Cytotoxic impact of nicotine products on periodontal ligament cells.

OBJECTIVES: The primary objective of this in vitro experiment was an assessment of proliferative capacity, metabolic activity, and potential cellular detriment of human periodontal ligament cells (hPDL) exposed to cigarette smoke (CS), electronic cigarette vapor (eCV), and heated tobacco product aerosol (HTP), or air (control). MATERIALS AND METHODS: Using a CAD/CAM-designed exposition chamber, hPDL were exposed to CS, eCV, HTP, or air (control) based on the Health Canada Intense Smoking Regime. Cell proliferation, metabolic activity, and cellular detriment were assessed at various time points. RESULTS: Compared to the control, hPDL exposed to CS exhibited significantly decreased cell numbers at all time points. HTP exposure led to reduced cell numbers 48 h and 72 h post-exposure, while eCV-exposed cells showed no significant decrease. The metabolic activity of eCV-treated hPDL was slightly reduced at 7 h but recovered at 24 h and 48 h. In contrast, CS-treated cells exhibited significantly decreased metabolic activity at 24 h and 48 h, and HTP-exposed cells showed a significant decrease after 48 h. Flow cytometry indicated both apoptotic and necrotic cell death following CS exposure, with necrotic cell death being more pronounced. CONCLUSIONS: eCV and HTP demonstrated comparatively reduced detrimental effects on hPDL compared to CS. CLINICAL RELEVANCE: The findings suggest that conventional cigarette smoke poses a substantial risk to periodontal health by significantly impairing cell proliferation and metabolic activity. However, alternatives such as eCV and HTP may offer a comparatively reduced risk.

Erk Inhibition as a Promising Therapeutic Strategy for High IL-8-Secreting and Low SPTAN1-Expressing Colorectal Cancer.

Tumor recurrence and drug resistance are responsible for poor prognosis in colorectal cancer (CRC). DNA mismatch repair (MMR) deficiency or elevated interleukin-8 (IL-8) levels are characteristics of CRCs, which have been independently correlated with treatment resistance to common therapies. We recently demonstrated significantly impaired therapeutical response and increased IL-8 release of CRC cell lines with reduced expression of MMR protein MLH1 as well as cytoskeletal non-erythrocytic spectrin alpha II (SPTAN1). In the present study, decreased intratumoral MLH1 and SPTAN1 expression in CRCs could be significantly correlated with enhanced serum IL-8. Furthermore, using stably reduced SPTAN1-expressing SW480, SW620 or HT-29 cell lines, the RAS-mediated RAF/MEK/ERK pathway was analyzed. Here, a close connection between low SPTAN1 expression, increased IL-8 secretion, enhanced extracellular-signal-regulated kinase (ERK) phosphorylation and a mesenchymal phenotype were detected. The inhibition of ERK by U0126 led to a significant reduction in IL-8 secretion, and the combination therapy of U0126 with FOLFOX optimizes the response of corresponding cancer cell lines. Therefore, we hypothesize that the combination therapy of FOLFOX and U0126 may have great potential to improve drug efficacy on this subgroup of CRCs, showing decreased MLH1 and SPTAN1 accompanied with high serum IL-8 in affected patients.

Cigarette smoke modulates binding of the transcription factor MZF1 to the VEGF promoter and regulates VEGF expression in dependence of genetic variation SNP 405.

