SHP2E76K mutant promotes lung tumorigenesis in transgenic mice

In vivo Targeting MEK and TNK2/SRC pathways in PTPN11 driven leukemia

PTPN11 encodes for a tyrosine phosphatase implicated in the pathogenesis of hematologic malignancies such as Juvenile Myelomonocytic Leukemia (JMML), Acute Myeloid Leukemia (AML), and Acute Lymphoblastic Leukemia (ALL). Since activating mutations of PTPN11 increase proliferative signaling and cell survival through the RAS/MAPK proliferative pathway there is significant interest in using MEK inhibitors for clinical benefit. Yet, single agent clinical activity has been minimal. Previously, we showed that PTPN11 is further activated by upstream tyrosine kinases TNK2/SRC, and that PTPN11-mutant JMML and AML cells are sensitive to TNK2 inhibition using dasatinib. In order to validate these findings, we adopted a genetically engineered mouse model of PTPN11 driven leukemia using the mouse strain 129S/Sv- Ptpn11 tm6Bgn /Mmucd crossed with B6.129P2- Lyz2 tm1(cre)Ifo /J. The F1 progeny expressing Ptpn11 D61Y within hematopoietic cells destined along the granulocyte-monocyte progenitor lineage developed a fatal myeloproliferative disorder characterized by neutrophilia and monocytosis, and infiltration of myeloid cells into the liver and spleen. Cohorts of Ptpn11 D61Y expressing animals treated with combination of dasatinib and trametinib for an extended period of time was well tolerated and had a significant effect in mitigating disease parameters compared to single agents. Finally, a primary patient-derived xenograft model using a myeloid leukemia with PTPN11 F71L also displayed improved disease response to combination. Collectively, these studies point to combined therapies targeting MEK and TNK2/SRC as a promising therapeutic potential for PTPN11-mutant leukemias.

Key Points

Combining MEK and TNK2/SRC inhibitors has therapeutic potential in PTPN11 mutant JMML and AML.

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.

Functional roles of SRC signaling in pancreatic cancer: Recent insights provide novel therapeutic opportunities

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a 5-year survival rate of <10%. Aberrant activation or elevated expression of the tyrosine kinase c-SRC (SRC) is frequently observed in PDAC and is associated with a poor prognosis. Preclinical studies have revealed a multifaceted role for SRC activation in PDAC, including promoting chronic inflammation, tumor cell proliferation and survival, cancer cell stemness, desmoplasia, hypoxia, angiogenesis, invasion, metastasis, and drug resistance. Strategies to inhibit SRC signaling include suppressing its catalytic activity, inhibiting protein stability, or by interfering with signaling components of the SRC signaling pathway including suppressing protein interactions of SRC. In this review, we discuss the molecular and immunological mechanisms by which aberrant SRC activity promotes PDAC tumorigenesis. We also provide a comprehensive update of SRC inhibitors in the clinic, and discuss the clinical challenges associated with targeting SRC in pancreatic cancer.

SHP2: The protein tyrosine phosphatase involved in chronic pulmonary inflammation and fibrosis

Chronic respiratory diseases (CRDs), including pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), lung cancer, and asthma, are significant global health problems due to their prevalence and rising incidence. The roles of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) in controlling tyrosine phosphorylation of targeting proteins modulate multiple physiological cellular responses and contribute to the pathogenesis of CRDs. Src homology-2 domain-containing PTP2 (SHP2) plays a pivotal role in modulating downstream growth factor receptor signaling and cytoplasmic PTKs, including MAPK/ERK, PI3K/AKT, and JAK/STAT pathways, to regulate cell survival and proliferation. In addition, SHP2 mutation and activation are commonly implicated in tumorigenesis. However, little is known about SHP2 in chronic pulmonary inflammation and fibrosis. This review discusses the potential involvement of SHP2 deregulation in chronic pulmonary inflammation and fibrosis, as well as the therapeutic effects of targeting SHP2 in CRDs.

If small molecules immunotherapy comes, can the prime be far behind?

