Characterisation of microRNA expression in post-natal mouse mammary gland development.

BACKGROUND: The differential expression pattern of microRNAs (miRNAs) during mammary gland development might provide insights into their role in regulating the homeostasis of the mammary epithelium. Our aim was to analyse these regulatory functions by deriving a comprehensive tissue-specific combined miRNA and mRNA expression profile of post-natal mouse mammary gland development.We measured the expression of 318 individual murine miRNAs by bead-based flow-cytometric profiling of whole mouse mammary glands throughout a 16-point developmental time course, including juvenile, puberty, mature virgin, gestation, lactation, and involution stages. In parallel whole-genome mRNA expression data were obtained. RESULTS: One third (n = 102) of all murine miRNAs analysed were detected during mammary gland development. MicroRNAs were represented in seven temporally co-expressed clusters, which were enriched for both miRNAs belonging to the same family and breast cancer-associated miRNAs. Global miRNA and mRNA expression was significantly reduced during lactation and the early stages of involution after weaning. For most detected miRNA families we did not observe systematic changes in the expression of predicted targets. For miRNA families whose targets did show changes, we observed inverse patterns of miRNA and target expression. The data sets are made publicly available and the combined expression profiles represent an important community resource for mammary gland biology research. CONCLUSION: MicroRNAs were expressed in likely co-regulated clusters during mammary gland development. Breast cancer-associated miRNAs were significantly enriched in these clusters. The mechanism and functional consequences of this miRNA co-regulation provide new avenues for research into mammary gland biology and generate candidates for functional validation.

Response to therapy in breast cancer.

Increasing numbers of patients with newly diagnosed breast cancer receive primary systemic therapy followed by surgery. Histopathology provides an accurate assessment of treatment efficacy on the basis of the extent of residual tumor and regressive changes within tumor tissue. However, only approximately 20% of breast cancer patients achieve a pathologic complete response, a fact that necessitates methods for monitoring therapeutic effectiveness early during therapy. (18)F-FDG PET and (18)F-FDG PET/CT provide essential information regarding a response to primary chemotherapy. Patients with low tumor metabolic activity on pretreatment (18)F-FDG PET are not likely to achieve a histopathologic response. The degree of changes in (18)F-FDG uptake after the initiation of therapy is correlated with the histopathologic response after the completion of therapy. Thus, tumor metabolic changes assessed early during therapy predict therapeutic effectiveness in individual patients. Early identification of ineffective therapy also might be helpful in patients with metastatic breast cancer because many palliative treatment options are available. Changes in metabolic activity generally occur earlier than changes in tumor size, which is the current standard for the assessment of a response. Although treatment stratification based on a metabolic response is an exciting potential application of PET, specific PET response assessment criteria still need to be developed and validated on the basis of patient outcomes before changes in treatment regimens can be implemented. There is increasing clinical evidence for metastatic breast cancer and other tumors that (18)F-FDG PET/CT is the most accurate imaging procedure for assessment of the response at the end of treatment when both CT information and tumor metabolic activity are considered. Importantly, in the setting of primary chemotherapy, neither PET/CT nor conventional imaging procedures can assess the extent of residual breast cancer as accurately as histopathology. Observation of changes in tumor blood flow or tumor cell proliferation is an additional encouraging approach for predicting a response. Ultimately, the prediction of therapeutic effectiveness by PET and PET/CT could help to individualize treatment and to avoid ineffective chemotherapies, with their associated toxicities.

Monitoring primary systemic therapy of large and locally advanced breast cancer by using sequential positron emission tomography imaging with [18F]fluorodeoxyglucose.

