The effect of modulation of gut microbiome profile on radiation-induced carcinogenesis and survival.

Non-lethal doses of ionizing radiation (IR) delivered to humans because of terrorist events, nuclear accidents or radiotherapy can result in carcinogenesis. Means of protecting against carcinogenesis are lacking. We questioned the role of the gut microbiome in IR-induced carcinogenesis. The gut microbiome was modulated by administering broad spectrum antibiotics (Ab) in the drinking water. Mice were given Ab 3 weeks before and 3 weeks after 3 Gy total body irradiation (TBI) or for 6 weeks one month after TBI. Three weeks of Ab treatment resulted in a 98% reduction in total 16S rRNA counts for 4 out of 6 of the phylum groups detected. However, 3 more weeks of Ab treatment (6 weeks total) saw an expansion in the phylum groups Proteobacteria and Actinobacteria. The Ab treatment altered the bacteria diversity in the gut, and shortened the lifespan when Ab were administered before and after TBI. Mortality studies indicated that the adverse Ab lifespan effects were due to a decrease in the time in which solid tumors started to appear and not to any changes in hematopoietic or benign tumors. In contrast, when Ab were administered one month after TBI, lifespan was unchanged compared to the control TBI group. Use of broad-spectrum antibiotics to simulate the germ-free condition did not afford an advantage on carcinogenesis or lifespan.

Transcript expression in endometrial cancers from Black and White patients.

OBJECTIVE: Previous studies suggest that differences in molecular features of endometrial cancers between racial groups may contribute to the poorer survival in Blacks. The objective of this investigation was to determine whether gene expression among endometrial cancers is different between Blacks and Whites. METHODS: Fresh frozen tumors from 25 Black patients were matched by stage, grade, and histology to endometrial cancer specimens from 25 White patients. Each case was macrodissected to produce specimens possessing a minimum of 75% cancer cellularity. A subset of 10 matched pairs was also prepared using laser microdissection (LMD) to produce specimens possessing a minimum of 95% cancer cells. Total RNA isolated from each sample was analyzed using the Affymetrix Human Genome U133 Plus 2.0 arrays. Data were analyzed using principal component analysis and binary class comparison analyses. RESULTS: Unsupervised analysis of the 50 endometrial cancers failed to identify global gene expression profiles unique to Black or White patients. In a subset analysis of 10 matched pairs from Blacks and Whites prepared using LMD and macrodissection, unsupervised analysis did not reveal a unique gene expression profile associated with race in either set, but associations were identified that relate to sample preparation technique, histology and stage. CONCLUSIONS: Our microarray data revealed no global gene expression differences and identified few individual gene differences between endometrial cancers from Blacks and Whites. More comprehensive methods of transcriptome analysis could uncover RNAs that may underpin the disparity of outcome or prevalence of endometrial cancers in Blacks and Whites.

Antiangiogenic agent sunitinib transiently increases tumor oxygenation and suppresses cycling hypoxia.

Structural and functional abnormalities in tumor blood vessels impact the delivery of oxygen and nutrients to solid tumors, resulting in chronic and cycling hypoxia. Although chronically hypoxic regions exhibit treatment resistance, more recently it has been shown that cycling hypoxic regions acquire prosurvival pathways. Angiogenesis inhibitors have been shown to transiently normalize the tumor vasculatures and enhance tumor response to treatments. However, the effect of antiangiogenic therapy on cycling tumor hypoxia remains unknown. Using electron paramagnetic resonance imaging and MRI in tumor-bearing mice, we have examined the vascular renormalization process by longitudinally mapping tumor partial pressure of oxygen (pO(2)) and microvessel density during treatments with a multi-tyrosine kinase inhibitor sunitinib. Transient improvement in tumor oxygenation was visualized by electron paramagnetic resonance imaging 2 to 4 days following antiangiogenic treatments, accompanied by a 45% decrease in microvessel density. Radiation treatment during this time period of improved oxygenation by antiangiogenic therapy resulted in a synergistic delay in tumor growth. In addition, dynamic oxygen imaging obtained every 3 minutes was conducted to distinguish tumor regions with chronic and cycling hypoxia. Sunitinib treatment suppressed the extent of temporal fluctuations in tumor pO(2) during the vascular normalization window, resulting in the decrease of cycling tumor hypoxia. Overall, the findings suggest that longitudinal and noninvasive monitoring of tumor pO(2) makes it possible to identify a window of vascular renormalization to maximize the effects of combination therapy with antiangiogenic drugs.

Low-field paramagnetic resonance imaging of tumor oxygenation and glycolytic activity in mice.

A priori knowledge of spatial and temporal changes in partial pressure of oxygen (oxygenation; pO(2)) in solid tumors, a key prognostic factor in cancer treatment outcome, could greatly improve treatment planning in radiotherapy and chemotherapy. Pulsed electron paramagnetic resonance imaging (EPRI) provides quantitative 3D maps of tissue pO(2) in living objects. In this study, we implemented an EPRI set-up that could acquire pO(2) maps in almost real time for 2D and in minutes for 3D. We also designed a combined EPRI and MRI system that enabled generation of pO(2) maps with anatomic guidance. Using EPRI and an air/carbogen (95% O(2) plus 5% CO(2)) breathing cycle, we visualized perfusion-limited hypoxia in murine tumors. The relationship between tumor blood perfusion and pO(2) status was examined, and it was found that significant hypoxia existed even in regions that exhibited blood flow. In addition, high levels of lactate were identified even in normoxic tumor regions, suggesting the predominance of aerobic glycolysis in murine tumors. This report presents a rapid, noninvasive method to obtain quantitative maps of pO(2) in tumors, reported with anatomy, with precision. In addition, this method may also be useful for studying the relationship between pO(2) status and tumor-specific phenotypes such as aerobic glycolysis.

Gene expression profiles derived from fine needle aspiration correlate with response to systemic chemotherapy in breast cancer.

BACKGROUND: Drug resistance in breast cancer is a major obstacle to successful chemotherapy. In this study we used cDNA microarray technology to examine gene expression profiles obtained from fine needle aspiration (FNA) of primary breast tumors before and after systemic chemotherapy. Our goal was to determine the feasibility of obtaining representative expression array profiles from limited amounts of tissue and to identify those expression profiles that correlate with treatment response. METHODS: Repeat presurgical FNA samples were taken from six patients who were to undergo primary surgical treatment. Additionally, a group of 10 patients who were to receive neoadjuvant chemotherapy underwent two FNAs before chemotherapy (adriamycin 60 mg/m2 and cyclophosphamide 600 mg/m2) followed by another FNA on day 21 after the first cycle. Total RNA was amplified with T7 Eberwine's procedure and labeled cDNA was hybridized onto a 7600-feature glass cDNA microarray. RESULTS: We identified candidate gene expression profiles that might distinguish tumors with complete response to chemotherapy from tumors that do not respond, and found that the number of genes that change after one cycle of chemotherapy was 10 times greater in the responding group than in the non-responding group. CONCLUSION: This study supports the suitability of FNA-derived cDNA microarray expression profiling of breast cancers as a comprehensive genomic approach for studying the mechanisms of drug resistance. Our findings also demonstrate the potential of monitoring post-chemotherapy changes in expression profiles as a measure of pharmacodynamic effect and suggests that these approaches might yield useful results when validated by larger studies.