Multiple roles for Bcl-3 in mammary gland branching, stromal collagen invasion, involution and tumor pathology

BACKGROUND

The Bcl-3 protein is an atypical member of the inhibitor of -κB family that has dual roles as a transcriptional repressor and a coactivator for dimers of NF-κB p50 and p52. Bcl-3 is expressed in mammary adenocarcinomas and can promote tumorigenesis and survival signaling and has a key role in tumor metastasis. In this study, we have investigated the role of Bcl-3 in the normal mammary gland and impact on tumor pathology.

METHODS

We utilized bcl-3^-/- mice to study mammary gland structure in virgins and during gestation, lactation and early involution. Expression of involution-associated genes and proteins and putative Bcl-3 target genes was examined by qRT-PCR and immunoblot analysis. Cell autonomous branching morphogenesis and collagen I invasion properties of bcl-3^-/- organoids were tested in 3D hydrogel cultures. The role of Bcl-3 in tumorigenesis and tumor pathology was also assessed using a stochastic carcinogen-induced mammary tumor model.

RESULTS

Bcl-3^-/- mammary glands demonstrated reduced branching complexity in virgin and pregnant mice. This defect was recapitulated in vitro where significant defects in bud formation were observed in bcl-3^-/- mammary organoid cultures. Bcl-3^-/- organoids showed a striking defect in protrusive collective fibrillary collagen I invasion associated with reduced expression of Fzd1 and Twist2. Virgin and pregnant bcl-3^-/- glands showed increased apoptosis and rapid increases in lysosomal cell death and apoptosis after forced weaning compared to WT mice. Bcl-2 and Id3 are strongly induced in WT but not bcl-3^-/- glands in early involution. Tumors in WT mice were predominately adenocarcinomas with NF-κB activation, while bcl-3^-/- lesions were largely squamous lacking NF-κB and with low Bcl-2 expression.

CONCLUSIONS

Collectively, our results demonstrate that Bcl-3 has a key function in mammary gland branching morphogenesis, in part by regulation of genes involved in extracellular matrix invasion. Markedly reduced levels of pro-survival proteins expression in bcl-3 null compared to WT glands 24 h post-weaning indicate that Bcl-3 has a role in moderating the rate of early phase involution. Lastly, a reduced incidence of bcl-3^-/- mammary adenocarcinomas versus squamous lesions indicates that Bcl-3 supports the progression of epithelial but not metaplastic cancers.

Multispectral label-free Raman spectroscopy can detect ovarian and endometrial cancer with high accuracy

Up to 70% of ovarian cancer patients are diagnosed with advanced-stage disease and the degree of cytoreduction is an important survival prognostic factor. The aim of this study was to evaluate if Raman spectroscopy could detect cancer from different organs within the abdominopelvic region, including the ovaries. A Raman spectroscopy probe was used to interrogate specimens from a cohort of nine patients undergoing cytoreductive surgery, including four ovarian cancer patients and three patients with endometrial cancer. A feature-selection algorithm was developed to determine which spectral bands contributed to cancer detection and a machine-learning model was trained. The model could detect cancer using only eight spectral bands. The receiver-operating-characteristic curve had an area-under-the-curve of 0.96, corresponding to an accuracy, a sensitivity and a specificity of 90%, 93% and 88%, respectively. These results provide evidence multispectral Raman spectroscopy could be developed to detect ovarian cancer intraoperatively.

Phosphorylated transducer and activator of transcription-3 (pSTAT3) immunohistochemical expression in paired primary and metastatic colorectal cancer

BACKGROUND

Signal Transducer and Activator of Transcription-3 (STAT3) mediates cellular functions. We assessed the IHC expression of phosphorylated STAT3 (pSTAT3) in paired primary tumors and liver metastases in patients with advanced stage colorectal cancer (CRC).

METHODS

We included patients with tissue blocks available from both the primary CRC and a surgically resected liver metastasis. The IHC pSTAT3 expression agreement was measured using Cohen's kappa statistic.

RESULTS

The study included 103 patients, 55% male, median age was 64. 43% tumors originated in rectum, and 63% of the primary tumors were synchronous. Expression of pSTAT3 was 76% in liver metastases and 71% in primary tumors. A difference in pSTAT3 staining between the primary tumor and liver metastases was noted in 64%. There was lost expression of pSTAT3 in the liver metastases in 28% and gained expression in 36% of cases compared to the primary. The kappa statistic comparing agreement between staining patterns of the primary tumors and liver metastases was a "less-than-chance", at -0.02. Median survival was 4.9 years, with no difference in survival outcomes by pSTAT3 expression in the primary tumor or liver metastases.

