miR-21, miR-17 and miR-19a induced by phosphatase of regenerating liver-3 promote the proliferation and metastasis of colon cancer

Background:

Phosphatase of regenerating liver-3 (PRL-3) is an oncogene known to promote tumour metastasis, especially in colorectal cancer (CRC). Here, we demonstrate that the miR-21, miR-17 and miR-19a expressions induced by PRL-3 are involved in the proliferation and metastasis of colon cancer.

Methods:

Microarray analysis and quantitative reverse-transcription polymerase chain reactions (qRT–PCR) were used to investigate the changes in miRNA expression due to the overexpression of PRL-3. Transwell chamber invasion assays, CCK-8 proliferation assays and RNA interference assays were used to explore the effects of PRL-3 on miR-21, miR-17 and miR-19a expression in colon cancer cells. Immunohistochemistry and qRT–PCR were performed in colon cancer tissues to evaluate the expression of PRL-3, signal transducer and activator of transcription 3 (STAT3), miR-21, miR-17 and miR-19a.

Results:

Our study demonstrated that the overexpression of PRL-3 in colon cancer cells induced the expression of miR-21, miR-17 and miR-19a by activating STAT3. Subsequently, these microRNAs contributed to the increased proliferation and invasiveness of the colon cancer cells. Positive correlations between PRL-3 and these microRNAs were also observed in matched primary colon cancer tissues and metastatic lesions.

Conclusion:

miR-21, miR-17 and miR-19a induced by PRL-3 contribute to the proliferation and invasion of colon cancer.

Directed flow of identified particles in Au+Au collisions at √[SNN]=200 GeV at RHIC

STAR's measurements of directed flow (v1) around midrapidity for π±, K±, KS0, p, and p[over ¯] in Au+Au collisions at √[sNN]=200  GeV are presented. A negative v1(y) slope is observed for most of produced particles (π±, K±, KS0, and p[over ¯]). In 5%-30% central collisions, a sizable difference is present between the v1(y) slope of protons and antiprotons, with the former being consistent with zero within errors. The v1 excitation function is presented. Comparisons to model calculations (RQMD, UrQMD, AMPT, QGSM with parton recombination, and a hydrodynamics model with a tilted source) are made. For those models which have calculations of v1 for both pions and protons, none of them can describe v1(y) for pions and protons simultaneously. The hydrodynamics model with a tilted source as currently implemented cannot explain the centrality dependence of the difference between the v1(y) slopes of protons and antiprotons.

Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at √S(NN)=200 GeV

We report transverse momentum (p(T)≤15  GeV/c) spectra of π(±), K(±), p, p[over ¯], K(S)(0), and ρ(0) at midrapidity in p+p and Au+Au collisions at √S(NN)=200  GeV. Perturbative QCD calculations are consistent with π(±) spectra in p+p collisions but do not reproduce K and p(p[over ¯]) spectra. The observed decreasing antiparticle-to-particle ratios with increasing p(T) provide experimental evidence for varying quark and gluon jet contributions to high-p(T) hadron yields. The relative hadron abundances in Au+Au at p(T)≳8  GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.

Strangeness enhancement in Cu-Cu and Au-Au collisions at √S(NN)=200 GeV

We report new STAR measurements of midrapidity yields for the Λ, Λ[over ¯], K(S)(0), Ξ(-), Ξ[over ¯](+), Ω(-), Ω[over ¯](+) particles in Cu+Cu collisions at √S(NN)==200  GeV, and midrapidity yields for the Λ, Λ[over ¯], K(S)(0) particles in Au+Au at √S(NN)==200  GeV. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions.

A novel oncogenic role for the miRNA-506-514 cluster in initiating melanocyte transformation and promoting melanoma growth

Malignant melanoma is the most aggressive form of skin cancer and its incidence has doubled in the last two decades. It represents only 4% of skin cancer cases per year, but causes as many as 74% of skin cancer deaths. Early detection of malignant melanoma is associated with survival rates of up to 90%, but later detection (stage III to stage IV) is associated with survival rates of only 10%. Dysregulation of microRNA (miRNA) expression has been linked to tumor development and progression by functioning either as a tumor suppressor, an oncogene or a metastasis regulator in multiple cancer types. To understand the role of miRNA in the pathogenesis of malignant melanoma and identify biomarkers of metastasis, miRNA expression profiles in skin punches from 33 metastatic melanoma patients and 14 normal healthy donors were compared. We identified a cluster of 14 miRNAs on the X chromosome, termed the miR-506-514 cluster, which was consistently overexpressed in nearly all melanomas tested (30-60 fold, P<0.001), regardless of mutations in N-ras or B-raf. Inhibition of the expression of this cluster as a whole, or one of its sub-clusters (Sub-cluster A) consisting of six mature miRNAs, led to significant inhibition of cell growth, induction of apoptosis, decreased invasiveness and decreased colony formation in soft agar across multiple melanoma cell lines. Sub-cluster A of the miR-506-514 cluster was critical for maintaining the cancer phenotype, but the overexpression of the full cluster was necessary for melanocyte transformation. Our results provide new insights into the functional role of this miRNA cluster in melanoma, and suggest new approaches to treat or diagnose this disease.

Hepatitis B virus X protein downregulates expression of the miR-16 family in malignant hepatocytes in vitro

BACKGROUND

Hepatitis B virus X protein (HBx) is involved in the initiation and progression of hepatocellular carcinoma (HCC) by regulating the host protein-coding genes. In this study, we showed that HBx altered the expression of microRNAs (miRNAs) to promote proliferation and transformation in malignant hepatocytes in vitro.

