Gene expression and promoter methylation of angiogenic and lymphangiogenic factors as prognostic markers in melanoma

Abstract

The high mortality rate of melanoma is broadly associated with its metastatic potential. Tumor cell dissemination is strictly dependent on vascularization; therefore, angiogenesis and lymphangiogenesis play an essential role in metastasis. Hence, a better understanding of the players of tumor vascularization and establishing them as new molecular biomarkers might help to overcome the poor prognosis of melanoma patients. Here, we further characterized a linear murine model of melanoma progression and showed that the aggressiveness of melanoma cells is closely associated with high expression of angiogenic factors, such as Vegfc , Angpt2, and Six1, and that blockade of the vascular endothelial growth factor pathway by the inhibitor axitinib abrogates their tumorigenic potential in vitro and in the in vivo chicken chorioallantoic membrane assay. Furthermore, analysis of The Cancer Genome Atlas data revealed that the expression of the angiogenic factor ANGPT2 ( P ‐value = 0.044) and the lymphangiogenic receptor VEGFR‐3 ( P ‐value = 0.002) were independent prognostic factors of overall survival in melanoma patients. Enhanced reduced representation bisulfite sequencing‐based methylome profiling revealed for the first time a link between abnormal VEGFC , ANGPT2, and SIX1 gene expression and promoter hypomethylation in melanoma cells. In patients, VEGFC ( P ‐value = 0.031), ANGPT2 ( P ‐value < 0.001), and SIX1 ( P ‐value = 0.009) promoter hypomethylation were independent prognostic factors of shorter overall survival. Hence, our data suggest that these angio‐ and lymphangiogenesis factors are potential biomarkers of melanoma prognosis. Moreover, these findings strongly support the applicability of our melanoma progression model to unravel new biomarkers for this aggressive human disease.

The lymphatic vasculature: An active and dynamic player in cancer progression

“…For example, metastatic cutaneous melanomas were characterized by higher intratumoral and peritumoral LVD when compared to non‐metastatic tumors 287 . This is in line with the observation that the overexpression of VEGF‐C and ANG2 correlated with a poorer prognosis in melanoma patients 288,289 . In addition, a multivariate risk analysis conducted on primary tumors and sentinel LN biopsies from 45 melanoma patients revealed that the lymphatic vascular area of primary melanomas was an extremely sensitive and specific prognostic marker for the occurrence of tumor‐draining LN metastasis and could predict the metastatic phenotype more accurately than measurements of tumor thickness measuring 290 .…”

Transcriptional signatures underlying dynamic phenotypic switching and novel disease biomarkers in a linear cellular model of melanoma progression

“…The murine model of melanoma progression has been previously described [ 6 , 7 , 8 , 10 , 11 , 12 , 13 , 14 ] and comprises spontaneously immortalized nonmalignant melanocytes (melan-a) [5] and 3 cell lines with increasing malignant potential (4C, 4C11- and 4C11+) derived from melan-a following sequential cycles of forced anchorage impediment. Briefly, anoikis -resistant yet still nontumorigenic cells (named 4C) were obtained after subjecting melan-a melanocytes to 4 cycles of de-adhesion/adhesion.…”

The Challenging Melanoma Landscape: From Early Drug Discovery to Clinical Approval

“…In addition to the aforementioned in vivo models, there is a panoply of other animal species that can be used to study melanoma. A relevant model is the chicken chorioallantoic membrane that consists of a highly vascularized extra-embryonic membrane [278,297]. The good visibility, accessibility, and cost-effectiveness of this model turns it a suitable candidate for evaluating cancer biology as well as performing HTS in vivo.…”