RESUMO
In order to metastasize, cancer cells need to acquire a motile phenotype. Previously, development of this phenotype was thought to rely on the acquisition of selected, random mutations and thus would occur late in cancer progression. However, recent studies show that cancer cells disseminate early, implying the existence of a different, faster route to the metastatic motile phenotype. Using a spontaneous murine model of melanoma, we show that a subset of bone marrow-derived immune cells (myeloid-derived suppressor cells or MDSC) preferentially infiltrates the primary tumor and actively promotes cancer cell dissemination by inducing epithelial-mesenchymal transition (EMT). CXCL5 is the main chemokine attracting MDSC to the primary tumor. In vitro assay using purified MDSC showed that TGF-ß, EGF, and HGF signaling pathways are all used by MDSC to induce EMT in cancer cells. These findings explain how cancer cells acquire a motile phenotype so early and provide a mechanistic explanation for the long recognized link between inflammation and cancer progression.
Assuntos
Transição Epitelial-Mesenquimal , Melanoma Experimental/patologia , Neoplasias Cutâneas/secundário , Neoplasias Uveais/patologia , Animais , Movimento Celular , Proliferação de Células , Quimiocinas/genética , Quimiocinas/metabolismo , Perfilação da Expressão Gênica , Granulócitos/metabolismo , Granulócitos/patologia , Oxirredutases Intramoleculares/metabolismo , Pulmão/metabolismo , Pulmão/patologia , Linfonodos/metabolismo , Linfonodos/patologia , Melanoma Experimental/metabolismo , Camundongos , Camundongos Transgênicos , Fator de Transcrição Associado à Microftalmia/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Interleucina-8B/metabolismo , Neoplasias Cutâneas/metabolismo , Células Tumorais Cultivadas , Neoplasias Uveais/metabolismoRESUMO
Resection of infiltrated tumor-draining lymph nodes (TDLNs) is a standard practice for the treatment of several cancers including breast cancer and melanoma. However, many randomized prospective trials have failed to show convincing clinical benefits associated with LN removal and the role of TDLNs in cancer dissemination is poorly understood. Here, we found in a well-characterized spontaneous mouse model of uveal melanoma that the growth of the primary tumor was accompanied by increased lymphangiogenesis and cancer cell colonization in the LNs draining the eyes. But, unexpectedly, early resection of the TDLNs increased the growth of the primary tumor and associated blood vessels as well as promoted cancer cell survival and dissemination. These effects were accompanied by increased tumor cell proliferation and expression of phosphorylated AKT. Topical application of a broad anti-inflammatory agent, Tobradex, or an oral treatment with cyclooxygenase-2 specific inhibitor, Celecoxib, reversed tumor progression observed after complete lymphadenectomy. Our study confirms the importance of tumor homeostasis in cancer progression by showing the enhancing effects of TDLN removal on tumor growth and cancer cell dissemination, and suggests that TDLN resection may only be beneficial if used in combination with anti-inflammatory drugs such as Tobradex and Celecoxib.
Assuntos
Movimento Celular , Proliferação de Células , Excisão de Linfonodo/efeitos adversos , Melanoma/cirurgia , Neoplasias Experimentais/cirurgia , Neoplasias Uveais/cirurgia , Animais , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase 2/farmacologia , Progressão da Doença , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Melanoma/genética , Melanoma/metabolismo , Melanoma/secundário , Camundongos , Camundongos Transgênicos , Neoplasias Experimentais/genética , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Neovascularização Patológica , Fenótipo , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-ret/genética , Fatores de Tempo , Carga Tumoral , Neoplasias Uveais/genética , Neoplasias Uveais/metabolismo , Neoplasias Uveais/patologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Surgical resection of tumors is often followed by regrowth at the primary site and metastases may emerge rapidly following removal of the primary tumor. Macrophages are important drivers of tumor growth, and here we investigated their involvement in postoperative relapse as well as explore macrophage depletion as an adjuvant to surgical resection. RETAAD mice develop spontaneous metastatic melanoma that begins in the eye. Removal of the eyes as early as 1 week of age did not prevent the development of metastases; rather, surgery led to increased proliferation of tumor cells locally and in distant metastases. Surgery-induced increase in tumor cell proliferation correlated with increased macrophage density within the tumor. Moreover, macrophages stimulate tumor sphere formation from tumor cells of post-surgical but not control mice. Macrophage depletion with a diet containing the CSF-1R specific kinase inhibitor Ki20227 following surgery significantly reduced postoperative tumor recurrence and abrogated enhanced metastatic outgrowth. Our results confirm that tumor cells disseminate early, and show that macrophages contribute both to post-surgical tumor relapse and growth of metastases, likely through stimulating a population of tumor-initiating cells. Thus macrophage depletion warrants exploration as an adjuvant to surgical resection.
Assuntos
Macrófagos/patologia , Melanoma Experimental/patologia , Melanoma Experimental/cirurgia , Animais , Processos de Crescimento Celular/fisiologia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Humanos , Macrófagos/metabolismo , Masculino , Melanoma Experimental/metabolismo , Camundongos , Camundongos Transgênicos , Recidiva Local de Neoplasia/prevenção & controle , Proteínas Proto-Oncogênicas c-ret/genética , Procedimentos Cirúrgicos Operatórios/métodosRESUMO
BACKGROUND: Cerenkov luminescence imaging (CLI) is an emerging imaging technique where visible light emitted from injected beta-emitting radionuclides is detected with an optical imaging device. CLI research has mostly been focused on positive contrast imaging for ascertaining the distribution of the radiotracer in a way similar to other nuclear medicine techniques. Rather than using the conventional technique of measuring radiotracer distribution, we present a new approach of negative contrast imaging, where blood vessel attenuation of Cerenkov light emitted by [68Ga]GaCl3 is used to image vasculature. METHODS: BALB/c nude mice were injected subcutaneously in the right flank with HT-1080 fibrosarcoma cells 14 to 21 days prior to imaging. On the imaging day, [68Ga]GaCl3 was injected and the mice were imaged from 45 to 90 min after injection using an IVIS Spectrum in vivo imaging system. The mice were imaged one at a time, and manual focus was used to bring the skin into focus. The smallest view with pixel size around 83 µm was used to achieve a sufficiently high image resolution for blood vessel imaging. RESULTS: The blood vessels in the tumor were clearly visible, attenuating 7% to 18% of the light. Non-tumor side blood vessels had significantly reduced attenuation of 2% to 4%. The difference between the attenuation of light of tumor vessels (10% ± 4%) and the non-tumor vessels (3% ± 1%) was significant. Moreover, a necrotic core confirmed by histology was clearly visible in one of the tumors with a 21% reduction in radiance. CONCLUSIONS: The negative contrast CLI technique is capable of imaging vasculature using [68Ga]GaCl3. Since blood vessels smaller than 50 µm in diameter could be imaged, CLI is able to image structures that conventional nuclear medicine techniques cannot. Thus, the negative contrast imaging technique shows the feasibility of using CLI to perform angiography on superficial blood vessels, demonstrating an advantage over conventional nuclear medicine techniques.
RESUMO
The immune system has multiple, complex, and sometimes opposing roles during cancer progression. While immune-compromised individuals have a higher incidence of cancers, inflammation is also associated with increased risk of disease progression. It is becoming apparent that simple measures of immune responses in the blood are of limited use in cancer. Instead, the importance of the exact identity and functional characteristics of tumor-infiltrating immune cells is increasingly recognized. This realization has led to recent studies that have revealed a critical role for chemokine expression in the tumor microenvironment and suggested a therapeutic potential of manipulating intratumoral expression of chemokines to alter the local immune milieu.