Cardiovascular involvement by osteosarcoma: an analysis of 20 patients.

BACKGROUND: Although hematogenous spread of osteosarcoma is well known, the imaging findings of cardiovascular involvement by osteosarcoma are seldom reported and can be difficult to recognize. The enhanced resolution of modern CT and MRI scanners may lead to better detection of cardiovascular involvement. OBJECTIVE: To describe the key imaging findings and clinical behavior of cardiovascular involvement by osteosarcoma. MATERIALS AND METHODS: We retrospectively reviewed the imaging findings and clinical characteristics of 20 patients with cardiovascular involvement by osteosarcoma identified by two pediatric radiologists from a review of imaging studies at our institution from 2007 to 2013. RESULTS: At initial diagnosis, the median age of the patients was 15.1 years (range 4.8-24.6 years), and 7 (35%) patients had detectable metastases. Median time to detection of cardiovascular metastases was 1.8 years (range 0-7.3 years). Sixteen patients died of disease; 4 have survived a median of 7.4 years since initial diagnosis. The sites of cardiovascular involvement were the systemic veins draining the primary and metastatic osteosarcoma, pulmonary arteries, pulmonary veins draining the pulmonary metastases, and heart. A dilated and mineralized terminal pulmonary arteriole is an early sign of metastatic osteosarcoma in the lung. Unfamiliarity with the imaging features resulted in under-recognition and misinterpretation of intravascular tumor thrombus as bland thrombus. CONCLUSION: Knowledge of imaging findings in the era of modern imaging modalities has enhanced our ability to detect cardiovascular involvement and lung metastases early and avoid misinterpreting tumor thrombus in draining systemic veins or pulmonary arteries as bland thrombus.

Bone Sarcomas in Pediatrics: Progress in Our Understanding of Tumor Biology and Implications for Therapy.

The pediatric bone sarcomas osteosarcoma and Ewing sarcoma represent a tremendous challenge for the clinician. Though less common than acute lymphoblastic leukemia or brain tumors, these aggressive cancers account for a disproportionate amount of the cancer morbidity and mortality in children, and have seen few advances in survival in the past decade, despite many large, complicated, and expensive trials of various chemotherapy combinations. To improve the outcomes of children with bone sarcomas, a better understanding of the biology of these cancers is needed, together with informed use of targeted therapies that exploit the unique biology of each disease. Here we summarize the current state of knowledge regarding the contribution of receptor tyrosine kinases, intracellular signaling pathways, bone biology and physiology, the immune system, and the tumor microenvironment in promoting and maintaining the malignant phenotype. These observations are coupled with a review of the therapies that target each of these mechanisms, focusing on recent or ongoing clinical trials if such information is available. It is our hope that, by better understanding the biology of osteosarcoma and Ewing sarcoma, rational combination therapies can be designed and systematically tested, leading to improved outcomes for a group of children who desperately need them.

Improving paclitaxel delivery: in vitro and in vivo characterization of PEGylated polyphosphoester-based nanocarriers.

Nanomaterials have great potential to offer effective treatment against devastating diseases by providing sustained release of high concentrations of therapeutic agents locally, especially when the route of administration allows for direct access to the diseased tissues. Biodegradable polyphosphoester-based polymeric micelles and shell cross-linked knedel-like nanoparticles (SCKs) have been designed from amphiphilic block-graft terpolymers, PEBP-b-PBYP-g-PEG, which effectively incorporate high concentrations of paclitaxel (PTX). Well-dispersed nanoparticles physically loaded with PTX were prepared, exhibiting desirable physiochemical characteristics. Encapsulation of 10 wt% PTX, into either micelles or SCKs, allowed for aqueous suspension of PTX at concentrations up to 4.8 mg/mL, as compared to <2.0 µg/mL for the aqueous solubility of the drug alone. Drug release studies indicated that PTX released from these nanostructures was defined through a structure-function relationship, whereby the half-life of sustained PTX release was doubled through cross-linking of the micellar structure to form SCKs. In vitro, physically loaded micellar and SCK nanotherapeutics demonstrated IC50 values against osteosarcoma cell lines, known to metastasize to the lungs (CCH-OS-O and SJSA), similar to the pharmaceutical Taxol formulation. Evaluation of these materials in vivo has provided an understanding of the effects of nanoparticle structure-function relationships on intratracheal delivery and related biodistribution and pharmacokinetics. Overall, we have demonstrated the potential of these novel nanotherapeutics toward future sustained release treatments via administration directly to the sites of lung metastases of osteosarcoma.