Anti-cancer immunotherapy, which includes cellular immunotherapy, immune checkpoint inhibitors and cancer vaccines, has transformed the treatment strategies of several malignancies in the past decades. Immune checkpoints blockade (ICB) is the most commonly tested therapy and has the potential to induce a durable immune response in different types of cancers. However, all approved immune checkpoint inhibitors (ICIs) are monoclonal antibodies (mAbs), which are fraught with disadvantages including lack of oral bioavailability, prolonged tissue retention and poor membrane permeability. Therefore, the research focus has shifted to developing small molecule inhibitors to obviate the limitations of mAbs. Given the complexity of the tumor micro-environment (TME), the combination of ICIs with various small molecule agonists/inhibitors are currently being tested in clinical trials to improve treatment outcomes and prevent tumor recurrence. In this review, we have summarized the mechanisms and therapeutic potential of several molecular targets, along with the current status of small molecule inhibitors.

Activating Mutation of SHP2 Establishes a Tumorigenic Phonotype Through Cell-Autonomous and Non-Cell-Autonomous Mechanisms

Gain-of-function mutation of SHP2 is a central regulator in tumorigenesis and cancer progression through cell-autonomous mechanisms. Activating mutation of SHP2 in microenvironment was identified to promote cancerous transformation of hematopoietic stem cell in non-autonomous mechanisms. It is interesting to see whether therapies directed against SHP2 in tumor or microenvironmental cells augment antitumor efficacy. In this review, we summarized different types of gain-of-function SHP2 mutations from a human disease. In general, gain-of-function mutations destroy the auto-inhibition state from wild-type SHP2, leading to consistency activation of SHP2. We illustrated how somatic or germline mutation of SHP2 plays an oncogenic role in tumorigenesis, stemness maintenance, invasion, etc. Moreover, the small-molecule SHP2 inhibitors are considered as a potential strategy for enhancing the efficacy of antitumor immunotherapy and chemotherapy. We also discussed the interconnection between phase separation and activating mutation of SHP2 in drug resistance of antitumor therapy.

Shp2-mediated MAPK pathway regulates ΔNp63 in epithelium to promote corneal innervation and homeostasis

Corneal nerve fibers serving sensory, reflex, and neurotrophic functions sustain corneal homeostasis and transparency to promote normal visual function. It is not known whether corneal epithelium is also important for the corneal innervation. Herein, we generated a compound transgenic mouse strain, K14rtTA;tetO-Cre (TC);Shp2flox/flox, in which Shp2 was conditionally knocked out from K14-positive cells including corneal epithelium (Shp2K14ce-cko) upon doxycycline (dox) administration. Our data reveal that Shp2K14ce-cko caused corneal denervation. More specifically, corneal epithelium thickness and corneal sensitivity reduced dramatically in Shp2K14ce-cko mice. In addition, corneal epithelial wound healing after debridement was delayed substantially in the mutant mice. These defects manifested in Shp2K14ce-cko mice resemble the symptoms of human neurotrophic keratopathy. Our in vitro study shows that neurite outgrowth of the mouse primary trigeminal ganglion cells (TGCs) was inhibited when as cocultured with mouse corneal epithelial cells (TKE2) transfected by Shp2-, Mek1/2-, or ∆Np63-targeted siRNA but not by Akt1/2-targeted siRNA. Furthermore, ∆Np63 RNA interference downregulated Ngf expression in TKE2 cells. Cotransfection experiments reveal that Shp2 tightly monitored ΔNp63 protein levels in HEK293 and TKE2 cells. Taken together, our data suggest that the Shp2-mediated MAPK pathway regulated ΔNp63, which in turn positively regulated Ngf in epithelium to promote corneal innervation and epithelial homeostasis.

Therapeutic potential of targeting SHP2 in human developmental disorders and cancers

Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, regulates cell proliferation, differentiation, apoptosis and survival via releasing intramolecular autoinhibition and modulating various signaling pathways, such as mitogen-activated protein kinase (MAPK) pathway. Mutations and aberrant expression of SHP2 are implicated in human developmental disorders, leukemias and several solid tumors. As an oncoprotein in some cancers, SHP2 represents a rational target for inhibitors to interfere. Nevertheless, its tumor suppressive effect has also been uncovered, indicating the context-specificity. Even so, two types of SHP2 inhibitors including targeting catalytic pocket and allosteric sites have been developed associated with resolved cocrystal complexes. Herein, we describe its structure, biological function, deregulation in human diseases and summarize recent advance in development of SHP2 inhibitors, trying to give an insight into the therapeutic potential in future.

