Synergistic effects of imatinib and carboplatin on VEGF, PDGF and PDGF-Rα/ß expression in squamous cell carcinoma of the head and neck in vitro

Head and neck squamous cell carcinoma (HNSCC) is an aggressive epithelial malignancy. The development of new treatment modalities in order to improve long-term survival of patients with HNSCC is imperative. Numerous studies have demonstrated that carcinogenesis and tumor cell dissemination is influenced by the tumor microenvironment. The protein-kinase-receptors (PTKs) are essential elements of the intracellular signal transduction pathway and regulate cell growth, development and apoptosis. Cell proliferation, migration, induction of tumor vascularization and carcinogenesis, invasion is regulated by a variety of angiogenic factors, such as PDGF (platelet-derived growth factor), VEGF (vascular endothelial growth factor) and their respective tyrosine kinase receptors (PDGF-R and VEGF-R). They present promising targets for anti-cancer therapy through abrogation of impaired signaling pathways. Indeed, imatinib, a small molecule drug targeting these protein kinases, has antiproliferative effects in several cancer types. The purpose of this study was to investigate the potential synergism of imatinib and carboplatin on the expression of PDGF, PDGF-R α/ß and VEGF in different HNSCC cell lines. Several tumor cell lines were subjected to increasing concentrations of carboplatin (3 and 7.5 µmol/l) and imatinib (18 and 30 µmol/l) and ELISA, immunohistochemical methods and RQ-PRC after 48, 72, 120 and 240 h were used to assess their expression levels. While PDGF-Rα/ß expression was unimpaired at lower imatinib concentrations (18 µmol/l), PDGF-Rα/ß expression was suppressed at 30 µmol/l, and suppression was enhanced by the presence of carboplatin. By RQ-PCR, a significant reduction of PDGF-Rα/ß expression was detected (p<0.5). We observed explicit significant reduction in VEGF levels with increasing concentrations of imatinib and with the combination of the two chemotherapeutic drugs (p<0.5). We report for the first time evidence of synergism of imatinib and carboplatin in suppressing VEGF, PDGF and PDGF-Rα/ß expression in HNSCC.

TGF-ß1 antisense impacts the SMAD signalling system in fibroblasts from keloid scars

AIM

To identify the effect of a TGF-β1 antisense treatment of keloid fibroblasts on the SMAD signalling system.

MATERIAL AND METHODS

In this cross-sectional study, keloid and adjacent healthy tissue was harvested from 9 patients with keloid scars after otoplasty. Keloid fibroblasts were placed in monolayer cultures. Expression of SMAD2, -3, -4, -6, and SMURF2 were analysed by immunohistochemistry. Analysis of treatment with antisense oligonucleotides was conducted by immunohistochemistry, and RT-PCR.

RESULTS

Immunohistochemical investigation demonstrated increased expression of SMAD2, -3 and -4, and decreased expression of SMURF2. TGF-β1 antisense therapy significantly down-regulated SMAD2 and SMAD4, up-regulated SMURF2 and showed no effect on SMAD3 and SMAD6.

CONCLUSION

TGF-β1 led to elevated levels of the SMAD signalling cascade, indicating an abnormal sensitivity of keloid-derived fibroblasts to this cytokine. Abrogation correlated with potential suppression of the fibro-proliferative progress. There is growing evidence for an abnormal response to this cytokine in the intracellular signal transduction in keloid-derived fibroblasts.

Effect of transforming growth factor-beta1 antisense oligonucleotides on matrix metalloproteinases and their inhibitors in keloid fibroblasts

OBJECTIVE

To identify changes in the expression of matrixmetalloproteinases (MMPs) and their specific inhibitors tissue inhibitors of metalloproteinases (TIMPs) after targeting of transforming growth factor-beta1 (TGF-beta1) with antisense oligonucleotides.

STUDY DESIGN

Cross-sectional study.

SETTING

The study was performed on tissue samples from nine patients with keloid scars after otoplasty presenting to the Otolaryngology-Head and Neck Surgery Department of the University Hospital in Mannheim, Germany.

SUBJECTS AND METHODS

Keloid fibroblasts and normal fibroblasts were harvested from auricular keloid scars and healthy skin regions of the same patients during resection procedure of the keloid. Cells were placed in monolayer cultures. Expression of MMPs and TIMPs were analyzed by immunohistochemistry. The effect of TGF-beta1 targeting using antisense oligonucleotides on the expression of both protein groups in keloid-derived fibroblasts was analyzed by enzyme-linked immunosorbent assay and reverse-transcription polymerase chain reaction.