Effect of concurrent metastatic disease on survival in children and adolescents undergoing lung resection for metastatic osteosarcoma.

PURPOSE: To evaluate the impact of treated extra-pulmonary metastatic disease on overall (OS) and event-free survival (EFS) for pediatric osteosarcoma patients undergoing pulmonary metastatectomy. METHODS: We retrospectively reviewed pediatric patients who were treated for osteosarcoma at our institution from 2001 to 2011 and received pulmonary metastatectomy (n=76). We compared OS and EFS between patients with metastases limited to the lungs (Group A, n=58) to those with treated extra-pulmonary metastases (Group B, n=18) at the time of first pulmonary metastatectomy. RESULTS: The estimated median OS and EFS from first pulmonary metastatectomy were 2.0years (95% CI 1.5-2.8years) and 5.5months (95% CI 3.0-8.1months), respectively. Median OS was significantly greater for Group A (2.6years, 95% CI 1.9-3.8) compared to Group B (0.9years, 95% CI 0.6-1.5) (log rank p=0.0001). Median EFS was significantly greater for Group A (7.9months, 95% CI 5.0-10.7) compared to Group B (1.6months, 95% CI 0.8-2.7) (log rank p<0.0001). Independent predictors of OS included extra-pulmonary metastatic disease at the time of first thoracotomy, bilateral pulmonary metastases, and >4 nodules resected at first thoracotomy (all p<0.001). CONCLUSIONS: Osteosarcoma patients with treated extra-pulmonary metastatic disease at the time of pulmonary metastatectomy have significantly worse survival compared to those with disease limited to the lungs.

Health disparities are important determinants of outcome for children with solid tumor malignancies.

PURPOSE: The purpose of this study was to identify health disparities in children with non-CNS solid tumor malignancies and examine their impact on disease presentation and outcome. METHODS: We examined the records of all children (age≤18years) diagnosed with a non-CNS solid tumor malignancy and enrolled in the Texas Cancer Registry between 1995 and 2009 (n=4603). The primary outcome measures were disease stage and overall survival (OS). Covariates included gender, age, race/ethnicity, year of diagnosis, socioeconomic status (SES), and driving distance to the nearest pediatric cancer treatment facility. Statistical analyses included life table methods, logistic, and Cox regression. Statistical significance was defined as p<0.05. RESULTS: Children with advanced-stage disease were more likely to be male, <10years old, and Hispanic or non-Hispanic Blacks (all p<0.05). Distance to treatment and SES did not impact stage of disease at presentation. However, Hispanic and non-Hispanic Blacks and patients in the lowest SES quartile had the worst 1- and 5-year survival (all p<0.05). The adjusted OS differed by age, race, and stage, but not SES or distance to the nearest treatment facility. CONCLUSIONS: Race/ethnicity plays an important role in survival for children with non-CNS solid tumor malignancies. Future work should better define these differences to establish mechanisms to decrease their impact.

New, tolerable γ-secretase inhibitor takes desmoid down a notch.

A phase I trial of PF-03084014, an oral reversible γ-secretase inhibitor, in solid tumor malignancies shows drug tolerability in patients. Evidence of Notch pathway inhibition was demonstrated in peripheral blood. A surprisingly high rate of response was seen in desmoid tumors, a rare but sometimes locally aggressive sarcoma.