DISCUSSION

STAT3 is not a prognostic marker in the selective setting of metastatic CRC to liver, but it may remain a potential therapeutic target given most liver metastases expressed pSTAT3. Discordant pSTAT3 expression in between primary tumors and paired liver metastases suggests that use of this class of drug to treat liver predominant metastatic colorectal cancer in a biomarker-driven approach may require confirmatory liver tumor biopsy.

Protective effects of resveratrol against osteonecrosis at the extraction site in bisphosphonate-treated rats

Resveratrol (RSV) is a phytoestrogen with a wide range of therapeutic effects, including antioxidant and anti-inflammatory effects. This study was performed to evaluate the protective role of RSV against osteonecrosis after tooth extraction in rats treated with bisphosphonates. Thirty-nine male Wistar rats, weighing 300-350 g, were divided into three groups (n = 13) according to the planned drug regimen: alendronate + dexamethasone (AL/DEX), alendronate + dexamethasone + RSV (AL/DEX/RSV), and no drugs (control group). The first and second molars of each rat were extracted and the extraction sites were analysed histologically 14 days later. The data collected were subjected to statistical analysis by means of Kruskal-Wallis, Mann-Whitney, χ², and Fisher's exact tests using IBM SPSS software at a significance level of 0.05. The incidence of osteonecrosis was significantly lower in the AL/DEX/RSV group (P = 0.001) and control group (P = 0.041) than in the AL/DEX group, while the amount of new bone formation did not differ significantly between the AL/DEX/RSV and AL/DEX groups (P > 0.05). RSV showed a protective effect by significantly reducing osteonecrosis, which could be due to its antioxidant effects.

Modulating SIRT1 activity variously affects thymic lymphoma development in mice

SIRT1 is a protein deacetylase with a broad range of biological functions, many of which are known to be important in carcinogenesis, however much of the literature regarding the role of SIRT1 in cancer remains conflicting. In this study we assessed the effect of SIRT1 on the initiation and progression of thymic T cell lymphomas. We employed mouse strains in which SIRT1 activity was absent or could be reversibly modulated in conjunction with thymic lymphoma induction using either the N-nitroso-N-methylurea (NMU) carcinogenesis or the nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) transgene. Decreased SIRT1 activity reduced the development of thymic lymphomas in the NMU-treated mice but was permissive for the formation of lung adenomas. Conversely, in the NPM-ALK transgenic mice, decreased SIRT1 activity had a modest promoting effect in the development of thymic lymphomas. The results of the work presented here add to the growing body of evidence that sirt1 is neither an outright oncogene nor a tumor suppressor. These opposing results in two models of the same disease suggest that the influence of sirt1 on carcinogenesis may lie in a role in tumor surveillance.

cIAP2 Is an Independent Signaling and Survival Factor during Mammary Lactational Involution and Tumorigenesis

Cellular inhibitor of apoptosis proteins-1 and -2 (cIAP1/2) are integral to regulation of apoptosis and signaling by the tumor necrosis factor (TNF) and related family of receptors. The expression of cIAP2 in tissues is typically low and considered functionally redundant with cIAP1, however cIAP2 can be activated by a variety of cellular stresses. Members of the TNFR family and their ligands have essential roles in mammary gland biology. We have found that cIAP2^-/- virgin mammary glands have reduced ductal branching and delayed lobuloalveogenesis in early pregnancy. Post-lactational involution involves two phases where the first phase is reversible and is mediated, in part, by TNFR family ligands. In cIAP2-/- mice mammary glands appeared engorged at mid-lactation accompanied by enhanced autophagic flux and decreased cIAP1 protein expression. Severely stretched myoepithelium was associated with BIM-EL expression and other indicators of anoikis. Within 24 h after forced or natural weaning, cIAP2^-/- glands had nearly completed involution. The TNF-related weak inducer of apoptosis (Tweak) which results in degradation of cIAP1 through its receptor, Fn14, began to increase in late lactation and was significantly increased in cIAP2^-/- relative to WT mice by 12 h post weaning accompanied by decreased cIAP1 protein expression. Carcinogen/progesterone-induced mammary tumorigenesis was significantly delayed in cIAP2^-/- mice and tumors contained high numbers of apoptotic cells. We conclude that cIAP2 has a critical role in the mammary gland wherein it prevents rapid involution induced by milk stasis-induced stress associated with Tweak activation and contributes to the survival of mammary tumor cells.

Is arthrocentesis of temporomandibular joint with corticosteroids beneficial? A systematic review

Background

Temporomandibular disorders (TMDs) are musculoskeletal conditions that can inhibit the normal function of temporomandibular joints (TMJs) and affect the patient’s quality of life, negatively. Arthrocentesis (AC) is a minimally invasive surgical procedure used for treating TMDs. The aim of present paper is to evaluate the advantages of administrating corticosteroid (CS) during AC by reviewing high quality released articles.

