<b>Background</b>: Accumulating evidence indicates that aberrant activation of the Hedgehog (Hh) signalling pathway by Glioma-associated oncogene (Gli) transcription factors is involved in the aggressive progression of cancers, including ovarian cancer.
HH signaling keeps XCI in check in pluripotent cells and is transduced by GLI transcription factors to binding sites in Tsix, the antisense repressor of XCI.
Glioma-associated oncogene homologue (Gli) reporter assay, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, and quantitative real-time reverse transcription-PCR for the target genes of the Hh signals were performed in HHIP stably expressing hepatoma cells.
GLI1 is a key downstream transcription effector of the Hedgehog (Hh) signaling pathway that is involved in promoting cell growth, differentiation and tissue patterning in embryonic development.
Gli1 is phosphorylated at S481 by Plk1, and this phosphorylation facilitates the nuclear export and binding of Gli1 with its negative regulator Sufu, leading to a reduction in Hh signaling activity.
Activation of the GLI/Hh signalling in T-LBL promotes cell survival and proliferation, since inhibition of the pathway using short-hairpin-RNA-mediated SMO knockdown, or cyclopamine as a specific antagonist, significantly reduces these cellular processes.
Advanced basal cell carcinomas (BCCs) circumvent Smoothened (SMO) inhibition by activating GLI transcription factors to sustain the high levels of Hedgehog (HH) signaling required for their survival.
Also, ATO suppresses endogenous Hedgehog (Hh) signaling, as it significantly reduces Gli1 transcriptional activity and expression levels of several Hh target genes.
As a physically binding protein of GLI1 transcription factor, Suppressor-of-Fused (SUFU) has been placed in the center of negative regulation of Hedgehog (Hh) signaling.
Blocking the Hh signal using either the Hh pathway inhibitor cyclopamine or Gli1 siRNA led to remarkably decreased cell proliferation in ovarian carcinoma cells.
Canonical Hedgehog (HH) signaling is characterized by Smoothened (Smo)-dependent activation of the transcription factors Gli1 and Gli2, which regulate HH target genes.
Conversely, deletion of the zinc finger domain at C-terminus of Zic2 significantly abrogated its interaction with Gli1, the retention of Gli1 in the nucleus, effects on Hh signalling activity and oncogenic properties in cervical cancer cells.
Further mechanistic studies demonstrated that the representative compound 9i could inhibit both PI3K/Akt/mTOR and hedgehog (Hh) signalings by inhibiting the phosphorylation of S6K and Akt as well as decreasing the SAG elevated expression of Gli1.
Furthermore, gene expression profiling of primary B-CLL cells (n = 48) indicates that the expression of Hh signaling molecules, such as GLI1, GLI2, SUFU, and BCL2, is significantly increased and correlates with disease progression of B-CLL patients with clinical outcome.
Here we identify atypical protein kinase C ι/λ (aPKC-ι/λ) as a novel GLI regulator in mammals. aPKC-ι/λ and its polarity signalling partners co-localize at the centrosome and form a complex with missing-in-metastasis (MIM), a scaffolding protein that potentiates HH signalling.
Here, we show that PCAF can directly acetylate cytoplasmic GLI1 protein at lysine 518, preventing its nuclear translocation and promoter occupancy, and consequently suppressing Hedgehog (Hh) signaling in HCC.
In the present study, we show that concomitant inhibition of Hedgehog (HH) signaling by the glioma-associated oncogene homolog1 (GLI1)-targeting agent GANT61 and the antiapoptotic BCL-2 protein family member MCL-1 by A-1210477 synergistically induces cell death in HH-driven cancers, i.e. rhabdomyosarcoma (RMS) and medulloblastoma (MB) cells.
Inhibition of hedgehog (Hh) signalling pathway, including its end effector GLI1, can reverse epithelial-to-mesenchymal transition (EMT) which plays an important role in drug resistance of pancreatic cancer cells to Erlotinib (ETB).
Interestingly, these cells also express the Hh receptor Patched and the downstream signalling components Smoothened and Gli1, suggesting autocrine Hh signalling in these cells.
Mesenchymal-related genes (WNT5A, CDH2, PDGFRB, EDNRA, ROBO1, ROR2, and MEF2C) were found to be activated by an EMT regulator, SIP1/ZFHX1B/ZEB2, which was a target of a primary transcriptional regulator GLI1 in Hh signal.