The narrow-spectrum HDAC inhibitor entinostat enhances NKG2D expression without NK cell toxicity, leading to enhanced recognition of cancer cells.

PURPOSE: Natural killer (NK) cell cytotoxicity correlates with the ligation of activating receptors (e.g., NKG2D) by their ligands (e.g., MHC class I-related chains [MIC] A and B) on target cells. Histone deacetylase inhibitors (HDACi) at high concentrations inhibit tumor growth and can increase NKG2D ligand expression on tumor targets, but are widely regarded as toxic to NK cells. METHODS: We investigated the mechanism of entinostat, a benzamide-derivative narrow-spectrum HDACi, in augmenting the cytotoxicity of NK cells against human colon carcinoma and sarcoma by assessing gene and protein expression, histone acetylation, and cytotoxicity in in vitro and murine models. RESULTS: We observed that entinostat dose- and time-dependent increase in MIC expression in tumor targets and NKG2D in primary human NK cells, both correlating with increased acetylated histone 3 (AcH3) binding to associated promoters. Entinostat pretreatment of colon carcinoma and sarcoma cells, NK cells, or both led to enhanced overall cytotoxicity in vitro, which was reversed by NKG2D blockade, and inhibited growth of tumor xenografts. Lastly, we showed decreased expression of MICA and ULBP2 transcription in primary human osteosarcoma. CONCLUSIONS: Entinostat enhances NK cell killing of cancer cells through upregulation of both NKG2D and its ligands, suggesting an attractive approach for augmenting NK cell immunotherapy of solid tumors such as colon carcinoma and sarcomas.

Understanding the role of Notch in osteosarcoma.

The Notch pathway has been described as an oncogene in osteosarcoma, but the myriad functions of all the members of this complex signaling pathway, both in malignant cells and nonmalignant components of tumors, make it more difficult to define Notch as simply an oncogene or a tumor suppressor. The cell-autonomous behaviors caused by Notch pathway manipulation may vary between cell lines but can include changes in proliferation, migration, invasiveness, oxidative stress resistance, and expression of markers associated with stemness or tumor-initiating cells. Beyond these roles, Notch signaling also plays a vital role in regulating tumor angiogenesis and vasculogenesis, which are vital aspects of osteosarcoma growth and behavior in vivo. Further, osteosarcoma cells themselves express relatively low levels of Notch ligand, making it likely that nonmalignant cells, especially endothelial cells and pericytes, are the major source of Notch activation in osteosarcoma tumors in vivo and in patients. As a result, Notch pathway expression is not expected to be uniform across a tumor but likely to be highest in those areas immediately adjacent to blood vessels. Therapeutic targeting of the Notch pathway is likewise expected to be complicated. Most pharmacologic approaches thus far have focused on inhibition of gamma secretase, a protease of the presenilin complex. This enzyme, however, has numerous other target proteins that would be expected to affect osteosarcoma behavior, including CD44, the WNT/ß-catenin pathway, and Her-4. In addition, Notch plays a vital role in tissue and organ homeostasis in numerous systems, and toxicities, especially GI intolerance, have limited the effectiveness of gamma secretase inhibitors. New approaches are in development, and the downstream targets of Notch pathway signaling also may turn out to be good targets for therapy. In summary, a full understanding of the complex functions of Notch in osteosarcoma is only now unfolding, and this deeper knowledge will help position the field to better utilize novel therapies as they are developed.

Developmental pathways hijacked by osteosarcoma.