Material and Methods

Searching on Cochrane Library, Web of Science, Google Scholar, PubMed, ProQuest, and Scopus databases were performed with focusing on proper key words. Related titles and abstracts, up to December 2017, were screened and selected based on inclusion criteria. The full text of all randomized controlled trials (RCTs) was extensively read and subjected to quality assessments.

Results

After initial search, a total of 2067 articles were included into the study. Finally, 7 studies were reliable enough in methodology and randomization to be included into the study. All of the observed studies showed improvements in jaw functions and pain relief with no statistical differences in both AC and control groups. One study reported painless maximum incisal opening in CS group than the control group.

Conclusions

Based on available RCTs, the AC of TMJ with CS seems to result in similar findings to other therapeutic drugs, with no significant differences.

Key words:Arthrocentesis, corticosteroid, temporomandibular joints, temporomandibular joint disorders.

PREX1 integrates G protein-coupled receptor and phosphoinositide 3-kinase signaling to promote glioblastoma invasion

A defining feature of the brain cancer glioblastoma is its highly invasive nature. When glioblastoma cells are isolated from patients using serum free conditions, they accurately recapitulate this invasive behaviour in animal models. The Rac subclass of Rho GTPases has been shown to promote invasive behaviour in glioblastoma cells isolated in this manner. However the guanine nucleotide exchange factors responsible for activating Rac in this context have not been characterized previously. PREX1 is a Rac guanine nucleotide exchange factor that is synergistically activated by binding of G protein αγ subunits and the phosphoinositide 3-kinase pathway second messenger phosphatidylinositol 3,4,5 trisphosphate. This makes it of particular interest in glioblastoma, as the phosphoinositide 3-kinase pathway is aberrantly activated by mutation in almost all cases. We show that PREX1 is expressed in glioblastoma cells isolated under serum-free conditions and in patient biopsies. PREX1 promotes the motility and invasion of glioblastoma cells, promoting Rac-mediated activation of p21-associated kinases and atypical PKC, which have established roles in cell motility. Glioblastoma cell motility was inhibited by either inhibition of phosphoinositide 3-kinase or inhibition of G protein βγ subunits. Motility was also inhibited by the generic dopamine receptor inhibitor haloperidol or a combination of the selective dopamine receptor D2 and D4 inhibitors L-741,626 and L-745,870. This establishes a role for dopamine receptor signaling via G protein βγ subunits in glioblastoma invasion and shows that phosphoinositide 3-kinase mutations in glioblastoma require a context of basal G protein–coupled receptor activity in order to promote this invasion.

Human induced pluripotent stem cell-derived lung progenitor and alveolar epithelial cells attenuate hyperoxia-induced lung injury

BACKGROUND AIMS

Bronchopulmonary dysplasia (BPD), a chronic lung disease characterized by disrupted lung growth, is the most common complication in extreme premature infants. BPD leads to persistent pulmonary disease later in life. Alveolar epithelial type 2 cells (AEC2s), a subset of which represent distal lung progenitor cells (LPCs), promote normal lung growth and repair. AEC2 depletion may contribute to persistent lung injury in BPD. We hypothesized that induced pluripotent stem cell (iPSC)-derived AECs prevent lung damage in experimental oxygen-induced BPD.

METHODS

Mouse AECs (mAECs), miPSCs/mouse embryonic stem sells, human umbilical cord mesenchymal stromal cells (hUCMSCs), human (h)iPSCs, hiPSC-derived LPCs and hiPSC-derived AECs were delivered intratracheally to hyperoxia-exposed newborn mice. Cells were pre-labeled with a red fluorescent dye for in vivo tracking.

RESULTS

Airway delivery of primary mAECs and undifferentiated murine pluripotent cells prevented hyperoxia-induced impairment in lung function and alveolar growth in neonatal mice. Similar to hUCMSC therapy, undifferentiated hiPSCs also preserved lung function and alveolar growth in hyperoxia-exposed neonatal NOD/SCID mice. Long-term assessment of hiPSC administration revealed local teratoma formation and cellular infiltration in various organs. To develop a clinically relevant cell therapy, we used a highly efficient method to differentiate hiPSCs into a homogenous population of AEC2s. Airway delivery of hiPSC-derived AEC2s and hiPSC-derived LPCs, improved lung function and structure and resulted in long-term engraftment without evidence of tumor formation.

CONCLUSIONS

hiPSC-derived AEC2 therapy appears effective and safe in this model and warrants further exploration as a therapeutic option for BPD and other lung diseases characterized by AEC injury.

