Experimental validation of Ankrd17 and Anapc10, two novel meiotic genes predicted by computational models in mice.

Prophase is a critical stage of meiosis, during which recombination-the landmark event of meiosis-exchanges information between homologous chromosomes. The intractability of mammalian gonads has limited our knowledge on genes or interactions between genes during this key stage. Microarray profiling of gonads in both sexes has generated genome-scale information. However, the asynchronous development of germ cells and the mixed germ/somatic cell population complicate the use of this resource. To elucidate functional networks of meiotic prophase, we have integrated global gene expression with other genome-scale datasets either within or across species. Our computational approaches provide a comprehensive understanding of interactions between genes and can prioritize candidates for targeted experiments. Here, we examined two novel prophase genes predicted by computational models: Ankrd17 and Anapc10. Their expression and localization were characterized in the developing mouse testis using in situ hybridization and immunofluorescence. We found ANKRD17 expression was predominantly restricted to pachytene spermatocytes and round spermatids. ANKRD17 was diffusely distributed throughout the nucleus of pachytene cells but excluded from the XY body and other heterochromatic regions. ANAPC10 was mainly expressed in the cytoplasm of spermatogonia and leptotene and pachytene spermatocytes. These experiments support our computational predictions of Ankrd17 and Anapc10 as potential prophase genes. More importantly, they serve as a proof of concept of our integrative computational and experimental approach, which has delivered a larger candidate gene set to the broader reproductive community.

Localization and regulation of murine Esco2 during male and female meiosis.

Meiosis is essential for generation of healthy gametes in both sexes and involves recombination and segregation of homologous chromosomes to produce haploid gametes. The initiation of meiosis in both sexes relies upon retinoic acid (RA) (Griswold MD, Hogarth CA, Bowles J, Koopman P. Initiating Meiosis: The Case for Retinoic Acid. Biol Reprod 2012; 86(35):1-7). Previous studies have demonstrated that the stimulated by retinoic acid gene 8 (Stra8) was required for meiotic progression in both the mouse ovary and postnatal testis. To identify additional candidates that may play a role during meiosis, we used microarray databases to generate lists of transcripts with expression profiles similar to that of Stra8 in the embryonic ovary and postnatal testis. One such gene, establishment of cohesion 1 homolog 2 (Saccharomyces cerevisiae) (Esco2), has been described as a regulator of sister chromatid cohesion during mitosis. This study describes the first in-depth analysis of ESCO2 localization and regulation during meiosis in both males and females. ESCO2 colocalized with the gamma H2A histone family member X (H2AFX) in pachytene spermatocytes, indicating that ESCO2 is a component of the XY body. In pachytene cells of the embryonic ovary, ESCO2 colocalized with H2AFX, which is consistent with the presence of ESCO2 in areas of double-stranded breaks. In addition, the expression of Esco2 was found to be regulated by RA in the postnatal testis. These data indicate that ESCO2 may play a vital role in meiosis in both males and females.

Breast cancer diagnosis in a specialised breast clinic: Are cancers detected by ultrasound alone less aggressive?

INTRODUCTION: The aim of this study was to determine the relationship between the way breast cancer is diagnosed and its prognostic features. METHODS: We studied new primary invasive and non-invasive breast cancers (670) diagnosed between 2013 and 2015 where detection included at least clinical examination, mammography and breast ultrasound (BUS). The cancers were classified into six Diagnostic Groups according to the results of each modality. RESULTS: Overall, 79% of cancers were positive on mammography, but another 20% were diagnosed on BUS after a negative mammogram. The largest group (37.6% of cases), had all three modalities positive (Group 1). BUS was the only modality positive in 14.6% (Group 4). Mammography alone was positive in 21.2%, of which 73.9% were ductal carcinoma in situ (DCIS). Invasive lobular carcinoma comprised 9.6% of the groups where mammography was positive, but 16.5% of the groups where mammography was negative and BUS positive. Dense breast tissue was more common in the groups where mammography was negative and BUS positive. Invasive cancers comprised 82.7% of Group 4 and 95.2% of Group 1. For those in Group 4, the average size (10.2 mm) and the percentages with lymphovascular invasion (11.1%), lymph node involvement (17.3%) and poor differentiation (12.3%) were less than half the corresponding figures for Group 1 (27.3 mm, 35%, 44%, 44%). CONCLUSION: This study illustrates the complementary benefits of mammography and BUS, especially where breast density is high. Tumours diagnosed by BUS alone had better prognostic features in terms of size, lymphovascular invasion, lymph node status, differentiation and hormone receptors, compared with cancers where all three modalities were positive.

Full-field digital mammography: Is the apparent increased detection of microcalcification leading to over-investigation and over-diagnosis?

