IGF2 is highly expressed in pediatric undifferentiated sarcomas and reveals two distinct cytoplasmic trafficking patterns

Synergic Action of Insulin-like Growth Factor-2 and miRNA-483 in Pterygium Pathogenesis

Pterygium is a multifactorial disease in which UV-B is speculated to play a key role by inducing oxidative stress and phototoxic DNA damage. In search for candidate molecules that are useful for justifying the intense epithelial proliferation observed in pterygium, our attention has been focused on Insulin-like Growth Factor 2 (IGF-2), mainly detected in embryonic and fetal somatic tissues, which regulate metabolic and mitogenic functions. The binding between IGF-2 and its receptor Insulin-like Growth Factor 1 Receptor (IGF-1R) activates the PI3K-AKT pathway, which leads to the regulation of cell growth, differentiation, and the expression of specific genes. Since IGF2 is regulated by parental imprinting, in different human tumors, the IGF2 Loss of Imprinting (LOI) results in IGF-2- and IGF2-derived intronic miR-483 overexpression. Based on these activities, the purpose of this study was to investigate the overexpression of IGF-2, IGF-1R, and miR-483. Using an immunohistochemical approach, we demonstrated an intense colocalized epithelial overexpression of IGF-2 and IGF-1R in most pterygium samples (Fisher's exact test, p = 0.021). RT-qPCR gene expression analysis confirmed IGF2 upregulation and demonstrated miR-483 expression in pterygium compared to normal conjunctiva (253.2-fold and 12.47-fold, respectively). Therefore, IGF-2/IGF-1R co-expression could suggest their interplay through the two different paracrine/autocrine IGF-2 routes for signaling transfer, which would activate the PI3K/AKT signaling pathway. In this scenario, miR-483 gene family transcription might synergically reinforce IGF-2 oncogenic function through its boosting pro-proliferative and antiapoptotic activity.

Transformation of a primitive myxoid mesenchymal tumor of infancy to an undifferentiated sarcoma: a first reported case

An 8-month-old girl underwent surgical resection of a cervical mass with histologic diagnosis of a primitive myxoid mesenchymal tumor of infancy (PMMTI). More than 5 years after the initial surgical intervention, the tumor recurred locally, with numerous distant metastases. The histologic morphology of this tumor was compatible with a diagnosis of an undifferentiated high-grade sarcoma. PMMTI is a recently described poorly differentiated fibroblastic soft-tissue tumor of infancy, of at least borderline biological behavior, characterized by local recurrence and a potential to metastasize. We present here the first case of a transformation of a PMMTI into an undifferentiated high-grade sarcoma.

Evaluation of the expression and role of IGF pathway biomarkers in human sarcomas

Recent studies have shown that insulin-like growth factor (IGF) signaling components have been involved in the pathogenesis and progression of different types of sarcomas. There has been some evidence to indicate the differential expression of IGF2 and insulin-like growth factor 1 receptor (IGF1R) in human sarcomas. The present study utilized immunohistochemistry (IHC) and in situ hybridization (ISH) to determine the expression of IGF2 and IGF1R in eighty-two cases of human sarcoma specimens and eight cases of non-tumor tissue (NTT). IGF2/IGF1R signaling was blocked by recombinant adenovirus-mediated IGF1R small hairpin RNA (shIGF1R), which was used to transfect into human osteosarcoma (OS) MG-63 cells. The expression of IGF2, IGF1R, matrix metallopeptidase-2 (MMP-2) and MMP-9 was detected by Real-time PCR. Cell migration was evaluated by wound healing assay. As a consequence, the expression of IGF1R and IGF2 was found in human OS with higher strong reactivity rate compared with the NTT (85.0 percent vs 50.0 percent, P=0.022; 95.0 percent vs 100.0 percent, P=0.042), elevating with the ascending order of tumor malignancy. Also, IGF1R had differential expression in different types of sarcomas (P=0.002), while IGF2 had no significant difference (P=0.105). Targeted blockade of IGF2/IGF1R signaling decreased the expression of IGF2, IGF1R, and MMP-2/-9, and diminished the migration capabilities of MG-63 cells. In conclusion, IGF1R is differentially-expressed in different types of human sarcomas, and targeted blockade of IGF1R pathway may inhibit human OS migration through down-regulation of MMP-2/-9 expression. IGF1R pathway may represent a significant therapeutic modality for the treatment of sarcomas.

