158 IU/1 x 10(7) cells, and they were inversely proportional to the amount of cellular epidermal growth factor receptor. Using the colorimetric MTT assay, PKC inhibitors Saf and Che showed comparable dose-dependent growth inhibition. The 50% inhibitory concentrations (IC50) were between 3.8-8.6 microM for Saf and 8.5-13.6 microM for Che with no relationship to PKC activity or cisplatin sensitivity of the respective cell lines. Combinations of cisplatin (IC50 = 0.4-5.8 microg/ml) and either PKC inhibitor (5 microM Saf, 10 microM Che) led to a significant decrease of cisplatin IC50 values in most cell lines. However, comparison with theoretical additive dose-response curves showed additive rather than synergistic effects for both PKC inhibitors.

Establishment and characterization of four cell lines derived from human head and neck squamous cell carcinomas for an autologous tumor-fibroblast in vitro model

To study interactions between tumor cells and stromal elements, we established carcinoma cell lines as well as tumor-derived and skin fibroblast cultures from four patients with squamous cell carcinoma of the head and neck. For the characterization of the tumor cell lines we a) determined population doubling times, b) assessed morphological features by light and electron microscopy, c) investigated the expression of typical markers by immunohistochemistry, including various intermediate filaments and surface antigens, d) compared these findings with expression patterns in the respective original tumor specimens, e) evaluated p53 mutations in tumor specimens and cell lines, f) performed chromosome analysis, g) investigated the tumorigenicity in athymic mice, and h) tested the formation of both tumor and mixed tumor-fibroblast multicellular spheroids. Tumor cell cultures were considered established cell lines when maintained and passaged over a period of two years after primary explantation. The in vitro morphology of the cell lines showed well preserved characteristics of squamous cell carcinoma, and electron microscopy as well as immunohistochemistry revealed their squamous type of differentiation. All cell lines presented the same p53 genotype as the respective original tumors. Furthermore, they were successfully xenotransplanted into nude mice and formed both pure and mixed three dimensional spheroids. This experimental model allows the in vitro and in vivo investigation of various tumor-fibroblast interactions.

Organisation of regulatory elements in two closely spaced Drosophila genes with common expression characteristics

Sperm tail proteins that are components of a specific structure formed late during spermatid elongation have been found to be encoded by the Mst(3)CGP gene family. These genes have been demonstrated to be regulated both at the transcriptional as well as at the translational level. We report here on the dissection of the regulatory regions for two members of the gene family, Mst84Da and Mst84Db. While high level transcription and negative translational control of Mst84Da is mediated by a short gene segment of 205 nt (-152/+53), Mst84Db expression is controlled by a number of distinct regulatory elements with different effects that all reside within the gene itself. We identify a transcriptional control element between +154 and +216, a translational repression element around +216 to +275 and an RNA stability element within the 3'UTR. Irrespective of the final common expression characteristics, correct regulation for any individual member of the gene family seems to be achieved by very different means. This confirms earlier observations that did not detect any other sequence elements in common apart from the TCE (translational control element).