The incidence of brain metastases among patients with metastatic breast cancer: a systematic review and meta-analysis

BACKGROUND

Patients with metastatic breast cancer (MBC) are living longer, but the development of brain metastases often limits their survival. We conducted a systematic review and meta-analysis to determine the incidence of brain metastases in this patient population.

METHODS

Articles published from January 2000 to January 2020 were compiled from four databases using search terms related to breast cancer, brain metastasis, and incidence. The overall and per patient-year incidence of brain metastases were extracted from studies including patients with human epidermal growth factor receptor-2 positive (HER2+), triple negative, and hormone receptor (HR)+/hormone receptor negative (HER2-) MBC; pooled overall estimates for incidence were calculated using random effects models.

RESULTS

937 articles were compiled, and 25 were included in the meta-analysis. Incidence of brain metastases in patients with HER2+ MBC, triple negative MBC, and HR+/HER2- MBC was reported in 17, 6, and 4 studies, respectively. The pooled cumulative incidence of brain metastases was 31% for the HER2+ subgroup (median follow-up: 30.7 months, IQR: 24.0-34.0), 32% for the triple negative subgroup (median follow-up: 32.8 months, IQR: 18.5-40.6), and 15% among patients with HR+/HER2- MBC (median follow-up: 33.0 months, IQR: 31.9-36.2). The corresponding incidences per patient-year were 0.13 (95% CI: 0.10-0.16) for the HER2+ subgroup, 0.13 (95%CI: 0.09-0.20) for the triple negative subgroup, and only 0.05 (95%CI: 0.03-0.08) for patients with HR+/HER2- MBC.

CONCLUSION

There is a high incidence of brain metastases among patients with HER2+ and triple negative MBC. The utility of a brain metastases screening program warrants investigation in these populations.

Abstract IA-018: Molecular landmarks of tumor hypoxia across cancer types

Many primary tumor sub-regions have low levels of molecular oxygen, termed hypoxia. Hypoxic tumors are at elevated risk for local failure and distant metastasis, but the molecular hallmarks of tumor hypoxia remain poorly defined. To fill this gap, we quantified hypoxia in 8,006 tumors across 19 tumor types. In ten tumor types, hypoxia was associated with elevated genomic instability. In all 19 tumor types, hypoxic tumors exhibited characteristic driver mutation signatures. We observed widespread hypoxia-associated dysregulation of miRNAs across cancers and functionally validated miR-133a-3p as a hypoxia-modulated miRNA. In localized prostate cancer, hypoxia was associated with elevated rates of chromothripsis, allelic loss of PTEN and shorter telomeres. These associations are particularly enriched in polyclonal tumors, representing a constellation of features resembling tumor nimbosus – an aggressive cellular phenotype. Overall, this work establishes that tumor hypoxia may drive aggressive molecular features across cancers and shape the clinical trajectory of individual tumors.

Citation Format: Vinayak Bhandari, Christianne Hoey, Lydia Liu, Emilie Lalonde, Jessica Ray, Julie Livingstone, Robert Lesurf, Yu-Jia Shiah, Tina Vujcic, Xiaoyong Huang, Shadrielle M.G. Espiritu, Lawrence E. Heisler, Fouad Yousif, Vincent Huang, Takafumi N. Yamaguchi, Cindy Q. Yao, Veronica Y. Sabelnykova, Michael Fraser, Melvin L.K. Chua, Theodorus van der Kwast, Stanley K. Liu, Paul C. Boutros, Robert G. Bristow. Molecular landmarks of tumor hypoxia across cancer types [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-018.