Adaptive Response Induced by Pre-Exposure to 915 MHz Radiofrequency: A Possible Role for Antioxidant Enzyme Activity

BACKGROUND

Over the past few years, the rapid use of high frequency electromagnetic fields like mobile phones has raised global concerns about the negative health effects of its use. Adaptive response is the ability of a cell or tissue to better resist stress damage by prior exposure to a lesser amount of stress. This study aimed to assess whether radiofrequency radiation can induce adaptive response by changing the antioxidant balance.

MATERIALS AND METHODS

In order to assess RF-induced adaptive response in tissues, we evaluated the level of GSH and the activity of GR in liver. 50 rats were divided into 5 groups. Three groups were pre-exposed to 915 MHz RF radiation, 4 hours per day for one week at different powers, as low, medium and high. 24 hours after the last exposure to radiation, they were exposed to 4 Gy sublethal dose of gamma radiation and then sacrificed after 5 hours. Their livers were removed, washed and were kept at -80o C until used.

RESULTS

Our finding showed that pre-exposure to 915 MHz radiofrequency radiation with specific power could induce adaptive response in liver by inducing changes in the activity and level of antioxidant enzymes.

CONCLUSION

It can be concluded that pre-exposure to microwave radiation could increase the level of GSH and the activity of GR enzyme, although these increases were seen just in low power group, and the GR activity was indicated in medium power group. This increase protects tissue from oxidative damage induced by sublethal dose of gamma radiation.

Phosphorylated signal transducer and activator of transcription–3 (p-STAT3) expression concordance in paired primary and metastatic colorectal cancers (mCRC): Updated analysis

e15137

Background: p-STAT3 is a transcription factor which is associated with poor prognosis in multiple cancers. Overexpression of p-STAT3 by immunohistochemistry (IHC) in tumors of patients with mCRC is associated with more aggressive disease and decreased survival. Concordance of p-STAT3 expression in primary and metastatic tumors was assessed to determine the temporal heterogeneity of expression and correlation with clinical outcomes. Methods: Patients with tissue available from both primary and liver metastases were identified retrospectively. Tissue microarrays (TMA) were constructed using 2 x 2mm cores. Nuclear p-STAT3 expression intensity by IHC was graded as absent, low, or high. Primary outcome was concordance of p-STAT3 expression between primary and metastatic sites. Secondary outcome was correlation of p-STAT3 expression with disease outcomes. Results: 91 patients were identified: 55% were male, median age at diagnosis was 63, 60% had left-sided disease and 81% of metastases were synchronous. Expression of p-STAT3 in primary tumors was 23% high, 47% low and absent in 30% compared to 29% high, 50% low, and 21% absent in metastases. Concordant expression was observed in 23% of patients whereas it increased in 46% and decreased in 31% from primary to metastasis. Pearson’s correlation was 0.119 indicating a weak concordance. After a median follow-up of 7 years, 50 of 91 patients died. One-year and 5-year survival rates were 92% and 44% respectively, while the median overall survival (mOS) was 4.7 years [95%CI 3.1-6.4]. No significant prognostic correlation between primary or metastatic p-STAT3 expression and mOS was found. Conclusions: There was low concordance of p-STAT3 expression in primary and metastatic tumors of patients with mCRC. Tumor staining heterogeneity due to sampling of small cores included in TMA and predominance of synchronous metastases may play a role. Further research in the use of p-STAT3 as a biomarker in patients with mCRC is needed.

PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma

Cellular senescence is a tumor suppressor mechanism where cells enter a permanent growth arrest following cellular stress. Oncogene-induced senescence (OIS) is induced in non-malignant cells following the expression of an oncogene or inactivation of a tumor suppressor. Previously, we have shown that protein kinase C iota (PKCι) depletion induces cellular senescence in glioblastoma cells in the absence of a detectable DNA damage response. Here we demonstrate that senescent glioblastoma cells exhibit an aberrant centrosome morphology. This was observed in basal levels of senescence, in p21-induced senescence, and in PKCι depletion-induced senescence. In addition, senescent glioblastoma cells are polyploid, Ki-67 negative and arrest at the G1/S checkpoint, as determined by expression of cell cycle regulatory proteins. These markers are all consistent with cells that have undergone mitotic slippage. Failure of the spindle assembly checkpoint to function properly can lead to mitotic slippage, resulting in the premature exit of mitotic cells into the G1 phase of the cell cycle. Although in G1, these cells have the replicated DNA and centrosomal phenotype of a cell that has entered mitosis and failed to divide. Overall, we demonstrate that PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma cells. To our knowledge, this is the first evidence of markers of mitotic slippage directly in senescent cells by co-staining for senescence-associated β-galactosidase and immunofluorescence markers in the same cell population. We suggest that markers of mitotic slippage be assessed in future studies of senescence to determine the extent of mitotic slippage in the induction of cellular senescence.

