Recent advances in the discovery of protein tyrosine phosphatase SHP2 inhibitors

Src homology 2 domain-containing protein tyrosine phosphatase (SHP2) is a non-receptor protein tyrosine phosphatase encoded by the Ptpn11 gene, which regulates cell growth, differentiation and apoptosis via modulating various signaling...

Correlation Analysis of DNA Methylation Level and Clinical Characteristics in JMML Patients

Objective: As a rare, aggressive pediatric myeloproliferative disease, juvenile myelomonocytic leukemia (JMML) encompassed both biological features of myelodysplastic syndrome and myeloproliferative neoplasm. Studies have shown that the methylation level in JMML patients is closely related to prognosis, and patients with high methylation level have poor prognosis. This study aimed to find clinical indicators that were associated with different methylation levels and prognosis. Methods: The clinical information of 24 JMML patients with DNA samples admitted to our center from December 2013 to May 2020 was retrospectively analyzed, and the DNA methylation level of their whole genome was detected. Results: The median age of onset was 14.5 months (0.1-153 months) among the 24 cases, including 17 males and 7 females. At diagnosis, the median WBC count was 27.1×10 9/L (6.2-98.1×10 9/L), and the median platelet count was 38×10 9/L (10-277×10 9/L). Chromosome karyotype abnormalities were found in 12.5% (3/24) of patients. Next-generation sequencing results showed that 79.2% (19/24) patients had at least one Ras pathway-related classical gene mutation, and 41.7% (10/24) patients had two or more somatic mutations. Genomic DNA methylation levels were divided into three groups: 10 cases in the hypomethylation group, 4 cases in the moderate methylation group, and 10 cases in the hypermethylation group. There were significant differences in age, platelets, PTPN11 gene mutation and the number of somatic mutations ≥2 in different methylation groups (P<0.05). The age of hypomethylated group was significantly lower than that of hypermethylated group (P<0.05), and the platelets of hypomethylated group was significantly higher than that of hypermethylated group (P<0.05). Patients ≤12m and platelets＞32×10 9/L had lower DNA methylation level (P<0.0001). The number of patients with PTPN11 gene mutation in the hypomethylated group was significantly lower than that in the hypermethylated group (P<0.05), and the number of patients with ≥2 mutations in the low and medium methylated groups was significantly lower than that in the hypermethylated group (P<0.05). Correlation analysis showed that hypermethylation level was significantly correlated with PTPN11 gene mutation and ≥2 somatic mutations (P<0.001). Conclusions: JMML patients with high methylation level in the DNA genome at diagnosis were older and with lower platelet levels, and hypermethylation were significantly correlated with high-risk prognostic factors such as PTPN11 gene mutation and ≥2 somatic mutations. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Decitabine for treatment of children with JMML

miR-514a-3p: a novel SHP-2 regulatory miRNA that modulates human cytotrophoblast proliferation

Src homology-2 (SH2) domain containing protein tyrosine phosphatase 2 (SHP-2), encoded by the PTPN11 gene, forms a central component of multiple signalling pathways and is required for insulin-like growth factor (IGF) induced placental growth. Altered expression of SHP-2 is associated with aberrant placental and fetal growth indicating that drugs modulating SHP-2 expression may improve adverse pregnancy outcome associated with altered placental growth. Placental PTPN11/SHP-2 expression is controlled by microRNAs (miRNAs) so SHP-2 regulatory miRNAs may have therapeutic potential, however the individual miRNA(s) regulating placental SHP-2 expression remain to be established. We performed in-silico analysis of 3’UTR target prediction databases to identify libraries of HeLa cells transfected with individual miRNA-mimetics, enriched in potential SHP-2 regulatory miRNAs. Analysis of PTPN11 levels by qPCR revealed that miR-758-3p increased, whilst miR-514a-3p reduced PTPN11 expression. miR-514a-3p and miR-758-3p expression within the human placenta was confirmed by qPCR; miR-514a-3p (but not miR-758-3p) levels inversely correlated with PTPN11 expression. To assess the interaction between these miRNAs and PTPN11/SHP-2, specific mimetics were transfected into first trimester human placental explants and explants cultured for up to 4 days. Overexpression of miR-514a-3p, but not miR-758-3p, significantly reduced PTPN11 and SHP-2 expression. microRNA-ribonucleoprotein complex (miRNP)-associated mRNA assays confirmed that this interaction was direct. miR-514a-3p overexpression attenuated IGF-I induced trophoblast proliferation (BrdU incorporation). miR-758-3p did not alter trophoblast proliferation. These data demonstrate that by modulating SHP-2 expression, miR-514a-3p is a novel regulator of IGF- signalling and proliferation in the human placenta and may have therapeutic potential in pregnancies complicated by altered placental growth.

The First Vietnamese Patient of LEOPARD Syndrome due to a PTPN11 Mutation: A Case Report and Review of the Literature

LEOPARD syndrome is a rare congenital anomaly that involves several organs. Patients with this syndrome develop multiple lentigines resembling a leopard’s hide. LEOPARD is an acronym of the major features constituting the syndrome including lentigines, electrocardiographic conduction defects, ocular hypertelorism, pulmonary valve stenosis, anomalies of genitalia, retardation of growth, and deafness. The syndrome is rare, and only 200 cases have been reported yet worldwide. We present the case of an 8-year-old female patient who visited the Ho Chi Minh City Hospital of Dermato-Venereology because of multiple brownish-black “dots” on her face and body. On examination, she also showed abnormalities in the maxillofacial bones, vertebrae, shoulders, sternum, and teeth, as well as deaf-mutism and growth retardation, which are typical of LEOPARD syndrome. Genetic analysis revealed a PTPN11 gene mutation in this case. To the best of our knowledge, this is the first case of LEOPARD syndrome reported in Vietnam.

