Phenotypic and genetic spectrum of isolated macrodactyly: somatic mosaicism of PIK3CA and AKT1 oncogenic variants
ORPHANET JOURNAL OF RARE DISEASES
Authors: Tian, Wen; Huang, Yingzhao; Sun, Liying; Guo, Yang; Zhao, Sen; Lin, Mao; Dong, Xiying; Zhong, Wenyao; Yin, Yuehan; Chen, Zefu; Zhang, Nan; Zhang, Yuanqiang; Wang, Lianlei; Lin, Jiachen; Yan, Zihui; Yang, Xinzhuang; Zhao, Junhui; Qiu, Guixing; Zhang, Jianguo; Wu, Zhihong; Wu, Nan
Background: Isolated macrodactyly is a severe congenital hand anomaly with functional and physiological impact. Known causative genes include PIK3CA, AKT1 and PTEN. The aim of this study is to gain insights into the genetics basis of isolated macrodactyly. Results: We enrolled 24 patients with isolated macrodactyly. Four of them were diagnosed with Proteus syndrome based on skin presentations characteristic to this disease. Targeted next-generation sequencing was performed using patients' blood and affected tissues. Overall, 20 patients carry mosaic PIK3CA pathogenic variants, i.e. p.His1047Arg (N = 7), p.Glu542Lys (N = 6), p.Glu545Lys (N = 2), p.His1047Leu (N = 2), p.Glu453Lys (N = 1), p.Gln546Lys (N = 1) and p.His1047Tyr (N = 1). Four patients who met the diagnostic criteria of Proteus syndrome carry mosaicAKT1p.Glu17Lys variant. Variant allele frequencies of these mosaic variants obtained through next-generation sequencing range from 10 to 33%. In genotype-phenotype correlation analysis of patients withPIK3CAvariant, we found that patients with the macrodactyly of the lower limbs tend to carryPIK3CAvariants located in the helical domain (P = 0.005). Conclusions: Mosaic PIK3CA and AKT1 variants can be found in all of our samples with isolated macrodactyly. Insights into phenotypic and genetic spectrum of isolated macrodactyly may be helpful in perusing a more precise and effective management of isolated macrodactyly.
Phosphorylation-Dependent Differences in CXCR4-LASP1-AKT1 Interaction between Breast Cancer and Chronic Myeloid Leukemia
Authors: Butt, Elke; Stempfle, Katrin; Lister, Lorenz; Wolf, Felix; Kraft, Marcella; Herrmann, Andreas B.; Viciano, Cristina Perpina; Weber, Christian; Hochhaus, Andreas; Ernst, Thomas; Hoffmann, Carsten; Zernecke, Alma; Frietsch, Jochen J.
The serine/threonine protein kinase AKT1 is a downstream target of the chemokine receptor 4 (CXCR4), and both proteins play a central role in the modulation of diverse cellular processes, including proliferation and cell survival. While in chronic myeloid leukemia (CML) the CXCR4 is downregulated, thereby promoting the mobilization of progenitor cells into blood, the receptor is highly expressed in breast cancer cells, favoring the migratory capacity of these cells. Recently, the LIM and SH3 domain protein 1 (LASP1) has been described as a novel CXCR4 binding partner and as a promoter of the PI3K/AKT pathway. In this study, we uncovered a direct binding of LASP1, phosphorylated at S146, to both CXCR4 and AKT1, as shown by immunoprecipitation assays, pull-down experiments, and immunohistochemistry data. In contrast, phosphorylation of LASP1 at Y171 abrogated these interactions, suggesting that both LASP1 phospho-forms interact. Finally, findings demonstrating different phosphorylation patterns of LASP1 in breast cancer and chronic myeloid leukemia may have implications for CXCR4 function and tyrosine kinase inhibitor treatment.