Excessive phototransduction signaling is thought to be involved in light-induced and inherited retinal degeneration. Using knockout mice with defects in rhodopsin shut-off and transducin signaling, we show that two different pathways of photoreceptor-cell apoptosis are induced by light. Bright light induces apoptosis that is independent of transducin and accompanied by induction of the transcription factor AP-1. By contrast, low light induces an apoptotic pathway that requires transducin. We also provide evidence that additional genetic factors regulate sensitivity to light-induced damage. Our use of defined mouse mutants resolves some of the complexity underlying the mechanisms that regulate susceptibility to retinal degeneration.

Liposarcoma remains the most common mesenchymal cancer, with a mortality rate of 60% among patients with this disease. To address the present lack of therapeutic options, we embarked upon a study of microRNA (miRNA) expression alterations associated with liposarcomagenesis with the goal of exploiting differentially expressed miRNAs and the gene products they regulate as potential therapeutic targets. MicroRNA expression was profiled in samples of normal adipose tissue, well-differentiated liposarcoma, and dedifferentiated liposarcoma by both deep sequencing of small RNA libraries and hybridization-based Agilent microarrays. The expression profiles discriminated liposarcoma from normal adipose tissue and well-differentiated from dedifferentiated disease. We defined over 40 miRNAs that were dysregulated in dedifferentiated liposarcomas in both the sequencing and the microarray analysis. The upregulated miRNAs included two cancer-associated species (miR-21, miR-26a), and the downregulated miRNAs included two species that were highly abundant in adipose tissue (miR-143, miR-145). Restoring miR-143 expression in dedifferentiated liposarcoma cells inhibited proliferation, induced apoptosis, and decreased expression of BCL2, TOP2A, PRC1, and PLK1. The downregulation of PRC1 and its docking partner PLK1 suggests that miR-143 inhibits cytokinesis in these cells. In support of this idea, treatment with a PLK1 inhibitor potently induced G2/M growth arrest and apoptosis in liposarcoma cells. Taken together, our findings suggest that miR-143 re-expression vectors or selective agents directed at miR-143 or its targets may have therapeutic value in dedifferentiated liposarcoma.

Liposarcomas are the most common type of soft tissue sarcoma but their genetics are poorly defined. To identify genes that contribute to liposarcomagenesis and serve as prognostic candidates, we undertook expression profiling of 140 primary liposarcoma samples, which were randomly split into training set (n ¼ 95) and test set (n ¼ 45). A multigene predictor for distant recurrence-free survival (DRFS) was developed by the supervised principal component method. Expression levels of the 588 genes in the predictor were used to calculate a risk score for each patient. In validation of the predictor in the test set, patients with low risk score had a 3-year DRFS of 83% versus 45% for high risk score patients (P ¼ 0.001). The HR for high versus low score, adjusted for histologic subtype, was 4.42 (95% CI, 1.26-15.55; P ¼ 0.021). The concordance probability for risk score was 0.732. In contrast, the concordance probability for histologic subtype, which had been considered the best predictor of outcome in liposarcoma, was 0.669. Genes related to adipogenesis, DNA replication, mitosis, and spindle assembly checkpoint control were all highly represented in the multigene predictor. Three genes from the predictor, TOP2A, PTK7, and CHEK1, were found to be overexpressed in liposarcoma samples of all five subtypes and in liposarcoma cell lines. RNAi-mediated knockdown of these genes in liposarcoma cell lines reduced proliferation and invasiveness and increased apoptosis. Taken together, our findings identify genes that seem to be involved in liposarcomagenesis and have promise as therapeutic targets, and support the use of this multigene predictor to improve risk stratification for individual patients with liposarcoma. Cancer Res; 71(7); 2697-705. Ó2011 AACR.