IGF2 mRNA binding protein p62/IMP2-2 in hepatocellular carcinoma: antiapoptotic action is independent of IGF2/PI3K signaling

The insulin-like growth factor II (IGF2) mRNA binding protein (IMP) p62/IMP2-2, originally isolated from a hepatocellular carcinoma (HCC) patient, induces a steatotic phenotype when overexpressed in mouse livers. Still, p62 transgenic livers do not show liver cell damage but exhibit a pronounced induction of Igf2 and activation of the downstream survival kinase AKT. The aim of this study was to investigate the relation between p62 and IGF2 expression in the human system and to study potential antiapoptotic actions of p62. p62 and IGF2 mRNA levels were assessed by real-time RT-PCR. For knockdown and overexpression experiments, human hepatoma HepG2 and PLC/PRF/5 cells were transfected with siRNA or plasmid DNA. Phosphorylated AKT and ERK1/2 were analyzed by Western blot. Investigations of 32 human HCC tissues showed a strong correlation between p62 and IGF2 expression. Of note, p62 expression was increased markedly in patients with poor outcome. In hepatoma cells overexpression of p62 lowered levels of doxorubicin-induced caspase-3-like activity. Vice versa, knockdown of p62 resulted in increased doxorubicin-induced apoptosis. However, neither PI3K inhibitors nor a neutralizing IGF2 antibody showed any effects. Western blot analysis revealed increased levels of phosphorylated ERK1/2 in hepatoma cells overexpressing p62 and decreased levels in p62 knockdown experiments. When p62-overexpressing cells were treated with ERK1/2 inhibitors, the apoptosis-protecting effect of p62 was completely abrogated. Our data demonstrate that p62 exerts IGF2-independent antiapoptotic action, which is facilitated via phosphorylation of ERK1/2. Furthermore, p62 might serve as a new prognostic marker in HCC.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Immunohistochemical expression and cluster analysis of mesenchymal and neural stem cell-associated proteins in pediatric soft tissue sarcomas

Pediatric undifferentiated soft tissue sarcomas (USTSs) are a group of malignancies composed predominantly of primitive round cell sarcomas, the histogenesis of which is uncertain. Thus, diagnosis and therapy remain a challenge. The aims of the current study were to determine whether differential expression of stem cell-associated proteins could be used to aid in determining the histogenesis of pediatric USTSs and to determine whether pediatric USTSs expressed a unique panel of stem cell-associated proteins to aid diagnosis. Tumors included 28 Ewing sarcoma/primitive neuroectodermal tumors (ESs), 22 embryonal rhabdomyosarcomas (ERMSs), 8 alveolar rhabdomyosarcomas (ARMSs), 5 synovial sarcomas (SSs), 5 malignant peripheral nerve sheath tumors (MPNSTs), and 13 USTSs. Stem cell antibodies included 3 mesenchymal stem cell markers (CD44, CD105, and CD166) and 5 neural stem cell markers (CD15, CD29, CD56, CD133, and nestin). Sections were scored followed by statistical analysis, clustering analysis, and visualizations using Partek Genomic Suite Software. The Euclidean clustering divided the tumors into 2 major groups. ESs and USTSs formed the majority of the 1st group, whereas ERMSs, ARMSs, MPNSTs, and SSs formed the 2nd group. Reduced expression of CD56 was strongly associated with the ES/USTS cluster (P < 0.0001). ESs and USTSs were further separated by CD166 staining, wherein increased expression was associated with ES (P < 0.0001). The 2nd group included the majority of other sarcomas, with no consistent separation between subtypes. The current study demonstrates the usefulness of applying stem cell markers to pediatric sarcomas and indicates that USTSs and ESs are closely related and may share a common histogenesis.