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PTEN antagonises Tcl1/hnRNPK-mediated G6PD pre-mRNA splicing which contributes to hepatocarcinogenesis
- Source :
- Gut. 63:1635-1647
- Publication Year :
- 2013
- Publisher :
- BMJ, 2013.
-
Abstract
- Background Mounting epidemiological evidence supports a role for phosphatase and tensin homologue (PTEN)-T cell leukaemia 1 (Tcl1) signalling deregulation in hepatocarcinogenesis. Objective To determine the molecular and biochemical mechanisms by which the PTEN/Tcl1 axis regulates the pentose phosphate pathway (PPP) in hepatocellular carcinoma (HCC). Methods We compared levels of PTEN and glucose-6-phosphate dehydrogenase (G6PD) mRNA in human HCC and healthy liver tissue. We measured PPP flux, glucose consumption, lactate production, nicotinamide adenine dinucleotide phosphate (NADPH) levels and lipid accumulation. We investigated the PTEN/Tcl1 axis using molecular biology, biochemistry and mass spectrometry analysis. We assessed proliferation, apoptosis and senescence in cultured cells, and tumour formation in mice. Results We showed that PTEN inhibited the PPP pathway in human liver tumours. Through the PPP, PTEN suppressed glucose consumption and biosynthesis. Mechanistically, the PTEN protein bound to G6PD, the first and rate-limiting enzyme of the PPP and prevented the formation of the active G6PD dimer. Tcl1, a coactivator for Akt, reversed the effects of PTEN on biosynthesis. Tcl1 promoted G6PD activity and also increased G6PD pre-mRNA splicing and protein expression in a heterogeneous nuclear ribonucleoprotein (hnRNPK)-dependent manner. PTEN also formed a complex with hnRNPK, which inhibited G6PD pre-mRNA splicing. Moreover, PTEN inactivated Tcl1 via glycogen synthase kinase-3β (GSK3β)-mediated phosphorylation. Importantly, Tcl1 knockdown enhanced the sensitivity of HCC to sorafenib, whereas G6PD knockdown inhibited hepatocarcinogenesis. Conclusions These results establish the counteraction between PTEN and Tcl1 as a key mechanism that regulates the PPP and suggest that targeting the PTEN/Tcl1/hnRNPK/G6PD axis could open up possibilities for therapeutic intervention and improve the prognosis of patients with HCC.
- Subjects :
- Male
Carcinoma, Hepatocellular
Heterogeneous nuclear ribonucleoprotein
RNA Splicing
Phosphatase
Glucosephosphate Dehydrogenase
Biology
Heterogeneous-Nuclear Ribonucleoprotein K
Pentose Phosphate Pathway
Mice
chemistry.chemical_compound
Liver Neoplasms, Experimental
Proto-Oncogene Proteins
RNA Precursors
Animals
Humans
Tensin
PTEN
Phosphorylation
Protein kinase B
Mice, Knockout
Mice, Inbred BALB C
Gene knockdown
PTEN Phosphohydrolase
Gastroenterology
Glucose
Glycogen Synthase
Ribonucleoproteins
chemistry
Cancer research
biology.protein
Nicotinamide adenine dinucleotide phosphate
Subjects
Details
- ISSN :
- 14683288 and 00175749
- Volume :
- 63
- Database :
- OpenAIRE
- Journal :
- Gut
- Accession number :
- edsair.doi.dedup.....d0cab007793b80c6c0e44e6d666f108c