Cancer of any type often can be described by an arrest, alteration or disruption in the normal development of a tissue or organ, and understanding of the normal counterpart's development can aid in understanding the malignant state. This is certainly true for osteosarcoma and the normal developmental pathways that guide osteoblast development that are changed in the genesis of osteogenic sarcoma. A carefully regulated crescendo-decrescendo expression of RUNX2 accompanies the transition from mesenchymal stem cell to immature osteoblast to mature osteoblast. This pivotal role is controlled by several pathways, including bone morphogenic protein (BMP), Wnt/ß-catenin, fibroblast growth factor (FGF), and protein kinase C (PKC). The HIPPO pathway and its downstream target YAP help to regulate proliferation of immature osteoblasts and their maturation into non-proliferating mature osteoblasts. This pathway also helps regulate expression of the mature osteoblast protein osteocalcin. YAP also regulates expression of MT1-MMP, a membrane-bound matrix metalloprotease responsible for remodeling the extracellular matrix surrounding the osteoblasts. YAP, in turn, can be regulated by the ERBB family protein Her-4. Osteosarcoma may be thought of as a cell held at the immature osteoblast stage, retaining some of the characteristics of that developmental stage. Disruptions of several of these pathways have been described in osteosarcoma, including BMP, Wnt/b-catenin, RUNX2, HIPPO/YAP, and Her-4. Further, PKC can be activated by several receptor tyrosine kinases implicated in osteosarcoma, including the ERBB family (EGFR, Her-2 and Her-4 in osteosarcoma), IGF1R, FGF, and others. Understanding these functions may aid in the understanding the mechanisms underpinning clinical observations in osteosarcoma, including both the lytic and blastic phenotypes of tumors, the invasiveness of the disease, and the tendency for treated tumors to ossify rather than shrink. Through a better understanding of the relationship between normal osteoblast development and osteosarcoma, we may gain insights into novel therapeutic avenues and improved outcomes.

Natural killer cell therapy and aerosol interleukin-2 for the treatment of osteosarcoma lung metastasis.

BACKGROUND: Survival of patients with osteosarcoma lung metastases has not improved in 20 years. We evaluated the efficacy of combining natural killer (NK) cells with aerosol interleukin-2 (IL-2) to achieve organ-specific NK cell migration and expansion in the metastatic organ, and to decrease toxicity associated with systemic IL-2. PROCEDURE: Five human osteosarcoma cell lines and 103 patient samples (47 primary and 56 metastatic) were analyzed for NKG2D ligand (NKG2DL) expression. Therapeutic efficacy of aerosol IL-2 + NK cells was evaluated in vivo compared with aerosol IL-2 alone and NK cells without aerosol IL-2. RESULTS: Osteosarcoma cell lines and patient samples expressed various levels of NKG2DL. NK-mediated killing was NKG2DL-dependent and correlated with expression levels. Aerosol IL-2 increased NK cell numbers in the lung and within metastatic nodules but not in other organs. Therapeutic efficacy, as judged by tumor number, size, and quantification of apoptosis, was also increased compared with NK cells or aerosol IL-2 alone. There were no IL-2-associated systemic toxicities. CONCLUSION: Aerosol IL-2 augmented the efficacy of NK cell therapy against osteosarcoma lung metastasis, without inducing systemic toxicity. Our data suggest that lung-targeted IL-2 delivery circumvents toxicities induced by systemic administration. Combining aerosol IL-2 with NK cell infusions, may be a potential new therapeutic approach for patients with osteosarcoma lung metastasis.

Understanding the Biology of Bone Sarcoma from Early Initiating Events through Late Events in Metastasis and Disease Progression.

The two most common primary bone malignancies, osteosarcoma (OS), and Ewing sarcoma (ES), are both aggressive, highly metastatic cancers that most often strike teens, though both can be found in younger children and adults. Despite distinct origins and pathogenesis, both diseases share several mechanisms of progression and metastasis, including neovascularization, invasion, anoikis resistance, chemoresistance, and evasion of the immune response. Some of these processes are well-studies in more common carcinoma models, and the observation from adult diseases may be readily applied to pediatric bone sarcomas. Neovascularization, which includes angiogenesis and vasculogenesis, is a clear example of a process that is likely to be similar between carcinomas and sarcomas, since the responding cells are the same in each case. Chemoresistance mechanisms also may be similar between other cancers and the bone sarcomas. Since OS and ES are mesenchymal in origin, the process of epithelial-to-mesenchymal transition is largely absent in bone sarcomas, necessitating different approaches to study progression and metastasis in these diseases. One process that is less well-studied in bone sarcomas is dormancy, which allows micrometastatic disease to remain viable but not growing in distant sites - typically the lungs - for months or years before renewing growth to become overt metastatic disease. By understanding the basic biology of these processes, novel therapeutic strategies may be developed that could improve survival in children with OS or ES.

