Real-time PCR based on SYBR-Green I fluorescence: An alternative to the TaqMan assay for a relative quantification of gene rearrangements, gene amplifications and micro gene deletions

BACKGROUND: Real-time PCR is increasingly being adopted for RNA quantification and genetic analysis. At present the most popular real-time PCR assay is based on the hybridisation of a dual-labelled probe to the PCR product, and the development of a signal by loss of fluorescence quenching as PCR degrades the probe. Though this so-called 'TaqMan' approach has proved easy to optimise in practice, the dual-labelled probes are relatively expensive. RESULTS: We have designed a new assay based on SYBR-Green I binding that is quick, reliable, easily optimised and compares well with the published assay. Here we demonstrate its general applicability by measuring copy number in three different genetic contexts; the quantification of a gene rearrangement (T-cell receptor excision circles (TREC) in peripheral blood mononuclear cells); the detection and quantification of GLI, MYC-C and MYC-N gene amplification in cell lines and cancer biopsies; and detection of deletions in the OPA1 gene in dominant optic atrophy. CONCLUSION: Our assay has important clinical applications, providing accurate diagnostic results in less time, from less biopsy material and at less cost than assays currently employed such as FISH or Southern blotting

GLI1 (glioma-associated oncogene homolog 1)

Review on GLI1 (glioma-associated oncogene homolog 1), with data on DNA, on the protein encoded, and where the gene is implicated

Sonic hedgehog pathway dysregulation in skin basal-cell carcinoma of a Polish population

Sonic hedgehog (Shh) pathway impairment plays a key role in the pathogenesis of basal-cell carcinomas (BCC), the most frequent skin tumor among Caucasians. Shh, Smo, and Gli2 family proteins are necessary for adequate and controlled cell proliferation. The aim of this study was to evaluate Shh, Smo, and Smo expression in BCC skin biopsies taken from sun-exposed areas. 41 BCC skin biopsies and 22 healthy skin specimens (the control group) taken from the same areas served as material for the study. All specimens were immunohistochemically stained with monoclonal antibodies directed against the chosen proteins. Shh and Smo expression (cytoplasmic pattern) were recorded semiquantitatively using a four-grade score (0–3). Gli2 expression (nuclear pattern) was determined using an image analysis system (semiautomatic function). The immunoexpression of the Shh and Smo proteins significantly increased in the BCC group, as compared with the normal controls (for Shh, the mean intensity was 1.67 in BCC vs. 1.17 in the control group, p < 0.001; for Smo, the mean intensity was 1.46 in BCC vs. 0.99 in the control group, p < 0.001). The staining for Gli2 in the BCC group was completely negative, but indicated the presence of Gli2 in the control patients (1.15 Gli2+ cells/100 cells). Sonic hedgehog pathway dysregulation may play an important role in skin cancerogenesis leading to BCC development

Downregulation of the Gli Transcription Factors Regulator Kif7 Facilitates Cell Survival and Migration of Choriocarcinoma Cells

published_or_final_versio

A Smo/Gli multitarget hedgehog pathway inhibitor impairs tumor growth

Pharmacological Hedgehog (Hh) pathway inhibition has emerged as a valuable anticancer strategy. A number of small molecules able to block the pathway at the upstream receptor Smoothened (Smo) or the downstream effector glioma-associated oncogene 1 (Gli1) has been designed and developed. In a recent study, we exploited the high versatility of the natural isoflavone scaffold for targeting the Hh signaling pathway at multiple levels showing that the simultaneous targeting of Smo and Gli1 provided synergistic Hh pathway inhibition stronger than single administration. This approach seems to effectively overcome the drug resistance, particularly at the level of Smo. Here, we combined the pharmacophores targeting Smo and Gli1 into a single and individual isoflavone, compound 22, which inhibits the Hh pathway at both upstream and downstream level. We demonstrate that this multitarget agent suppresses medulloblastoma growth in vitro and in vivo through antagonism of Smo and Gli1, which is a novel mechanism of action in Hh inhibition

Targeting GLI factors to inhibit the Hedgehog pathway

Hedgehog (Hh) signaling has emerged in recent years as an attractive target for anticancer therapy because its aberrant activation is implicated in several cancers. Major progress has been made in the development of SMOOTHENED (SMO) antagonists, although they have shown several limitations due to downstream SMO pathway activation or the occurrence of drug-resistant SMO mutations. Recently, particular interest has been elicited by the identification of molecules able to hit glioma-associated oncogene (GLI) factors, the final effectors of the Hh pathway, which provide a valid tool to overcome anti-SMO resistance. Here, we review results achieved in developing GLI antagonists, explaining their mechanisms of action and highlighting their therapeutic potential. We also underline the relevance of structural details in their discovery and optimization

The stem cell connection of primary brain tumors

Gliomas account for more than half of adult primary intracranial tumors, with anaplastic astrocytomas and glioblastoma multiforme (also known as malignant gliomas) being the most common. Plethora of evidence supports the notion that malignant glioma and other types of primary brain tumors arise from cells with stem cell/progenitor cell properties. To designate this cellular population a novel term has been introduced: glioma stem cells. These cells form a small subset of all cancer cells and share some features of normal stem cells, e.g. a capacity for self-renewal, multipotency and relative quiescence. These chemo- and radiation resistant cells are mainly responsible for maintaining tumor volume leading to therapy failure and recurrence. This review summarizes new findings on the interaction between the glioma stem cells, the tumor micro-environment, and specific cancer-causing genetic changes in the evolution of primary central nervous system tumors.Biomedical Reviews 2009; 20: 31-39

The centrosomal deubiquitylase USP21 regulates Gli1 transcriptional activity and stability

USP21 is a centrosome-associated deubiquitylase (DUB) that has been implicated in the formation of primary cilia - crucial organelles for the regulation of the Hedgehog (Hh) signaling pathway in vertebrates. Here, we identify KCTD6 - a cullin-3 E3-ligase substrate adapter that has been previously linked to Hh signaling - as well as Gli1, the key transcription factor responsible for Hh signal amplification, as new interacting partners of USP21. We identify a cryptic structured protein interaction domain in KCTD6, which is predicted to have a similar fold to Smr domains. Importantly, we show that both depletion and overexpression of catalytically active USP21 suppress Gli1-dependent transcription. Gli proteins are negatively regulated through protein kinase A (PKA)-dependent phosphorylation. We provide evidence that USP21 recruits and stabilises Gli1 at the centrosome where it promotes its phosphorylation by PKA. By revealing an intriguing functional pairing between a spatially restricted deubiquitylase and a kinase, our study highlights the centrosome as an important hub for signal coordination