Selective microwave sensors exploiting the interaction of analytes with trap states in TiO2 nanotube arrays

Sensing of molecular analytes by probing the effects of their interaction with microwaves is emerging as a cheap, compact, label-free and highly sensitive detection and quantification technique. Microstrip ring-type resonators are particularly favored for this purpose due to their planar sensing geometry, electromagnetic field enhancements in the coupling gap and compatibility with established printed circuit board manufacturing. However, the lack of selectivity in what is essentially a permittivity-sensing method is an impediment to wider adoption and implementation of this sensing platform. By placing a polycrystalline anatase-phase TiO2 nanotube membrane in the coupling gap of a microwave resonator, we engineer selectivity for the detection and differentiation of methanol, ethanol and 2-propanol. The scavenging of reactive trapped holes by aliphatic alcohols adsorbed on TiO2 is responsible for the alcohol-specific detection while the different short chain alcohols are distinguished on the basis of differences in their microwave response. Electrodeless microwave sensors which allow spectral and time-dependent monitoring of the resonance frequency and quality factor provide a wealth of information in comparison with electrode-based resistive sensors for the detection of volatile organic compounds. A high dynamic range (400 ppm-10,000 ppm) is demonstrated for methanol detection.

Abstract P4-09-08: miR-135a is associated with a metastatic phenotype in invasive lobular carcinoma

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer. Classic type ILC is generally regarded as indolent in nature with its favourable biologic characteristics such as low grade, ER positivity and luminal A subtype. Despite this, patients with ILC can develop significant distant recurrence or metastases. Thus the ability to identify those patients at highest risk of recurrence or metastasis, and identification of novel therapies for ILC are urgently required. To this end, we recently profiled the miRNA expression in primary surgical ILC specimens from patients who went on to have metastatic disease compared to those who remained tumor free long term. As miRNA are stable in formalin fixed paraffin embedded tissues1, we speculated they could be robust biomarkers. RNA was isolated from laser capture microdissected ILC tumor epithelium, and subjected to miRNome analysis using a PCR-based amplification method. Many differentially expressed miRNAs were identified, and we initially focused further validation on those which had been previously linked to metastasis. One of these, miR-135a, was elevated in tumors from ILC patients who developed metastases compared to those that did not. We utilized two representative ILC cell lines which differ in their invasive ability, MDA-MB-134VI (non-invasive) and MDA-MB-330 (invasive), to test whether miR-135a regulated ILC invasion. We found that levels of miR-135a correlated with the invasive potential of ILC cell lines and was elevated in the invasive MDA-MB-330 cells compared to less invasive MDA-MB-134VI cells. We also found that decreasing miR-135a expression using specific hairpin inhibitors in MDA-MB-330 cells resulted in decreased cell invasion. As miR-135a has been shown to regulate invasion via targeting metastasis suppressor 1 (MTSS1) mRNA for degradation2, we examined whether MTSS1 levels were inversely associated with miR-135a levels in ILC cells. As predicted, in MDA-MB-330 cells where miR-135a levels were significantly higher, levels of MTSS1 were the lowest while MTSS1 levels were higher in parallel with decreased levels of miR-135a in the non-invasive MDA-MB-134VI cells. Overexpressing miR-135a using miRNA mimics in normal mammary epithelial cells (HMEC) where miR-135a is normally low, reduced levels of MTSS1 supporting suggestions it is a direct target of miR-135a. We also confirmed reduced mRNA levels of MTSS1 in surgical specimens from ILC patients who developed metastases compared to those that did not. Taken together, our results suggest that high levels of miR-135a, and low levels of MTSS1 may be useful prognostic information to assess risk of metastasis in ILC.

References

1. Bovell L, Shanmugam C, Katkoori VR, et al: miRNAs are stable in colorectal cancer archival tissue blocks. Front Biosci (Elite Ed) 4:1937-40, 2012

2. Zhou W, Li X, Liu F, et al: MiR-135a promotes growth and invasion of colorectal cancer via metastasis suppressor 1 in vitro. Acta Biochim Biophys Sin (Shanghai) 44:838-46, 2012.

Citation Format: Howe GA, Zhao H, Daneshmand M, Clemons M, Robertson SJ, Arnaout A, Addison CL. miR-135a is associated with a metastatic phenotype in invasive lobular carcinoma. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-08.

