RESUMO
BACKGROUND: Recurrence of colorectal cancer (CRC) may arise due to the persistence of drug-resistant and cancer-initiating cells that survive exposure to chemotherapy. Proteins responsible for this recurrence include the chemokine receptor CXCR4, which is known to enable CRC metastasis, as well as the cancer-initiating cell marker and peptidase CD26, which terminates activity of its chemokine CXCL12. METHODS: We evaluated the expression and function of CXCR4 and CD26 in colon cancer cell lines and xenografts following treatment with common chemotherapies using radioligand binding, flow cytometry, immunofluorescence, and enzymatic assays. RESULTS: 5-Fluorouracil, oxaliplatin and SN-38 (the active metabolite of irinotecan), as well as cisplatin, methotrexate and vinblastine, each caused decreases in cell-surface CXCR4 and concomitant increases in CD26 on HT-29, T84, HRT-18, SW480 and SW620 CRC cell lines. Flow cytometry indicated that the decline in CXCR4 was associated with a significant loss of CXCR4+/CD26- cells. Elevations in CD26 were paralleled by increases in both the intrinsic dipeptidyl peptidase activity of CD26 as well as its capacity to bind extracellular adenosine deaminase. Orthotopic HT-29 xenografts treated with standard CRC chemotherapeutics 5-fluorouracil, irinotecan, or oxaliplatin showed dramatic increases in CD26 compared to untreated tumors. Consistent with the loss of CXCR4 and gain in CD26, migratory responses to exogenous CXCL12 were eliminated in cells pretreated with cytotoxic agents, although cells retained basal motility. Analysis of cancer-initiating cell CD44 and CD133 subsets revealed drug-dependent responses of CD26/CD44/CD133 populations, suggesting that the benefits of combining standard chemotherapies 5-fluoruracil and oxaliplatin may be derived from their complementary elimination of cell populations. CONCLUSION: Our results indicate that conventional anticancer agents may act to inhibit chemokine-mediated migration through eradication of CXCR4+ cells and attenuation of chemokine gradients through elevation of CD26 activity.
Assuntos
Quimiocina CXCL12/biossíntese , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/genética , Dipeptidil Peptidase 4/biossíntese , Receptores CXCR4/biossíntese , Animais , Camptotecina/administração & dosagem , Camptotecina/análogos & derivados , Carcinogênese/efeitos dos fármacos , Linhagem da Célula , Movimento Celular/efeitos dos fármacos , Quimiocina CXCL12/genética , Neoplasias do Colo/patologia , Dipeptidil Peptidase 4/genética , Fluoruracila/administração & dosagem , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células HT29 , Humanos , Receptores de Hialuronatos/genética , Irinotecano , Camundongos , Metástase Neoplásica , Receptores CXCR4/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Recent evidence suggests that a subpopulation of cancer cells, cancer stem cells (CSCs), is responsible for tumor growth in colorectal cancer. However, the role of CSCs in colorectal cancer metastasis is unclear. Here, we identified a subpopulation of CD26(+) cells uniformly present in both the primary and metastatic tumors in colorectal cancer patients with liver metastasis. Furthermore, in patients without distant metastasis at the time of presentation, the presence of CD26(+) cells in their primary tumors predicted distant metastasis on follow-up. Isolated CD26(+) cells, but not CD26(-) cells, led to development of distant metastasis when injected into the mouse cecal wall. CD26(+) cells were also associated with enhanced invasiveness and chemoresistance. Our findings have uncovered a critical role of CSCs in metastatic progression of cancer. Furthermore, the ability to predict metastasis based on analysis of CSC subsets in the primary tumor may have important clinical implication as a selection criterion for adjuvant therapy.
Assuntos
Biomarcadores Tumorais/biossíntese , Carcinoma/diagnóstico , Neoplasias Colorretais/diagnóstico , Dipeptidil Peptidase 4/biossíntese , Neoplasias Hepáticas/diagnóstico , Células-Tronco Neoplásicas/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Biomarcadores Tumorais/genética , Carcinoma/tratamento farmacológico , Carcinoma/genética , Carcinoma/metabolismo , Carcinoma/fisiopatologia , Carcinoma/secundário , Ensaios de Migração Celular , Transformação Celular Neoplásica/genética , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Neoplasias Colorretais/fisiopatologia , Dipeptidil Peptidase 4/genética , Progressão da Doença , Resistencia a Medicamentos Antineoplásicos/genética , Fluoruracila/farmacologia , Seguimentos , Perfilação da Expressão Gênica , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/fisiopatologia , Neoplasias Hepáticas/secundário , Camundongos , Camundongos SCID , Invasividade Neoplásica/genética , Transplante de Neoplasias , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Compostos Organoplatínicos/farmacologia , Oxaliplatina , Prognóstico , RNA Interferente Pequeno/genética , Carga Tumoral/efeitos dos fármacos , Carga Tumoral/genética , Células Tumorais CultivadasRESUMO
Dipeptidyl peptidase (DPP) IV inhibitors provide a new strategy for the treatment of type 2 diabetes. Human DPP-IV gene was cloned from differentiated Caco-2 cells and expressed in Pichia pastoris. The recombinant enzyme was used in a new system for screening of DPP-IV inhibitors. By high throughput screening, a novel compound (W5188) was identified from 75,000 compounds with an IC(50) of 6.5 microM. This method is highly reproducible and reliable for discovery of DPP-IV inhibitors as shown by Z' value of 0.73 and S/N ratio of 6.89.