RESULTS

Immunohistochemical investigation demonstrated increased expression of MMP-2, -3, -9, and -13 and TIMP-1 and -2. TGF-beta1 antisense therapy significantly down-regulated MMP secretion in vitro.

CONCLUSION

Usage of TGF-beta1 antisense oligodeoxynucleotides (ODNs) may show a potential chemopreventive or therapeutic option for keloids by blocking the effect of TGF-beta1. Furthermore, antisense ODNs can be used as an investigative approach toward a better understanding of molecular mechanisms in keloid pathophysiology.

Keloids: current concepts of pathogenesis (review)

Excess scar formation occurs after dermal injury as a result of abnormal wound healing. Hypertrophic scars and keloids both represent fibrotic skin conditions which can be very difficult, even frustrating, to treat. Identification of differences between hypertrophic scars, keloids and normal scars are a prerequisite for finding the correct therapeutical concept. Despite the relatively high prevalence of keloids in the general population, the mechanisms underlying keloid formation are only partially understood. This fact is reflected in the multiple treatment modalities, of which no single treatment has proven to be widely effective. Advances in our understanding of the wound healing process reveal new pathophysiological concepts for keloid formation. Our article presents an overview on physiological wound healing and the pathogenesis of scar formation, differentiates keloids from hypertrophic scars and reviews current hypotheses for keloid formation. This information might assist in deciphering the complexity of keloid pathogenesis and help in the development of an efficacious therapeutical strategy.

Mutation analysis of "Endoglin" and "Activin receptor-like kinase" genes in German patients with hereditary hemorrhagic telangiectasia and the value of rapid genotyping using an allele-specific PCR-technique

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is an autosomal dominant disorder which is clinically characterised by recurrent epistaxis, mucocutaneous telangiectasia and visceral arteriovenous malformations. Genetic linkage studies identified two genes primarily related to HHT: endoglin (ENG) on chromosome 9q33-34 and activin receptor-like kinase1 (ACVRL1) on chromosome 12q13. We have screened a total of 41 unselected German patients with the suspected diagnosis of HHT. Mutation analysis for the ENG and ACVRL1 genes in all patients was performed by PCR amplification. Sequences were then compared to the HHT database http://www.hhtmutation.org sequences of the ENG mRNA (accession no. BC014271.2) and the ACVRL1 mRNA (accession no. NM000020.1).

RESULTS

We identified 15 different mutations in 18 cases by direct sequencing. Among these mutations, one novel ENG mutation could be detected which has not yet been described in the literature before. The genotype-phenotype correlation was consistent with a higher frequency of pulmonary arteriovenous malformations in patients with ENG mutations than in patients with ACVRL1 mutations in our collective.

CONCLUSION

For rapid genotyping of mutations and SNPs (single nucleotide polymorphisms) in ENG and ACVRL1, allele-specific PCR methods with sequence-specific primers (PCR-SSP) were established and their value analysed.

Lymphatic vessel density in correlation to lymph node metastasis in head and neck squamous cell carcinoma

BACKGROUND

In head and neck squamous cell carcinoma (HNSCC), metastatic dissemination to regional lymph nodes serves as a major prognostic indicator for incipient disease progression and constitutes the guideline for subsequent therapeutic strategies. In this study, whether intratumoral (IT) and peritumoral (PT) lymphatic vessel density (LVD) might be a predictive indicator to the risk of lymph node metastasis was investigated.

PATIENTS AND METHODS

Tumour lymph vessels in fresh frozen sections of 105 head and neck cancer were quantified by immunostaining for the lymphatic endothelial marker LYVE-1. These results underwent correlation with the nodal status of the patient.

RESULTS

There was a significant relationship between a high IT LVD and nodal metastasis (N+) (p=0.049, Mann-Whitney test). Analysed separately by anatomic regions, a significant correlation was only shown in oral carcinoma (p=0.032, Mann-Whitney test). Intratumoral LVD was lower compared to peritumoral LVD. Logistic regression, however, showed that the only predictive parameter for the nodal status was the localisation of the primary tumour but not LVD.

CONCLUSION

This study confirmed that IT LVD is low in HNSCC. In this group of tumours there was a significant correlation between IT LVD and nodal involvement.