Central giant cell lesions with an unusual behavior in patient with Noonan syndrome: A case report with 8-year follow-up

This study describes a patient with Noonan syndrome affected by multiple Central Giant Cell Lesions (CGCL) in jaws. The lesions presented an unusual behavior since there was no regression size after puberty. The syndrome was diagnosed by collecting clinical information, represented by ocular hypertelorism, low insertion of ears, pulmonary stenosis, cryptorchidism, cardiac abnormalities, short stature, multiple CGCL in the jaws, and blood analysis that found a mutation of the PTPN11 gene. The treatment consisted of systemic calcitonin for a period of 14 months and three surgical procedures at distinct moments. The patient is currently with 20 years and in the eighth-year of follow-up. Although he presented an improvement in deformity, radiological findings showed remodeling without resolution of mandibular injuries, making it clear that injuries will did not always regress after puberty and not confirm previously publications in the literature. We therefore advocate a larger time of follow-up before patient discharge in these cases.

PTPN11 Mutations in the Ras-MAPK Signaling Pathway Affect Human White Matter Microstructure

We examined whether PTPN11 mutations affect the white matter connectivity of the developing human brain. Germline activating mutations to the PTPN11 gene cause overactivation of the Ras-Mitogen-Activated Protein Kinase pathway. Activating mutations cause Noonan syndrome (NS), a developmental disorder associated with hyperactivity and cognitive weakness in attention, executive function, and memory. In mouse models of NS, PTPN11 mutations cause reduced axon myelination and white matter formation, while the effects of PTPN11 mutations on human white matter are largely unknown. For the first time, we assessed 17 children with NS (9 females, mean age, 8.68 ± 2.39) and 17 age- and sex-matched controls (9 female, mean age, 8.71 ± 2.40) using diffusion brain imaging for white matter connectivity and structural magnetic resonance imaging to characterize brain morphology. Children with NS showed widespread reductions in fractional anisotropy (FA; 82 613 voxels, t = 1.49, P < 0.05) and increases in radial diffusivity (RD; 94 044 voxels, t = 1.22, P < 0.05), denoting decreased white matter connectivity. In NS, the FA of the posterior thalamic radiation correlated positively with inhibition performance, whereas connectivity in the genu of the corpus callosum was inversely associated with auditory attention performance. Additionally, we observed negative and positive correlations, respectively, between memory and the cingulum hippocampus, and memory and the cingulum cingulate gyrus. These findings elucidate the neural mechanism underpinning the NS cognitive phenotype, and may serve as a brain-based biomarker.

Allosteric inhibitors of SHP2: an updated patent review (2015-2020)

: Srchomology-2-domain-containing PTP 2 (SHP2) is a nonreceptor phosphatase encoded by the PTPN11 gene. Over expression of SHP2 is associated with various human diseases, such as Noonan syndrome, LEOPARD syndrome, and cancers. To overcome the shortcomings of existing orthosteric inhibitors, novel inhibitors targeting the allosteric site of SHP2 with high selectivity and low toxicity are under development. This paper reviews allosteric inhibitors of SHP2 published in patents from 2015 to 2020. The molecules are classified according to the chemical structure of the central core. SHP2 has long been considered as an ‘undruggable’ protein. Fortunately, a critical breakthrough was made by researchers from Novartis AG Ltd., who identified SHP099 as a highly potent, selective, soluble, and orally bioavailable SHP2 allosteric inhibitor. Currently, there are several allosteric inhibitors of SHP2 in clinical development. However, drug resistance is still a major challenge. The combination of SHP2 allosteric inhibitors and immunotherapy drugs or molecular targeted drugs is emerging as a promising therapeutic strategy against drug resistance.

Combined PTPN11 and MYBPC3 Gene Mutations in an Adult Patient with Noonan Syndrome and Hypertrophic Cardiomyopathy

In this report, an atypical case of Noonan syndrome (NS) associated with sarcomeric hypertrophic cardiomyopathy (HCM) in a 33-year-old patient was described. Genetic testing revealed two different disease-causing mutations: a mutation in the PTPN11 gene, explaining NS, and a mutation in the MYBPC3 gene, known to be associated with HCM. This case exemplifies the challenge in achieving a definite etiological diagnosis in patients with HCM and the need to exclude other diseases mimicking this condition (genocopies or phenocopies). Compound heterozygous mutations are rare but possible in HCM patients. In conclusion, this study highlights the important role of genetic testing as a necessary diagnostic tool for performing a definitive etiological diagnosis of HCM.

Prolonged thrombocytopenia in a neonate with Noonan syndrome: a case report

We report a case of a Chinese neonate who was diagnosed with Noonan syndrome and had persistent, self-limited thrombocytopenia. The neonate was admitted to the Neonatology Department 20 minutes after birth because of respiratory distress. From birth until 2 months of age, platelet values fluctuated between approximately 6 and 30 × 109/L. There was no intracranial hemorrhage. However, the child had a transient hypocalcemic seizure and fever. We excluded thrombocytopenia caused by perinatal asphyxia, immune thrombocytopenia, fetomaternal alloimmune thrombocytopenia, juvenile myelomonocytic leukemia, and chromosome 13, 18, and 21 trisomy syndromes. Despite treatment with anti-infective agents and transfusion of platelets and immunoglobulin, the platelet count did not return to the normal range. Genetic testing confirmed a PTPN11 gene mutation, which led to the diagnosis of Noonan syndrome. At 3 months of age, the platelet count gradually increased without intervention and returned to the normal range by 6 months. We speculate that the thrombocytopenia in this case was closely related to Noonan syndrome.