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Purpose: Epidermal growth factor receptor (EGFR) is critically involved in progression and therapy resistance of squamous cell carcinoma (SCC). Albeit EGFR targeting could improve the effect of radiotherapy on patients' outcome, the clinical results failed to meet expectations from preclinical studies. In this work, we evaluated the potential of the radionuclide Yttrium-90 ((90)Y) bound to Cetuximab ((90)Y-Cetuximab) as novel targeting approach for SCC cells in vitro., Materials and Methods: FaDu and A431 cell lines were used. EGFR subcellular localization, clonogenic survival, radiation-induced γH2AX foci and EGFR signaling were examined. Cells were treated with DTPA, DTPA-Cetuximab, (90)Y and (90)Y-Cetuximab alone or in combination with external X-ray irradiation., Results: Dose- and cell line-dependently, (90)Y-Cetuximab mediated a significant reduction in clonogenicity relative to unbound (90)Y. Combined 2-Gy external radiation plus 2-Gy equivalent dose of (90)Y-Cetuximab was more effective than equivalent doses of (90)Y and X-ray radiation. Analogous effects were observed in the number of residual radiation-induced foci. Additionally, EGFR, ERK1/2 and AKT phosphorylation showed alterations upon different treatments., Conclusions: Our findings show that Cetuximab-conjugated (90)Y has a significant potential to eradicate human SCC cells. A combination of radioimmunotherapeutic compounds and external radiotherapy might be a promising treatment strategy for clinical application. more...

Purpose: The objective of the present study was to provide evidence for the hypothesis of fibroblasts and the desmoplastic reaction, respectively, to impact the formation and maturation of the vascular network in human colon tumours via a retrospective in situ study. An in vivo xenograft model was evaluated to verify its potential for fibroblast-related functional studies., Materials and Methods: In situ: Fiftytwo G2/G3 colon tumours were histomorphologically categorised into low (<50%), medium (50-75%) and high (>75%) grade desmoplasia based on hematoxylin/eosin and Elastica van Gieson stained paraffin sections. Low and high grade desmoplastic tumours were identified and stained for endothelial and pericyte markers to morphometrically analyse microvessel count (MVC), vascular surface area (VSA) and vascular maturation status. In vivo: One out of three established subcutaneous xenograft model in NMRI (nu/nu) mice was adapted to monitor the impact of primary human fibroblasts on xenograft formation and morphology., Results: Vascular structures in human colon tumours are predominantly located in the fibroblastic stromal regions. Highly desmoplastic tumours, however, have significantly lower MVC and VSA values at the invasion front with signs for augmented vascular maturation as compared with low grade desmoplastic colon cancers. Our in vivo approach verified that only high proportions of co-injected normal fibroblasts accelerate xenograft formation of HCT-116 colon cancer cells., Conclusions: The in situ data clearly support the hypothesis of fibroblasts to contribute to vascular maturation phenomena in colon cancers. The in vivo design of only 500 tumour cells co-injected with normal fibroblast is feasible, results in 100% engraftment and is the basis for further developments. more...

Purpose: Tumour lactate levels have been shown to correlate with high radioresistance in tumour models in vivo. The study aimed to evaluate the impact of pathophysiological extracellular lactate concentrations and acidosis on the in vitro survival and radioresponse of various cancer cell lines., Materials and Methods: HCT-116, HT29 (colorectal) and FaDu (HNSCC) carcinoma cells were studied. Lactate release rates were determined, and expression of the monocarboxylate transporter MCT1 and its cofactor CD147 were monitored by immunofluorescence and flow cytometry. Colony formation was compared for cells exposed to 20 mM exogenous lactate, acidosis (pH 6.4) and lactate plus acidosis relative to control and dose response curves (0.5-10 Gy) were documented., Results: All cell lines expressed MCT1 and CD147 and showed comparable lactate release rates. High lactate levels and acidosis slightly decreased HCT-116 colony forming capacity. This effect was neither additive nor did it affect radioresponse. Clonogenic survival of HT29 cells, however, was critically reduced in a lactate-enriched or acidic milieu and a synergistic effect was observed. Here, both conditions enhanced radiosensitivity. Exogenous lactate also impaired colony formation of FaDu cells but acidosis was ineffective. This cell line was more susceptible to irradiation under lactate exposure independent of pH., Conclusions: Tumour cell behaviour and radioresponse in a lactate environment is multifaceted. The consideration of lactate accumulation as a parameter affecting radiotherapeutic intervention and as a target for new therapeutic strategies is interesting but requires extended mechanistic studies. more...

Purpose: To give a state-of-the-art overview on the promise of three-dimensional (3-D) culture systems for anticancer drug development, with particular emphasis on multicellular tumor spheroids (MCTS)., Results and Conclusions: Cell-based assays have become an integral component in many stages of routine anti-tumor drug testing. However, they are almost always based on homogenous monolayer or suspension cultures and thus represent a rather artificial cellular environment. 3-D cultures--such as the well established spheroid culture system--better reflect the in vivo behavior of cells in tumor tissues and are increasingly recognized as valuable advanced tools for evaluating the efficacy of therapeutic intervention. The present article summarizes past and current applications and particularly discusses technological challenges, required improvements and recent progress with the use of the spheroid model in experimental therapeutics, as a basis for sophisticated drug/therapy screening. A brief overview is given focusing on the nomenclature of spherical 3-D cultures, their potential to mimic many aspects of the pathophysiological situation in tumors, and currently available protocols for culturing and analysis. A list of spheroid-forming epithelial cancer cell lines of different origin is provided and the recent trend to use spheroids for testing combination treatment strategies is highlighted. Finally, various spheroid co-culture approaches are presented that have been established to study heterologous cell interactions in solid tumors and thereby are able to reflect the cellular tumor environment with increasing accuracy. The intriguing observation that in order to retain certain tumor initiating cell properties, some primary tumor cell populations must be maintained exclusively in 3-D culture is mentioned, adding a new but fascinating challenge for future therapeutic campaigns. more...