BACKGROUND: Vascular endothelial growth factor (VEGF) affects carcinogenesis of the upper aerodigestive tract. Cigarette smoke (CSE) influences VEGF-gene regulation. The single nucleotide polymorphism +405 G/C (SNP +405 G/C) and the transcriptional factor (TF) myeloid zinc finger 1 (MZF1) are endogenic regulators of the VEGFpromoter as the polymorphism 405 potentially affects binding of the transcription factor MZF1. Therefore, this in vitro study analysed cancer cells of the upper aerodigestive tract after CSE incubation concerning MZF1-binding specificity and VEGF expression in dependency of VEGF polymorphism +405 G/C compared to wild type (wt). METHODS: In human alveolar epithelial-like type-II cells (A549) and oral squamous cell cancer cells (HNSCCUM-02T) SNP +405 G/C- and MZF1-dependent VEGF promoter activity and VEGF expression were analysed by qRT-PCR and Western blot after incubation with 10% CSE. Temporary knock-down of MZF1 was performed using siRNA. MZF1 binding was analysed by Co-Chromatin-Immunoprecipitation (Co-ChiP) (each test n = 3). RESULTS: We found a stronger MZF1 binding to VEGF polymorphism 405 in A549 cells (P < .05) compared to HNSCCUM-02T cells (P = .02), where MZF1 binding was reduced. MZF1 knock out reduced VEGF promoter activity in HNSCCUM-02T cells, showing the relevance of the factor for transcriptional activation of the VEGF promoter. Finally, we found that CSE increases promoter activity in both cell lines and no significant differences between the two analysed polymorphisms concerning their activating capacity. CONCLUSION: In summary, both VEGF promoter polymorphisms are similar effective in terms of transcriptional activity, and MZF1 is a transcriptional activator of VEGF promoter. Moreover, cigarette smoke increases MZF1 binding of VEGF-promoter and directly affects VEGF-gene regulation.

The impact of cigarette smoke on activity of single nucleotide polymorphisms of the vascular endothelial growth factor-promoter gene in cells of the upper aerodigestive tract.

BACKGROUND: The vascular endothelial growth factor (VEGF) is involved in tumorigenesis of the upper aerodigestive tract. Different single nucleotide polymorphisms (SNPs) turn the regulation of the VEGF gene into a highly complex process, particularly influenced by exogenic factors like cigarette smoke (CSE). Analysis of the SNP- and CSE-dependent VEGF-gene regulation can help to improve antiangiogenic therapies and prognosis. Therefore, the aim of this study was to analyse the influence of CSE on the SNP-dependent regulation of the VEGF-gene in vitro. METHODS: Human alveolar epithelial-like type-II cells (A549) were transfected with different SNPs and incubated with CSE. SNP- and CSE-dependent VEGF-promoter activity and mRNA stability was measured using qRT-PCR and Western blot analysis. RESULTS: Transfection with SNP -460 (ATC) and incubation with 10% CSE resulted in +19% elevated VEGF-promoter activity (P < 0.05). Transfection with SNP -2578/-460 (CTC) and 10% CSE incubation resulted in a 14% reduction of VEGF-promoter activity (P < 0.05). Regarding mRNA stability, transfection with SNP +936 T allele led to half-life of 1.11 hours, which decreased to 0.2 hours after incubation with CSE. In contrast, on protein level SNP +936 T transfection showed a not significant increase up to 176% (P > 0.05), while incubation with CSE led to a significant decrease to 61% (P = 0.002). CONCLUSION: Transcriptional regulation of the VEGF gene by SNP -460 (ATC) in combination with CSE represents a mechanism for elevated VEGF expression and may be associated with a worse prognosis. The influence of +SNP 936 on mRNA stability may be responsible for regulation of VEGF plasma levels.

An acute exposure to ozone impairs human olfactory functioning.

