RESUMO
The discovery of recurrent mutations in subunits of the vacuolar-type H+-translocating ATPase (v-ATPase) in follicular lymphoma (FL) highlights a role for the amino acid- and energy-sensing pathway to mTOR in the pathogenesis of this disease. Here, through the use of complementary experimental approaches involving mammalian cells and Saccharomyces cerevisiae, we have demonstrated that mutations in the human v-ATPase subunit ATP6V1B2 (also known as Vma2 in yeast) activate autophagic flux and maintain mTOR/TOR in an active state. Engineered lymphoma cell lines and primary FL B cells carrying mutated ATP6V1B2 demonstrated a remarkable ability to survive low leucine concentrations. The treatment of primary FL B cells with inhibitors of autophagy uncovered an addiction for survival for FL B cells harboring ATP6V1B2 mutations. These data support the idea of mutational activation of autophagic flux by recurrent hotspot mutations in ATP6V1B2 as an adaptive mechanism in FL pathogenesis and as a possible new therapeutically targetable pathway.
Assuntos
Morte Celular Autofágica , Linfoma Folicular/enzimologia , Mutação , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , ATPases Vacuolares Próton-Translocadoras/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular , Humanos , Linfoma Folicular/genética , Linfoma Folicular/patologia , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Serina-Treonina Quinases TOR/genética , ATPases Vacuolares Próton-Translocadoras/genéticaRESUMO
PURPOSE: This study was performed to further our understanding of the biological and genetic basis of follicular lymphoma and to identify potential novel therapy targets. EXPERIMENTAL DESIGN: We analyzed previously generated whole exome sequencing data of 23 follicular lymphoma cases and one transformed follicular lymphoma case and expanded findings to a combined total of 125 follicular lymphoma/3 transformed follicular lymphoma. We modeled the three-dimensional location of RRAGC-associated hotspot mutations. We performed functional studies on novel RRAGC mutants in stable retrovirally transduced HEK293T cells, stable lentivirally transduced lymphoma cell lines, and in Saccharomyces cerevisiae RESULTS: We report recurrent mutations, including multiple amino acid hotspots, in the small G-protein RRAGC, which is part of a protein complex that signals intracellular amino acid concentrations to MTOR, in 9.4% of follicular lymphoma cases. Mutations in RRAGC distinctly clustered on one protein surface area surrounding the GTP/GDP-binding sites. Mutated RRAGC proteins demonstrated increased binding to RPTOR (raptor) and substantially decreased interactions with the product of the tumor suppressor gene FLCN (folliculin). In stable retrovirally transfected 293T cells, cultured in the presence or absence of leucine, multiple RRAGC mutations demonstrated elevated MTOR activation as evidenced by increased RPS6KB/S6-kinase phosphorylation. Similar activation phenotypes were uncovered in yeast engineered to express mutations in the RRAGC homolog Gtr2 and in multiple lymphoma cell lines expressing HA-tagged RRAGC-mutant proteins. CONCLUSIONS: Our discovery of activating mutations in RRAGC in approximately 10% of follicular lymphoma provides the mechanistic rationale to study mutational MTOR activation and MTOR inhibition as a potential novel actionable therapeutic target in follicular lymphoma. Clin Cancer Res; 22(21); 5383-93. ©2016 AACR.
Assuntos
Linfoma Folicular/genética , Proteínas Monoméricas de Ligação ao GTP/genética , Mutação/genética , Recidiva Local de Neoplasia/genética , Serina-Treonina Quinases TOR/genética , Aminoácidos/genética , Sítios de Ligação/genética , Linhagem Celular , Genes Supressores de Tumor/fisiologia , Guanosina Difosfato/genética , Guanosina Trifosfato/genética , Células HEK293 , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Fosforilação/genética , Proteína Regulatória Associada a mTOR/genética , Transdução de Sinais/genéticaRESUMO
The objective of this article was to explore the effect of correction orbital hypertelorism using inverted U-shaped osteotomy by combined intracranial-extracranial approach. Eleven cases of severe orbital hypertelorism were performed. The measurement of interorbital and intercanthal distance was studied preoperatively and postoperatively by 3-dimensional computed tomography. The interorbital distance of the 11 patients are significantly decreased .The intercanthal distance decreased from 6.7 and 4.8 cm to 5.0 and 3.8 cm, respectively. The inverted U-shaped osteotomy technique may be an effective and safe technique for the stability of the corrected orbital framework and the prevention of recurrence in severe cases of orbital hypertelorism. Moreover, this method has little trauma compared with box osteotomy technique.