Dual- versus single-agent HER2 inhibition and incidence of intracranial metastatic disease: a systematic review and meta-analysis

Observational studies have suggested that HER2 inhibition with trastuzumab may be associated with an increased incidence of intracranial metastatic disease (IMD) due to its ability to prolong survival. We hypothesized that prolonged survival associated with dual-agent HER2 inhibition may be associated with an even higher incidence of IMD. This study pooled estimates of IMD incidence and survival among patients with HER2-positive breast cancer receiving dual- versus single-agent HER2 targeted therapy, as well as trastuzumab versus chemotherapy, observation, or another HER2-targeted agent. We searched PubMed, EMBASE, and CENTRAL from inception to 25 March 2020. We included randomized controlled trials that reported IMD incidence for patients with HER2-positive breast cancer receiving trastuzumab as the experimental or control arm irrespective of disease stage. Among 465 records identified, 19 randomized controlled trials (32,572 patients) were included. Meta-analysis of four studies showed that dual HER2-targeted therapy was associated with improved overall survival (HR 0.76; 95% CI, 0.66–0.87) and progression-free survival (HR 0.77; 95% CI, 0.68–0.87) compared to single HER2-targeted therapy, but the risk of IMD was similar (RR 1.03; 95% CI, 0.83–1.27). Our study challenges the hypothesis that prolonged survival afforded by improved extracranial disease control is associated with increased IMD incidence.

microRNAs identified in prostate cancer: Correlative studies on response to ionizing radiation

As the most frequently diagnosed non-skin cancer in men and a leading cause of cancer-related death, understanding the molecular mechanisms that drive treatment resistance in prostate cancer poses a significant clinical need. Radiotherapy is one of the most widely used treatments for prostate cancer, along with surgery, hormone therapy, and chemotherapy. However, inherent radioresistance of tumor cells can reduce local control and ultimately lead to poor patient outcomes, such as recurrence, metastasis and death. The underlying mechanisms of radioresistance have not been fully elucidated, but it has been suggested that miRNAs play a critical role. miRNAs are small non-coding RNAs that regulate gene expression in every signaling pathway of the cell, with one miRNA often having multiple targets. By fine-tuning gene expression, miRNAs are important players in modulating DNA damage response, cell death, tumor aggression and the tumor microenvironment, and can ultimately affect a tumor’s response to radiotherapy. Furthermore, much interest has focused on miRNAs found in biofluids and their potential utility in various clinical applications. In this review, we summarize the current knowledge on miRNA deregulation after irradiation and the associated functional outcomes, with a focus on prostate cancer. In addition, we discuss the utility of circulating miRNAs as non-invasive biomarkers to diagnose, predict response to treatment, and prognosticate patient outcomes.

miR-191 promotes radiation resistance of prostate cancer through interaction with RXRA

Radiation therapy is a common treatment for prostate cancer, however recurrence remains a problem. MicroRNA expression is altered in prostate cancer and may promote therapy resistance. Through bioinformatic analyses of TCGA and CPC-GENE patient cohorts, we identified higher miR-191 expression in tumor versus normal tissue, and increased expression in higher Gleason scores. In vitro and in vivo experiments demonstrated that miR-191 overexpression promotes radiation survival, and contributes to a more aggressive phenotype. Retinoid X receptor alpha, RXRA, was discovered to be a novel target of miR-191, and knockdown recapitulated radioresistance. Furthermore, treatment of prostate cancer cells with the RXRA agonist 9-cis-retinoic acid restored radiosensitivity. Supporting this relationship, patients with high miR-191 and low RXRA abundance experienced quicker biochemical recurrence. Reduced RXRA translated to a higher risk of distant failure after radiotherapy. Notably, this miR-191/RXRA interaction was conserved in a novel primary cell line derived from radiorecurrent prostate cancer. Together, our findings demonstrate that miR-191 promotes prostate cancer survival after radiotherapy, and highlights retinoids as a potential option to improve radiotherapy response.

