Demonstration of dose dependent cytotoxic activity in SW480 colon cancer cells by ¹⁷⁷Lu-labeled siRNA targeting IGF-1R

The Interplay Between Non-coding RNAs and Insulin-Like Growth Factor Signaling in the Pathogenesis of Neoplasia

The insulin-like growth factors (IGFs) are polypeptides with similar sequences with insulin. These factors regulate cell growth, development, maturation, and aging via different processes including the interplay with MAPK, Akt, and PI3K. IGF signaling participates in the pathogenesis of neoplasia, insulin resistance, diabetes mellitus, polycystic ovarian syndrome, cerebral ischemic injury, fatty liver disease, and several other conditions. Recent investigations have demonstrated the interplay between non-coding RNAs and IGF signaling. This interplay has fundamental roles in the development of the mentioned disorders. We designed the current study to search the available data about the role of IGF-associated non-coding RNAs in the evolution of neoplasia and other conditions. As novel therapeutic strategies have been designed for modification of IGF signaling, identification of the impact of non-coding RNAs in this pathway is necessary for the prediction of response to these modalities.

Application of decoy oligodeoxynucleotides strategy for inhibition of cell growth and reduction of metastatic properties in nonresistant and erlotinib-resistant SW480 cell line

Signal transducer and activator of transcription 3 (STAT3) is a critical regulator for angiogenesis, cell cycle progression, apoptosis, and drug resistance. Resistance toward EGF receptor (EGFR) inhibitors is a significant clinical concern for metastatic colon cancer patients. The present study aimed to evaluate the blocking influences of STAT3 decoy oligodeoxynucleotides (ODNs) on the STAT3 survival signaling pathway in nonresistant and erlotinib-resistant SW480 colon cancer cells. First, STAT3 decoy and scramble ODNs were designed according to STAT3 elements in the promoter region of MYCT1 gene and tested for the interaction of STAT3 protein with designed ODNs via in silico molecular docking study. Then, the efficiency of transfection and subcellular localization of ODNs were assessed using flow cytometry and fluorescence microscopy, respectively. Cell viability, cell cycle, and apoptosis tests, scratch and colony formation assays, and real-time PCR were also used to study the cancerous properties of cells. A considerable decrease in proliferation of colon cancer cells was observed with blockade of STAT3 signaling due to cell cycle arrest and induced apoptosis via downregulation of cyclin D1 and Bcl-XL, respectively. Furthermore, upon transfecting STAT3 decoy ODNs, colony formation potential and migration activity in both SW480 colon cancer cell lines were decreased compared to the control groups. From this study, it could be concluded that STAT3 is critical for cell growth inhibition and metastatic properties reduction of resistant SW480 colon cancer cells; therefore, STAT3 decoy ODNs could be considered as potential therapeutics along with current remedies for treating drug-resistant colon cancer.

DDAB cationic lipid-mPEG, PCL copolymer hybrid nano-carrier synthesis and application for delivery of siRNA targeting IGF-1R into breast cancer cells

BACKGROUND AND OBJECTIVE

To use siRNA molecule as a therapeutic agent in gene silencing, an efficient delivery system is necessary. Stability and clearance by reticuloendothelial of siRNA still remains the major challenges for clinical application. Herein, we could develop new lipid-polymer hybrid nanoparticles (LPHNP) as a siRNA carrier to silence insulin-like growth factor type I (IGF-1R) gene overexpression in MCF-7 human breast cancer cell line.

