Correlation Between The Expression Of Laminin-5γ2, Angiopoietin-2 And Vasculogenic Mimicry In Mouse Malignant Melanoma

OBJETIVE:The animal modle of malignant melanoma with vasculogenic mimicry were erected and study the morphologic structure of vasculogenic mimicry.To study the relationship between Laminin-5y2, Angiopoietin-2 secreted by the tumor cells and vasculogenic mimicry (VM).METHODS:B16 melanoma cell was incubated in the BALB/C mouse's armpit subcutaneouly and the vasculogenic mimicry would be verify to exist in the tumor tissue and the structure was clarified with microscopy and transmission electron microscope . The expressions of Laminin-5γ2, Angiopoietin-2 protein was detected by using immunohistochemical(SP) method.RESULT: (1)The melanoma appeared in the BALB/C and vasculogenic mimicry also appear in the melanoma . The wall of vasculogenic mimicry was composed of tumor cells without endoehelialcells and red blood cells lay in the channel of vasculogenic mimicry .And the basement membrane of VM was PAS positive.(2)The rate of Laminin-5y2 protein expression in malignant melanoma was 73.8% (31/42) , and was correlated to the volume of tumor. The expressions in early growth (diameter0.05).(7)The rate of CD31 expression of malignant melanoma cells in vasculogenic mimicry have been verified to exist in the tumor tissue was 69.7% (23/33) . There was positive correlation between CD31 and exsiting of vasculogenic mimicry in malignant melanoma (P<0.05).(8)There was no correlation between Laminin-5y2 protein and Angiopoietin-2 protein in malignant melanoma (P>0.05).(9)There was positive correlation between Laminin-5y2 protein and CD31 expression of some melanoma cells in tumor tissue (P<0.05).(lO)There was positive correlation between Angiopoietin-2 protein and CD31 expression of some melanoma cells in tumor tissue (P<0.05).CONCLUSIONS:(l)The animal experiment, microscopy andtransmission electron microscope proved that vasculogenic mimicry exists in malignant melanoma. Tumors contained PAS-positive back-to-back loops and networks. By conventional hematoxylin-eosin stains and with high magnification, the PAS-positive loops were seen to have a solid component in some areas which splayed open to reveal hollow channels, some of which contained red blood cells, and vascular spaces was not lined by an endothelium, replaced by tumor cells. These PAS-positive patterns were presumed to be associated with the tumor microcirculation for several reasons.(2)Vasculogenic mimicry describes a process where aggressive tumor cells in three-dimensionalmatrices mimic embryonic vasculogenesis by formin extracellular matrix (ECM)-rich, patterned tubular networks.Melanoma cell secretion periodic acid Schiff positive material and CD31 antigen take part in the process of matrix remodeling . (3)Vasculogenic mimicry requires the cooperative interaction of two material. The product of Laminin-5 gamma 2 chain fragment and tumor cell secretion CD31 antigen take part in process of vasculogenic mimicry.(4)Angiopoietin-2 plays an important role in the progress of angiogenesis,tumor growth.The increased expression in mouse malignant melanoma showed high invasion.(5)The melanoma of BALB/C mice are ideal tumor models that havethe high rates of bearing tumor .It was a good way to study the vasculogenic mimicry that B16 melanoma cell was incubated in BALB/C.