PURPOSE: To evaluate positron emission tomography (PET) using [(18)F]fluorodeoxyglucose (FDG) for prediction of histopathologic response early during primary systemic therapy of large or locally advanced breast cancer. PATIENTS AND METHODS: In a prospective multicenter trial, 272 FDG-PET scans were performed in 104 patients at baseline (n = 104) and after the first (n = 87) and second cycle (n = 81) of chemotherapy. The level and relative changes in standardized uptake value (SUV) of FDG uptake were assessed regarding their ability to predict histopathologic response. All patients underwent surgery after chemotherapy, and histopathologic response defined as minimal residual disease or gross residual disease served as the reference standard. RESULTS: Seventeen (16%) of 104 patients were histopathologic responders and 87 were (84%) nonresponders. All patients for whom baseline SUV was less than 3.0 (n = 24) did not achieve a histopathologic response. SUV decreased by 51% +/- 18% after the first cycle of chemotherapy in histopathologic responders (n = 15), compared with 37% +/- 21% in nonresponders (n = 54; P = .01). A threshold of 45% decrease in SUV correctly identified 11 of 15 responders, and histopathologic nonresponders were identified with a negative predictive value of 90%. Similar results were found after the second cycle when using a threshold of 55% relative decrease in SUV. CONCLUSION: FDG-PET allows for prediction of treatment response by the level of FDG uptake in terms of SUV at baseline and after each cycle of chemotherapy. Moreover, relative changes in SUV after the first and second cycle are a strong predictor of response. Thus, FDG-PET may be helpful for individual treatment stratification in breast cancer patients.

MicroRNA: implications for cancer.

MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression post-transcriptionally. After the discovery of the first miRNA in the roundworm Caenorhabditis elegans, these short regulatory RNAs have been found to be an abundant class of RNAs in plants, animals, and DNA viruses. About 3% of human genes encode for miRNAs, and up to 30% of human protein coding genes may be regulated by miRNAs. MicroRNAs play a key role in diverse biological processes, including development, cell proliferation, differentiation, and apoptosis. Accordingly, altered miRNA expression is likely to contribute to human disease, including cancer. This review will summarize the emerging knowledge of the connections between human miRNA biology and different aspects of carcinogenesis. Various techniques available to investigate miRNAs will also be discussed.

Histopathologic assessment of tumor regression after neoadjuvant chemotherapy in advanced-stage ovarian cancer.

To date, no histopathologic criteria have been established to describe treatment response after neoadjuvant chemotherapy in ovarian cancer. The aim of this study was to identify histopathologic features of tumor regression in ovarian cancer specimens obtained after neoadjuvant chemotherapy regarding their ability to indicate treatment response. This study systematically evaluated histopathologic features of tumor regression in advanced-stage ovarian cancer treated with neoadjuvant chemotherapy (n = 49) and in a control group treated with primary surgery (n = 35). In addition, the largest tumor size was measured in the surgical specimens. Overall survival served as the reference standard with a median follow-up of 49 months. There was a significantly higher presence of regressive changes in the postchemotherapy group compared with the untreated control group (P < or = .04). The presence of scattered solitary tumor cells, fibrosis, foamy macrophages, and giant cells of foreign-body type each indicated previous neoadjuvant chemotherapy with high specificity (80.0%-100%) but with low sensitivity (18.4%-63.3%). Inflammatory cell infiltrates, isolated psammoma bodies, and hemosiderin were also associated with previous chemotherapy but with lower specificity. The presence of necrosis was significantly correlated with larger tumor size within the specimens (rho = 0.5, P < .0001) and was more often found in the control group. For both groups, the extent of regressive changes, evaluated as a single parameter or in combination, showed no correlation with overall survival. However, patients with absence of residual tumor, scattered solitary tumor cells, or residual tumor foci of 5 mm or less after neoadjuvant chemotherapy had a significantly longer median overall survival of 45.6 versus 27.3 months in patients with larger tumors (P = .02). Various histopathologic features generally associated with posttreatment changes did not allow differentiation of responding from nonresponding patients and provided no prognostic information. The residual tumor size after neoadjuvant chemotherapy was the only criterion significantly correlated with treatment response and subsequent overall survival.

Giant aortic aneurysm 18 years after repair of double-outlet right ventricle with pulmonary stenosis.

Substantial long-term morbidity after a successful operation in complex congenital heart defects is a matter of concern. We present a patient with a giant ascending aortic aneurysm 18 years after repair of a double-outlet right ventricle with pulmonary stenosis. Our report emphasizes the need for ongoing follow-up into adulthood.

Early graft failure of small-sized porcine valved conduits in reconstruction of the right ventricular outflow tract.

