The role of hypoxia related angiogenesis in uterine smooth muscle tumors

Abstract

Mechanisms of hypoxia-related angiogenesis are important for uterine smooth muscle tumors. Factors that are related to angiogenesis during hypoxia include vascular endothelial growth factor (VEGF), hypoxia inducible factor 1α (HIF1α), T-cell intracellular antigen1 (TIA1), eukaryotic translation initiation factor 2α (eIF2α) and thrombospondin 1 (TSP1). We investigated immunoreactivities of VEGF, HIF1α, TIA1, eIF2α and TSP1 using an indirect immunoperoxidase method for formalin fixed, paraffin embedded tumors that had been diagnosed as leiomyoma (LMY), cellular leiomyoma (CLM) or leiomyosarcoma (LMS). TSP1 immunoreactivity was scored as moderate, mild or minimal, while VEGF, eIF2α and TIA1 immunoreactivities were scored as mild, moderate and strong in LMY, CLM and LMS samples, respectively. HIF1α immunoreactivity was scored as mild to minimal in LMY, CLM and LMS samples, but showed no statistically significant differences among samples. Although angiogenic factors showed strong immunohistochemical staining intensity in LMS, anti-angiogenic factors showed minimal immunohistochemical intensity. There was no difference in HIF-1α immunoreactivity compared to LMY, CLM and LMS samples. We suggest that HIF1α protein synthesis could be suppressed by eIF2α and TIA1. Furthermore, VEGF could be activated by pathways such as COX2, Ras, NF-ĸB or c-myc instead of HIF1α. Angiogenesis could trigger and accelerate tumor development; therefore, anti-angiogenic therapy could be useful for treatment of tumors.