SHP2 deficiency promotes Staphylococcus aureus pneumonia following influenza infection

Objectives

Secondary bacterial pneumonia is common following influenza infection. However, it remains unclear about the underlying molecular mechanisms.

Materials and methods

We established a mouse model of post‐influenza S aureus pneumonia using conditional Shp2 knockout mice (LysM^Cre/+:Shp2^flox/flox). The survival, bacterial clearance, pulmonary histology, phenotype of macrophages, and expression of type I interferons and chemokines were assessed between SHP2 deletion and control mice (Shp2^flox/flox). We infused additional KC and MIP‐2 to examine the reconstitution of antibacterial immune response in LysM^Cre/+:Shp2^flox/flox mice. The effect of SHP2 on signal molecules including MAPKs (JNK, p38 and Erk1/2), NF‐κB p65 and IRF3 was further detected.

Results

LysM^Cre/+:Shp2^flox/flox mice displayed impaired antibacterial immunity and high mortality compared with control mice in post‐influenza S aureus pneumonia. The attenuated antibacterial ability was associated with the induction of type I interferon and suppression of chemo‐attractants KC and MIP‐2, which reduced the infiltration of neutrophils into the lung upon secondary bacterial invasion. In additional, Shp2 knockout mice displayed enhanced polarization to alternatively activated macrophages (M2 phenotype). Further in vitro analyses consistently demonstrated that SHP2‐deficient macrophages were skewed towards an M2 phenotype and had a decreased antibacterial capacity. Moreover, SHP2 modulated the inflammatory response to secondary bacterial infection via interfering with NF‐κB and IRF3 signalling in macrophages.

Conclusions

Our findings reveal that the SHP2 expression enhances the host immune response and prompts bacterial clearance in post‐influenza S aureus pneumonia.

Gain-Of-Function E76K-Mutant SHP2 Promotes Cell Proliferation, Metastasis, And Tumor Growth In Glioblastoma Through Activation Of The ERK/CREB Pathway

Purpose

The aim of this study was to investigate the effects of gain-of-function (GOF) E76K-mutant Src homology-2 domain containing protein tyrosine phosphatase-2 (SHP2) on the biological behaviors of glioblastoma (GBM) cells, and explore the molecular mechanisms of GBM progression.

Methods

Firstly, a negative control vector and vectors overexpressing SHP2 and E76K-mutant SHP2 were transduced into GBM cells (U87 and A172) using a lentivirus. The effect of GOF-mutant SHP2 on proliferation was measured using the MTT assay, flow cytometry, colony formation assay, and soft agar assay. Moreover, the migration and invasion of GBM cells were determined through the transwell assay. Related proteins of the extracellular signal-regulated kinase/cAMP response element binding protein (ERK/CREB) pathway were detected by Western blotting analysis. A xenograft model was established to confirm the tumor-promoting effect of GOF-mutant SHP2 in vivo. Finally, ERK was inhibited using a mitogen-activated protein kinase/ERK kinase inhibitor (U0126) to further explore the molecular mechanism of GOF-mutant SHP2 affecting GBM cells.

Results

After transduction, the expression of SHP2 in the SHP2-mutant and SHP2-overexpression groups was higher than that observed in the control and normal groups. Our data indicated that GOF-mutant SHP2 enhanced the abilities of GBM cells for proliferation, migration, and invasion in vitro, and promoted tumor growth in vivo. Mechanistically, the ERK/CREB pathway was activated, and the levels of relevant proteins were increased in the SHP2-mutant group. Furthermore, following inhibition of ERK in the GOF-SHP2 mutant group, the activation of CREB was also depressed, and the malignant biological behaviors were weakened accordingly.

Conclusion

The GOF-mutant SHP2 promoted GBM cell proliferation, metastasis, and tumor growth through the ERK/CREB pathway, providing a promising target for the treatment of GBM.

