Vascular responses to radiotherapy and androgen-deprivation therapy in experimental prostate cancer

Background: Radiotherapy (RT) and androgen-deprivation therapy (ADT) are standard treatments for advanced prostate cancer (PC). Tumor vascularization is recognized as an important physiological feature likely to impact on both RT and ADT response, and this study therefore aimed to characterize the vascular responses to RT and ADT in experimental PC. Methods: Using mice implanted with CWR22 PC xenografts, vascular responses to RT and ADT by castration were visualized in vivo by DCE MRI, before contrast-enhancement curves were analyzed both semi-quantitatively and by pharmacokinetic modeling. Extracted image parameters were correlated to the results from ex vivo quantitative fluorescent immunohistochemical analysis (qIHC) of tumor vascularization (9 F1), perfusion (Hoechst 33342), and hypoxia (pimonidazole), performed on tissue sections made from tumors excised directly after DCE MRI. Results: Compared to untreated (Ctrl) tumors, an improved and highly functional vascularization was detected in androgen-deprived (AD) tumors, reflected by increases in DCE MRI parameters and by increased number of vessels (VN), vessel density ( VD), and vessel area fraction ( VF) from qIHC. Although total hypoxic fractions ( HF) did not change, estimated acute hypoxia scores ( AHS) – the proportion of hypoxia staining within 50 μm from perfusion staining – were increased in AD tumors compared to in Ctrl tumors. Five to six months after ADT renewed castration-resistant (CR) tumor growth appeared with an even further enhanced tumor vascularization. Compared to the large vascular changes induced by ADT, RT induced minor vascular changes. Correlating DCE MRI and qIHC parameters unveiled the semi-quantitative parameters area under curve ( AUC) from initial time-points to strongly correlate with VD and VF, whereas estimation of vessel size ( VS) by DCE MRI required pharmacokinetic modeling. HF was not correlated to any DCE MRI parameter, however, AHS may be estimated after pharmacokinetic modeling. Interestingly, such modeling also detected tumor necrosis very strongly. Conclusions: DCE MRI reliably allows non-invasive assessment of tumors’ vascular function. The findings of increased tumor vascularization after ADT encourage further studies into whether these changes are beneficial for combined RT, or if treatment with anti-angiogenic therapy may be a strategy to improve the therapeutic efficacy of ADT in advanced PC.publishedVersio

Metabolic markers in relation to hypoxia; staining patterns and colocalization of pimonidazole, HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4

Contains fulltext : 96097.pdf (postprint version ) (Open Access)BACKGROUND: The cellular response of malignant tumors to hypoxia is diverse. Several important endogenous metabolic markers are upregulated under hypoxic conditions. We examined the staining patterns and co-expression of HIF-1alpha, CAIX, LDH-5, GLUT-1, MCT1 and MCT4 with the exogenous hypoxic cell marker pimonidazole and the association of marker expression with clinicopathological characteristics. METHODS: 20 biopsies of advanced head and neck carcinomas were immunohistochemically stained and analyzed. All patients were given the hypoxia marker pimonidazole intravenously 2 h prior to biopsy taking. The tumor area positive for each marker, the colocalization of the different markers and the distribution of the markers in relation to the blood vessels were assessed by semiautomatic quantitative analysis. RESULTS: MCT1 staining was present in hypoxic (pimonidazole stained) as well as non-hypoxic areas in almost equal amounts. MCT1 expression showed a significant overall correlation (r = 0.75, p < 0.001) and strong spatial relationship with CAIX. LDH-5 showed the strongest correlation with pimonidazole (r = 0.66, p = 0.002). MCT4 and GLUT-1 demonstrated a typical diffusion-limited hypoxic pattern and showed a high degree of colocalization. Both MCT4 and CAIX showed a higher expression in the primary tumor in node positive patients (p = 0.09 both). CONCLUSIONS: Colocalization and staining patterns of metabolic and hypoxia-related proteins provides valuable additional information over single protein analyses and can improve the understanding of their functions and environmental influences

Tissue response models

The risk of radiation effects to normal tissues is an important factor, both in the process of considering radiotherapy and in the optimization of personalized radiotherapy for individual patients. Severe toxicity may cause a lifelong reduction in quality of life and sometimes the risk of morbidity even limits dose and efficacy of the treatment. Developments in treatment technology have increased the possibilities to reduce dose to normal tissues. Moreover, the same developments have also increased the number of ways to influence numerous characteristics of the three-dimensional dose distribution. For example, multi-leaf collimators offer increased control of beam shapes. Increasing computation power improves the ability of treatment planning systems to handle an increasing number of beams, or even rotational techniques. Finally the availability of particle therapy offers beams with entirely new dose-depth curves and for heavier ions even variations in the biological effects of dose

