Comparison of the effects of carbon ion and photon irradiation on the angiogenic response in human lung adenocarcinoma cells.

PURPOSE: Radiotherapy resistance is a commonly encountered problem in cancer treatment. In this regard, stabilization of endothelial cells and release of angiogenic factors by cancer cells contribute to this problem. In this study, we used human lung adenocarcinoma (A549) cells to compare the effects of carbon ion and X-ray irradiation on the cells' angiogenic response. METHODS AND MATERIALS: A549 cells were irradiated with biologically equivalent doses for cell survival of either carbon ions (linear energy transfer, 170 keV/µm; energy of 9.8 MeV/u on target) or X-rays and injected with basement membrane matrix into BALB/c nu/nu mice to generate a plug, allowing quantification of angiogenesis by blood vessel enumeration. The expression of angiogenic factors (VEGF, PlGF, SDF-1, and SCF) was assessed at the mRNA and secreted protein levels by using real-time reverse transcription-PCR and enzyme-linked immunosorbent assay. Signal transduction mediated by stem cell factor (SCF) was assessed by phosphorylation of its receptor c-Kit. For inhibition of SCF/c-Kit signaling, a specific SCF/c-Kit inhibitor (ISCK03) was used. RESULTS: Irradiation of A549 cells with X-rays (6 Gy) but not carbon ions (2 Gy) resulted in a significant increase in blood vessel density (control, 20.71 ± 1.55; X-ray, 36.44 ± 3.44; carbon ion, 16.33 ± 1.03; number per microscopic field). Concordantly, irradiation with X-rays but not with carbon ions increased the expression of SCF and subsequently caused phosphorylation of c-Kit in endothelial cells. ISCK03 treatment of A549 cells irradiated with X-rays (6 Gy) resulted in a significant decrease in blood vessel density (X-ray, 36.44 ± 3.44; X-ray and ISCK03, 4.33 ± 0.71; number of microscopic field). These data indicate that irradiation of A549 cells with X-rays but not with carbon ions promotes angiogenesis. CONCLUSIONS: The present study provides evidence that SCF is an X-ray-induced mediator of angiogenesis in A549 cells, a phenomenon that could not be observed with carbon ion irradiation. Thus, in this model system evaluating angiogenesis, carbon ion irradiation may have a therapeutic advantage. This observation should be confirmed in orthotopic lung tumor models.

Genetic alterations after carbon ion irradiation in human lung adenocarcinoma cells.

The aim of this study was to investigate the difference in gene expression profiles of human lung adenocarcinoma cells and identify genes whose expression is altered by heavy ions but not X-rays. The lung adenocarcinoma cell line A549 was irradiated with carbon ion beams and X-rays using biologically equivalent doses (2 Gy and 6 Gy, respectively). The transcriptional profiling was determined with a high density cDNA microarray containing 11.800 genes, and genetic network and gene ontology analysis was performed. The changes in selected genes involved were validated by quantitative real-time polymerase chain reaction (qRT-PCR). The microarray analysis identified 49 mapped, network-eligible genes, the expression level of which was altered by carbon ions but not by X-rays. From these, 29 were upregulated while 20 genes were downregulated 4 h post-irradiation with carbon ions in A549 cells, as compared to the control. Among these, three genes (CCND2, RARG and E2F5) were involved in the aryl hydrocarbon receptor signalling and G1/S cell cycle checkpoint pathways. The microarray data were corroborated by qRT-PCR analysis of the selected genes (p<0.05). Our findings provide information on the genetic signature of carbon ions in human lung adenocarcinoma cells and add to the understanding of the complicated molecular response to carbon ion irradiation.

Botulinum toxin prevents radiotherapy-induced salivary gland damage.

Radiotherapy of head and neck malignancies results in severe damage to salivary glands. Irradiation-induced sialadenitis with xerostomia leads to a significant deterioration of the quality of life which lasts life-long. Here we show in a preliminary study that intraglandular application of botulinum toxin performed prior to radiation reduces significantly the radiation induced toxicity of the glandular tissue in rats.

Increased expression of EphA7 correlates with adverse outcome in primary and recurrent glioblastoma multiforme patients.

BACKGROUND: Malignant gliomas are lethal cancers, highly dependent on angiogenesis and treatment options and prognosis still remain poor for patients with recurrent glioblastoma multiforme (GBM). Ephs and ephrins have many well-defined functions during embryonic development of central nervous system such as axon mapping, neural crest cell migration, hindbrain segmentation and synapse formation as well as physiological and abnormal angiogenesis. Accumulating evidence indicates that Eph and ephrins are frequently overexpressed in different tumor types including GBM. However, their role in tumorigenesis remains controversial, as both tumor growth promoter and suppressor potential have been ascribed to Eph and ephrins while the function of EphA7 in GBM pathogenesis remains largely unknown. METHODS: In this study, we investigated the immunohistochemical expression of EphA7 in a series of 32 primary and recurrent GBM and correlated it with clinical pathological parameters and patient outcome. In addition, intratumor microvascular density (MVD) was quantified by immunostaining for endothelial cell marker von Willebrand factor (vWF). RESULTS: Overexpression of EphA7 protein was predictive of the adverse outcome in GBM patients, independent of MVD expression (p = 0.02). Moreover, high density of MVD as well as higher EphA7 expression predicted the disease outcome more accurately than EphA7 variable alone (p = 0.01). There was no correlation between MVD and overall survival or recurrence-free survival (p > 0.05). However, a statistically significant correlation between lower MVD and tumor recurrence was observed (p = 0.003). CONCLUSION: The immunohistochemical assessment of tissue EphA7 provides important prognostic information in GBM and would justify its use as surrogate marker to screen patients for tyrosine kinase inhibitor therapy.