AlloDriver: a method for the identification and analysis of cancer driver targets

Identifying the variants that alter protein function is a promising strategy for deciphering the biological consequences of somatic mutations during tumorigenesis, which could provide novel targets for the development of cancer therapies. Here, based on our previously developed method, we present a strategy called AlloDriver that identifies cancer driver genes/proteins as possible targets from mutations. AlloDriver utilizes structural and dynamic features to prioritize potentially functional genes/proteins in individual cancers via mapping mutations generated from clinical cancer samples to allosteric/orthosteric sites derived from three-dimensional protein structures. This strategy exhibits desirable performance in the reemergence of known cancer driver mutations and genes/proteins from clinical samples. Significantly, the practicability of AlloDriver to discover novel cancer driver proteins in head and neck squamous cell carcinoma (HNSC) was tested in a real case of human protein tyrosine phosphatase, receptor type K (PTPRK) through a L1143F driver mutation located at the allosteric site of PTPRK, which was experimentally validated by cell proliferation assay. AlloDriver is expected to help to uncover innovative molecular mechanisms of tumorigenesis by perturbing proteins and to discover novel targets based on cancer driver mutations. The AlloDriver is freely available to all users at http://mdl.shsmu.edu.cn/ALD.

Prevalence and role of HER2 mutations in cancer

HER2 activating mutations act as oncogenic drivers in various cancer types. In the clinic, they can be identified by next generation sequencing (NGS) in either tumor biopsies or circulating cell-free DNA (cfDNA). Preclinical data indicate that HER2 "hot spot" mutations are constitutively active, have transforming capacity in vitro and in vivo and show variable sensitivity to anti-HER2 based therapies. Recent clinical trials also revealed activity of HER2-targeted drugs against a variety of tumors harboring HER2 mutations. Here, we review the prevalence and type of HER2 mutations identified in different human cancers, their biochemical and biological characterization, and their sensitivity to anti HER2-based therapies in both preclinical and clinical settings.

Synthetic lethality of TNK2 inhibition in PTPN11-mutant leukemia

The protein tyrosine phosphatase PTPN11 is implicated in the pathogenesis of juvenile myelomonocytic leukemia (JMML), acute myeloid leukemia (AML), and other malignancies. Activating mutations in PTPN11 increase downstream proliferative signaling and cell survival. We investigated the signaling upstream of PTPN11 in JMML and AML cells and found that PTPN11 was activated by the nonreceptor tyrosine/serine/threonine kinase TNK2 and that PTPN11-mutant JMML and AML cells were sensitive to TNK2 inhibition. In cultured human cell-based assays, PTPN11 and TNK2 interacted directly, enabling TNK2 to phosphorylate PTPN11, which subsequently dephosphorylated TNK2 in a negative feedback loop. Mutations in PTPN11 did not affect this physical interaction but increased the basal activity of PTPN11 such that TNK2-mediated activation was additive. Consequently, coexpression of TNK2 and mutant PTPN11 synergistically increased mitogen-activated protein kinase (MAPK) signaling and enhanced colony formation in bone marrow cells from mice. Chemical inhibition of TNK2 blocked MAPK signaling and colony formation in vitro and decreased disease burden in a patient with PTPN11-mutant JMML who was treated with the multikinase (including TNK2) inhibitor dasatinib. Together, these data suggest that TNK2 is a promising therapeutic target for PTPN11-mutant leukemias.

Clinicopathological and prognostic significance of SHP2 and Hook1 expression in patients with thyroid carcinoma

Some thyroid carcinomas (TCs) have an aggressive biological behavior and poor prognosis, and lacking of effective molecular markers is still the main obstacle for clinical stratified diagnosis and treatment of TC. The aim of the study was to discover the clinicopathological and prognostic implications of Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2) and Hook microtubule tethering protein 1 (Hook1) expression in TC. The expression of SHP2 and Hook1 was detected by immunohistochemistry on tissue microarrays from 313 primary TCs who underwent surgery in January 2006 and January 2010 in Zhejiang Cancer Hospital. The χ² test, Kaplan-Meier method, and Cox proportional-hazards regression models were used to analyze the associations between their expressions and clinicopathological features and prognosis. The expression rates of SHP2 and Hook1 in TC were 57.5% (180/313) and 22.0% (69/313), respectively. SHP2 was positively correlated with Hook1 in TC. SHP2 expression differed significantly by age, histologic variants, maximal tumor diameter, intrathyroidal dissemination, metastases, and disease stage (P < .05). Moreover, patients with high SHP2 expression had reduced risk for death of disease compared with those with low SHP2 expression (hazard ratio, 0.267; 95% confidence interval, 0.105-0.684; P = .006) in univariate analysis, but that multivariate analysis failed to suggest that SHP2 was an independent prognostic factor. Hook1 expression differed significantly by histologic variants, maximal tumor diameter, and intrathyroidal dissemination (P < .05). However, there was no significant correlation between Hook1 expression and outcome in TC (P > .05). Our results suggested that SHP2 may be a favorable indicator of prognosis in TC.

