Tumor angiogenesis is one of the most important hallmarks of cancer, which enables its development, progression and metastasis.14 Osteosarcoma http://www.selleckchem.com/products/Sunitinib-Malate-(Sutent).html is a heterogeneous disease with tumors that express a variety of aberrant proteins of angiogenesis.15�C17 Current blood tests that identify circulating tumor antigens associated with angiogenesis are elevated most commonly in patients with metastatic disease and appear to reflect tumor bulk. They are too insensitive to be used for screening and early diagnosis of primary osteosarcoma.18 Angiogenesis analysis of peripheral blood serum shows the presence of biomarkers that characterize cancer. Proangiogenic factors are found in the serum osteosarcoma patients, ie, vascular endothelial growth factor (VEGF), placental growth factor (PLGF), basic fibroblast growth factor (bFGF) and angiogenin (ANG).
7,18�C20 Elevated levels of serum ANG, VEGF, PLGF and bFGF are also valuable diagnostic parameters.7,21,22 However, because of the difficulties in general standardization, this parameter may be difficult to interpret in younger patients.23�C27 ANG is the unique factor for all mammals.28,29 Human ANG is a single chain, non-glycosylated polypeptide of 14.4 kDa.30,31 ANG shows 33% homology to ribonuclease A. The homology of human and bovine ANG is 65% at the protein level. The ANG gene has been called RNASE5 (ribonuclease A family 5). ANG is homologous with pancreatic ribonuclease (RNASE1) and yeast RNASE1. The understanding that the growth of tumors is dependent on angiogenesis has led to the development of new approaches to treatment and new agents directed at tumor vasculature.
7,32 The expression of ANG is currently regarded as the major proangiogenic factor for most types of human cancer. ANG displays multiple physiological and pathological functions by targeting both vascular and non-vascular systems.6,33,34 In contrast to the detection of serum tumor angiogenic antigens, the detection of natural serum immunoglobin M (IgM) antibodies to tumor-associated antigen may provide reliable markers for osteosarcoma diagnosis and prognosis.20,35�C38 Natural IgM antibodies to tumor-associated antigens circulate in the blood much earlier than serum antigen.39�C41 Natural IgM antibodies produced against such tumor-associated antigens of angiogenesis may provide an in vivo amplification of an early carcinogenic signal and therefore may allow earlier detection of cancer than current methods allow.
42 Natural IgM antibodies to tumor antigens have been reported in patients with early-stage cancer, and a panel of serum Batimastat antibodies can detect cancer many years prior to radiograph detection.4,35,43�C45 Early tumor detection is a key to ensure effective treatment. The immune system thus may play a role in preventing osteosarcoma by destroying cancer cells soon after they arise or by destroying viruses that lead to cancer or both.