BACKGROUND: The quest for an alternative to homografts for reconstruction of the right ventricular outflow tract is ongoing. The Shelhigh No-React (NR-4000PA series) treated porcine pulmonic valve conduit (SPVC) was developed as a potential alternative. METHODS: During a 12-month period from May 2004 to May 2005, the SPVC was implanted in 34 patients, of whom 62% were younger than 1 year. Median age at operation was 7 months (range, 5 days to 12 years). Thirteen SPCV conduits size 10, 11 size 12, 8 size 14, and 2 size 16 were initially implanted. Since May 2005, however, we have temporarily abandoned its implantation as we were concerned about a number of early failures. RESULTS: Until November 2005, 1 early and 1 late death have occurred. Both were not conduit related. Fifteen conduits were replaced in 13 patients. Of these, 10 were size 10, 3 size 12, 2 size 14, and none size 16. Mean time to replacement of the SPVC was 313 +/- 116 days. A pseudointimal peel formation and chronic inflammation with foreign-body reaction was found in all explanted conduits at all levels. The maximum of the inflammatory reaction occurred at the valvular level around the porcine tissues, with shrinkage of the valve and hemodynamic compromise. At valvular level, small punctuate calcifications were observed in 2 cases. In 6 patients an acute inflammatory component was observed. At late follow-up (mean follow-up 366 +/- 102 days, 34 patient-years), echocardiography showed a mean graft gradient of 39.8 +/- 29.7 mm Hg, with mild to moderate insufficiency in 4 patients. CONCLUSIONS: Although the No-React treated valve largely resists calcification, pseudointimal peel formation was found in all explanted conduits and led to multilevel conduit stenoses. The small-sized SPVC can not be regarded as an ideal conduit for right ventricular outflow tract reconstruction.

Histopathologic and Metabolic Criteria for Assessment of Treatment Response in Breast Cancer.

Increasing use of neoadjuvant chemotherapy in locally advanced breast cancer necessitates methods for evaluation of therapeutic response. Histopathology provides accurate assessment of treatment efficacy but only approximately 20% of breast cancer patients achieve complete pathologic response after neoadjuvant chemotherapy. Therefore, methods that predict therapeutic effectiveness could help individualize treatment and avoid ineffective chemotherapies. Metabolic imaging using positron emission tomography (PET) and F-18 fluorodeoxyglucose (FDG) seems to provide early response assessment in vivo. Change in FDG uptake after chemotherapy initiation correlates with histopathologic response after completion. PET response assessment criteria and imaging protocols need to be developed and validated. This article compares complementary approaches for assessment of treatment response, namely histologic features of the tumor on the microscopic level versus in vivo metabolic changes on a macroscopic level.

Prediction of response to neoadjuvant chemotherapy by sequential F-18-fluorodeoxyglucose positron emission tomography in patients with advanced-stage ovarian cancer.

PURPOSE: The aim of this study was to evaluate sequential F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) to predict patient outcome after the first and third cycle of neoadjuvant chemotherapy in advanced-stage (International Federation of Gynecology and Obstetrics stages IIIC and IV) ovarian cancer. PATIENTS AND METHODS: Thirty-three patients received three cycles of carboplatin-based chemotherapy, followed by cytoreductive surgery. Quantitative FDG-PET of the abdomen and pelvis was acquired before treatment and after the first and third cycle of chemotherapy. Changes in tumoral FDG uptake, expressed as standardized uptake values (SUV), were compared with clinical and histopathologic response; overall survival served as a reference. RESULTS: A significant correlation was observed between FDG-PET metabolic response after the first (P = .008) and third (P = .005) cycle of chemotherapy and overall survival. By using a threshold for decrease in SUV from baseline of 20% after the first cycle, median overall survival was 38.3 months in metabolic responders compared with 23.1 months in metabolic nonresponders. At a threshold of 55% decrease in SUV after the third cycle median overall survival was 38.9 months in metabolic responders compared with 19.7 months in nonresponders. There was no correlation between clinical response criteria (P = .7) or CA125 response criteria (P = .5) and overall survival. There was only a weak correlation (P = .09) between histopathologic response criteria and overall survival. CONCLUSION: Sequential FDG-PET predicted patient outcome as early as after the first cycle of neoadjuvant chemotherapy and was more accurate than clinical or histopathologic response criteria including changes in tumor marker CA125. FDG-PET appears to be a promising tool for early prediction of response to chemotherapy.