Small molecule ErbB inhibitors decrease proliferative signaling and promote apoptosis in philadelphia chromosome-positive acute lymphoblastic leukemia.

The presence of the Philadelphia chromosome in patients with acute lymphoblastic leukemia (Ph(+)ALL) is a negative prognostic indicator. Tyrosine kinase inhibitors (TKI) that target BCR/ABL, such as imatinib, have improved treatment of Ph(+)ALL and are generally incorporated into induction regimens. This approach has improved clinical responses, but molecular remissions are seen in less than 50% of patients leaving few treatment options in the event of relapse. Thus, identification of additional targets for therapeutic intervention has potential to improve outcomes for Ph+ALL. The human epidermal growth factor receptor 2 (ErbB2) is expressed in ~30% of B-ALLs, and numerous small molecule inhibitors are available to prevent its activation. We analyzed a cohort of 129 ALL patient samples using reverse phase protein array (RPPA) with ErbB2 and phospho-ErbB2 antibodies and found that activity of ErbB2 was elevated in 56% of Ph(+)ALL as compared to just 4.8% of Ph(-)ALL. In two human Ph+ALL cell lines, inhibition of ErbB kinase activity with canertinib resulted in a dose-dependent decrease in the phosphorylation of an ErbB kinase signaling target p70S6-kinase T389 (by 60% in Z119 and 39% in Z181 cells at 3 µM). Downstream, phosphorylation of S6-kinase was also diminished in both cell lines in a dose-dependent manner (by 91% in both cell lines at 3 µM). Canertinib treatment increased expression of the pro-apoptotic protein Bim by as much as 144% in Z119 cells and 49% in Z181 cells, and further produced caspase-3 activation and consequent apoptotic cell death. Both canertinib and the FDA-approved ErbB1/2-directed TKI lapatinib abrogated proliferation and increased sensitivity to BCR/ABL-directed TKIs at clinically relevant doses. Our results suggest that ErbB signaling is an additional molecular target in Ph(+)ALL and encourage the development of clinical strategies combining ErbB and BCR/ABL kinase inhibitors for this subset of ALL patients.

Complications in the surgical treatment of pediatric melanoma.

PURPOSE: The purpose of this study was to characterize the complications associated with surgical treatment of pediatric melanoma. METHODS: We retrospectively reviewed all pediatric patients who received surgical treatment for melanoma at our institution between 1992 and 2010. We compared complications between three groups: wide local excision only (WLE), WLE and sentinel lymph node biopsy (SLNB), and WLE and completion lymph node dissection (CLND). RESULTS: One hundred twenty-five patients were identified: 37 patients received WLE only, 47 received WLE and SLNB, and 41 patients had WLE and CLND. Complication rates differed between the three groups: 19% in WLE, 11% in WLE+SLNB, and 39% in WLE+CLND (P=.006). The risk of complications was significantly lower among patients having WLE+SLNB versus WLE+CLND (OR 0.19, 95% CI 0.06-0.57, P=.0032). Lymphedema was a common complication with a higher incidence in the CLND group compared to the SLNB group (19.5% vs. 2.1%, P=.01). Complications were more frequent in inguinal compared to axillary dissections (52.0% vs. 17.1%, P=.006). CONCLUSIONS: In the surgical treatment of pediatric melanoma, the addition of a completion lymph node dissection significantly increases complication risk. Thus, it is critical to determine which patients truly benefit from this procedure.

UBE4B levels are correlated with clinical outcomes in neuroblastoma patients and with altered neuroblastoma cell proliferation and sensitivity to epidermal growth factor receptor inhibitors.