Protein arginine methyltransferase 7 promotes breast cancer cell invasion through the induction of MMP9 expression

Recent evidence points to the protein arginine methyltransferase (PRMT) family of enzymes playing critical roles in cancer. PRMT7 has been identified in several gene expression studies to be associated with increased metastasis and decreased survival in breast cancer patients. However, this has not been extensively studied. Here we report that PRMT7 expression is significantly upregulated in both primary breast tumour tissues and in breast cancer lymph node metastases. We have demonstrated that reducing PRMT7 levels in invasive breast cancer cells using RNA interference significantly decreased cell invasion in vitro and metastasis in vivo. Conversely, overexpression of PRMT7 in non-aggressive MCF7 cells enhanced their invasiveness. Furthermore, we show that PRMT7 induces the expression of matrix metalloproteinase 9 (MMP9), a well-known mediator of breast cancer metastasis. Importantly, we significantly rescued invasion of aggressive breast cancer cells depleted of PRMT7 by the exogenous expression of MMP9. Our results demonstrate that upregulation of PRMT7 in breast cancer may have a significant role in promoting cell invasion through the regulation of MMP9. This identifies PRMT7 as a novel and potentially significant biomarker and therapeutic target for breast cancer.

Inhibition of glioblastoma malignancy by Lgl1

lethal giant larvae (lgl) was first identified as a tumor suppressor in Drosophila, where its loss repressed the differentiation and promoted the invasion of neuroblasts, the Drosophila equivalent of the neural stem cell. Recently we have shown that a human homolog of Lgl, Lgl1 (LLGL1), is constitutively phosphorylated and inactivated in glioblastoma cells; this occurs as a downstream consequence of PTEN loss, one of the most frequent genetic events in glioblastoma. Here we have investigated the consequences of this loss of functional Lgl1 in glioblastoma in vivo. We used a doxycycline-inducible system to express a non-phosphorylatable, constitutively active version of Lgl1 (Lgl3SA) in either a glioblastoma cell line or primary glioblastoma cells isolated under neural stem cell culture conditions from patients. In both types of cells, expression of Lgl3SA, but not wild type Lgl1, inhibited cell motility in vitro. Induction of Lgl3SA in intracerebral xenografts markedly reduced the in vivo invasion of primary glioblastoma cells. Lgl3SA expression also induced the differentiation of glioblastoma cells in vitro and in vivo along the neuronal lineage. Thus the central features of Lgl function as a tumor suppressor in Drosophila are conserved in human glioblastoma.

VEGF-Mediated Induction of PRD1-BF1/Blimp1 Expression Sensitizes Tumor Vasculature to Oncolytic Virus Infection

Oncolytic viruses designed to attack malignant cells can in addition infect and destroy tumor vascular endothelial cells. We show here that this expanded tropism of oncolytic vaccinia virus to the endothelial compartment is a consequence of VEGF-mediated suppression of the intrinsic antiviral response. VEGF/VEGFR2 signaling through Erk1/2 and Stat3 leads to upregulation, nuclear localization, and activation of the transcription repressor PRD1-BF1/Blimp1. PRD1-BF1 does not contribute to the mitogenic effects of VEGF, but directly represses genes involved in type I interferon (IFN)-mediated antiviral signaling. In vivo suppression of VEGF signaling diminishes PRD1-BF1/Blimp1 expression in tumor vasculature and inhibits intravenously administered oncolytic vaccinia delivery to and consequent spread within the tumor.

Loss of periostin/OSF-2 in ErbB2/Neu-driven tumors results in androgen receptor-positive molecular apocrine-like tumors with reduced Notch1 activity

INTRODUCTION

Periostin (Postn) is a secreted cell adhesion protein that activates signaling pathways to promote cancer cell survival, angiogenesis, invasion, and metastasis. Interestingly, Postn is frequently overexpressed in numerous human cancers, including breast, lung, colon, pancreatic, and ovarian cancer.

METHODS

Using transgenic mice expressing the Neu oncogene in the mammary epithelium crossed into Postn-deficient animals, we have assessed the effect of Postn gene deletion on Neu-driven mammary tumorigenesis.

RESULTS

Although Postn is exclusively expressed in the stromal fibroblasts of the mammary gland, Postn deletion does not affect mammary gland outgrowth during development or pregnancy. Furthermore, we find that loss of Postn in the mammary epithelium does not alter breast tumor initiation or growth in mouse mammary tumor virus (MMTV)-Neu expressing mice but results in an apocrine-like tumor phenotype. Surprisingly, we find that tumors derived from Postn-null animals express low levels of Notch protein and Hey1 mRNA but increased expression of androgen receptor (AR) and AR target genes. We show that tumor cells derived from wild-type animals do not proliferate when transplanted in a Postn-null environment but that this growth defect is rescued by the overexpression of active Notch or the AR target gene prolactin-induced protein (PIP/GCDFP-15).