Shp2 confers cisplatin resistance in small cell lung cancer via an AKT-mediated increase in CA916798

The tyrosine phosphatase Shp2 is associated with tumorigenesis in small cell lung cancer (SCLC). However, the relationship between Shp2 and resistance to chemotherapy remains unclear. Here, we show that Shp2 plays an important role in inducing resistance to cisplatin-based chemotherapy via the SHP2-AKT-CA916798 pathway. In an SCLC cell line, overexpression of Shp2 induced cisplatin resistance and the increased expression of AKT, pAKT, pmTOR, and CA916798. Conversely, depletion of Shp2 in a cisplatin-resistant cell line via RNA interference increased cisplatin sensitivity and decreased AKT, pAKT, pmTOR, and CA916798 expression levels. Activation of AKT stimulated CA916798 expression and altered the level of Shp2. A mouse xenograft model verified the results obtained from the in vitro experiments. In addition, we collected and analyzed clinical SCLC specimens and found that Shp2 levels correlated with CA916798 expression in tumor tissues. Importantly, higher levels of Shp2 or CA916798 were associated with a poorer prognosis in SCLC patients who received chemotherapy. Together, our findings indicate that Shp2 induces cisplatin resistance in SCLC patients via the SHP2-AKT-CA916798 pathway. Therefore, Shp2 and CA916798 may be promising biomarkers for predicting resistance to chemotherapy and may function as targets for enhancing treatments.

Shp2 regulates migratory behavior and response to EGFR-TKIs through ERK1/2 pathway activation in non-small cell lung cancer cells

In the clinical treatment of lung cancer, therapy failure is mainly caused by cancer metastasis and drug resistance. Here, we investigated whether the tyrosine phosphatase Shp2 is involved in the development of metastasis and drug resistance in non-small cell lung cancer (NSCLC). Shp2 was overexpressed in a subset of lung cancer tissues, and Shp2 knockdown in lung cancer cells inhibited cell proliferation and migration, downregulated c-Myc and fibronectin expression, and upregulated E-cadherin expression. In H1975 cells, which carry double mutations (L858R + T790M) in epidermal growth factor receptor (EGFR) that confers resistance toward the tyrosine kinase inhibitor gefitinib, Shp2 knockdown increased cellular sensitivity to gefitinib; conversely, in H292 cells, which express wild-type EGFR and are sensitive to gefitinib, Shp2 overexpression increased cellular resistance to gefitinib. Moreover, by overexpressing Shp2 or using U0126, a small-molecule inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2), we demonstrated that Shp2 inhibited E-cadherin expression and enhanced the expression of fibronectin and c-Myc through activation of the ERK1/2 pathway. Our findings reveal that Shp2 is overexpressed in clinical samples of NSCLC and that Shp2 knockdown reduces the proliferation and migration of lung cancer cells, and further suggest that co-inhibition of EGFR and Shp2 is an effective approach for overcoming EGFR T790M mutation acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). Thus, we propose that Shp2 could serve as a new biomarker in the treatment of NSCLC.

