A Novel Model of Metastatic Conjunctival Melanoma in Immune-Competent Mice

Abstract

PURPOSE. Conjunctival melanoma (CM) is an ocular surface tumor that can lead to fatal metastases. Patients developing, tumor-associated lymphangiogenesis have a significantly increased risk of metastatic disease, because tumor spread primarily occurs via lymphatic vessels to the draining lymph node. Here, we describe a novel immune-competent mouse model of CM that displays tumor-associated lymphangiogenesis with development of metastatic tumors.METHODS. C57BL/6N mice received C57BL/6N-derived dermal melanoma cells (hepatocyte growth factor [HGF] cyclin dependent kinase-4 [Cdk4]þ) or B16F10 via subconjunctival injection. A clinical score quantified primary tumor growth and metastases were identified by macroscopic examination of the draining lymph nodes, lung, and spleen. Confirmation of tumors and metastases was achieved by immunohistochemical staining for markers of pigmented cells (tyrosinase related protein-2 [TRP2]) and S-100, and of cell proliferation (Ki67). The intra-and peritumoral CD31þ blood and lymphatic vessel endothelium hyaluronan receptor-1 (LYVE-1)þ lymphatic vessels were quantified immunohistochemically.RESULTS. All mice rapidly developed aggressive TRP2þ, S100þ, and Ki67þ CM. Metastatic tumors were found in the lymph node (9%) and lung (6%) of HGF-Cdk4 R24C -treated mice and in the spleen (8%) and lung (17%) of B16F10-treated mice. The amount of peri-and intratumoral blood vessels was significantly increased compared with lymphatic vessels.CONCLUSIONS. This CM model in immune-competent animals offers new possibilities to study the pathobiology of tumor growth, invasion, and mechanisms of metastatic tumor spread, and provides a robust model to explore new immune-based and antilymphangiogenic treatment modalities of this malignancy.Keywords: conjunctival melanoma, mouse model, (lymph)-angiogenesis, ocular melanoma, B16F10, hepatocyte growth factor, metastasis C onjunctival melanoma (CM) is the second most common malignancy of the ocular surface. The current treatment of primary CM is complete surgical removal of the tumor combined with adjuvant therapy in terms of radio-, cryo-, topical chemo-, and/or immunotherapy. However, even though surgical specimens indicate intact tumor-negative margins and apparent tumor removal, CM patients still display an unusually high rate of local recurrence (36%-62% of patients [1][2][3][4][5][6] ). Tumor recurrence coincides with a high risk for the development of metastases, which occurs in 12% to 25% of patients. [1][2][3] Metastatic tumors in CM patients are typically first detected in the lymph nodes draining the tumor-containing eye, indicating the primary route of tumor cell dissemination occurs via the lymphatic vessels. In support of this, we previously demonstrated that lymphangiogenesis is associated with the transition of premalignant precursors into CM.7 Moreover, the extent of lymphatic vessels within CM coincided with an increased risk of local recurrence, lymphatic spread of tumor cells, and development of metastatic disease. [8][9][10] Melanomas ar...

Evaluation of (fli:GFP) Casper Zebrafish Embryos as a Model for Human Conjunctival Melanoma

“…15,16 Mice have previously been used as a model to study human CM, 17,18 but there are some limitations. The major disadvantages are a slow growth and spread of the tumor, which can take weeks to months, and the high cost for reproduction and housing.…”

Neue adjuvante Therapien beim okulären Melanom

“…Die konjunktivalen und uvealen Melanomzellen produzieren prolymphangiogene Wachstumsfaktoren, insbesondere Moleküle der VEGF-Familie [23,24]. Neben bestehenden Modellen für das Uveamelanom konnten wir ein Mausmodell des malignen Melanoms der Konjunktiva (Bindehaut) in immunkompetenten Mäusen erstmals etablieren [25]. Im fortgeschrittenen Tumorwachstum entwickelten diese Mäuse lokale und Fernmetastasen in verschiedenen Organen.…”

“…Darüber hinaus sind diese Mäuse immunkompetent und bieten somit ein potenzielles Modell zur Testung eines immunmodulierenden Therapieansatzes. Wir konnten zeigen, dass sich tumorinduzierte Lymphgefäße und melanomassoziierte Immunzellinfiltrate, insbesondere Makrophagen und T-Lymphozyten, im murinen Tumorgewebe in unmittelbarer Nachbarschaft befinden [25]. Diese stromale Interaktion beobachteten wir nicht nur im Tiermodell, sondern auch im gesunden Humangewebe des Auges sowie klinisch bei einem Patienten mit intraokulärer Metastase [26][27][28].…”

Systemic BRAF/MEK Inhibitors as a Potential Treatment Option in Metastatic Conjunctival Melanoma

“…In case of metastasis, both types of tumor usually spread to the regional lymph nodes first, while UM primarily metastasizes hematogenously to the liver [5,8,9,10,27,28,29,30,31,32,33]. Both CM and skin melanoma are highly positive for S100 on immunohistochemical staining.…”

“…In UM, however, S100 expression has been shown to be significantly lower than in CM. Furthermore, serum levels of S100 can also serve as a prognostic marker in skin melanoma [27,28,29,30,31,32,33,34,35,36]. Other pigment markers that have been assessed with regard to their labeling of skin melanoma, CM, or UM are tyrosinase, p75 NTR (p75 neurotrophin receptor), HMB (human melanoma black)-45, HMB-50, melan-A, and microphthalmia-associated transcription factor [34,36].…”