INTRODUCTION: Modern full-field digital mammography (FFDM) appears to have increased the detection of breast microcalcification. This retrospective study aimed to assess whether this is associated with over-investigation and possible over-diagnosis of breast pathology of lesser significance. METHODS: Three 2-year periods were studied, in which different mammographic technologies were used exclusively viz., classical screen-film mammography (SFM) in 2003-04, computed radiography (CR) in 2009-10 and FFDM in 2012-13. The study was limited to women in whom biopsy was done for indeterminate, suspicious or malignant (ISM) calcification as the only mammographic abnormality. RESULTS: Between the first and the third time periods, the use of core biopsies and vacuum-assisted biopsies (VABs) for 'ISM calcification only' increased from 0. 6% to 1.4% of all mammograms, and biopsies with malignant results increased from 0.18% to 0.33% of all mammograms. VAB became the preferred technique for biopsy over the study period. The proportion of cores and VABs with a malignant result did not change significantly over the three time periods (24-28%), nor did the proportion of invasive cancers, ductal carcinoma in situ (DCIS) (60-63%) or atypia on subsequent excision. The proportion of DCIS which was of high grade was greatest in the FFDM era (69%). Less than 9% of DCIS were of low grade in all three time periods. CONCLUSIONS: Despite increased numbers of biopsies being performed, there was no increase in findings of breast pathology of lesser significance. Improved technology (FFDM and VAB) allows immediate biopsy of small clusters of indeterminate microcalcification, rather than using mammographic surveillance, and this study found no evidence that this has been associated with over-investigation or over-diagnosis.

New insights into tumor dormancy: Targeting DNA repair pathways.

Over the past few decades, major strides have advanced the techniques for early detection and treatment of cancer. However, metastatic tumor growth still accounts for the majority of cancer-related deaths worldwide. In fact, breast cancers are notorious for relapsing years or decades after the initial clinical treatment, and this relapse can vary according to the type of breast cancer. In estrogen receptor-positive breast cancers, late tumor relapses frequently occur whereas relapses in estrogen receptor-negative cancers or triple negative tumors arise early resulting in a higher mortality risk. One of the main causes of metastasis is tumor dormancy in which cancer cells remain concealed, asymptomatic, and untraceable over a prolonged period of time. Under certain conditions, dormant cells can re-enter into the cell cycle and resume proliferation leading to recurrence. However, the molecular and cellular regulators underlying this transition remain poorly understood. To date, three mechanisms have been identified to trigger tumor dormancy including cellular, angiogenic, and immunologic dormancies. In addition, recent studies have suggested that DNA repair mechanisms may contribute to the survival of dormant cancer cells. In this article, we summarize the recent experimental and clinical evidence governing cancer dormancy. In addition, we will discuss the role of DNA repair mechanisms in promoting the survival of dormant cells. This information provides mechanistic insight to explain why recurrence occurs, and strategies that may enhance therapeutic approaches to prevent disease recurrence.

Nuclear PTEN tumor-suppressor functions through maintaining heterochromatin structure.

The tumor suppressor, PTEN, is one of the most commonly mutated genes in cancer. Recently, PTEN has been shown to localize in the nucleus and is required to maintain genomic stability. Here, we show that nuclear PTEN, independent of its phosphatase activity, is essential for maintaining heterochromatin structure. Depletion of PTEN leads to loss of heterochromatic foci, decreased chromatin compaction, overexpression of heterochromatic genes, and reduced protein stability of heterochromatin protein 1 α. We found that the C-terminus of PTEN is required to maintain heterochromatin structure. Additionally, cancer-associated PTEN mutants lost their tumor-suppressor function when their heterochromatin structure was compromised. We propose that this novel role of PTEN accounts for its function in guarding genomic stability and suppressing tumor development.

Mammographic and ultrasound features of invasive lobular carcinoma of the breast.

INTRODUCTION: Invasive lobular cancer (ILC) is an important contributor to false negative mammography. This study aims to assess the value of digital mammography and to identify imaging features that could assist the radiologist to suggest the diagnosis of ILC prior to biopsy. METHODS: Three hundred sixty-one cases of pure ILC diagnosed at the Wesley Breast Clinic during the period 1995-2010 were reviewed by one of the authors (AP). Radiological features were categorized, and clinical features and needle sampling results were recorded. RESULTS: Mammography was negative in 29.9% of ILCs. The commonest positive finding was a localized spiculated mass (41.8%). Thirty-four point nine per cent of lesions were visible in only one view, usually cranio-caudal. Calcification was not a feature of ILC. The use of digital mammography in 30% of cases did not decrease the false negative rate for ILC. Breast ultrasound (BUS) showed an abnormality in 97.8%, most commonly a localized irregular hypoechoic mass with shadowing. CONCLUSIONS: Digital mammography does not reduce false negative mammography in ILC. The poor visibility of ILCs may be partly related to their low density (mass/unit volume). ILCs may sometimes be poor attenuators of X-rays but excellent attenuators of ultrasound, causing marked acoustic shadowing. Bilateral whole BUS has a very low false negative rate in experienced hands and is mandatory in symptomatic women. The combination of poor visibility on mammography with high visibility on ultrasound, as well as certain characteristic ultrasound appearances of ILC, may enable the radiologist to suggest ILC as a diagnostic possibility, prior to biopsy.