The platelet-derived growth factor receptor as a target for vascular endothelial growth factor-mediated anti-angiogenetic therapy in head and neck cancer

Inhibition of angiogenesis by blocking angiogenic cytokines or their pathways has become a major target in experimental cancer therapies. This therapeutical approach requires a profound knowledge of growth factor profiles that contribute to tumor growth and progression. The respective knowledge is presently rather incomplete for head and neck squamous cell carcinomas (HNSCC). Therefore we studied the serum levels and expression of platelet-derived growth factor (PDGF) in HNSCC patients and in cell culture as well as the effect of a PDGF-receptor (PDGF-R) inhibition by Imatinib (Gleevec, STI571) on the secretion and expression activity of PDGF and vascular endothelial growth factor (VEGF) by postulating there is a correlation between the PDGF and VEGF networks. PDGF levels in patients with HNSCC, PDGF and VEGF secretion by HNSCC cells, were measured by ELISA, expression of PDGF and VEGF by RT-PCR. We found significantly increased PDGF levels in HNSCC patients' sera as well as in HNSCC cell lines. Treatment of the cell lines with Imatinib, a partially selective PDGF-R inhibitor, resulted in reduced secretion of PDGF and VEGF. This inhibiting effect was also reflected on the expression level of VEGF. In conclusion, the present study confirms the crucial role of PDGF in HNSCC growth and strongly suggests a correlation between the PDGF/PDGF-R and VEGF/VEGF-R pathway networks in HNSCC. Although further studies must be performed for a more complete understanding of this interaction, a targeting therapy for the inhibition of PDGF-R tyrosine phosphorylation by Imatinib may be a promising strategy for future tumor therapy by autocrine and paracrine inhibition of tumor growth and angiogenesis, presumably through simultaneous down-regulation of PDGF and VEGF.

Does the genotype of HHT patients with mutations of the ENG and ACVRL1 gene correlate to different expression levels of the angiogenic factor VEGF?

The aim of this study was to determine in what way HHT (hereditary hemorrhagic telangiectasia) patients with mutations for the endoglin (ENG) or activin receptor-like kinase 1 (ACVRL1) gene show different expression levels of the angiogenic factor VEGF (vascular endothelial growth factor) by correlating VEGF to the HHT genotype. In 18 HHT patients, who were screened for ENG and ACVRL1 gene mutations and 25 healthy controls the VEGF plasma level as well as the VEGF tissue expression were determined by ELISA technique and cryostat sections of the nasal mucosa. In general, the VEGF plasma levels as well as the VEGF tissue expression were significantly higher in HHT patients compared to healthy controls. However, the correlation of VEGF to the HHT genotype did not show any significant differences, i.e. the VEGF plasma levels as well as the VEGF tissue expression in HHT patients with ENG gene mutations did not differ significantly to those of HHT patients with ACVRL1 gene mutations or mutations for both the genes. In spite of the fact that the angiogenic factor VEGF seems to play an important role in the pathogenesis of HHT, it cannot serve as a specific diagnostic screening marker. These results underline the importance and necessity of molecular analyses in HHT patients.

Abrogation of TGF-beta by antisense oligonucleotides modulates expression of VEGF and increases angiogenic potential in isolated fibroblasts from radiated skin

The transforming growth factor-beta (TGF-beta) has been identified as an important component of wound healing. Recent developments in molecular therapy offer good prospects for the modulation of wound healing, specifically those targeting TGF-beta. The aim of this study was to analyze the effect of TGF-beta targeting on the expression of angiogenic vascular endothelial growth factor (VEGF), a key regulator of angiogenesis and in vitro angiogenic activity in fibroblasts isolated from radiation-induced chronic dermal wounds. The expression of angiogenic VEGF in tissue samples from radiation-induced chronic dermal wounds was investigated by immunohistochemistry and microarray technique. The effect of TGF-beta targeting using antisense oligonucleotides on the expression of VEGF in isolated fibroblasts was analyzed by ELISA and multiplex RT-PCR. Human endothelial cells (ECs) were grown in conditioned medium produced from the treated fibroblasts. EC migration was measured using a modified Boyden chamber; EC tube formation was analyzed under a light microscope. Immunohistochemical investigation and microarray analysis demonstrated a decreased expression of VEGF protein and mRNA in tissue samples from radiation-induced chronic dermal wounds compared to normal human skin. Antisense TGF-beta oligonucleotide treatment significantly up-regulated VEGF secretion in vitro. Addition of conditioned medium from TGF-beta antisense-treated fibroblasts resulted in an increase in EC cell migration and tube formation. In conclusion, our results demonstrate that TGF-beta antisense oligonucleotide technology may be a potential therapeutic option for stimulation of angiogenesis in radiation-induced dermal wounds.

