RESUMEN
Inherited thrombocytopenia is a genetically heterogeneous disease characterized by varying degrees of thrombocytopenia and risk of haematological malignancy, and the genetic cause of many cases remains unknown. We performed whole-exome sequencing of a family with thrombocytopenia and myeloid malignancy and identified a novel TUBB1 variant, T149P. Screening of other thrombocytopenia pedigrees identified another TUBB1 variant, R251H. TUBB1 encodes the tubulin ß-1 chain, a major component of microtubules abundant in megakaryocytes. Variant TUBB1 disrupted the normal assembly of microtubules and impaired proplatelet formation in vitro. In addition, DNA damage response was severely attenuated by loss of TUBB1. We found that the nuclear accumulation of p53 (also termed TP53) and the expression of pro-apoptotic genes triggered by genotoxic stress were blocked in TUBB1-deficient cells and, accordingly, apoptosis after DNA damage was diminished by knockdown of TUBB1. Thus, we have demonstrated that microtubule dysfunction confers resistance to apoptosis, even in DNA damage-accumulated cells, which explains genome instability in the affected individuals. These studies will lead us to a better understanding of how microtubule dysfunction can contribute to the accumulation of DNA damage, genetic instability and leukaemogenesis.
Asunto(s)
Trombocitopenia/genética , Tubulina (Proteína)/genética , Anciano , Secuencia de Aminoácidos , Animales , Apoptosis/fisiología , Línea Celular Tumoral , Proliferación Celular/fisiología , Femenino , Inestabilidad Genómica , Mutación de Línea Germinal , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Linaje , Alineación de Secuencia , Trombocitopenia/patología , Proteína p53 Supresora de Tumor/genética , Secuenciación del ExomaRESUMEN
We present a patient with refractory multiple myeloma who showed a good response to a combination therapy with oral melphalan, dexamethasone, and thalidomide (MDT). A 48-year-old woman with myeloma refractory to thalidomide, dexamethasone, and clarithromycin received 6 mg melphalan for 4 days every 6 weeks in combination with thalidomide (100 mg daily) and dexamethasone (5 mg daily for 2 days every week). Four months after the initiation of MDT therapy, a 78% reduction of monoclonal protein was achieved. Although the efficacy of oral MDT combination therapy in elderly patients with newly diagnosed myeloma has been reported, the present data demonstrate the effectiveness of MDT therapy for refractory myeloma and warrant further exploration with this MDT regimen to treat myeloma.