MicroRNA‑198 suppresses prostate tumorigenesis by targeting MIB1

MicroRNAs are small non-coding RNA molecules which act as modulators of gene function, and have been identified as playing important roles in cancer as both tumor suppressors and oncogenes. The present study aimed to examine the role of miR-198 in prostate cancer aggression by analyzing how it influences several hallmarks of cancer. Abundance of miR-198 in prostate cancer and association with clinical characteristics was analyzed using a CPC-Gene prostate cancer dataset. Overexpression of miR-198 was performed using transient transfection of miR-198 mimic prior to assaying proliferation, cell cycle, and colony formation in LNCaP and DU145 cell lines using standard protocols. In vivo tumor formation in athymic nude mice was examined using LNCaP xenografts with stable overexpression conferred using lentiviral miR-198 transduction. Protein and mRNA abundance of MIB1 was determined using western blotting and RT-qPCR respectively, while miR-198 binding to MIB1 was validated using a luciferase reporter assay. miR-198 abundance was lower in high Gleason grade prostate cancer relative to intermediate and low-grade cancer. Overexpression of miR-198 diminished proliferation of prostate cancer cell lines, increased G0/G1 cell cycle arrest, and significantly impaired colony formation. Elevated miR-198 abundance was also demonstrated to impair tumor formation in vivo using LNCaP xenografts. Mindbomb E3 ubiquitin protein ligase 1 (MIB1) was demonstrated to be directly targeted by miR-198, and knockdown of MIB1 recapitulated the effects of miR-198 on proliferation and colony formation. The present evidence supports miR-198 as an important tumor suppressor in prostate cancer, and demonstrates for the first time that it acts by targeting MIB1. The present study reinforces the importance and complexity of miRNA in regulating prostate cancer aggression.

Circulating miRNAs as non-invasive biomarkers to predict aggressive prostate cancer after radical prostatectomy

BACKGROUND

Prostate cancer is an extremely heterogeneous disease. Despite being clinically similar, some tumours are more likely to recur after surgery compared to others. Distinguishing those that need adjuvant or salvage radiotherapy will improve patient outcomes. The goal of this study was to identify circulating microRNA that could independently predict prostate cancer patient risk stratification after radical prostatectomy.

METHODS

Seventy-eight prostate cancer patients were recruited at the Odette Cancer Centre in Sunnybrook Health Sciences Centre. All patients had previously undergone radical prostatectomy. Blood samples were collected simultaneously for PSA testing and miRNA analysis using NanoString nCounter technology. Of the 78 samples, 75 had acceptable miRNA quantity and quality. Patients were stratified into high- and low-risk categories based on Gleason score, pathological T stage, surgical margin status, and diagnostic PSA: patients with Gleason ≥ 8; pT3a and positive margin; pT3b and any margin; or diagnostic PSA > 20 µg/mL were classified as high-risk (n = 44) and all other patients were classified as low-risk (n = 31).

RESULTS

Using our patient dataset, we identified a four-miRNA signature (miR-17, miR-20a, miR-20b, miR-106a) that can distinguish high- and low-risk patients, in addition to their pathological tumour stage. High expression of these miRNAs is associated with shorter time to biochemical recurrence in the TCGA dataset. These miRNAs confer an aggressive phenotype upon overexpression in vitro.

CONCLUSIONS

This proof-of-principle report highlights the potential of circulating miRNAs to independently predict risk stratification of prostate cancer patients after radical prostatectomy.

RSPO3 is a prognostic biomarker and mediator of invasiveness in prostate cancer

Background

While prostate cancer can often manifest as an indolent disease, the development of locally-advanced or metastatic disease can cause significant morbidity or mortality. Elucidation of molecular mechanisms contributing to disease progression is crucial for more accurate prognostication and effective treatments. R-Spondin 3 (RSPO3) is a protein previously implicated in the progression of colorectal and lung cancers. However, a role for RSPO3 in prostate cancer prognosis and behaviour has not been explored.