TGF-beta1 antisense therapy modulates expression of matrix metalloproteinases in keloid-derived fibroblasts

Transforming growth factor-beta1 (TGF-beta1) has been identified as an important regulator of wound healing. Recent developments in molecular therapy offer exciting prospects for the modulation of wound healing, specifically those targeting TGF-beta1. The purpose of this study was to analyze the effect of TGF-beta1 targeting on the expression of matrix metalloproteinases (MMPs) in fibroblasts cultured from earlobe keloids. The expression of MMP-2 and -9 in tissue samples from keloids was investigated by immunohistochemistry. The effect of TGF-beta1 targeting using antisense oligonucleotides on the expression of MMPs in keloid-derived fibroblasts was analysed by ELISA and multiplex RT-PCR. Immunohistochemical studies demonstrated an increased expression of MMP protein in tissue samples from keloids compared to normal human skin. Antisense TGF-beta1 oligonucleotide treatment significantly downregulated MMP-9 secretion in vitro. In conclusion, TGF-beta1 antisense oligonucleotide technology may be a potential therapeutic option for the inhibition of proteolytic tissue destruction in keloids.

Skeletal Muscle Regeneration: MSC versus Satellite Cells

Problem

Differentiating stem cells into the myogenic linage in order to create functional muscle tissue is a challenging endeavour. In this work, adipose-derived mesenchymal stem cells (MSC) and satellite cells derived from muscle biopsies were compared regarding proliferation and myogenic differentiation potential under standardized cell culture conditions. This data was obtained in order to discover the most promising type of stem cell for regeneration of muscle tissue and to determine the optimal culture conditions for later clinical use.

Methods

Human MSC were isolated from adipose tissue, and primary human skeletal myoblasts were extracted from muscle biopsies by enzymatic digestion. Proliferation was analysed using the AlamarBlue® assay. Gene expression of marker genes – such as Myogenin, Myo D, Myf 5 and MHC – were analysed by RT-PCR. Immunostainings against desmin and sarcomeric-actin were performed as differentiation markers.

Results

MSC cell cultures showed a greater proliferation rate compared with satellite cell cultures. In both stem cell cultures, myogenic differentiation/heritage could be verified by immunostainings against the muscle-specific marker desmin. Gene expression and protein analysis revealed a more stable differentiation of human satellite cell cultures.

Conclusion

Characterization of both human MSC cultures and satellite cell cultures – and thereby an understanding of myogenesis – might lead to their clinical usage in skeletal muscle tissue engineering. The results in this study appear to indicate that human satellite cell cultures have a more stable differentiation under in vitro conditions and that they might offer a greater potential for skeletal muscle tissue engineering purposes.

Significance

Our study contributes to the understanding of myogenic differentiation of MSC and satellite cells and helps to improve culture systems for later clinical utilization.

Integrin expression in stem cells from bone marrow and adipose tissue during chondrogenic differentiation

The use of adult mesenchymal stem cells (MSC) in cartilage tissue engineering offers new perspectives in the generation of transplants for reconstructive surgery. The extracelular matrix (ECM) plays a key role in modulating the function and phenotype of the embedded cells and contains the integrins as adhesion receptors mediating cell-cell and cell-matrix interactions. In our study, characteristic changes in integrin expression during the course of chondrogenic differentiation of MSC from bone marrow and adipose tissue were compared. MSC were isolated from bone marrow biopsies and adipose tissue. During cell culture, chondrogenic differentiation was performed. The expression of integrins and their signaling components were analysed with microarray and immunohistochemistry in freshly isolated MSC and after chondrogenic differentiation. The fibronectin receptor (integrin alpha5beta1) was expressed by undifferentiated MSC, and expression rose during chondrogenic differentiation in both types of MSC. The components of the vitronectin/osteopontin receptors (alphavbeta5) were not expressed by freshly isolated MSC, and expression rose with ongoing differentiation. Receptors for the collagens (alpha1beta1, alpha2beta1, alpha3beta1) were weakly expressed by undifferentiated MSC and were activated during differentiation. Intracellular signaling components integrin-linked kinase (ILK) and CD47 showed increased expression with ongoing differentiation. For all integrins, no significant differences were be found in the 2 types of MSC. Integrin-mediated signaling appeared to play an important role in the generation and maintenance of the chondrocytic phenotype during chondrogenic differentiation. Particularly, the receptors for fibronectin, vitronectin, osteopontin and the collagens may be involved in the generation of the ECM. Intracellularly, their signals might be transduced by ILK and CD47. To fully harness the potential of these cells, future studies should be directed to ascertain their cellular and molecular characteristics for optimal identification, isolation, and expansion.