BACKGROUND: The UBE4B gene, which is located on chromosome 1p36, encodes a ubiquitin ligase that interacts with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs), a protein involved in epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. The authors analyzed the roles of UBE4B in the outcomes of patients with neuroblastoma and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition. METHODS: The association between UBE4B expression and the survival of patients with neuroblastoma was examined using available microarray data sets. UBE4B and EGFR protein levels were measured in patient tumor samples, EGFR degradation rates were measured in neuroblastoma cell lines, and the effects of UBE4B on neuroblastoma tumor cell growth were analyzed. The effects of the EGFR inhibitor cetuximab were examined in neuroblastoma cells that expressed wild-type and mutant UBE4B. RESULTS: Low UBE4B gene expression is associated with poor outcomes in patients with neuroblastoma. UBE4B overexpression reduced neuroblastoma tumor cell proliferation, and UBE4B expression was inversely related to EGFR expression in tumor samples. EGFR degradation rates correlated with cellular UBE4B levels. Enhanced expression of catalytically active UBE4B resulted in reduced sensitivity to EGFR inhibition. CONCLUSIONS: The current study demonstrates associations between UBE4B expression and the outcomes of patients with neuroblastoma and between UBE4B and EGFR expression in neuroblastoma tumor samples. Moreover, levels of UBE4B influence neuroblastoma tumor cell proliferation, EGFR degradation, and response to EGFR inhibition. These results suggest UBE4B-mediated growth factor receptor trafficking may contribute to the poor prognosis of patients who have neuroblastoma tumors with 1p36 deletions and that UBE4B expression may be a marker that can predict responses of neuroblastoma tumors to treatment.

Anti-tumor effects of the Notch pathway in gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are driven by gain-of-function mutations of KIT or PDGFRa. The introduction of imatinib has significantly extended survival for patients. However, most patients develop resistances. Notch signaling is a conserved developmental pathway known to play a critical role in the development of several cancers, functioning as a tumor promoter or a tumor suppressor. Given that the normal progenitor cell for GIST, the interstitial cell of Cajal, has characteristics similar to those of cells of neuroendocrine origin, we hypothesized that Notch pathway impacts the biology of GIST cells. In this study, we retrovirally and pharmacologically manipulated the Notch pathway in human GIST cells. We also performed a retrospective analysis of a cohort on 15 primary tumors to determine the role of Hes1, a major target gene of Notch, as a prognostic marker for GIST. Constitutively, active intracellular domain of Notch1 (ICN1) expression potently induced growth arrest and downregulated KIT expression in vitro. Additionally, treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid caused dose-dependent upregulation of Notch1 expression and a parallel decrease in viability in these cells. Retroviral silencing of downstream targets of Notch (dominant-negative Hes1) and pharmacological inhibition of Notch activation (γ-secretase inhibition) partially rescued GIST cells from suberoylanilide hydroxamic acid treatment. GIST patients with high Hes1 mRNA levels have a significantly longer relapse-free survival. These results identify a novel anti-tumor effect of Notch1 and cross talk between the Notch and KIT pathways. Thus, activation of this pathway by treatment with histone deacetylase inhibitors is an appealing potential therapeutic strategy for GISTs. Précis: This study is the first report of the tumor suppressor effects of Notch pathway in gastrointestinal stromal tumors via a negative feedback with the oncogene KIT and may lead the development of new therapeutic strategies for GISTs patients.

Triplex DNA-binding proteins are associated with clinical outcomes revealed by proteomic measurements in patients with colorectal cancer.