Methods

We compare the relative levels of RSPO3 expression between normal prostate tissue and prostate cancer in two independent patient cohorts (Taylor and GSE70768—Cambridge). We also examine the association of biochemical relapse with RSPO3 levels in these cohorts. For elucidation of the biological effect of RSPO3, we use siRNA technology to reduce the levels of RSPO3 in established prostate cancer cell lines, and perform in vitro proliferation, invasion, western blotting for EMT markers and clonogenic survival assays for radiation resistance. Furthermore, we show consequences of RSPO3 knockdown in an established chick chorioallantoic membrane (CAM) assay model of metastasis.

Results

RSPO3 levels are lower in prostate cancer than normal prostate, with a tendency for further loss in metastatic disease. Patients with lower RSPO3 expression have lower rates of biochemical relapse-free survival. SiRNA-mediated loss of RSPO3 results in no change to clonogenic survival and a lower proliferative rate, but increased invasiveness in vitro with induction of epithelial–mesenchymal transition (EMT) markers. Consistent with these results, lower RSPO3 expression translates to greater metastatic capacity in the CAM assay. Together, our preclinical findings identify a role of RSPO3 downregulation in prostate cancer invasiveness, and provide a potential explanation for how RSPO3 functions as a positive prognostic marker in prostate cancer.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1878-3) contains supplementary material, which is available to authorized users.

Circulating blood miRNAs for prostate cancer risk stratification: miRroring the underlying tumor biology with liquid biopsies

Current risk stratification methods for prostate cancer – although they have seen marked improvements over the past decades – are far from perfect. Despite the significant utility of prostate-specific antigen as a biomarker to monitor for disease recurrence, it cannot predict which tumors will recur or recommend the best treatment for patients. Similarly, although biopsies are imperative for diagnosis and staging, they are saddled with limitations and risks. We must move toward a noninvasive biomarker that has predictive and prognostic efficacy. We therefore review the current literature on circulating miRNA biomarkers, apply their use to two significant clinical problems (ie, how limitations of prostate biopsies can impact diagnosis and treatment management, and the need to tailor treatment for a clinically heterogeneous disease), and evaluate how circulating miRNAs have inherent properties that make them ideal liquid biomarkers. We also outline current gaps in knowledge that must be addressed before they can be implemented into routine clinical practice. With further research on their function and validation of their biomarker utility in large prospective cohorts, circulating miRNAs will likely prove to be the liquid biopsies of tomorrow.

Molecular landmarks of tumor hypoxia across cancer types

Many primary-tumor subregions have low levels of molecular oxygen, termed hypoxia. Hypoxic tumors are at elevated risk for local failure and distant metastasis, but the molecular hallmarks of tumor hypoxia remain poorly defined. To fill this gap, we quantified hypoxia in 8,006 tumors across 19 tumor types. In ten tumor types, hypoxia was associated with elevated genomic instability. In all 19 tumor types, hypoxic tumors exhibited characteristic driver-mutation signatures. We observed widespread hypoxia-associated dysregulation of microRNAs (miRNAs) across cancers and functionally validated miR-133a-3p as a hypoxia-modulated miRNA. In localized prostate cancer, hypoxia was associated with elevated rates of chromothripsis, allelic loss of PTEN and shorter telomeres. These associations are particularly enriched in polyclonal tumors, representing a constellation of features resembling tumor nimbosus, an aggressive cellular phenotype. Overall, this work establishes that tumor hypoxia may drive aggressive molecular features across cancers and shape the clinical trajectory of individual tumors.

miRNA-106a and prostate cancer radioresistance: a novel role for LITAF in ATM regulation