TGF-beta antisense oligonucleotides modulate expression of matrix metalloproteinases in isolated fibroblasts from radiated skin

BACKGROUND

Transforming growth factor-beta (TGF-beta) has been identified as an important component of wound healing. Recent developments in molecular therapy offer exciting prospects for the modulation of wound healing, specifically those targeting TGF-beta. The purpose of this study was to analyze the effect of TGF-beta targeting on the expression of matrix metalloproteinases (MMPs) in fibroblasts isolated from radiation-induced chronic dermal wounds.

MATERIALS AND METHODS

The expression of MMPs in tissue samples from radiation-induced chronic dermal wounds was investigated by immunohistochemistry and microarray technique. The effect of TGF-beta targeting using antisense oligonucleotides on the expression of MMPs in isolated fibroblasts was analysed by ELISA and multiplex RT-PCR.

RESULTS

Immunohistochemical investigation and microarray analysis demonstrated an increased expression of MMP protein and mRNA in tissue samples from radiation-induced chronic dermal wounds compared to normal human skin. Antisense TGF-beta oligonucleotide treatment significantly down-regulated MMP secretion in vitro.

CONCLUSION

TGF-beta antisense oligonucleotide technology may be a potential therapeutic option for the inhibition of proteolytic tissue destruction in radiation-induced chronic wounds.

Characterization of human myoblast cultures for tissue engineering

Skeletal muscle tissue engineering, a promising specialty, aims at the reconstruction of skeletal muscle loss. In vitro tissue engineering attempts to achieve this goal by creating differentiated, functional muscle tissue through a process in which stem cells are extracted from the patient, e.g. by muscle biopsies, expanded and differentiated in a controlled environment, and subsequently re-implanted. A prerequisite for this undertaking is the ability to cultivate and differentiate human skeletal muscle cell cultures. Evidently, optimal culture conditions must be investigated for later clinical utilization. We therefore analysed the proliferation of human cells in different environments and evaluated the differentiation potential of different culture media. It was shown that human myoblasts have a higher rate of proliferation in the alamarBlue assay when cultured on gelatin-coated culture flasks rather than polystyrene-coated flasks. We also demonstrated that myoblasts treated with a culture medium with a high concentration of growth factors [growth medium (GM)] showed a higher proliferation compared to cultures treated with a culture medium with lower amounts of growth factors [differentiation medium (DM)]. Differentiation of human myoblast cell cultures treated with GM and DM was analysed until day 16 and myogenesis was verified by expression of MyoD, myogenin, alpha-sarcomeric actin and myosin heavy chain by semi-quantitative RT-PCR. Immunohistochemical staining for desmin, Myf-5 and alpha-sarcomeric actin was performed to verify the myogenic phenotype of extracted satellite cells and to prove the maturation of cells. Cultures treated with DM showed positive staining for alpha-sarcomeric actin. Notably, markers of differentiation were also detected in cultures treated with GM, but there was no formation of myotubes. In the enzymatic assay of creatine phosphokinase, cultures treated with DM showed a higher activity, evidencing a higher degree of differentiation. In this study, we obtained detailed information regarding the cultivation and differentiation of human myoblast cultures in different environments. By exploring optimal culture conditions for skeletal muscle tissue engineering, we acquired culture data for comparison with other sources of stem cells in order to find the most applicable stem cell for focussed clinical usage.

Tissue engineering in head and neck reconstructive surgery: what type of tissue do we need?

Craniofacial tissue loss due to congenital defects, disease or injury is a major clinical problem. The head and neck region is composed of several tissues. The most prevalent method of reconstruction is autologous grafting. Often, there is insufficient host tissue for adequate repair of the defect side, and extensive donor site morbidity may result from the secondary surgical procedure. The field of tissue engineering has the potential to create functional replacements for damaged or pathologic tissues.