METHODS

Dimethyldioctadecylammonium bromide-methoxy poly(ethylene glycol)-poly (ε-caprolactone) (DDAB-mPEG-PCL) LPHNPs were synthesized using a single step nanoprecipitation method and characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) microscope. Cytotoxicity of the nanoparticles was assessed in the MCF7 cell line using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Desired LPHNP-siRNA complex was determined using different Nitrogen:Phosphate ratio (N/P) ratios and gel retardation. To determine the encapsulation efficiency of siRNA (%) in LPHNP, its absorbance was measured. The effect of the siRNA-LPHNP complex on IGF-1R silencing was assessed by reverse transcription-polymerase chain reaction (RT-PCR) RESULTS: LPHNP was synthesized using a single-step sonication method with a size below 100 nM. The viability of cells treated with hybrid nanoparticles was significantly greater than the corresponding cationic lipid (P < 0.01). As demonstrated by gel retardation assay, efficient siRNA binding to LPHNP occurred at N/P equal to 40 and siRNA encapsulation efficiency was found to be 95% ± 4 at this ratio. LPHNP-IGF-1R siRNA complex could be able to down-regulate the target more efficiently when it compared with the corresponded controls (P < 0.001).

CONCLUSION

In conclusion, our results suggest that DDAB cationic lipid and mPEG-PCL copolymer hybrid nanoparticle may be a good candidate for efficient siRNA delivery.

Crosstalk between Epidermal Growth Factor Receptors (EGFR) and integrins in resistance to EGFR tyrosine kinase inhibitors (TKIs) in solid tumors

Cell adhesion to the extracellular matrix (ECM) is important in a variety of physiological and pathologic processes, including development, tumor invasion, and metastasis. Integrin-mediated attachment to ECM proteins has emerged to cue events primitively important for the transformed phenotype of human cancer cells. Cross-talk between integrins and growth factor receptors takes an increasingly prominent role in defining adhesion, motility, and cell growth. This functional interaction has expanded beyond to link integrins with resistance to Tyrosine kinase inhibitors (TKIs) of Epidermal Growth Factor Receptors (EGFRs). In this regard, integrin-mediated adhesion has two separate functions one as a clear collaborator with growth factor receptor signaling and the second as a basic mechanism contributing in Epithelial to Mesenchymal Transition (EMT) which affects response to chemotherapy. This review provides an overview of these mechanisms and describes treatment options for selectively targeting and disrupting integrin interaction to EGFR for cancer therapy.

Curcumin mediated down-regulation of αV β3 integrin and up-regulation of pyruvate dehydrogenase kinase 4 (PDK4) in Erlotinib resistant SW480 colon cancer cells

Erlotinib is a potent, selective, and orally active inhibitor of the epidermal growth factor receptor, but the development of erlotinib resistance during chemotherapy can lead to treatment failure. To shed light on the erlotinib-resistant pathway, this study investigated the effect of combination therapy using curcumin- and erlotinib-loaded nanoparticles on the expression of α_v β₃ integrin and pyruvate dehydrogenase kinase 4 (PDK4) in an erlotinib-resistant SW480 colon cancer cell line. An erlotinib-resistant SW480 colon cancer cell line was produced by long-term exposure to erlotinib. Curcumin-loaded Methoxy poly ethylene glycol Poly caprolactone (cur/mPEG-PCL) and erlotinib-loaded mPEG-PCL (erl/mPEG-PCL) micelles were provided using a single step nanoprecipitation method and used as combination therapy of resistant SW480 cancer cells. After that, gene expression levels of PDK4, αv, and β3 mRNA were determined by the semiquantitative reverse transcription-polymerase chain reaction. Protein levels of whole α_v β₃ integrin were evaluated using the enzyme-linked immunosorbent assay method. In SW480 cell line, the IC50 of nonresistant and resistant cells was 87.6 ± 1.2 nM and 19.1 ± 0.14 μM, for erlotinib and it was about 21.8 and 30 μM for curcumin, respectively. Although PDK4 expression was not significantly different in resistant and nonresistant cells, its expression was up regulated (1.4 fold) in resistant cells by a combination therapy of cur/mPEG-PCL at a dose of 3 μM and erl/mPEG-PCL at a dose of 5 μM. β₃ mRNA and the protein level of whole α_v β₃ integrin was significantly higher in resistant SW480 cells as compared with those in nonresistant cells. In terms of treatment, a combination of 6-μM cur/mPEG-PCL and 5-μM erl/mPEG-PCL down regulated β₃ gene expression 6.6-fold in resistant cells as compared with nonresistant cells. At the protein level, a combination of 3-μM-cur/mPEG-PCL and 10-μM erl/mPEG-PCL reduced α_v β₃ protein in resistant cells. The results indicated that combination therapy using cur/mPEG-PCL and erl/mPEG-PCL could decrease α_v β₃ integrin expression and increase PDK4 gene expression in resistant colon cancer cells, which may have effects on drug resistance signaling pathways.

