Osteosarcoma remains a leading cause of cancer death in adolescents. Treatment paradigms and survival rates have not improved in two decades. Driving the lack of therapeutic inroads, the molecular etiology of osteosarcoma remains elusive. MicroRNAs (miRNAs) have demonstrated far-reaching effects on the cellular biology of development and cancer. Their role in osteosarcomagenesis remains largely unexplored. Here we identify for the first time an miRNA signature reflecting the pathogenesis of osteosarcoma from surgically procured samples from human patients. The signature includes high expression of miR-181a,miR-181b, and miR-181c as well as reduced expression of miR-16, miR-29b, and miR-142-5p. We also demonstrate that miR-181b and miR-29b exhibit restricted expression to distinct cell populations in the tumor tissue. Further, higher expression of miR-27a and miR-181c* in pre-treatment biopsy samples characterized patients who developed clinical metastatic disease. In addition, higher expression of miR-451 and miR-15b in pre-treatment samples correlated with subsequent positive response to chemotherapy. In vitro and in vivo functional validation in osteosarcoma cell lines confirmed the tumor suppressive role of miR-16 and the pro-metastatic role of miR-27a. Furthermore, predicted target genes for miR-16 and miR-27a were confirmed as down-regulated by real-time PCR. Affymetrix array profiling of cDNAs from the osteosarcoma specimens and controls were interrogated according to predicted targets of miR-16, miR142-5p, miR-29b, miR-181a/b, and miR-27a. This analysis revealed positive and negative correlations highlighting pathways of known importance to osteosarcoma, as well as novel genes. Thus, our findings establish a miRNA signature associated with pathogenesis of osteosarcoma as well as critical pre-treatment biomarkers of metastasis and responsiveness to therapy.

https://cancerres.aacrjournals.org/content/canres/72/7/1865.full.pdf

miRNA Signatures Associate with Pathogenesis and Progression of Osteosarcoma

During bone homeostasis, osteoblast and osteoclast differentiation is coupled and regulated by multiple signaling pathways and their downstream transcription factors. Here, we show that microRNA 34 (miR-34) is significantly induced by BMP2 during osteoblast differentiation. In vivo, osteoblast-specific gain of miR-34c in mice leads to an age-dependent osteoporosis due to the defective mineralization and proliferation of osteoblasts and increased osteoclastogenesis. In osteoblasts, miR-34c targets multiple components of the Notch signaling pathway, including Notch1, Notch2 and Jag1 in a direct manner, and influences osteoclast differentiation in a non-cell-autonomous fashion. Taken together, our results demonstrate that miR-34c is critical during osteoblastogenesis in part by regulating Notch signaling in bone homeostasis. Furthermore, miR-34c-mediated post-transcriptional regulation of Notch signaling in osteoblasts is one possible mechanism to modulate the proliferative effect of Notch in the committed osteoblast progenitors which may be important in the pathogenesis of osteosarcomas. Therefore, understanding the functional interaction of miR-34 and Notch signaling in normal bone development and in bone cancer could potentially lead to therapies modulating miR-34 signaling.

/pdf/mirna-34c-regulates-notch-signaling-during-bone-development-3k0efv2jca.pdf

miRNA-34c regulates Notch signaling during bone development

Background
MicroRNAs (miRNAs) are a class of endogenously expressed, small noncoding RNAs, which suppress its target mRNAs at the post-transcriptional level. Studies have demonstrated that miR-34a, which is a direct target of the p53 tumor suppressor gene, functions as a tumor suppressor and is associated with the tumor growth and metastasis of various human malignances. However, the role of miR-34a in osteosarcoma has not been totally elucidated. In the present study, the effects of miR-34a on osteosarcoma and the possible mechanism by which miR-34a affected the tumor growth and metastasis of osteosarcoma were investigated.

/pdf/microrna-34a-inhibits-the-proliferation-and-metastasis-of-y8px5tt6re.pdf

MicroRNA-34a Inhibits the Proliferation and Metastasis of Osteosarcoma Cells Both In Vitro and In Vivo

MicroRNA miR-34a is recognized as a master regulator of tumor suppression. The strategy of miR-34a replacement has been investigated in clinical trials as the first attempt of miRNA application in cancer treatment. However, emerging outcomes promote the re-evaluation of existing knowledge and urge the need for better understanding the complex biological role of miR-34a. The targets of miR-34a encompass numerous regulators of cancer cell proliferation, survival and resistance to therapy. MiR-34a expression is transcriptionally controlled by p53, a crucial tumor suppressor pathway, often disrupted in cancer. Moreover, miR-34a abundance is fine-tuned by context-dependent feedback loops. The function and effects of exogenously delivered or re-expressed miR-34a on the background of defective p53 therefore remain prominent issues in miR-34a based therapy. In this work, we review p53-independent mechanisms regulating the expression of miR-34a. Aside from molecules directly interacting with MIR34A promoter, processes affecting epigenetic regulation and miRNA maturation are discussed. Multiple mechanisms operate in the context of cancer-associated phenomena, such as aberrant oncogene signaling, EMT or inflammation. Since p53-dependent tumor-suppressive mechanisms are disturbed in a substantial proportion of malignancies, we summarize the effects of miR-34a modulation in cell and animal models in the clinically relevant context of disrupted or insufficient p53 function.

/pdf/alternative-mechanisms-of-mir-34a-regulation-in-cancer-569kgs2tvc.pdf

Alternative mechanisms of miR-34a regulation in cancer.

MicroRNAs in the Pathogenesis of Cancer

Functional elucidation of MiR-34 in osteosarcoma cells and primary tumor samples.

Observation of circulation in replanted severed fingers often relies on the clinical experience of the doctor. This article discusses nail fold capillary loops (NFCL) observation in the monitoring of the perfusion and circumfluence of replanted digits. In our study, 30 patients with a total of 39 replanted digits were selected. The WX-9A900 Microcirculation Checkout System (MCS) was adopted to perform evaluation of circulation postoperatively. The digits were monitored by clinical examination and MCS at 5- to 7-h intervals for 24 h and then at 2-days intervals for 14 days. Our results showed that seven digits were observed with inadequate venous circumfluence, and large, long NFCL presented within 6-12 h postoperatively. Among the replanted digits, two replants resulted in venous crisis that did respond to an arterial interdiction test, and needed venous grafts. Two digits were observed to have insufficient arterial supply, one of which resulted in arterial crisis. In this case, NFCL could not be observed and had no response to vein interdiction test. This case needed venous graft to rebuild blood perfusion, and survived eventually. We concluded therefore, that compared with the former studies, NFCL correlates closely with the perfusion and circumfluence of the replanted digits. MCS is noninvasive, reliable, and a direct method in postoperative monitoring of digit replanted.

Wei Lu

Papers

Functional elucidation of MiR-34 in osteosarcoma cells and primary tumor samples.

Nail fold capillary observation in replanted severed fingers