INTRODUCTION: Ozone is a ubiquitous and irritant gas. We questioned whether an acute exposure to 0.2 ppm ozone impaired olfactory functioning. METHODS: Healthy, normosmic subjects were exposed according to a parallel group design either to 0.2 ppm ozone (n = 15) or to sham (n = 13) in an exposure chamber for two hours. Possible irritating effects were assessed by questionnaire (range 0-5). The detection threshold of n-butanol was measured with the Sniffin' Sticks test before and after exposure. Olfactory thresholds were logarithmized and a two-way analysis of variance (ANOVA) with repeated measurements was carried out to test the effects of exposure (ozone vs. sham) and time (before vs. after exposure). Additionally, nasal secretions were taken at a preliminary examination and after exposure to determine interleukins 1ß and 8. RESULTS: No irritating effects to the upper airways were observed. In the ozone group, the median score for cough increased from 0 to 2 at the end of exposure (sham group 0 and 0, respectively, p < 0.001). The ANOVA showed a main effect for ozone exposure (F (1, 26) = 27.6, p = 0.0002), indicating higher olfactory thresholds in the ozone group. Concentrations of interleukins in nasal secretions did not increase following ozone exposure. CONCLUSIONS: This study shows a clear impairment of olfactory functioning following an acute exposure to 0.2 ppm ozone.

Knockdown of hnRNPK leads to increased DNA damage after irradiation and reduces survival of tumor cells.

Radiotherapy is an important treatment option in the therapy of multiple tumor entities among them head and neck squamous cell carcinoma (HNSCC). However, the success of radiotherapy is limited by the development of radiation resistances. Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is a cofactor of p53 and represents a potential target for radio sensitization of tumor cells. In this study, we analyzed the impact of hnRNPK on the DNA damage response after gamma irradiation. By yH2AX foci analysis, we found that hnRNPK knockdown increases DNA damage levels in irradiated cells. Tumor cells bearing a p53 mutation showed increased damage levels and delayed repair. Knockdown of hnRNPK applied simultaneously with irradiation reduced colony-forming ability and survival of tumor cells. Taken together, our data shows that hnRNPK is a relevant modifier of DNA damage repair and tumor cell survival. We therefore recommend further studies to evaluate the potential of hnRNPK as a drug target for improvement of radiotherapy success.

Semiquantifiable angiogenesis parameters in association with the malignant transformation of oral leukoplakia.

BACKGROUND: Aim of the study was to assess the role of angiogenesis in the process of malignant transformation of clinical diagnosed oral leucoplakia (OL). MATERIALS AND METHODS: A total of 131 histological preparations [oral leukoplakia/hyperkeratosis without dysplasia (OL; n = 49), oral leukoplakia/hyperkeratosis with mild dysplasia (OL-SIN1; n = 33), with moderate dysplasia (OL-SIN2; n = 13) and leukoplakia-derived oral squamous cell carcinoma (OL-OSCC; n = 36)] were evaluated for microvessel density (MVD), vessel diameter as well as for vascular endothelial growth factor (VEGF-A) expression. Data were compared within the groups. RESULTS: For MVD, there were significant differences between OL and OL-SIN 2/OL-OSCC (P < 0.05) and between OL-SIN 1 and OL-OSCC (P < 0.05). For OL-OSCC, vessel diameters were significantly increased compared with OL (P < 0.05). Expression of VEGF-A increased significantly gradually from OL-SIN 1 to OSCC (each P < 0.05). This was especially evident for lesions of the tongue when compared to the others. CONCLUSION: Angiogenesis increases during the transition from OL through dysplasia to OL-OSCC. In particular, OL-OSCCs of the tongue, VEGF-A expression may be used for estimation of malignant progression of OL.

Downregulation of EGFR in hypoxic, diffusion-limited areas of squamous cell carcinomas of the head and neck.

BACKGROUND: The receptor for the epidermal growth factor (EGFR) is widely considered to be one of the central drivers of oncogenesis in squamous cell carcinomas of the head and neck region (HNSCC). Inhibition of EGFR using monoclonal antibodies is established both in the curative and the palliative setting in this disease. HNSCCs are known to contain abundant hypoxic tissue areas and hypoxia has been shown to be involved in the (down)regulation of EGFR membrane expression. METHODS: A novel method for multiplex immunofluorescence and single-cell segmentation (via DAPI-stained nuclei) was established, to study the expression of EGFR, the endogenous hypoxia marker CA IX, and intratumoural diffusion distances from microvessels (using CD34 staining) in 58 human HNSCCs and 9 normal/cancer adjacent tissues. RESULTS: EGFR was found to be significantly downregulated with increasing distance from tumour microvessels, whereas the opposite was true for CA IX. Larger diffusion-limited areas were correlated with higher expression of CA IX. CONCLUSIONS: The hypoxic tumour microenvironment may have a major role in mediating resistance against anti-EGFR strategies by downregulating EGFR molecules on tumour cells.