BACKGROUND: Tri- and tetra-nucleotide repeats in mammalian genomes can induce formation of alternative non-B DNA structures such as triplexes and guanine (G)-quadruplexes. These structures can induce mutagenesis, chromosomal translocations and genomic instability. We wanted to determine if proteins that bind triplex DNA structures are quantitatively or qualitatively different between colorectal tumor and adjacent normal tissue and if this binding activity correlates with patient clinical characteristics. METHODS: Extracts from 63 human colorectal tumor and adjacent normal tissues were examined by gel shifts (EMSA) for triplex DNA-binding proteins, which were correlated with clinicopathological tumor characteristics using the Mann-Whitney U, Spearman's rho, Kaplan-Meier and Mantel-Cox log-rank tests. Biotinylated triplex DNA and streptavidin agarose affinity binding were used to purify triplex-binding proteins in RKO cells. Western blotting and reverse-phase protein array were used to measure protein expression in tissue extracts. RESULTS: Increased triplex DNA-binding activity in tumor extracts correlated significantly with lymphatic disease, metastasis, and reduced overall survival. We identified three multifunctional splicing factors with biotinylated triplex DNA affinity: U2AF65 in cytoplasmic extracts, and PSF and p54nrb in nuclear extracts. Super-shift EMSA with anti-U2AF65 antibodies produced a shifted band of the major EMSA H3 complex, identifying U2AF65 as the protein present in the major EMSA band. U2AF65 expression correlated significantly with EMSA H3 values in all extracts and was higher in extracts from Stage III/IV vs. Stage I/II colon tumors (p=0.024). EMSA H3 values and U2AF65 expression also correlated significantly with GSK3 beta, beta-catenin, and NF- B p65 expression, whereas p54nrb and PSF expression correlated with c-Myc, cyclin D1, and CDK4. EMSA values and expression of all three splicing factors correlated with ErbB1, mTOR, PTEN, and Stat5. Western blots confirmed that full-length and truncated beta-catenin expression correlated with U2AF65 expression in tumor extracts. CONCLUSIONS: Increased triplex DNA-binding activity in vitro correlates with lymph node disease, metastasis, and reduced overall survival in colorectal cancer, and increased U2AF65 expression is associated with total and truncated beta-catenin expression in high-stage colorectal tumors.

Slow down to stay alive: HER4 protects against cellular stress and confers chemoresistance in neuroblastoma.

BACKGROUND: Neuroblastoma (NBL) is a common pediatric solid tumor, and outcomes for patients with advanced neuroblastoma remain poor despite extremely aggressive treatment. Chemotherapy resistance at relapse contributes heavily to treatment failure. The poor survival of patients with high-risk NBL prompted this investigation into novel treatment options with the objective of gaining a better understanding of resistance mechanisms. On the basis of previous work and on data from publicly available studies, the authors hypothesized that human epidermal growth factor receptor 4 (Her4) contributes to resistance. METHODS: Her4 expression was reduced with small-hairpin RNA (shRNA) to over express intracellular HER4, and the authors tested its impact on tumor cell survival under various culture conditions. The resulting changes in gene expression after HER4 knockdown were measured by using a messenger RNA (mRNA) array. RESULTS: HER4 expression was up-regulated in tumor spheres compared with the expression in monolayer culture. With HER4 knockdown, NBL cells became less resistant to anoikis and serum starvation. Moreover, HER4 knockdown increased the chemosensitivity of NBL cells to cisplatin, doxorubicin, etoposide, and activated ifosfamide. In mRNA array analysis, HER4 knockdown predominately altered genes related to cell cycle regulation. In NBL spheres compared with monolayers, cell proliferation was decreased, and cyclin D expression was reduced. HER4 knockdown reversed cyclin D suppression. Overexpressed intracellular HER4 slowed the cell cycle and induced chemoresistance. CONCLUSIONS: The current results indicated that HER4 protects NBL cells from multiple exogenous apoptotic stimuli, including anoikis, nutrient deficiency, and cytotoxic chemotherapy. The intracellular fragment of HER4 was sufficient to confer this phenotype. HER4 functions as a cell cycle suppressor, maintaining resistance to cellular stress. The current findings indicate that HER4 overexpression may be associated with refractory disease, and HER4 may be an important therapeutic target.