Recurrence of high-grade prostate cancer after radiotherapy is a significant clinical problem, resulting in increased morbidity and reduced patient survival. The molecular mechanisms of radiation resistance are being elucidated through the study of microRNA (miR) that negatively regulate gene expression. We performed bioinformatics analyses of The Cancer Genome Atlas (TCGA) dataset to evaluate the association between miR-106a and its putative target lipopolysaccharide-induced TNF-α factor (LITAF) in prostate cancer. We characterized the function of miR-106a through in vitro and in vivo experiments and employed transcriptomic analysis, western blotting, and 3'UTR luciferase assays to establish LITAF as a bona fide target of miR-106a. Using our well-characterized radiation-resistant cell lines, we identified that miR-106a was overexpressed in radiation-resistant cells compared to parental cells. In the TCGA, miR-106a was significantly elevated in high-grade human prostate tumors relative to intermediate- and low-grade specimens. An inverse correlation was seen with its target, LITAF. Furthermore, high miR-106a and low LITAF expression predict for biochemical recurrence at 5 years after radical prostatectomy. miR-106a overexpression conferred radioresistance by increasing proliferation and reducing senescence, and this was phenocopied by knockdown of LITAF. For the first time, we describe a role for miRNA in upregulating ATM expression. LITAF, not previously attributed to radiation response, mediates this interaction. This route of cancer radioresistance can be overcome using the specific ATM kinase inhibitor, KU-55933. Our research provides the first report of miR-106a and LITAF in prostate cancer radiation resistance and high-grade disease, and presents a viable therapeutic strategy that may ultimately improve patient outcomes.

Microrna-198: A novel tumor suppressor in prostate cancer

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Background: microRNAs (miRNAs) are small non-coding RNA molecules which act as repressors of gene function, and have been identified as playing substantial roles in cancer as both tumor suppressors and oncogenes. miR-198 has been reported to be down-regulated in several cancers, with low expression associated with worse overall survival. In addition, miR-198 has demonstrated tumor suppressor effects by altering several hallmarks of cancer. Despite compelling evidence in other cancers, miR-198's role in prostate cancer aggression has not yet been evaluated. Methods: Experiments were conducted by overexpressing miR-198 in three prostate cancer cell lines: DU145, LNCaP and 22RV1. To examine miR-198's effect on hallmarks of cancer in vitro, we used standard protocols to assay proliferation, colony formation, cell cycle profile, migration, and invasive potential. Gene array, qPCR, western blotting, and siRNA knockdown experiments were used to establish miR-198 downstream targets. Results: Overexpression of the candidate tumor suppressor miR-198 diminished proliferation in all prostate cancer cell lines and significantly impaired colony formation in soft agar. Subsequently, miR-198 expression was also demonstrated to reduce growth and tumor formation in vivo using LNCaP xenografts. Gene arrays and in silico target prediction identified several candidate targets, none of which have been previously linked to miR-198. MIB1, an E3 ubiquitin ligase, was the only target we have since identified to be reduced with miR-198 overexpression at both the RNA and protein levels. Knockdown of MIB1 recapitulated miR-198's effects on proliferation and colony formation, and further experiments are underway to demonstrate a direct binding relationship. An additional gene array with MIB1 siRNA will be performed to highlight pathways through which MIB1/miR-198 suppress tumorigenesis. Conclusions: Our evidence supports miR-198 as an important tumor suppressor in prostate cancer, with elevated expression impairing proliferation, colony formation, and in vivo tumor formation. This investigation into miR-198 highlights a potential role as a prostate cancer biomarker, or as a potential target of therapeutics to restore miRNA activity.

Overcoming miR-106a induced radioresistance in prostate cancer: Targeting senescence with KU-55933