SHP2 negatively regulates HLA-ABC and PD-L1 expression via STAT1 phosphorylation in prostate cancer cells

Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2) is a ubiquitous protein tyrosine phosphatase that activates the signal transduction pathways of several growth factors and cytokines. In our study, SHP2 expression was very high in prostate cancer (PCa) cell lines, and the expression of phospho-signal transducer and activator of transcription 1 (p-STAT1) and STAT1 was very low. SHP2 knockdown upregulated the expression of p-STAT1 and downregulated phospho-extracellular signal regulated kinase (p-ERK). SHP2 depletion also increased the expression of human leukocyte antigen (HLA)-ABC and programmed death ligand 1 (PD-L1). When tumor cells were pretreated with Janus kinase 2 (JAK2) inhibitor, SHP2 depletion failed to induce HLA-ABC and PD-L1 expression. Furthermore, treating tumor cells with the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitor PD0325901 did not upregulate HLA-ABC and PD-L1. SHP2 depletion was associated with increased T-cell activation (CD25 MFI of CD8⁺) by coculture of allogeneic healthy donor peripheral blood monocytes (PBMC) with SHP2 siRNA pretreated PCa cell lines. These results show that SHP2 targeting upregulates HLA-ABC and PD-L1 expression via STAT1 phosphorylation in PCa cells and SHP2 depletion could increase T-cell activation.

LNDriver: identifying driver genes by integrating mutation and expression data based on gene-gene interaction network

BACKGROUND

Cancer is a complex disease which is characterized by the accumulation of genetic alterations during the patient's lifetime. With the development of the next-generation sequencing technology, multiple omics data, such as cancer genomic, epigenomic and transcriptomic data etc., can be measured from each individual. Correspondingly, one of the key challenges is to pinpoint functional driver mutations or pathways, which contributes to tumorigenesis, from millions of functional neutral passenger mutations.

RESULTS

In this paper, in order to identify driver genes effectively, we applied a generalized additive model to mutation profiles to filter genes with long length and constructed a new gene-gene interaction network. Then we integrated the mutation data and expression data into the gene-gene interaction network. Lastly, greedy algorithm was used to prioritize candidate driver genes from the integrated data. We named the proposed method Length-Net-Driver (LNDriver).

CONCLUSIONS

Experiments on three TCGA datasets, i.e., head and neck squamous cell carcinoma, kidney renal clear cell carcinoma and thyroid carcinoma, demonstrated that the proposed method was effective. Also, it can identify not only frequently mutated drivers, but also rare candidate driver genes.

Relationship between gene mutation and lung cancer metastasis

Cancer is a genetic disease occurring through a multi-step process. Many important genes responsible for the genesis of various cancers have been discovered, their mutations precisely identified and the pathways through which they act characterized. One question that remains unanswered is whether the development of new, more specific therapeutic agents is the best way to minimize cancer morbidity and mortality in the long-term. Metastasis is the relentless pursuit of cancer to escape its primary site and colonize distant organs. Phenotypic changes during cancer progression reflect the sequential accumulation of genetic alterations, which endow cancer cells with the ability to undergo their own divergent evolution and create distinct metastatic species. In order to understand this process, it is crucial to identify genes whose alterations accumulate during cancer progression and correlate with metastatic phenotypes of cancer cells.

Preclinical Modeling of KIF5B-RET Fusion Lung Adenocarcinoma

RET fusions have been found in lung adenocarcinoma, of which KIF5B-RET is the most prevalent. We established inducible KIF5B-RET transgenic mice and KIF5B-RET-dependent cell lines for preclinical modeling of KIF5B-RET-associated lung adenocarcinoma. Doxycycline-induced CCSP-rtTA/tetO-KIF5B-RET transgenic mice developed invasive lung adenocarcinoma with desmoplastic reaction. Tumors regressed upon suppression of KIF5B-RET expression. By culturing KIF5B-RET-dependent BaF3 (B/KR) cells with increasing concentrations of cabozantinib or vandetanib, we identified cabozantinib-resistant RET^V804L mutation and vandetanib-resistant-RET^G810A mutation. Among cabozantinib, lenvatinib, ponatinib, and vandetanib, ponatinib was identified as the most potent inhibitor against KIF5B-RET and its drug-resistant mutants. Interestingly, the vandetanib-resistant KIF5B-RET^G810A mutant displayed gain-of-sensitivity (GOS) to ponatinib and lenvatinib. Treatment of doxycycline-induced CCSP-rtTA/tetO-KIF5B-RET bitransgenic mice with ponatinib effectively induced tumor regression. These results indicate that KIF5B-RET-associated lung tumors are addicted to the fusion oncogene and ponatinib is the most effective inhibitor for targeting KIF5B-RET in lung adenocarcinoma. Moreover, this study finds a novel vandetanib-resistant RET^G810A mutation and identifies lenvatinib and ponatinib as the secondary drugs to overcome this vandetanib resistance mechanism. Mol Cancer Ther; 15(10); 2521-9. ©2016 AACR.