Liposarcomas are aggressive mesenchymal cancers with poor outcomes that exhibit remarkable histologic diversity, with five recognized subtypes. Currently, the mainstay of therapy for liposarcoma is surgical excision since liposarcomas are often resistant to traditional chemotherapy. In light of the high mortality associated with liposarcoma and the lack of effective systemic therapy, we sought novel genomic alterations driving liposarcomagenesis that might serve as therapeutic targets. ZIC1, a critical transcription factor for neuronal development, is overexpressed in all five subtypes of liposarcoma compared with normal fat and in liposarcoma cell lines compared with adipose-derived stem cells (ASC). Here we show that ZIC1 contributes to the pathogenesis of liposarcoma. ZIC1 knockdown inhibits proliferation, reduces invasion, and induces apoptosis in dedifferentiated and myxoid/round cell liposarcoma cell lines, but not in either ASC or a lung cancer cell line with low ZIC1 expression. ZIC1 knockdown is associated with increased nuclear expression of p27 protein, and the down-regulation of pro-survival target genes: BCL2L13, JunD, Fam57A, and EIF3M. Our results demonstrate that ZIC1 expression is essential for liposarcomagenesis and that targeting ZIC1 or its downstream targets may lead to novel therapy for liposarcoma.

The authors hypothesized that the decay of metarhodopsin to apo-opsin and free all-trans-retinaldehyde is faster with Pro347Ser-substituted rhodopsin than it is with wild-type rhodopsin. Consistent with this, the lipofuscin fluorophores A2PE, A2E, and A2PE-H(2), which form from retinaldehyde, were elevated in Pro347Ser transgenic mice.

10526 Background: The Notch pathway directs normal fat cell development, but its aberrant activation may promote the development of sarcomas. The expression of the Notch pathway in liposarcoma (LPS), however, is unknown. We examined Notch signaling components in LPS's and suppressed Notch activation with drug targeting in LPS cell lines. Methods: RNA was isolated from 18 normal fat and 140 LPS tissue samples from five LPS subtypes: well-differentiated (33%), de-differentiated DD (25%), myxoid (12%), round cell (6%), and pleomorphic (13%), and were hybridized to Affymetrix U133A arrays. Microarray data were normalized with the RMA method. Correlation analysis identified genes expressed between sample classes, using Empirical Bayes t-test, and genes associated with survival, using Cox regression. The Notch pathway in two LPS lines, DDLS and LS141, was suppressed with a novel gamma-secretase inhibitor (GSI) or with siRNA to Notch receptors. Viability was assessed by colony formation, apoptosis by DAPI staining, and Notch expression by immunoblotting. Results: Expression of Notch-3 and its targets, Hes-1, Hey-1, and survivin, was increased in LPS subtypes, compared to fat tissue (p<0.001). Inhibition of Notch signaling with GSI's or siRNA to Notch-1 suppressed the viability of both DD LPS lines (p<0.05), inducing a G1/S arrest followed by apoptosis. Transfection of siRNA to each Notch receptor, especially Notch-3, also suppressed the viability of DD LPS's (p<0.05). Expression of Notch-3 (p=0.027, HR=2.64), Notch-4 (p=0.026, HR=2.70), the ligand JAG-2 (p=0.049, HR=2.32), and Hey-1 (p=0.001, HR=4.25) was associated with reduced distant recurrence free survival in patients with DD LPS's. Expression of the negative Notch regulator Fbxw7 was associated with improved overall survival in patients with LPS (p=0.008, HR=-1.42). Conclusions: Elements of the Notch pathway (receptors, ligands, targets, and modifiers) are overexpressed in LPS's compared to normal fat tissue and associate with outcome. Suppression of Notch signaling decreased DD LPS cell line viability and induced apoptosis. Notch inhibition may represent a new therapeutic strategy for patients with LPS's and deserves further validation in a clinical trial. No significant financial relationships to disclose.

Supplementary Methods, Tables 1-4, Figures 1-7 from Small RNA Sequencing and Functional Characterization Reveals MicroRNA-143 Tumor Suppressor Activity in Liposarcoma

Supplementary Methods, Tables 1-4, Figures 1-7 from Small RNA Sequencing and Functional Characterization Reveals MicroRNA-143 Tumor Suppressor Activity in Liposarcoma