Growth differentiation factor 15 as a radiation-induced marker in oral carcinoma increasing radiation resistance.

BACKGROUND: Growth differentiation factor 15 (GDF15) is involved in tumor pathogenesis of oral squamous cell carcinoma (OSCC). The aim of this study was an investigation of the potential influence of GDF15 on radioresistance of OSCC cells in vitro. METHODS: Oral squamous cell carcinoma cell lines were irradiated with 0, 2, or 6 Gy, and GDF15 expression in the supernatant per survived cell colony was examined with ELISA. Non-irradiated and OSCC cell lines irradiated with 6 Gy were evaluated for GDF15 expression using immunofluorescent staining. For further investigation of GDF15 effects on radioresistance, a GDF15 knockdown model in a human OSCC cell line was established, and apoptotic activity after radiation was measured using the Caspase-Glo 3/7 system. RESULTS: ELISA and immunofluorescent staining indicated an increased GDF15 expression in 5 OSCC cell lines compared with human gingival epithelial cells. Irradiation with two and six gray resulted in a significant elevation of GDF15 expression per survived cell colony in the irradiated OSCC cell lines (P < 0.001). Furthermore, a dose-dependent expression of GDF15 was seen. Immunofluorescent staining confirmed an elevated GDF15 expression in irradiated OSCC cell lines (n = 10; P ≤ 0.001). Apoptotic activity was significantly increased after irradiation in the GDF15 knockdown group compared with control cells (n = 24; P < 0.001). CONCLUSION: This study describes for the first time the vital role of GDF15 both in tumorigenesis and in radioresistance of OSCC cells. With its anti-apoptotic effects, GDF15 possibly promotes tumor progression and might protect carcinoma cells against irradiation effects. Consequently, GDF15 may be a promising therapeutic target in oral cancer.

Angiogenesis-related prognosis in patients with oral squamous cell carcinoma-role of the VEGF +936 C/T polymorphism.

BACKGROUND: The aim of the study was the immunohistological assessment of VEGF-single nucleotide polymorphism (SNP)-related angiogenic activity in oral squamous cell carcinoma (OSCC) in correlation with prognosis. METHODS: Fifty OSCC samples were immunostained with CD31-antibodies. Mean microvessel density (MVD) and staining intensity were determined and associated with clinicopathological/prognostic features as well as with the VEGF +936C/T SNP. RESULTS: A significant higher MVD could be seen for T3 and T4 compared with T1 and T2, N > 0 vs. N0 as well as G3-G4 vs. G1-G2 OSCCs (all: P < 0.05). A higher MVD was also associated with increased and earlier rates of local relapses, more metastases, and a significant decreased overall as well as disease-free survival (all: P < 0.05). When comparing T1 and T2 samples with +936-T-allele with T 1&2 samples without this allele, staining intensity was significantly increased (P = 0.002). CONCLUSIONS: Angiogenesis influences local as well as distant growth of OSCCs with a significant correlation between prognostic parameters. The correlation between VEGF +936-T-allele and increased CD31 immunostain needs further confirmation.

Toxicological Analysis by Assessment of Vascularization and Cell Viability Using the Chicken's Chorioallantoic Membrane (CAM Assay).