Targeting CRMP-4 by lentivirus-mediated RNA interference inhibits SW480 cell proliferation and colorectal cancer growth

The aim of the present study was to investigate the expression level of collapsin response mediator protein 4 (CRMP-4) in human colorectal cancer (CRC) tissue and to evauluate its impact on SW480 cell proliferation, in addition to tumor growth in a mouse xenograft model. Clinical CRC tissue samples were collected to detect the CRMP-4 protein expression levels using western blot and immunohistochemistry analyses. A specific small interfering RNA sequence targeting the CRMP-4 gene (DPYSL3) was constructed and transfected into an SW480 cell line using a lentivirus vector to obtain a stable cell line with low expression of CRMP-4. The effectiveness of the interference was evaluated using western blot and reverse transcription-quantitative polymerase chain reaction, and the cell proliferation was determined using MTT and BrdU colorimetric methods. Tumor growth was assessed by subcutaneously inoculating the constructed cells into BALB/c nude mice. The protein expression levels of CRMP-4 were markedly increased in colon tumor tissue of the human samples. The proliferation of SW480 cells and the tumor growth rate in nude mice of the si-CPMR-4 group were evidently depressed compared with the si-scramble group. Thus, the present results suggest that CRMP-4 may be involved in the pathogenesis of CRC.

The mechanisms of 5-FU-PLA-O-CMC-NPS-mediated inhibition of the proliferation of colorectal cancer cell line SW480

We aimed to investigate how 5-FU-PLA-O-CMC-NP (5-FPOCN) inhibits the proliferation of the SW480 colon cancer cell line. Following the treatment of cell line SW480 with 0.1, 1, 10 or 100 μg/ml 5-FPOCN or 5-fluorouracil (fluorouracil, 5-Fu) for 0, 24, 48, or 72, the rate of cell was tested by the tetrazolium assay (MTT). After the SW480 cells were treated with 5-FPOCN or 5-FU for 72 h, the growth rate and apoptosis were detected. After the SW480 cells were treated with 5-FPOCN or 5-FU for 24, 48, 72, or 120, flow cytometry (FCM) was used to determine the cell cycle distribution. The changes in the expression of P21, CyclinD1 and Rb were detected by Western blotting and real-time PCR. We found that different doses of 5-FPOCN can significantly inhibit the growth rate of SW480 cells, and this effect is dose and time dependent. However, there is no significant difference from 72 to 120 h (P>0.05). After 5-FPOCN treatment for 72 h, there is a negative correlation between the concentration of 5-FPOCN and the activity of SW480 cells and a positive correlation between the concentration of 5-FPOCN and SW480 cell apoptosis. G1 phase was significantly increased, and S phase was significantly decreased in 5-FPOCN-treated SW480 cells at 72 h compared to the control group (P<0.05); there was a positive correlation between the concentration of 5-FPOCN and the above changes. It was suggested that 5-FPOCN can delay G1/S phase and that this is a dose-dependent effect. The expression of P21 protein and messenger RNA (mRNA) and Rb protein and mRNA was significantly increased in 5-FPOCN-treated SW480 cells at 72 h compared to the control group, and this was a dose- and time-dependent effect. CyclinD1 protein and mRNA expression was reduced as the dose increased, and its expression was negatively associated with the increased expression of P21. We concluded that 5-FPOCN can significantly inhibit the growth of colon cancer SW480 cells. 5-FPOCN increased P21 expression and decreased cyclin family and pRb expression to promote cell cycle delay and apoptosis.