Inhibition of Shp2 suppresses mutant EGFR-induced lung tumors in transgenic mouse model of lung adenocarcinoma

Epidermal growth factor receptor (EGFR) mutants drive lung tumorigenesis and are targeted for therapy. However, resistance to EGFR inhibitors has been observed, in which the mutant EGFR remains active. Thus, it is important to uncover mediators of EGFR mutant-driven lung tumors to develop new treatment strategies. The protein tyrosine phosphatase (PTP) Shp2 mediates EGF signaling. Nevertheless, it is unclear if Shp2 is activated by oncogenic EGFR mutants in lung carcinoma or if inhibiting the Shp2 PTP activity can suppress EGFR mutant-induced lung adenocarcinoma. Here, we generated transgenic mice containing a doxycycline (Dox)-inducible PTP-defective Shp2 mutant (tetO-Shp2CSDA). Using the rat Clara cell secretory protein (CCSP)-rtTA-directed transgene expression in the type II lung pneumocytes of transgenic mice, we found that the Gab1-Shp2 pathway was activated by EGFRL858R in the lungs of transgenic mice. Consistently, the Gab1-Shp2 pathway was activated in human lung adenocarcinoma cells containing mutant EGFR. Importantly, Shp2CSDA inhibited EGFRL858R-induced lung adenocarcinoma in transgenic animals. Analysis of lung tissues showed that Shp2CSDA suppressed Gab1 tyrosine phosphorylation and Gab1-Shp2 association, suggesting that Shp2 modulates a positive feedback loop to regulate its own activity. These results show that inhibition of the Shp2 PTP activity impairs mutant EGFR signaling and suppresses EGFRL858R-driven lung adenocarcinoma.

Overexpression of major CDKN3 transcripts is associated with poor survival in lung adenocarcinoma

Background:

The cyclin-dependent kinase inhibitor 3 (CDKN3) has been perceived as a tumour suppressor. Paradoxically, CDKN3 is often overexpressed in human cancer. It was unclear if CDKN3 overexpression is linked to alternative splicing variants or mutations that produce dominant-negative CDKN3.

Methods:

We analysed CDKN3 expression and its association with patient survival in three cohorts of lung adenocarcinoma. We also examined CDKN3 mutations in the Cancer Genome Atlas (TCGA) and the Moffitt Cancer Center's Total Cancer Care (TCC) projects. CDKN3 transcripts were further analysed in a panel of cell lines and lung adenocarcinoma tissues. CDKN3 mRNA and protein levels in different cell cycle phases were examined.

Results:

CDKN3 is overexpressed in non small cell lung cancer. High CDKN3 expression is associated with poor overall survival in lung adenocarcinoma. Two CDKN3 transcripts were detected in all samples. These CDKN3 transcripts represent the full length CDKN3 mRNA and a normal transcript lacking exon 2, which encodes an out of frame 23-amino acid peptide with little homology to CDKN3. CDKN3 mutations were found to be very rare. CDKN3 mRNA and protein were elevated during the mitosis phase of cell cycle.

Conclusions:

CDKN3 overexpression is prognostic of poor overall survival in lung adenocarcinoma. CDKN3 overexpression in lung adenocarcinoma is not attributed to alternative splicing or mutation but is likely due to increased mitotic activity, arguing against CDKN3 as a tumour suppressor.