The chorioallantoic membrane (CAM) assay is an increasingly popular method using a hen's egg as an experimental organism. Animal models have been established in scientific research for centuries. Yet, awareness of animal welfare in society rises, and the transferability of findings obtained in rodent models to human physiology is challenged. Thus, using fertilized eggs as an alternative platform for animal experimentation might be a promising alternative. The CAM assay is utilized for toxicological analysis by determination of CAM irritation as well as analysis of organ damage and ultimately death of the embryo. Furthermore the CAM provides a micromilieu suited for the implantation of xenografts. Xenogene tissues and tumors grow on the CAM due to a lack of rejection by the immune system and a dense vascular network providing oxygen and nutrients. Multiple analytical methods including in vivo microscopy and various imaging techniques are applicable to this model. Additionally, ethical aspects, a comparatively low financial burden, and low bureaucratic hurdles legitimize the CAM assay.We here describe an in ovo model utilized for xenotransplantation of a human tumor. The model can be used to evaluate the efficacy as well as the toxicity of different therapeutic agents after intravascular injection. Additionally, we present the evaluation of vascularization and viability by intravital microscopy, ultrasonography, and immunohistochemistry.

Analysis of cytogenetic aberrations in sporadic vestibular schwannoma by comparative genomic hybridization.

Vestibular schwannomas (VS) are benign tumors of the nervous system that are usually sporadic but also occur in the inherited disorder neurofibromatosis type 2 (NF2). The NF2 gene is a tumor suppressor gene located on chromosome 22. Loss of the NF2 protein product, Merlin, is universal in both sporadic and NF2-related schwannomas and the loss or mutation of the gene is the only established causative event underlying schwannoma formation. Comparative genomic hybridization (CGH) was used to screen 20 sporadic VS to identify additional chromosomal regions that may harbor genes involved in VS-tumorigenesis. The most common change were losses on chromosome 22q. Additionally, losses were observed on chromosome 9p indicating a possible participation of the CDKN2A tumor suppressor gene in the genesis of VS. Gains were observed on 17q, 19p and 19q, which have been reported before in malignant peripheral nerve sheath tumors that are associated with neurofibromatosis type 1. Importantly, high level amplifications have been observed on 16p and 16q as well as on 9q, suggesting the possible involvement of several oncogenes in the tumorigenesis of VS. Our data suggest the involvement of various oncogenes and tumor suppressor genes might play a role in the genesis of the vestibular schwannomas apart from the inactivation of the NF2 gene.

Expression analysis suggests a potential cytoprotective role of Birc5 in the inner ear.

Hearing impairment is a worldwide health problem. Employing semi-quantitative immunological detection methods, we found that the apoptosis inhibitor protein Birc5 is expressed in cell types critical for hearing perception. In the guinea pig model, moderate noise exposure causing only a temporary mean hearing impairment of 33dB significantly enhanced Birc5 expression in the spiral ligament, nerve fibers and the organ of Corti. In contrast, intratympanic gentamicin injection inducing permanent cell damage and mean hearing loss of 24dB correlated with a significant Birc5 downregulation in the ligament, nerve fibers and the organ of Corti. The cytoprotective activity of the guinea pig and human Birc5 protein was confirmed by cloning of the gene and by subsequent ectopic expression and challenging studies against the ototoxin gentamicin in epithelial and auditory cell models. As the mammalian cochlea is unable to regenerate upon damage, these data suggest that modulation of Birc5 expression may represent a novel physiological mechanism to protect the inner ear against stress-induced cell damage. Hence, the targeted modulation of Birc5 levels may lead to novel otoprotective therapeutic strategies.

A 29-gauge atraumatic needle for amniocentesis.

