The genetic depletion or the triptolide inhibition of TFIIH in p53 deficient cells induce a JNK-dependent cell death in Drosophila

Abstract

SummaryTranscription factor IIH (TFIIH) participates in transcription, nucleotide excision repair and the control of the cell cycle. In the present study, we demonstrate that the Dmp52 subunit of TFIIH in Drosophila physically interacts with the fly p53 homologue, Dp53. The depletion of Dmp52 in the wing disc generates chromosome fragility, increases apoptosis and produces wings with a reduced number of cells; cellular proliferation, however, is not affected. Interestingly, instead of suppressing the apoptotic phenotype, the depletion of Dp53 in Dmp52-depleted wing disc cells increases apoptosis and the number of cells that suffer from chromosome fragility. The apoptosis induced by the depletion of Dmp52 alone is partially dependent on the JNK pathway. In contrast, the enhanced apoptosis caused by the simultaneous depletion of Dp53 and Dmp52 is absolutely JNK-dependent. In this study, we also show that the anti-proliferative drug triptolide, which inhibits the ATPase activity of the XPB subunit of TFIIH, phenocopies the JNK-dependent massive apoptotic phenotype of Dp53-depleted wing disc cells; this observation suggests that the mechanism by which triptolide induces apoptosis in p53-deficient cancer cells involves the activation of the JNK death pathway.

Cancer Drug Development Using Drosophila as an in vivo Tool: From Bedside to Bench and Back

“…Inhibited the differentiation of stem cells into enterocytes [47] Acivicin Inhibited tumor formation in Drosophila by inhibiting CTP synthase [22] Gefitinib and erlotinib Suppressed eye and wing phenotypes induced by EGFR in Drosophila; inhibited dp-ERK1/2 in the eye and wing imaginal discs of wild-type larvae [56] Artemisinin, curcumin Exhibited anticancer activities against brain cancer through generation of reactive oxygen species [60] TAE684, crizotinib Ameliorated the rough-eye phenotype caused by overexpression of hALK F1174L and hALK R1275Q in Drosophila; the effect of crizotinib was less than that of TAE684 [70,71] Imipramine Inhibited fascin pathway in Drosophila; known mediator of tumor invasion and metastasis [76] Triptolide Induced apoptosis in third-instar larval wing discs of Drosophila by inhibiting the ATPase activity of the XPB subunit of TFIIH [84] F14512 Exhibited antiproliferative properties in Drosophila cells; stabilized ternary Topo II-DNA-cleavable complexes at unique sites located in moderately repeated sequences [87] AY9944 Inhibited Hh-induced internalization of the transmembrane protein Ptc as well as the expression of the Hh target gene en; depleted cholesterol from the plasma membrane and its intracellular accumulation in Drosophila tissues [89] Bouvardin Enhanced the effects of radiation in Drosophila larvae through inhibition of the elongation step of protein synthesis [92] Trametinib and fluvastatin Improved tracheal development and reduced over-proliferation and whole-animal toxicity in a Ras-PTEN Drosophila lung cancer model [94]. several aspects of tumor development [23], small molecules that disrupt the function of STAT, such as sunitinib and dasatinib, are now being developed for cancer therapy [24].…”

“…It has the potential to specifically inhibit the ATPase activity of the XPB subunit of TFIIH [82] and to induce apoptosis in cancer cells [83]. In one study, the efficacy of triptolide was examined in third-instar larval wing discs of Drosophila that were deficient in Dp53 [84]. Triptolide was found to induce apoptosis in the larval wing discs in a dose-and time-dependent manner.…”

“…High-throughput screening is an extremely powerful assay that allows quick screening of drugs in vivo against a predetermined target at large scale in a costeffective manner. In brief, cells, embryos, larvae, or adult Drosophila with cancer-causing TFIIH Not defined Larval wing disc [84] Topo II Not defined Adult eye cells [87] Hh Not defined Tissues [89] genes tagged with a luciferase or GFP reporter can be cultured with food containing drugs. After a specific period of time, the effect of the drug on the cancer phenotype can be quantified by various means (Figure 4).…”

The basal transcription machinery as a target for cancer therapy

“…In Drosophila , triptolide phenocopies mutations in TFIIH subunits, inducing apoptosis in the wing discs. Interestingly, apoptosis is enhanced in p53-deficient cells by JNK pathway activation [84]. This finding is interesting as the majority of solid tumors harbor mutations in p53 or components of the p53 pathway, suggesting that triptolide potentially induces apoptosis via JNK in these malignancies.…”

Genome-wide association analysis identified splicing single nucleotide polymorphism in CFLAR predictive of triptolide chemo-sensitivity

“…XPB, also known as ERCC3 is a subunit of transcription factor TFIIH. Triptolide has been shown to influence gene expression by globally reducing gene expression although to not to same extent for all genes by blocking transcription initiation [ 40 , 41 ]. Antiproliferative effects of triptolide due to inhibition of XPB/TFIIH has also been shown to phenocopy JNK-dependent apoptosis phenotype in Dp53 deficient wing disc cells in Drosophila [ 42 ].…”