ErbB receptors as prognostic and therapeutic drug targets in bone and soft tissue sarcomas

Anlotinib destabilizes PAX3-FOXO1 to induce rhabdomyosarcoma cell death via upregulating NEK2

BACKGROUND

Rhabdomyosarcoma (RMS) is one of the most common soft tissue sarcomas in children and adolescents, in which PAX3-FOXO1 fusion gene positive patients have very poor prognosis. PAX3-FOXO1 has been identified as an independent prognostic predictor in RMS, with no currently available targeted therapeutic intervention. The novel tyrosine kinase inhibitor anlotinib exhibits a wide range of anticancer effects in multiple types of cancers; however, there have been no relevant studies regarding its application in RMS.

MATERIALS AND METHODS

We investigated the effects of PAX3-FOXO1 on the therapeutic efficacy of anlotinib using the CCK-8 assay, flow cytometry, invasion assay, wound healing assay, western blotting, quantitative polymerase chain reaction(qPCR), and xenograft experiments. RNA-seq and co-immunoprecipitation assays were conducted to determine the specific mechanism by which anlotinib regulates PAX3-FOXO1 expression.

RESULTS

Anlotinib effectively inhibited RMS cell proliferation and promoted apoptosis and G2/M phase arrest while impeding tumor growth in vivo. Downregulation of PAX3-FOXO1 enhances the antitumor effects of anlotinib. Anlotinib upregulates protein kinase NEK2 and increases the degradation of PAX3-FOXO1 via the ubiquitin-proteasome pathway, leading to a reduction in PAX3-FOXO1 protein levels.

CONCLUSION

Anlotinib effectively inhibited the malignant progression of RMS and promoted degradation of the fusion protein PAX3-FOXO1. Anlotinib could be a targeted therapeutic approach to treat PAX3-FOXO1 fusion-positive RMS.

Drugging Hijacked Kinase Pathways in Pediatric Oncology: Opportunities and Current Scenario

Childhood cancer is considered rare, corresponding to ~3% of all malignant neoplasms in the human population. The World Health Organization (WHO) reports a universal occurrence of more than 15 cases per 100,000 inhabitants around the globe, and despite improvements in diagnosis, treatment and supportive care, one child dies of cancer every 3 min. Consequently, more efficient, selective and affordable therapeutics are still needed in order to improve outcomes and avoid long-term sequelae. Alterations in kinases' functionality is a trademark of cancer and the concept of exploiting them as drug targets has burgeoned in academia and in the pharmaceutical industry of the 21st century. Consequently, an increasing plethora of inhibitors has emerged. In the present study, the expression patterns of a selected group of kinases (including tyrosine receptors, members of the PI3K/AKT/mTOR and MAPK pathways, coordinators of cell cycle progression, and chromosome segregation) and their correlation with clinical outcomes in pediatric solid tumors were accessed through the R2: Genomics Analysis and Visualization Platform and by a thorough search of published literature. To further illustrate the importance of kinase dysregulation in the pathophysiology of pediatric cancer, we analyzed the vulnerability of different cancer cell lines against their inhibition through the Cancer Dependency Map portal, and performed a search for kinase-targeted compounds with approval and clinical applicability through the CanSAR knowledgebase. Finally, we provide a detailed literature review of a considerable set of small molecules that mitigate kinase activity under experimental testing and clinical trials for the treatment of pediatric tumors, while discuss critical challenges that must be overcome before translation into clinical options, including the absence of compounds designed specifically for childhood tumors which often show differential mutational burdens, intrinsic and acquired resistance, lack of selectivity and adverse effects on a growing organism.

EGFR is required for FOS-dependent bone tumor development via RSK2/CREB signaling

Osteosarcoma (OS) is a rare tumor of the bone occurring mainly in young adults accounting for 5% of all childhood cancers. Because of the limited therapeutic options, there has been no survival improvement for OS patients in the past 40 years. The epidermal growth factor receptor (EGFR) is highly expressed in OS; however, its clinical relevance is unclear. Here, we employed an autochthonous c‐Fos‐dependent OS mouse model (H2‐c‐fosLTR) and human OS tumor biopsies for preclinical studies aimed at identifying novel biomarkers and therapeutic benefits of anti‐EGFR therapies. We show that EGFR deletion/inhibition results in reduced tumor formation in H2‐c‐fosLTR mice by directly inhibiting the proliferation of cancer‐initiating osteoblastic cells by a mechanism involving RSK2/CREB‐dependent c‐Fos expression. Furthermore, OS patients with co‐expression of EGFR and c‐Fos exhibit reduced overall survival. Preclinical studies using human OS xenografts revealed that only tumors expressing both EGFR and c‐Fos responded to anti‐EGFR therapy demonstrating that c‐Fos can be considered as a novel biomarker predicting response to anti‐EGFR treatment in OS patients.

A 2015 update on predictive molecular pathology and its role in targeted cancer therapy: a review focussing on clinical relevance

In April 2013 our group published a review on predictive molecular pathology in this journal. Although only 2 years have passed many new facts and stimulating developments have happened in diagnostic molecular pathology rendering it worthwhile to present an up-date on this topic. A major technical improvement is certainly given by the introduction of next-generation sequencing (NGS; amplicon, whole exome, whole genome) and its application to formalin-fixed paraffin-embedded (FFPE) tissue in routine diagnostics. Based on this 'revolution' the analyses of numerous genetic alterations in parallel has become a routine approach opening the chance to characterize patients' malignant tumors much more deeply without increasing turn-around time and costs. In the near future this will open new strategies to apply 'off-label' targeted therapies, e.g. for rare tumors, otherwise resistant tumors etc. The clinically relevant genetic aberrations described in this review include mutation analyses of RAS (KRAS and NRAS), BRAF and PI3K in colorectal cancer, KIT or PDGFR alpha as well as BRAF, NRAS and KIT in malignant melanoma. Moreover, we present several recent advances in the molecular characterization of malignant lymphoma. Beside the well-known mutations in NSCLC (EGFR, ALK) a number of chromosomal aberrations (KRAS, ROS1, MET) have become relevant. Only very recently has the clinical need for analysis of BRCA1/2 come up and proven as a true challenge for routine diagnostics because of the genes' special structure and hot-spot-free mutational distribution. The genetic alterations are discussed in connection with their increasingly important role in companion diagnostics to apply targeted drugs as efficient as possible. As another aspect of the increasing number of druggable mutations, we discuss the challenges personalized therapies pose for the design of clinical studies to prove optimal efficacy particularly with respect to combination therapies of multiple targeted drugs and conventional chemotherapy. Such combinations would lead to an extremely high complexity that would hardly be manageable by applying conventional study designs for approval, e.g. by the FDA or EMA. Up-coming challenges such as the application of methylation assays and proteomic analyses on FFPE tissue will also be discussed briefly to open the door towards the ultimate goal of reading a patients' tissue as 'deeply' as possible. Although it is yet to be shown, which levels of biological information are most informative for predictive pathology, an integrated molecular characterization of tumors will likely offer the most comprehensive view for individualized therapy approaches. To optimize cancer treatment we need to understand tumor biology in much more detail on morphological, genetic, proteomic as well as epigenetic grounds. Finally, the complex challenges on the level of drug design, molecular diagnostics, and clinical trials make necessary a close collaboration among academic institutions, regulatory authorities and pharmaceutical companies.