OBJECTIVE: To compare perforation characteristics of standard 22 G (0.7 mm) to 29 G needle (0.34 mm) for amniocentesis. METHODS: Seventeen human chorio-amnion membranes were perforated immediately after cesarean section using 22 G needle for spinal anesthesia and 29 G "pencil-point" needles for amniocentesis under in-vitro conditions. Area of perforation was determined using a microscope and volume of fluid leakage was measured over a period of 5 min. RESULTS: Membrane perforation with the 22 G needle resulted in a mean damaged area of 225,147.4 µm(2), a hole with a mean area of 50,154 µm(2) and amniotic fluid volume passage of 17.5 mL/5 min, whereas the 29 G needle generated a mean damaged area of 114,812.4 µm(2), a hole with an average area of 1382.5 µm(2) and volume passage of 0.28 mL/5 min. These differences were significant. CONCLUSION: The hole formed by membrane perforation with 29 G "pencil-point" needle for amniocentesis is 36 times smaller, and the amniotic fluid loss is 61 times less than that measured with the 22 G standard needle for spinal anesthesia. Significant reduction of complications following amniocentesis is expected with the 29 G needle.

Cytogenetic analysis of a malignant triton tumour by comparative genomic hybridization (CGH) and review of the literature.

Malignant triton tumour (MTT) is a rare, highly malignant neoplasm, characterized by a mixture of cells with nerve sheath and skeletal muscle differentiation. Cytogenetic analyses of this neoplasm are rare to date and none comparative genomic hybridisation (CGH) analysis has been published. In the present study we report about the genomic imbalances of a MMT analysed by CGH, in a 39-year-old male patient without neurofibromatosis. We observed the amplifications at chromosomal location 1p, 6p, 16p, 16q, 17p, 17q, 19p, 19q, 20p, and 22q. Comparing our results with those of previous studies, we found evidence for recurrent genomic aberrations at the chromosomes 1, 16, 17, 19, and 22 suggesting the involvement of several oncogenes in the genesis of MTT.

Determination of the LD50 with the chick embryo chorioallantoic membrane (CAM) assay as a promising alternative in nanotoxicological evaluation.

Toxicity tests in rodents are still considered a controversial topic concerning their ethical justifiability. The chick embryo chorioallantoic membrane (CAM) assay may offer a simple and inexpensive alternative. The CAM assay is easy to perform and has low bureaucratic hurdles. At the same time, the CAM assay allows the application of a broad variety of analytical methods in the field of nanotoxicological research. We evaluated the CAM assay as a methodology for the determination of nanotoxicity. Therefore we calculated the median lethal dose (LD50), performed in vivo microscopy and immunohistochemistry to identify organ-specific accumulation profiles, potential organ damage, and the kinetics of the in vivo circulation of the nanoparticles. Zinc oxide nanoparticles were intravascularly injected on day 10 of the egg development and showed an LD50 of 17.5 µM (1.4 µg/mLeggcontent). In comparison, the LD50 of equivalent amounts of Zn2+ was 4.6 µM (0.6 µg/mLeggcontent). Silica encapsulated ZnO@SiO2 nanoparticles conjugated with fluorescein circulated in the bloodstream for at least 24 h. Particles accumulated mostly in the liver and kidney. In immunohistochemical staining, organ damage was detected only in liver tissue after intravascular injection of zinc oxide nanoparticles in very high concentrations. Zinc oxide nanoparticles showed a different pharmacokinetic profile compared to Zn2+ ions. In conclusion, the CAM assay has proven to be a promising methodology for evaluating nanotoxicity and for the assessment of the in vivo accumulation profiles of nanoparticles. These findings may qualify the methodology for risk assessment of innovative nanotherapeutics in the future.

Single nucleotide polymorphisms of the vascular endothelial growth factor gene associated with incidence of oral squamous cell carcinoma.