Expression and clinical significance of tyrosine phosphatase SHP2 in thyroid carcinoma

Protein-tyrosine phosphatase SHP2 is encoded by the gene PTPN11. SHP2 is hypothesized to have a critical role in cancer, via the activation of mutations that have been detected in several types of leukaemia and in certain solid tumours, including liver, breast, gastric and cervical cancer. However, to the best of our knowledge, there have been no previous reports evaluating the significance of SHP2 expression in thyroid cancer. The present study evaluated SHP2 expression in 65 thyroid cancer specimens, 40 specimens of self-matched adjacent peritumour tissues and 40 specimens of normal thyroid tissue, using immunohistochemical and western blot analyses with an anti-SHP2 antibody. Western blotting was also used to assess SHP2 expression in thyroid cancer cell lines (SW579, IHH-4, FTC-133, TPC-1, DRO, TA-K, and ML-1) and Nthy-ori3-1 normal thyroid cells. In addition, SHP2 antisense oligonucleotides were used to block SHP2 expression in SW579 cells, and growth inhibition assays were conducted. Increased SHP2 expression was detected in the tumour tissues compared with that of the normal thyroid tissues (P<0.05). SHP2 expression was significantly correlated with poor tumour differentiation (P<0.05), late TNM stage (P<0.05) and lymph node metastasis (P<0.05), suggesting that SHP2 may represent a potential target for thyroid cancer therapy.

Functions of Shp2 in cancer

Diagnostics and therapies have shown evident advances. Tumour surgery, chemotherapy and radiotherapy are the main techniques in treat cancers. Targeted therapy and drug resistance are the main focus in cancer research, but many molecular intracellular mechanisms remain unknown. Src homology region 2-containing protein tyrosine phosphatase 2 (Shp2) is associated with breast cancer, leukaemia, lung cancer, liver cancer, gastric cancer, laryngeal cancer, oral cancer and other cancer types. Signalling pathways involving Shp2 have also been discovered. Shp2 is related to many diseases. Mutations in the ptpn11 gene cause Noonan syndrome, LEOPARD syndrome and childhood leukaemia. Shp2 is also involved in several cancer-related processes, including cancer cell invasion and metastasis, apoptosis, DNA damage, cell proliferation, cell cycle and drug resistance. Based on the structure and function of Shp2, scientists have investigated specific mechanisms involved in cancer. Shp2 may be a potential therapeutic target because this phosphatase is implicated in many aspects. Furthermore, Shp2 inhibitors have been used in experiments to develop treatment strategies. However, conflicting results related to Shp2 functions have been presented in the literature, and such results should be resolved in future studies.

Functional short tandem repeat polymorphism of PTPN11 and susceptibility to hepatocellular carcinoma in Chinese populations

Background

PTPN11, which encodes tyrosine phosphatase Shp2, is a critical gene mediating cellular responses to hormones and cytokines. Loss of Shp2 promotes hepatocellular carcinoma (HCC), suggesting that PTPN11 functions as a tumor suppressor in HCC tumorgenesis. The aim of this study was to evaluate the effects of the short tandem repeat (STR) polymorphism (rs199618935) within 3'UTR of PTPN11 on HCC susceptibility in Chinese populations.

Methodology/Principal Findings

We analyzed the associations in 400 patients from Jiangsu province of China, validating the findings in an additional 305 patients from Shanghai of China. Unconditional logistic regression was used to analyze the association between rs199618935 and HCC risk. Additional biochemical investigations and in-silico studies were used to evaluate the possible functional significance of this polymorphism. Logistic regression analysis showed that compared with individuals carrying shorter alleles (11 and 12 repeats), those subjects who carry longer alleles (13 and 14 repeats) had a significantly decreased risk of HCC [adjusted odds ratio (OR)  = 0.63, 95% confidence interval (CI)  = 0.53–0.76, P = 2.00×10⁻⁷], with the risk decreased even further in those carrying allele 15 and 16 (adjusted OR = 0.46, 95% CI = 0.34–0.62, P = 1.00×10⁻⁷). Biochemical investigations showed that longer alleles of rs199618935 conferred higher PTPN11 expression in vivo and in vitro. The altered luciferase activities in reporter gene system suggested that STR regulation of PTPN11 expression could be a transcriptional event. Finally, in-silico prediction revealed that different alleles of rs199618935 could alter the local structure of PTPN11 mRNA.

Conclusions/Significance

Taken together, our findings suggested that the STR polymorphism within PTPN11 contributes to hepatocarcinogenesis, possibly by affecting PTPN11 expression through a structure-dependent mechanism. The replication of our studies and further functional studies are needed to validate our findings.