CONCLUSIONS

Together our data suggest that loss of Postn in an ErbB2/Neu/HER2 overexpression model results in apocrine-like tumors that activate an AR-dependent pathway. This may have important implications for the treatment of breast cancers involving the therapeutic targeting of periostin or Notch signaling.

Creation of 3-dimensional prostate cancer maps: methodology and clinical and research implications

CONTEXT

The creation of 3-dimensional prostate cancer maps could assist with surgical intervention, radiotherapy treatment planning and for correlative pathology-imaging research.

OBJECTIVES

To develop methodology for creating detailed, 3-dimensional, prostate cancer maps (3DPCM) of tumor location, extra prostatic extension sites, and positive margins and to assess the adequacy of current clinical target volumes for postoperative radiotherapy to the prostate using 3DPCM coregistered with preoperative magnetic resonance imaging.

DESIGN

Parallel slices of prostatectomy specimens were created with ProCUT, and 2-dimensional cancer maps were generated as line diagrams after microscopic examination of each slice. The 2-dimensional cancer maps were aligned and stacked to create a 3DPCM, which was coregistered with the preoperative magnetic resonance imaging scan. The map was exported to the radiotherapy planning system and was used to determine the areas at greater risk, which were then compared against the current Radiation Therapy Oncology Group guidelines for contouring postoperative clinical target volumes to assess the adequacy of coverage.

RESULTS

Twenty-eight patients with a mean age of 66 years (range, 52-73) underwent radical prostatectomy and postoperative radiotherapy. Seventeen patients (61%) received adjuvant radiotherapy for pT3 disease and/or positive margins, and the rest underwent salvage radiotherapy. Thirty-nine percent (11 of 28) of the patients had Gleason scores of 8 or 9. The contours based on the Radiation Therapy Oncology Group guidelines for postoperative radiotherapy resulted in inadequate coverage of extraprostatic extensions in 79% (22 of 28) and positive margins in 64% (18 of 28) of the cases.

CONCLUSIONS

We have developed a methodology for creation of 3DPCM. Modification of the radiotherapy contours, based on the 3DPCM coregistered with pretreatment magnetic resonance imaging, covers the areas at high risk of recurrence. The 3DPCM could become an important clinical and research tool for urologists, pathologists, radiologists, and oncologists.

PTEN loss represses glioblastoma tumor initiating cell differentiation via inactivation of Lgl1

Glioblastoma multiforme is an aggressive and incurable type of brain tumor. A subset of undifferentiated glioblastoma cells, known as glioblastoma tumor initiating cells (GTICs), has an essential role in the malignancy of this disease and also appears to mediate resistance to radiation therapy and chemotherapy. GTICs retain the ability to differentiate into cells with reduced malignant potential, but the signaling pathways controlling differentiation are not fully understood at this time. PTEN loss is a very common in glioblastoma multiforme and leads to aberrant activation of the phosphoinositide 3-kinase pathway. Increased signalling through this pathway leads to activation of multiple protein kinases, including atypical protein kinase C. In Drosophila, active atypical protein kinase C has been shown to promote the self-renewal of neuroblasts, inhibiting their differentiation along a neuronal lineage. This effect is mediated by atypical protein kinase c-mediated phosphorylation and inactivation of Lgl, a protein that was first characterized as a tumour suppressor in Drosophila. The effects of the atypical protein kinase C/Lgl pathway on the differentiation status of GTICs, and its potential link to PTEN loss, have not been assessed previously. Here we show that PTEN loss leads to the phosphorylation and inactivation of Lgl by atypical protein kinase C in glioblastoma cells. Re-expression of PTEN in GTICs promoted their differentiation along a neuronal lineage. This effect was also seen when atypical protein kinase C was knocked down using RNA interference, and when a non-phosphorylatable, constitutively active form of Lgl was expressed in GTICs. Thus PTEN loss, acting via atypical protein kinase C activation and Lgl inactivation, helps to maintain GTICs in an undifferentiated state.

