ABSTRACT
Imatinib is the first line of therapy for patients with metastatic or gastrointestinal stromal tumors (GIST). However, drug resistance limits the long-term effect of imatinib. Long non-coding RNAs (lncRNAs) are emerging as key players in regulating drug resistance in cancer. In this study, we investigated the association between lncRNA CCDC26 and IGF-1R in GIST and their involvement in drug resistance. Considering the key role of lncRNAs in drug resistance in cancer, we hypothesized that IGF-1R is regulated by lncRNAs. The expression of a series of reported drug resistance-related lncRNAs, including CCDC26, ARF, H19, NBR2, NEAT1, and HOTAIR, in GIST cells treated with imatinib H19 was examined at various time-points by qRT-PCR. Based on our results and published literature, CCDC26, a strongly down-regulated lncRNA following imatinib treatment, was chosen as our research target. GIST cells with high expression of CCDC26 were sensitive to imatinib treatment while knockdown of CCDC26 significantly increased the resistance to imatinib. Furthermore, we found that CCDC26 interacted with c-KIT by RNA pull down, and that CCDC26 knockdown up-regulated the expression of IGF-1R. Moreover, IGF-1R inhibition reversed CCDC26 knockdown-mediated imatinib resistance in GIST. These results indicated that treatments targeting CCDC26-IGF-1R axis would be useful in increasing sensitivity to imatinib in GIST.
Subject(s)
Humans , Receptors, Somatomedin/genetics , Drug Resistance, Neoplasm , Intracellular Signaling Peptides and Proteins/genetics , RNA, Long Noncoding/genetics , Imatinib Mesylate/pharmacology , Antineoplastic Agents/pharmacology , Signal Transduction , Down-Regulation/genetics , Gene Expression Regulation, Neoplastic , Receptors, Somatomedin/metabolism , Receptor, IGF Type 1 , Apoptosis , Cell Line, Tumor , Intracellular Signaling Peptides and Proteins/metabolism , RNA, Long Noncoding/metabolism , Flow CytometryABSTRACT
To explore how cytohesin-1 (CYTH-1) small interfering RNA (siRNA) influences the insulin-like growth factor receptor (IGFR)-associated signal transduction in prostate cancer, we transfected human prostate cancer PC-3 cell lines with liposome-encapsulatedCYTH-1 siRNA in serum-free medium and exposed the cells to 100 nM IGF-1. The mRNA and protein levels of the signal molecules involved in the IGFR signaling pathways were determined by real-time PCR and detected by Western blotting. The relative mRNA levels of CYTH-1, c-Myc, cyclinD1 and IGF-1R (CYTH-1 siRNA group vs scrambled siRNA group) were 0.26 vs 0.97, 0.34 vs 1.06, 0.10 vs 0.95, and 0.27 vs 0.41 (P < 0.05 for all), respectively. The relative protein levels of CYTH-1, pIGF-1R, pIRS1, pAkt1, pErk1, c-Myc, and cyclinD1 (CYTH-1 siRNA group vsscrambled siRNA group) were 0.10 vs 1.00 (30 min), 0.10 vs 0.98 (30 min), 0.04 vs 0.50 (30 min), 0.10 vs 1.00 (30 min), 0.10 vs 1.00 (30 min), 0.13 vs 0.85 (5 h), and 0.08 vs 0.80 (7 h), respectively. The tyrosine kinase activity of IGF-1R was associated with CYTH-1. The proliferative activity of PC-3 cells transfected with CYTH-1 siRNA was significantly lower than that of cells transfected with scrambled siRNA at 48 h (40.5 vs87.6 percent, P < 0.05) and at 72 h (34.5 vs 93.5 percent, P < 0.05). In conclusion, the interference of siRNA with cytohesin-1 leads to reduced IGFR signaling in prostate cancer; therefore, CYTH-1 might serve as a new molecular target for the treatment of prostate cancer.
Subject(s)
Humans , Male , Guanine Nucleotide Exchange Factors/antagonists & inhibitors , Prostatic Neoplasms/metabolism , RNA, Small Interfering/pharmacology , Receptors, Somatomedin/metabolism , Signal Transduction/drug effects , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , GTPase-Activating Proteins/genetics , GTPase-Activating Proteins/metabolism , Guanine Nucleotide Exchange Factors/genetics , Insulin-Like Growth Factor I/metabolism , Phosphorylation , Prostatic Neoplasms/pathology , Real-Time Polymerase Chain Reaction , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolismABSTRACT
We addressed the effect of targeting type I insulin-like growth factor receptor (IGF-IR), with antisense strategies in in vivo growth of breast cancer cells. We used C4HD tumors from an experimental model of hormonal carcinogenesis in which medroxyprogesterone acetate induced mammary adenocarcinomas in Balb/c mice. Intratumor or systemic administration of phosphorothiolated antisense oligodeoxynucleotides (AS[S]ODN) to IGF-IR mRNA resulted in a significant inhibition of C4HD tumor growth. The antitumor effect was specific since inhibition of tumor growth was dose-dependent and no effect was observed in mice treated with sense S[S]ODN. Tumors from AS[S]ODN-treated mice showed a decrease in IGF-IR expression and in insulin receptor substrate-1 tyrosine phosphorylation. Activation of PI-3K/Akt, p42/p44 MAPK and ErbB-2 was abolished in tumors treated with AS[S]ODN. Progesterone receptor expression or activity remained invariable. This is the first demonstration that breast cancer growth can be inhibited by direct in vivo administration of IGF-IR AS[S]ODN.
Evaluamos el efecto del bloqueo de la expresión del receptor del factor de crecimiento semejante a lainsulina tipo I (IGF-IR) sobre el crecimiento in vivo de cáncer de mama empleando una estrategiaantisentido. Utilizamos el adenocarcinoma mamario murino progestágeno-dependiente C4HD. La administración intratumoral o sistémica de oligodeoxinucleótidos antisentido fosfotiolados al ARNm del IGF-IR (AS[S]ODN) inhibió el crecimiento tumoral. El efecto antitumoral fue específico debido a su dosis-dependencia y a la faltade efecto en ratones tratados con el S[S]ODN sentido. Los tumores obtenidos de ratones tratados con AS[S]ODN mostraron: disminución en la expresión de IGF-IR y en la fosforilación del sustrato del receptor de insulina-1, inhibición de la activación de PI-3K/Akt, p42/p44MAPK y ErbB-2, mientras que la expresión y activación del receptor de progesterona no se afectó. Es la primera demostración que el