Tyrosine phosphatase PTPN11/SHP2 in solid tumors - bull's eye for targeted therapy?

Encoded by PTPN11, the Src-homology 2 domain-containing phosphatase 2 (SHP2) integrates signals from various membrane-bound receptors such as receptor tyrosine kinases (RTKs), cytokine and integrin receptors and thereby promotes cell survival and proliferation. Activating mutations in the PTPN11 gene may trigger signaling pathways leading to the development of hematological malignancies, but are rarely found in solid tumors. Yet, aberrant SHP2 expression or activation has implications in the development, progression and metastasis of many solid tumor entities. SHP2 is involved in multiple signaling cascades, including the RAS-RAF-MEK-ERK-, PI3K-AKT-, JAK-STAT- and PD-L1/PD-1- pathways. Although not mutated, activation or functional requirement of SHP2 appears to play a relevant and context-dependent dichotomous role. This mostly tumor-promoting and infrequently tumor-suppressive role exists in many cancers such as gastrointestinal tumors, pancreatic, liver and lung cancer, gynecological entities, head and neck cancers, prostate cancer, glioblastoma and melanoma. Recent studies have identified SHP2 as a potential biomarker for the prognosis of some solid tumors. Based on promising preclinical work and the advent of orally available allosteric SHP2-inhibitors early clinical trials are currently investigating SHP2-directed approaches in various solid tumors, either as a single agent or in combination regimes. We here provide a brief overview of the molecular functions of SHP2 and collate current knowledge with regard to the significance of SHP2 expression and function in different solid tumor entities, including cells in their microenvironment, immune escape and therapy resistance. In the context of the present landscape of clinical trials with allosteric SHP2-inhibitors we discuss the multitude of opportunities but also limitations of a strategy targeting this non-receptor protein tyrosine phosphatase for treatment of solid tumors.

High Throughput Study for Molecular Mechanism of Metformin Pre-Diabetic Protection via Microarray Approach.

BACKGROUND: Metformin is a biguanide that exhibits antidiabetic, anticarcinogenic, and anti-inflammatory properties. Despite well-known pancreatic protective effects, metformin's influence on pancreatic islet ß-cell is yet considerably unknown. Protecting the functional insulin-producing ß-cells in the pancreas is a key therapeutic challenge in patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM). OBJECTIVE: The current study aimed to analyze the protective effects of metformin on streptozocin- induced diabetic rats in T1DM in hepatic tissues. METHODS: In the present study, male Wistar rats (n=24) were randomly assigned into 2 groups (n=12 for each control and test), and metformin (100 mg/kg/day) was given for 7 weeks. Afterward, diabetes was induced by streptozocin (STZ) at a single dose of 150 mg/kg. Blood glucose was examined daily before and after STZ induction. The animals were euthanized by cervical dislocation 5 days after streptozocin injection, after which liver and pancreas were harvested from each rat. RESULTS: The biochemical analyses revealed that metformin resulted in significantly reduced plasma glucose levels and higher pancreatic insulin levels in the test group. Using a restrictive cut-off of at least 2-FC and an adjusted p-value (q-value) of ≤0.05, a sum of 747 genes for the metformin group were shown to be differentially regulated compared to controls (320 Down and 427 Up), by which they were obtained from the liver. Furthermore, the evidence is attained that metformin may hinder the loss of critical ß-cells by reducing inflammatory and apoptosis signaling, promoting fatty acid ß-oxidation, and inducing metabolism. CONCLUSION: Collectively, this study has demonstrated a decrease in blood glucose levels and a rise in insulin-levels and thus consequent prophylactic effects in metformin-given STZ-induced diabetic rats.