BACKGROUND: Vascular endothelial growth factor (VEGF) plays an important role in promoting angiogenesis and is overexpressed in several malignancies. Polymorphisms of the VEGF gene can alter VEGF protein expression, which may be biologically significant and account for heterogeneity in disease risk and outcome. The aim of this case-control study was to evaluate potential associations between single nucleotide polymorphisms (SNP) of the VEGF gene with susceptibility of oral squamous cell carcinoma (OSCC). PATIENTS AND METHODS: Five VEGF SNP (-1154 G/A, +405 G/C, +936 C/T, -2578 C/A and -460 C/T) were determined in peripheral blood isolated from 80 patients with OSCC and from 40 age- and gender-matched healthy volunteers (RT-PCR). RESULTS: The +936 T allele and the -2578 C/A SNP were expressed significantly more often in the OSCC-group (P=0.002; P<0.0001) where three associations between two SNPs (+936 and +405, -2578 and -1154, -460 and -2578) were found. CONCLUSION: Our findings provide support that +936 T allele and -2578 C/A SNP of the VEGF gene alone or in combination with other SNP are associated with OSCC. The SNPs may be used as biomarker for the development of specialized anti-VEGF drugs. Further studies must confirm the value of preoperative genetic analysis for prognosis.

The Chorioallantoic Membrane Assay in Nanotoxicological Research-An Alternative for In Vivo Experimentation.

Nanomaterials unveil many applicational possibilities for technical and medical purposes, which range from imaging techniques to the use as drug carriers. Prior to any human application, analysis of undesired effects and characterization of their toxicological profile is mandatory. To address this topic, animal models, and rodent models in particular, are most frequently used. However, as the reproducibility and transferability to the human organism of animal experimental data is increasingly questioned and the awareness of animal welfare in society increases at the same time, methodological alternatives are urgently required. The chorioallantoic membrane (CAM) assay is an increasingly popular in ovo experimental organism suitable for replacement of rodent experimentation. In this review, we outline several application fields for the CAM assay in the field of nanotoxicology. Furthermore, analytical methods applicable with this model were evaluated in detail. We further discuss ethical, financial, and bureaucratic aspects and benchmark the assay with other established in vivo models such as rodents.

HSP27 regulates viability and migration of cancer cell lines following irradiation.

Despite improvements of radiotherapy and better outcomes of cancer patients resistances still limit the therapeutic success. The combined treatment of tumors by the use of irradiation as well as targeted therapies is a promising approach. By the use of a proteomic screening of lung and head and neck cancer cell lines we identified the heat shock protein HSP27 as a potential target protein for a combined treatment strategy. Overall expression of HSP27 was distinctly lower in HNSCCUM-02T cells which have a high HSP27 phosphorylation ratio, whereas A549 cells revealed the opposite. Irradiation and inhibition of HSP27 phosphorylation by MKII inhibition resulted in a significantly reduced viability in both cell lines. While irradiation impaired migration only in HNSCCUM-02T cells, MKII inhibition exerted that effect in both cell lines. In contrast, knockdown of HSP27 compromised the viability only in A549 cells. Additionally, MKII inhibition counteracts radiation-induced phosphorylation of HSP27 which causes an additive toxicity and reduced migratory capacity in HNSCCUM-02T when combined. Inhibition of HSP27 expression and phosphorylation in combination with radiotherapy may be an effective treatment option to overcome resistances.

Nuclear export is essential for the tumor-promoting activity of survivin.

Survivin appears to function as an apoptosis inhibitor and a regulator of cell division during development and tumorigenesis. Here we report the molecular characterization of the nucleocytoplasmic transport of survivin and its potential implications for tumorigenesis. We identified an evolutionary conserved Crm1-dependent nuclear export signal (NES) in survivin. In dividing cells, the NES is essential for tethering survivin and the survivin/Aurora-B kinase complex to the mitotic machinery, which in turn appears to be essential for proper cell division. In addition, export seems to be required for the cytoprotective activity of survivin, as export-deficient survivin fails to protect tumor cells against chemo- and radiotherapy-induced apoptosis. These findings appear to be clinically relevant since preferential nuclear localization of survivin correlated with enhanced survival in colorectal cancer patients. Targeting survivin's nuclear export by the application of NES-specific antibodies promoted its nuclear accumulation and inhibited its cytoprotective function. We demonstrate that nuclear export is essential for the biological activity of survivin and promote the identification of molecular decoys to specifically interfere with survivin's nuclear export as potential anticancer therapeutics.