Vascular responses to radiotherapy and androgen-deprivation therapy in experimental prostate cancer

Background: Radiotherapy (RT) and androgen-deprivation therapy (ADT) are standard treatments for advanced prostate cancer (PC). Tumor vascularization is recognized as an important physiological feature likely to impact on both RT and ADT response, and this study therefore aimed to characterize the vascular responses to RT and ADT in experimental PC. Methods: Using mice implanted with CWR22 PC xenografts, vascular responses to RT and ADT by castration were visualized in vivo by DCE MRI, before contrast-enhancement curves were analyzed both semi-quantitatively and by pharmacokinetic modeling. Extracted image parameters were correlated to the results from ex vivo quantitative fluorescent immunohistochemical analysis (qIHC) of tumor vascularization (9 F1), perfusion (Hoechst 33342), and hypoxia (pimonidazole), performed on tissue sections made from tumors excised directly after DCE MRI. Results: Compared to untreated (Ctrl) tumors, an improved and highly functional vascularization was detected in androgen-deprived (AD) tumors, reflected by increases in DCE MRI parameters and by increased number of vessels (VN), vessel density ( VD), and vessel area fraction ( VF) from qIHC. Although total hypoxic fractions ( HF) did not change, estimated acute hypoxia scores ( AHS) – the proportion of hypoxia staining within 50 μm from perfusion staining – were increased in AD tumors compared to in Ctrl tumors. Five to six months after ADT renewed castration-resistant (CR) tumor growth appeared with an even further enhanced tumor vascularization. Compared to the large vascular changes induced by ADT, RT induced minor vascular changes. Correlating DCE MRI and qIHC parameters unveiled the semi-quantitative parameters area under curve ( AUC) from initial time-points to strongly correlate with VD and VF, whereas estimation of vessel size ( VS) by DCE MRI required pharmacokinetic modeling. HF was not correlated to any DCE MRI parameter, however, AHS may be estimated after pharmacokinetic modeling. Interestingly, such modeling also detected tumor necrosis very strongly. Conclusions: DCE MRI reliably allows non-invasive assessment of tumors’ vascular function. The findings of increased tumor vascularization after ADT encourage further studies into whether these changes are beneficial for combined RT, or if treatment with anti-angiogenic therapy may be a strategy to improve the therapeutic efficacy of ADT in advanced PC

Effects of nicotinamide and carbogen in different murine colon carcinomas: immunohistochemical analysis of vascular architecture and microenvironmental parameters

To investigate oxygenation, perfusion, and cell proliferation in two murine colon carcinoma lines with known differences in chemotherapy sensitivity and analyze the effect of nicotinamide and carbogen on these tumor characteristics. Mice with s.c. transplanted C38 and C26a murine colon tumors were treated with nicotinamide and carbogen and compared with control tumors. Two markers of hypoxia, CCI-103F and pimonidazole, were injected before and after treatment with nicotinamide/carbogen, respectively, allowing each tumor to serve as its own control. Hoechst33342 was used as a perfusion marker and bromodeoxyuridine (BrdUrd) as a proliferation marker. Frozen tumors were cut for multistep immunostaining and computer-controlled microscope scanning for hypoxic fractions (HF), perfused fractions (PF), vascular density, and BrdUrd-labeling index (LI). Microscopic observation of C38 and C26a tumors showed extensive differences in vascular architecture, distribution patterns of hypoxia, and BrdUrd-labeling. Quantitative analysis of C38 and C26a tumors showed a decrease in HF in response to all treatment modalities. For C38 tumors, the average decrease in HF in response to carbogen containing treatments was larger than to nicotinamide alone. In C26a tumors, no difference in average decrease in HF was observed between the treatments. The PF of C38 and C26a did not change in response to treatment. The LI of C38 and C26a decreased upon all treatments, which was statistically significant in the combination treatment of C38. The mechanism that can simultaneously explain all the observed changes in response to treatment may be the conversion of metabolism from less respiration toward more glycolysis due to increased glucose levels (Crabtree effect), although other mechanisms of actions cannot be exclude