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Background: Prostate cancer is a leading cause of cancer related death in men worldwide, with recurrence being a major clinical problem after radiotherapy. There is an unmet need to better characterize radioresistant tumors and identify biomarkers to improve patient outcomes. Methods: We identified that miR-106a was overexpressed in radiation resistant cell lines compared to parental cells. We analyzed The Cancer Genome Atlas dataset to assess miR-106a expression in normal prostate, and low- to high-grade prostate tumors. To assess the functional role of miR-106a, we performed in vitro and in vivo assays for radiation response, including clonogenic survival, proliferation, senescence, and tumor xenograft growth after radiation. We performed gene array and pathway analyses to identify downstream effectors of miR-106a. Results: MiR-106a expression was significantly higher in prostate tumors with Gleason score > 7 compared to Gleason ≤ 7, suggesting miR-106a is involved in high grade disease. MiR-106a overexpression confers radioresistance in vitro and in vivo, by targeting LITAF. We now extend miR-106a’s effects to upregulation of ATM at the promoter level, thereby increasing ATM transcript and protein in the cell. Unexpectedly, we found that miR-106a’s mechanism of radioresistance through ATM upregulation does not alter DNA damage repair. ATM upregulation affects clonogenic survival through reduced senescence. KU-55933, a specific ATM kinase inhibitor, resensitizes miR-106a overexpressing cells to radiation by inducing senescence, a predominant mode of cell death in prostate cancer. Conclusions: Our research challenges the current paradigm of ATM and DNA damage repair by outlining another mechanism of radioresistance through alteration of senescence. Our findings suggest that miR-106a may be a promising biomarker for high-grade disease and radioresistant prostate cancer. In addition, we have identified a therapeutic intervention for miR-106a induced radioresistance. Improvements in bioavailability of KU-55933 may lead to its clinical use in combination with radiation therapy to radiosensitize miR-106a induced radioresistant prostate cancer.

Loss of RSPO3 as a potential mechanism of greater invasiveness in prostate cancer

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Background: While prostate cancer can often manifest as an indolent disease, locally-advanced or metastatic disease can cause significant morbidity or mortality. Better understanding of molecular mechanisms leading to more aggressive presentations can lead to identification of prognostic or predictive biomarkers, as well as to possible therapeutic targets. Methods: We describe the generation of prostate cancer cell lines that have been selected through a course of hypofractionated radiotherapy. We show that R-spondin 3, a protein implicated previously as a marker of aggressive disease in colorectal and non-small cell lung cancer, is downregulated in these cell lines compared to parental cells. Then, we test the functional consequences of R-spondin 3 downregulation by siRNA-mediated interference using in vitro assays of radiation resistance, proliferation, and invasiveness . Experiments investigating any change in metastatic propensity following R-spondin 3 downregulation are forthcoming. We further investigate signaling pathways that may be implicated in the mechanism of R-spondin 3 action. Lastly, we use the Oncomine Platform to look for any changes in R-spondin 3 levels between normal prostate tissue and prostate adenocarcinoma. Results: Although siRNA-mediated loss of R-spondin 3 does not confer radiation resistance in vitro, it does result in increased invasiveness in Matrigel assays. Paradoxically, R-spondin 3 downregulation results in decreased proliferation. Interference with R-spondin 3 also results in decreased β-catenin, ERK, and Akt signaling, but increased JNK signaling. In support of our in vitro results, R-spondin 3 expression is lower in human prostate adenocarcinoma compared to normal prostate in several gene expression datasets. Conclusions: Our preliminary data suggest that R-spondin 3 loss may lead to increased disease aggression via altered cell signaling. R-spondin 3 downregulation may represent a potential biomarker to identify patients at greater risk of developing locally advanced or metastatic disease, or a potential mechanism to target in future therapeutic efforts.

Long non-coding RNA urothelial carcinoma associated 1 (UCA1) mediates radiation response in prostate cancer

Radioresistance remains a significant obstacle in the treatment of Prostate Cancer (PCa). To simulate the clinical scenario of irradiation resistance (IRR), we created DU145-IRR PCa cell lines by treatment with 2 Gy daily IR for 59 fractions. DU145-IRR cells acquired an aggressive phenotype as evidenced by increased clonogenic survival, tumorigenic potential and invasiveness. We performed transcriptome profiling to discover dysregulated genes in DU145-IRR cells and identified the long non-coding RNA (lncRNA), Urothelial carcinoma-associated 1 (UCA1). We first investigated the role of UCA1 in radiation response and found that UCA1 abundance was significantly higher in DU145-IRR cells compared to control cells. UCA1 siRNA-knockdown reversed the aggressive phenotype and significantly increased sensitivity to IR. UCA1 depletion inhibited growth, induced cell cycle arrest at the G2/M transition and decreased activation of the pro-survival Akt pathway. We then studied the clinical significance of UCA1 expression in two independent cohorts of PCa patients: MSKCC (130 patients) and CPC-GENE (209 patients). UCA1 over-expression was associated with decreased 5-year disease-free survival in MSKCC patients (HR = 2.9; p = 0.007) and a trend toward lower biochemical recurrence-free survival in CPC-GENE patients (HR = 2.7; p = 0.05). We showed for the first time that UCA1 depletion induces radiosensitivity, decreases proliferative capacity and disrupts cell cycle progression, which may occur through altered Akt signaling and induced cell cycle arrest at the G2/M transition. Our results indicate that UCA1 might have prognostic value in PCa and be a potential therapeutic target.

