No abstract

Abstract. insulin-like growth factor 2 (igf2) and 1 (igf1) and insulin (inS) promote proliferation of rhabdomyosarcoma (rMS) cells by interacting with the insulin-like growth factor 1 receptor (igf1r) and the insulin receptor (inSr). loss of imprinting (loi) by Dna hypermethylation at the differentially methylated region (DMr) for the igf2-H19 locus is commonly observed in rMS cells and results in an increase in the expression of proliferation-promoting igf2 and downregulation of proliferation-inhibiting non-coding H19 mirnas. one of these mirnas, mir-675, has been reported in murine cells to be a negative regulator of igf1r expression. to better address the role of igf2 and 1, as well as inS signaling in the pathogenesis of rMS and the involvement of loi at the igf2-H19 locus, we employed the Dna demethylating agent 5-azacytidine (azac). We observed that azac-mediated demethylation of the DMr at the igf2-H19 locus resulted in downregulation of igf2 and an increase in the expression of H19. this epigenetic change resulted in a decrease in rMS proliferation due to downregulation of igf2 and, igf1r expression in an mir-675-dependent manner. interestingly, we observed that mir-675 not only inhibited the expression of igf1r in a similar manner in human and murine cells, but we also observed its negative effect on the expression of the INSR. These results confirm the crucial role of loi at the igf2-H19 DMr in the pathogenesis of rMS and are relevant to the development of new treatment strategies.

BackgroundLow calorie intake, or calorie restriction (CR) without malnutrition, has been demonstrated in several animal species, including mice, to increase both median and maximum lifespan as well as delay reproductive senescence. Our previous work demonstrated a positive correlation between life span and the number of very small embryonic-like stem cells (VSELs) in long living Laron dwarf mice. These animals have very low levels of circulating insulin-like growth factor 1 (IGF-1) in peripheral blood (PB), maintain higher numbers of hematopoietic stem cells (HSPCs) in bone marrow (BM), and display prolonged fecundity compared with wild type littermates. Since CR lowers the level of IGF-1 in PB, we become interested in the effect of CR on the number of VSELs and HSPCs in BM as well as on the morphology of ovaries and testes.MethodsIn our studies four-week-old female and male mice were subjected to CR by employing an alternate-day ad libitum feeding diet for a period of 9 months.ResultsWe observed that mice on CR had a higher number of BM-residing VSELs than control mice fed ad libitum. These changes correlated with higher numbers of HSPCs in BM, spleen, and peripheral blood (PB) as well as with an increase in the number of primordial and primary follicles in ovaries. At the same time, however, no changes were observed in the testes of mice under CR.ConclusionWe conclude that CR positively affects the pool of VSELs in adult tissues and explains the positive effect of CR on longevity.

Rhabdomyosarcoma (RMS) is a malignant soft tissue cancer that develops mostly in children and young adults. With regard to histopathology, four rhabdomyosarcoma types are distinguishable: embryonal, alveolar, pleomorphic and spindle/sclerosing. Currently, increased amounts of evidence indicate that not only gene mutations, but also epigenetic modifications may be involved in the development of RMS. Epigenomic changes regulate the chromatin architecture and affect the interaction between DNA strands, histones and chromatin binding proteins, thus, are able to control gene expression. The main aim of the study was to assess the role of protein arginine methyltransferases (PRMT) in the cellular biology of rhabdomyosarcoma. In the study we used two pan-inhibitors of PRMT, called AMI-1 and SAH, and evaluated their effects on proliferation and apoptosis of RMS cells. We observed that AMI-1 and SAH reduce the invasive phenotype of rhabdomyosarcoma cells by decreasing their proliferation rate, cell viability and ability to form cell colonies. In addition, microarray analysis revealed that these inhibitors attenuate the activity of the PI3K-Akt signaling pathway and affect expression of genes related to it.

BackgroundInsulin-like growth factors and insulin are important factors promoting cancer growth and metastasis. The molecules act through IGF1 (IGF1R) and insulin (InsR) receptors. Rhambodmyosarcomas (RMS) overproduce IGF2 – a potent ligand for IGF1R and, at the same time, highly express IGF1 receptor. The purpose of the study was to evaluate possible application of picropodophyllin (PPP) – a potent IGF1R inhibitor.MethodsIn our study we used a number of in vitro assays showing influence of IGF1R blockage on RMS cell lines (both ARMS and ERMS) proliferation, migration, adhesion, cell cycling and signal transduction pathways. Additionally, we tested possible concomitant application of PPP with commonly used chemotherapeutics (vincristine, actinomycin-D and cisplatin). Moreover, we performed an in vivo study where PPP was injected intraperitoneally into RMS tumor bearing SCID mice.ResultsWe observed that PPP strongly inhibits RMS proliferation, chemotaxis and adhesion. What is more, application of the IGF1R inhibitor attenuates MAPK phosphorylation and cause cell cycle arrest in G2/M phase. PPP increases sensitivity of RMS cell lines to chemotherapy, specifically to vincristine and cisplatin. In our in vivo studies we noted that mice treated with PPP grew smaller tumors and displayed significantly decreased seeding into bone marrow.ConclusionsThe cyclolignan PPP effectively inhibits RMS tumor proliferation and metastasis in vitro and in an animal model.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-017-3495-y) contains supplementary material, which is available to authorized users.