A new spontaneously transformed syngeneic model of high-grade serous ovarian cancer with a tumor-initiating cell population

Improving screening and treatment options for patients with epithelial ovarian cancer has been a major challenge in cancer research. Development of novel diagnostic and therapeutic approaches, particularly for the most common subtype, high-grade serous ovarian cancer (HGSC), has been hampered by controversies over the origin of the disease and a lack of spontaneous HGSC models to resolve this controversy. Over long-term culture in our laboratory, an ovarian surface epithelial (OSE) cell line spontaneously transformed OSE (STOSE). The objective of this study was to determine if the STOSE cell line is a good model of HGSC. STOSE cells grow faster than early passage parental M0505 cells with a doubling time of 13 and 48 h, respectively. STOSE cells form colonies in soft agar, an activity for which M0505 cells have negligible capacity. Microarray analysis identified 1755 down-regulated genes and 1203 up-regulated genes in STOSE compared to M0505 cells, many associated with aberrant Wnt/β-catenin and Nf-κB signaling. Upregulation of Ccnd1 and loss of Cdkn2a in STOSE tumors is consistent with changes identified in human ovarian cancers by The Cancer Genome Atlas. Intraperitoneal injection of STOSE cells into severe combined immunodeficient and syngeneic FVB/N mice produced cytokeratin+, WT1+, inhibin-, and PAX8+ tumors, a histotype resembling human HGSC. Based on evidence that a SCA1+ stem cell-like population exists in M0505 cells, we examined a subpopulation of SCA1+ cells that is present in STOSE cells. Compared to SCA1- cells, SCA1+ STOSE cells have increased colony-forming capacity and form palpable tumors 8 days faster after intrabursal injection into FVB/N mice. This study has identified the STOSE cells as the first spontaneous murine model of HGSC and provides evidence for the OSE as a possible origin of HGSC. Furthermore, this model provides a novel opportunity to study how normal stem-like OSE cells may transform into tumor-initiating cells.

PIK3CA, BRAF, and PTEN status and benefit from cetuximab in the treatment of advanced colorectal cancer--results from NCIC CTG/AGITG CO.17

PURPOSE

Cetuximab improves survival in patients with K-ras wild-type advanced colorectal cancer. We examined the predictive and prognostic significance of additional biomarkers in this setting, in particular BRAF, PIK3CA, and PTEN.

EXPERIMENTAL DESIGN

Available colorectal tumor samples were analyzed from the CO.17 study. BRAF mutations were identified in tumor-derived DNA by direct sequencing and PIK3CA mutations were identified using a high-resolution melting screen with confirmation by sequencing. PTEN expression by immunohistochemistry (IHC) was performed on tissue microarrays. For each biomarker, prognostic and predictive effects were examined using a Cox model with tests for treatment-biomarker interaction.

RESULTS

A total of 572 patients with pretreated colorectal cancer were randomly assigned to receive cetuximab or best supportive care (BSC). Of 401 patients assessed for BRAF status, 13 (3.2%) had mutations. Of 407 patients assessed for PIK3CA status, 61 (15%) had mutations. Of 205 patients assessed for PTEN, 148 (72%) were negative for IHC expression. None of BRAF, PIK3CA, or PTEN was prognostic for overall or progression-free survival in the BSC arm. None was predictive of benefit from cetuximab, either in the whole study population or the K-ras wild-type subset. In the K-ras wild-type subgroup, the overall survival adjusted HR according to BRAF mutation status was 1.39 (interaction P = 0.69), PIK3CA mutation status HR = 0.79 (interaction P = 0.63), and PTEN expression HR = 0.75 (interaction P = 0.61).

CONCLUSIONS

In chemotherapy-refractory colorectal cancer, neither PIK3CA mutation status nor PTEN expression were prognostic, nor were they predictive of benefit from cetuximab. Evaluation of predictive significance of BRAF mutations requires a larger sample size.

Randomized dose-finding clinical trial of oncolytic immunotherapeutic vaccinia JX-594 in liver cancer

Oncolytic viruses and active immunotherapeutics have complementary mechanisms of action (MOA) that are both self amplifying in tumors, yet the impact of dose on subject outcome is unclear. JX-594 (Pexa-Vec) is an oncolytic and immunotherapeutic vaccinia virus. To determine the optimal JX-594 dose in subjects with advanced hepatocellular carcinoma (HCC), we conducted a randomized phase 2 dose-finding trial (n=30). Radiologists infused low- or high-dose JX-594 into liver tumors (days 1, 15 and 29); infusions resulted in acute detectable intravascular JX-594 genomes. Objective intrahepatic Modified Response Evaluation Criteria in Solid Tumors (mRECIST) (15%) and Choi (62%) response rates and intrahepatic disease control (50%) were equivalent in injected and distant noninjected tumors at both doses. JX-594 replication and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression preceded the induction of anticancer immunity. In contrast to tumor response rate and immune endpoints, subject survival duration was significantly related to dose (median survival of 14.1 months compared to 6.7 months on the high and low dose, respectively; hazard ratio 0.39; P=0.020). JX-594 demonstrated oncolytic and immunotherapy MOA, tumor responses and dose-related survival in individuals with HCC.