Abstract 830: MiRNA-106a and LITAF are novel modulators of prostate cancer radioresistance

Prostate cancer (PCa) is the second most prevalent cancer affecting men worldwide, with radiotherapy being a primary treatment modality. PCa recurrence is a major clinical problem with up to a 40% biochemical recurrence rate at five years after external beam radiotherapy (ionizing radiation, IR). Therefore, there is an unmet need to characterize radioresistance in order to improve therapy and patient outcomes. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression. MiRNAs are aberrantly expressed in cancer, specifically, miR-106a has been found to be overexpressed in various cancer types. The purpose of this study is to determine whether miR-106a confers IR resistance and tumor aggression in PCa.

Utilizing The Cancer Genome Atlas Data Portal, bioinformatics analysis discovered that miR-106a was significantly overexpressed in PCa samples relative to normal prostate. This suggests that miR-106a is involved in prostate carcinogenesis. Clonogenic survival assays revealed that cells overexpressing miR-106a had increased survival after IR treatment compared to control cells. Proliferation assays showed that miR-106a cells had a higher proliferation rate than control cells in both unirradiated and IR-treated cells. Affymetrix gene array analysis was used to identify possible targets of miR-106a. Combining results from the gene array, in silico prediction algorithms, and in vitro analyses, we identified lipopolysaccharide-induced TNFα factor (LITAF) as a target of miR-106a. In addition, LITAF knockdown lead to increased proliferation and clonogenic survival following IR, recapitulating the phenotype of miR-106a overexpression. Cells were stained for β-galactosidase expression following IR to assess senescence, as a mode of cell death. We found that both miR-106a overexpression and LITAF knockdown resulted in significantly fewer senescent cells post-IR. Upon examination of critical DNA damage response genes, we found that miR-106a overexpression and LITAF knockdown increased expression of ATM mRNA and protein. Upregulation of ATM is associated with IR resistance, elucidating the mechanism by which miR-106a overexpression and LITAF knockdown are involved in radioresistance. Tumor xenograft experiments, using a PCa cell line stably overexpressing miR-106a, confirmed that miR-106a increases proliferation compared to control tumors before and after IR.

Thus, our results strongly suggest that miR-106a is involved in PCa aggression and confers a radiation-resistant phenotype, by targeting the novel radiation response gene LITAF.

Note: This abstract was not presented at the meeting.

Citation Format: Christianne Hoey, Jessica Ray, Paul Boutros, Stanley K. Liu. MiRNA-106a and LITAF are novel modulators of prostate cancer radioresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 830. doi:10.1158/1538-7445.AM2017-830

The challenges of early discharge. Common newborn problems in the first few weeks of life

In a thorough discussion of a published series on early discharge, Britton, Britton and Beebe note that methodological limitations, study design problems and heterogeneity sorely limit the conclusions that may be drawn from published studies about early discharge. These authors found that the 1980 recommendations of the AAP about early discharge are still appropriate. They recommend individualizing the discharge decision based on mother-infant health, as well as on psychosocial and socioeconomic factors. These authors apparently seek to temper the headlong rush to early discharge with an awareness of the wider societal context within which childbirth must be understood. Although the literature paints a positive picture of early home discharge, existing research still lacks the statistical power and scientific evidence to support this practice. There are many positive reasons for the early discharge of a mother-infant dyad, but they may have nothing to do with monetary savings. As with many things we do in our clinical practice, there is much room for the input of nurse practitioners, not only in providing care, but also in the shaping of health care policy.

