Concomitant Targeting of EGF Receptor, TGF-beta and Src Points to a Novel Therapeutic Approach in Pancreatic Cancer

To test the hypothesis that concomitant targeting of the epidermal growth factor receptor (EGFR) and transforming growth factor-beta (TGF-β) may offer a novel therapeutic approach in pancreatic cancer, EGFR silencing by RNA interference (shEGFR) was combined with TGF-β sequestration by soluble TGF-β receptor II (sTβRII). Effects on colony formation in 3-dimensional culture, tumor formation in nude mice, and downstream signaling were monitored. In both ASPC-1 and T3M4 cells, either shEGFR or sTβRII significantly inhibited colony formation. However, in ASPC-1 cells, combining shEGFR with sTβRII reduced colony formation more efficiently than either approach alone, whereas in T3M4 cells, shEGFR-mediated inhibition of colony formation was reversed by sTβRII. Similarly, in vivo growth of ASPC-1-derived tumors was attenuated by either shEGFR or sTβRII, and was markedly suppressed by both vectors. By contrast, T3M4-derived tumors either failed to form or were very small when EGFR alone was silenced, and these effects were reversed by sTβRII due to increased cancer cell proliferation. The combination of shEGFR and sTβRII decreased phospho-HER2, phospho-HER3, phoshpo-ERK and phospho-src (Tyr416) levels in ASPC-1 cells but increased their levels in T3M4 cells. Moreover, inhibition of both EGFR and HER2 by lapatinib or of src by SSKI-606, PP2, or dasatinib, blocked the sTβRII-mediated antagonism of colony formation in T3M4 cells. Together, these observations suggest that concomitantly targeting EGFR, TGF-β, and src may constitute a novel therapeutic approach in PDAC that prevents deleterious cross-talk between EGFR family members and TGF-β-dependent pathways

Deep Sequencing of MYC DNA-Binding Sites in Burkitt Lymphoma

BACKGROUND: MYC is a key transcription factor involved in central cellular processes such as regulation of the cell cycle, histone acetylation and ribosomal biogenesis. It is overexpressed in the majority of human tumors including aggressive B-cell lymphoma. Especially Burkitt lymphoma (BL) is a highlight example for MYC overexpression due to a chromosomal translocation involving the c-MYC gene. However, no genome-wide analysis of MYC-binding sites by chromatin immunoprecipitation (ChIP) followed by next generation sequencing (ChIP-Seq) has been conducted in BL so far. METHODOLOGY/PRINCIPAL FINDINGS: ChIP-Seq was performed on 5 BL cell lines with a MYC-specific antibody giving rise to 7,054 MYC-binding sites after bioinformatics analysis of a total of approx. 19 million sequence reads. In line with previous findings, binding sites accumulate in gene sets known to be involved in the cell cycle, ribosomal biogenesis, histone acetyltransferase and methyltransferase complexes demonstrating a regulatory role of MYC in these processes. Unexpectedly, MYC-binding sites also accumulate in many B-cell relevant genes. To assess the functional consequences of MYC binding, the ChIP-Seq data were supplemented with siRNA- mediated knock-downs of MYC in BL cell lines followed by gene expression profiling. Interestingly, amongst others, genes involved in the B-cell function were up-regulated in response to MYC silencing. CONCLUSION/SIGNIFICANCE: The 7,054 MYC-binding sites identified by our ChIP-Seq approach greatly extend the knowledge regarding MYC binding in BL and shed further light on the enormous complexity of the MYC regulatory network. Especially our observations that (i) many B-cell relevant genes are targeted by MYC and (ii) that MYC down-regulation leads to an up-regulation of B-cell genes highlight an interesting aspect of BL biology

Assessing Causality in the Relationship Between Adolescents’ Risky Sexual Online Behavior and Their Perceptions of this Behavior

The main aim of this study was to investigate the causal nature of the relationship between adolescents’ risky sexual behavior on the internet and their perceptions of this behavior. Engagement in the following online behaviors was assessed: searching online for someone to talk about sex, searching online for someone to have sex, sending intimate photos or videos to someone online, and sending one’s telephone number and address to someone exclusively known online. The relationship between these behaviors and adolescents’ perceptions of peer involvement, personal invulnerability, and risks and benefits was investigated. A two-wave longitudinal study among a representative sample of 1,445 Dutch adolescents aged 12–17 was conducted (49% females). Autoregressive cross-lagged structural equation models revealed that perceived peer involvement, perceived vulnerability, and perceived risks were all significant predictors of risky sexual online behavior 6 months later. No reverse causal paths were found. When the relationships between perceptions and risky sexual online behavior were modeled simultaneously, only perceived peer involvement was a determinant of risky sexual online behavior. Findings highlight the importance of addressing peer involvement in future interventions to reduce adolescents’ risky sexual online behavior

CD10 is a marker for cycling cells with propensity to apoptosis in childhood ALL

CD10 constitutes a favourable prognostic marker for childhood acute lymphoblastic leukaemia. Since correlations between CD10, cell cycle and apoptotic abilities were demonstrated in various cell types, we investigated whether differences existed in the cycling/apoptotic abilities of CD10-positive and CD10-negative B acute lymphoblastic leukaemia cells. Twenty-eight cases of childhood acute lymphoblastic leukaemia (mean age of 6.8 years) were subdivided into two groups according to high (17 cases, 93.2±4.5%, MRFI 211±82 CD10-positive cells) or low (11 cases, 11.5±6.2%, MRFI 10±7 CD10-negative cells) expression of CD10. CD10-positive acute lymphoblastic leukaemia cells were cycling cells with elevated c-myc levels and propensity to apoptosis, whereas CD10-negative acute lymphoblastic leukaemia cells had lower cycling capacities and c-myc levels, and were resistant to apoptosis in vitro. A close correlation between all these properties was demonstrated by the observations that the few CD10-positive cells found in the CD10-negative acute lymphoblastic leukaemia group displayed elevated c-myc and cycling capacities and were apoptosis prone. Moreover, exposure of CD10-positive acute lymphoblastic leukaemia B cells to a peptide nucleic acid anti-gene specific for the second exon of c-myc caused inhibition of c-myc expression and reduced cell cycling and apoptotic abilities as well as decreased CD10 expression