RESUMO
Cancer stem cells (CSCs) exist in colon cancer and exhibit characteristics of stem cells which are due to lineages of tissues where they arise. Epithelial to mesenchymal transition (EMT)-undergoing cancer cells display CSC properties and therapeutic resistance. Cancer and stromal cells comprise of a tumor microenvironment. One way the two populations communicate with each other is to secret CXC ligands (CXCLs). CXCLs are capable of causing chemotaxis of specific types of stromal cells and control angiogenesis. Double immunofluorescence, western blot analysis, and colony-formation assay were carried out to compare parental and CPT-11-resistant LoVo cells. CPT-11-R LoVo colon cancer cells showed increased expression of CXCL1, CXCL2, CXCL3, and CXCL8. They displayed significantly increased intracellular protein levels of CXCL2 and CXCR2. CPT-11-R LoVo cells showed significantly elevated expression in aldehyde dehydrogenase 1 (ALDH1), cluster of differentiation 24 (CD24), cluster of differentiation 44 (CD44), and epithelial cell adhesion molecule (EpCAM). CXCL2 knockdown by short hairpin RNA resulted in reduced expression of CSC proteins, cyclins, EMT markers, G proteins, and matrix metalloproteinases (MMPs). Finally, Gαi-2 was found to promote expression of CSC genes and tumorigenesis which were more apparent in the resistant cells. In addition, Gαq/11 showed a similar pattern with exceptions of EpCAM and MMP9. Therefore, CXCL2-CXCR2 axis mediates through Gαi-2 and Gαq/11 to promote tumorigenesis and contributes to CSC properties of CPT-11-R LoVo cells.
Assuntos
Quimiocina CXCL2/metabolismo , Neoplasias do Colo/patologia , Resistencia a Medicamentos Antineoplásicos , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/metabolismo , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Irinotecano/farmacologia , Células-Tronco Neoplásicas/patologia , Receptores de Interleucina-8B/metabolismo , Carcinogênese/efeitos dos fármacos , Carcinogênese/genética , Carcinogênese/patologia , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Células-Tronco Neoplásicas/metabolismo , RNA Interferente Pequeno/metabolismo , Transdução de Sinais/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genéticaRESUMO
Clinically used chemotherapeutics can effectively eliminate most tumor cells. However, they cause unwanted side effects and result in chemoresistance. To overcome such problems, phytochemicals are now used to treat cancers by means of targeted therapy. Thymoquinone (TQ) is used to treat different cancers (including colon cancer) and is an NF-κB inhibitor. Irinotecan resistant (CPT-11-R) LoVo colon cancer cell line was previous constructed by step-wise CPT-11 challenges to un-treated parental LoVo cells and expresses EGFR/IKKα/ß/NF-κB pathway. TQ resulted in reduced total and phosphorylation of IKKα/ß and NF-κB and decreased metastasis in CPT-11-R cells. TQ not only reduced activity of ERK1/2 and PI3K but also activated JNK and p38. Furthermore, TQ was also found to suppress metastasis through activation of JNK and p38. Therefore, TQ suppressed metastasis through NF-κB inhibition and activation of JNK and p38 in CPT-11-R LoVo colon cancer cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 669-678, 2017.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Benzoquinonas/farmacologia , Camptotecina/análogos & derivados , Fator de Transcrição RelA/antagonistas & inibidores , Camptotecina/farmacologia , Linhagem Celular Tumoral , Movimento Celular , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/patologia , Resistencia a Medicamentos Antineoplásicos , Transição Epitelial-Mesenquimal , Humanos , Irinotecano , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Metástase Neoplásica , Fosfatidilinositol 3-Quinases/metabolismo , Fator de Transcrição RelA/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Chemotherapy causes unwanted side effects and chemoresistance, limiting its effectiveness. Therefore, phytochemicals are now used as alternative treatments. Thymoquinone (TQ) is used to treat different cancers, including colon cancer. The irinotecan-resistant (CPT-11-R) LoVo colon cancer cell line was previously constructed by stepwise CPT-11 challenges to untreated parental LoVo cells. TQ dose-dependently increased the total cell death index and activated apoptosis at 2 µM, which then diminished at increasing doses. The possibility of autophagic cell death was then investigated. TQ caused mitochondrial outer membrane permeability (MOMP) and activated autophagic cell death. JNK and p38 inhibitors (SP600125 and SB203580, respectively) reversed TQ autophagic cell death. TQ was also found to activate apoptosis before autophagy, and the direction of cell death was switched toward autophagic cell death at initiation of autophagosome formation. Therefore, TQ resulted in caspase-independent, autophagic cell death via MOMP and activation of JNK and p38 in CPT-11-R LoVo colon cancer cells.