Economic advantages of breast-feeding in an HMO: setting a pilot study

We performed a pilot study on newborns randomly chosen from term singleton deliveries born to mothers in an HMO group between September 1992 and August 1993. Breast-fed infants were breast-feeding at 6 months (n = 41), whereas bottle-fed infants were bottle-fed from birth (n = 107), Medical care and costs for the first 12 months were retrospectively analyzed, including office visits, drug prescriptions, and hospitalizations. Both groups had similar numbers of office visits and pharmacy costs. Breast-fed infants had fewer inpatient admissions (0.13 vs. 0.20 discharges per 1,000 babies), and their average total medical costs were $200 less than those of bottle-fed infants. Extrapolating to the total number of deliveries during this period, an increase in breast-feeding from the current rate (17%) to the Healthy People 2000 goal (50%) could save up to $140,000 annually.

Community photoscreening of six to nine month old infants for amblyopiogenic risk factors

Photorefraction (PR) is gaining acceptance as potentially the most effective objective screening technique for amblyopia risk factors in the preverbal child. This study determined the validity and feasibility of using the Auckland eccentric photorefractor in the detection of amblyopiogenic factors in six to nine month old infants in an established community-based vision screening program. Photographs were analysed and compared to results of clinical examination including cycloplegic refraction. Amblyopia risk factors were present in 7.2% of the infants clinically examined. Analysis only of readable photographs in children who were also clinically examined, gave sensitivities ranging from 71% to 79%, and specificities ranging from 81% to 86%. Inclusion in the analysis of photo-failures lowered sensitivity figures to 56% to 61%, and specificity to 63% to 70%. Photofailures were predominantly due to poor operator technique. Calculation of kappa scores indicated fair observer reliability. In conclusion, PR could provide a feasible and sufficiently reliable screening technique in the infant, but requires adequate training and auditing of screening personnel performance for optimum effectiveness.

ADA's focus: carving a niche in healthcare reform

Healthcare reform was the pressing topic at the 76th Annual American Dietetic Association (ADA) meeting and exhibition held in Anaheim, California, in late October. Explained ADA President Susan Calvert Finn, Ph.D., R.D., about the program content, "This meeting, by addressing new evidence of the link between diet and disease, as well as the role of nutrition services as a preventive health strategy, is extremely relevant to today's healthcare reform discussions. The connection between diet and disease will be highlighted so policy makers working on the healthcare reform bill will understand the medical importance of our research."

Healthcare reform: second opinions. If you must insure part-timers. Part 1

One of the central goals of the Clinton healthcare reform proposal is to provide insurance coverage for all Americans. This will be possible largely by requiring all employers to pay insurance for all their employees, including part-timers. The proposed plan requires all employers to offer full medical benefit packages to any employee who works more than 30 hours a week, and to cover employees who work 10 to 30 hours a week on a prorated basis. The following are foodservice operators' opinions on how this legislation, if passed, will affect their operations.

The flood ... foodservice directors in the Midwest test their endurance during one of the worst floods this century

The summer of 1993 will be remembered as the time when record amounts of rain flooded the Mississippi and its tributary rivers, causing one of the decade's worst natural disasters. Accounts from the hard-hit Des Moines area exemplify what many foodservice operators and their staff did to help their customers and neighbors struck by the disaster.

Tuberculous meningitis in the elderly

Six cases of tuberculous meningitis, all occurring in patients over the age of 65, are described. All patients presented with an acute illness, primarily with a confusional state. Headache was a symptom in only two patients and the cases were not confined to ethnic minority groups. The mortality was 50%.