METHODS

miRNA microarray and quantitative reverse-transcription polymerase chain reactions (qRT-PCRs) were performed to identify miRNAs that were differentially regulated by HBx in HCC cells. Protein, mRNA, and miRNA expression analyses; cell cycle and apoptosis analyses; loss/gain-of-function analysis; and luciferase reporter assays were performed to delineate the consequences of miR-16 family repression in HepG2 cells.

RESULTS

Hepatitis B virus X protein induced widespread deregulation of miRNAs in HepG2 cells, and the downregulation of the miR-16 family was reproducible in HepG2, SK-HEP-1, and Huh7 cells. CCND1, a target of the miR-16 family, was derepressed by HBx in HepG2 cells. c-Myc mediated the HBx-induced repression of miR-15a/16 in HepG2 cells. Ectopically expressed miR-15a/16 suppressed the proliferation, clonogenicity, and anchorage-independent growth of HBx-expressing HepG2 cells by arresting them in the G1 phase and inducing apoptosis, whereas reduced expression of miR-16 accelerated the growth and cell-cycle progression of HepG2 cells.

CONCLUSIONS

Hepatitis B virus X protein altered the in vitro expression of miRNAs in host malignant hepatocytes, particularly downregulating the miR-16 family. Repression of miR-15a/16 is c-Myc mediated and is required for the HBx-induced transformation of HepG2 cells in vitro. Therefore, miR-16 family may serve as a therapeutic target for hepatitis B virus (HBV)-associated HCC.

Abstract P6-15-08: KGFR Tyrosine Kinase Inhibitors for the Treatment of Breast Cancer

Background: Keratinocyte growth factor (KGF) produces a rapid increase in the proliferation and motility of estrogen receptor (ER)-positive breast cancer cells (Zang, XP and Pento, JT, Clin. & Exptl. Metastasis 18: 573-80, 2001). It has been demonstrated that the KGF receptor (KGFR) is up-regulated in breast cancer; thus, KGF/KGFR signaling appears to be an early event in breast cancer progression (Zang, XP, Lerner, ML, Bahr, SJ, Brackett, DJ and Pento, JT, Cancer Genomics & Proteomics, 3: 369-72, 2006). Molecular modeling was used to create group of KGFR selective tyrosine kinase inhibitors (TKI) (Pento, JT and Li, PK, Drugs of the Future, 32: 965-72, 2007). The present study examined the effect of a group of these compounds on KGF-mediated proliferation and Erk signaling in MCF-7 breast cancer cells. In addition, the oncolytic potential of compound L-27, a potent KGFR TKI, was examined in an orthotopic xenograft model of human breast cancer.

Methods: A group of high affinity KGFR TKI were tested for their ability to inhibit KGF-mediated proliferation and Erk phosphorylation in MCF-7 cells using MTS and ELISA assays. In addition, immuno-cytochemistry was used to examine the influence of the 5 most potent inhibitor compounds on the density of cell membrane KGFR. The effects of a KGFR TKI on breast cancer growth and progression in vivo was examined using an orthotopic xenograft model, with clones of MCF-7 cells which were transfected with a KGF-producing plasmid to enhance cell growth and metastasis and a GFP reporter to quantify tumor growth and metastasis. PET imaging was also used to identify metastatic development.

Results: From the initial group of 53 compounds, 5 compounds were observed to produce greater than 50% inhibition of KGF-mediated cancer cell proliferation, reduce Erk phosphorylation and the density of the KGFR on the membrane surface of the cancer cells. Compound L-27, one of the most potent KGFR inhibitors, reduced the growth of MCF-7 tumors and metastatic development in the xenograft model in a dose-related fashion at doses of 4, 10 and 25 mg/kg. Animal weights in the treatment groups remained the same as the control group; indicating a lack of toxicity at the doses employed.

Discussion: The novel compounds tested in this project reduce or abolish KGF-mediated proliferation, Erk signaling and KGFR membrane density in vitro. In addition, compound L-27, a potent KGFR inhibitor in vitro, was found to reduce the progression of MCF-7 tumor xenografts in vivo. In conclusion, the KGFR TKI represent a novel class of anticancer agents for the prevention of metastatic progression and may provide a new therapeutic approach for the treatment of breast and other cancers. Acknowledgement: This work was supported by the grants from DoD (DAMD17-01-1-0591) and the NCI (CA-89740) and (CA-125493).

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-15-08.

Development of rapid immunoassays for the detection of ractopamine in swine urine

The monoclonal antibodies (mAbs) against ractopamine (Rac) were prepared and their properties identified by indirect competitive enzyme-linked immunoabsorbant assay (ELISA). The IC(50) of mAbs was 2.7 ng ml(-1) towards Rac or 9.3 ng ml(-1) towards Rac-glucuronides and no cross-reactivity (CR) towards other competitors except dobutamine (CR: 3.76%). Based on the mAbs, the Rac-kit (kit) and Rac-strip (strip) were developed to detect Rac residues in swine urine. The strip and kit assay could be performed within 5-10 min and 2 h, respectively, allowing the analysis of urine samples without the need for sample clean-up. The detection limits were 1 ng ml(-1) for kit and 3 ng ml(-1) with the unaided eye, and 0.2 ng ml(-1) with the Strip Reader for strip. The correlation coefficients (R(2)) were 0.988 for kit in the range 0-128.0 ng ml(-1), and 0.987 for strip in the range 0-10.8 ng ml(-1). Comparing the gas chromatography-mass spectrometry (GC-MS) with the kit or strip in swine urine spiked with Rac standards, the differences ranged from 1.4% to 4.5% for kit and 1.0% to 4.7% for strip. However, the differences were greater than 54% for the kit and 55% for the strip test for the analysis of urine from swine treated with Rac. The results obtained from GC-MS using hydrolysed urine samples were generally in good agreement with those obtained from strip or kit using non-hydrolysed urine samples.