Synergistic anticancer effects of crocin combined with deuterium-depleted water on HT-29 cells.

Colorectal cancer is one of the most common types of cancer in the world and the study of the role of nutrients in preventing or inhibiting the growth of this cancer is of interest to scientists. In this article, the synergistic effect of deuterium-depleted water(DDW) and crocin at specific concentrations on HT-29 cells was investigated. In this regard, HT-29 cells were grown in RPMI medium containing DDW, alone and in combination with crocin for 24, 48 and 72 h. Cell viability, cell cycle changes and antioxidant enzymes status were determined by MTT assay, flow cytometry and quantitative luminescence methods, respectively. The results of these analyses proved the cell growth inhibitory effect of deuterium alone and its synergistic effect in combination with crocin. The cell cycle analysis showed an increase in the number of cells in the G0 and G1 phases whereas there was a decrease in the number of cells in the S, G2 and M phases. The activities of superoxide dismutase and catalase enzymes also decreased compared to the control group that is a reason to increase Malonyl dialdehyde factor. The results suggested that a combination of DDW and crocin can open a new strategic approach in the prevention and treatment of colorectal cancer.

Breast Tumor Targeting with PAMAM-PEG-5FU-99mTc As a New Therapeutic Nanocomplex: In In-vitro and In-vivo studies.

Dendrimer-based targeted drug delivery, as an innovative polymeric drug-delivery system, is promising for cancer therapy. Folate receptors (FR) are overexpressed in many types of tumor cells, such as breast cell carcinomas, which allow folate-targeted delivery. Therefor polyethylene glycol (PEG) modified-PAMAM G4 dendrimers were functionalized with folic acid (FA), as targeting agent. Then, 5-FU (5-fluorouracil) and 99mTc (technetium-99 m) as therapeutic agents were respectively loaded and conjugated to previous nano-complex (PEG-PAMAM G4-FA-5FU-99mTc). The value of drug loading was calculated by TGA analysis (16.97%). Drug release profiles of PEG-PAMAM G4-FA-5FU-99mTc and PEG-PAMAM G4-FA-5FU were evaluated. The radiochemical purity of PEG-PAMAM G4-FA-5FU-99mTc and PEG-PAMAM G4-FA-99mTc was obtained at >95% with excellent in-vitro and in-vivo stabilities. PEG-PAMAM G4-FA-5FU-99mTc was synthesized and the stability studies were carried out by the ITLC methods in serum (86.67% and 83.75%) and PBS. Combinational therapy effects of 5-FU and 99mTc containing nano-complexes were evaluated on 4 T1 (mouse breast cancer) and MDA-MB-231 (human breast adenocarcinoma) cancer cell lines. Excellent uptake values were obtained for FA-decorated nano-complexes on 4 T1 and MDA-MB-231 cell lines. Subsequently, tumor inhibition effects of PEG-PAMAM G4-FA-5FU-99mTc and PEG-PAMAM G4-FA-5FU were evaluated using the breast tumor-bearing BALB/C mice. Graphical abstract Breast Tumor Targeting with PAMAM-PEG-5FU- 99mTc As a New Therapeutic Nanocomplex: in In-vitro and In-vivo Studies was presented. This targeted drug delivery system can significantly increase the efficiency of cancer therapy, and reduce the treatment cost and time.

Deuterium Depleted Water Inhibits the Proliferation of Human MCF7 Breast Cancer Cell Lines by Inducing Cell Cycle Arrest.

Recent studies have shown that the depletion of naturally occurring deuterium can result in tumor regression. The aim of the present study was to show the growth inhibitory effects of DDW discretely and in combination with 5-FU on MCF-7 breast cancer cells and to determine possible mechanisms underlying these changes. MCF7 cells were grown in RPMI medium with decreasing deuterium concentrations of DDW individually, 5-FU alone and both for 24, 48, and 72 h. Cell viability was determined with the MTT assay. The cell cycle and antioxidant enzymes status were measured using flow cytometry and quantitative luminescence methods, respectively. Our results showed that treatment with DDW especially in 30-100 ppm concentrations imposed the highest cell growth inhibitory effect. The cell cycle analysis revealed that DDW caused the cell cycle arrest in the G1/S transition, reduced the number of the cells in the S phase and significantly increased the population of cells in the G1 phase in MCF-7 cells. The activities of superoxide dismutase (SOD) and catalase (CAT) enzymes also increased in the same low concentrations of DDW. In conclusion, DDW can open new strategic approach in breast cancer therapy. Highlights DDW cause lethality in cancer cells. DDW augmented 5-FU inhibitory effects on breast cancer cell lines. Cell inhibitory results lead to the discovery of synergic effects of DDW-drug combinations Synergistic anti cancer effects of DDW with 5-FU is enhanced by decreasing deuterium content of the DDW. DDW exerts effects on the cell cycle, changes in cell configuration and induces antioxidant enzymes in vitro. DDW can be considered as an adjuvant to conventional anticancer agents in future trials.

Lentiviral-mediated BCL2 gene knockdown using comparative microRNA adaptive shRNAs.

B-cell lymphoma 2 (BCL2) family proteins play a critical role in tuning cell death processes. Almost in half of all human cancers, a dysregulation in BCL2 family gene expression has been shown which made it an impressive target for human gene therapy as a novel approach in cancers. In this study we will optimize lentiviral-mediated RNA interference (RNAi), recombinant lentiviruses accommodating anti-BCL2 micro adaptive short hairpin RNAs (shRNAs), to downregulate BCL2 in human embryonic kidney 293T (HEK293T) cells to produce stable cell lines. We tested 4 different Dharmacon™ GIPZ™ shRNAmir lentiviral vectors targeting BCL2 in different positions and a pGIPZ non-silencing shRNAmir lentiviral vector (as a negative control). Lentivirus packaging was performed by the calcium phosphate precipitation method. HEK293T cells were transduced by each type of recombinant lentiviruses individually and selected by puromycin within 10 days. The relative mRNA level and protein expression were assayed by using real-time polymerase chain reaction (PCR) technic and western blotting, respectively. Lentivirus (LV) packaging was performed in high efficiency (transfection rate was > 90%). Recombinant viruses of 4 expression vector addition to a control vector were produced then transduced to HEK293T cells successfully. All the 4 cell groups showed a significant down regulation of BCL2 gene (~90-95%) at mRNA level compared to the control group (p<0.01) but differences between silenced groups were not significant (P > 0.05). We showed that the lentivirus-mediated RNAi technique is an efficient method to establish HEK293 cell lines with stable down-regulation of BCL2 gene.

Production and characterization of 166Ho polylactic acid microspheres.

Microsphere and particle technology with selective transport of radiation represents a new generation of therapeutics. Poly-L-lactic acid (PLLA) microspheres loaded with holmium-166 acetylacetonate ((166)Ho-PLLA-MS) are novel microdevices. In this research, (165)HoAcAc-PLLA microparticles were prepared by the solvent evaporation technique. Microspheres were irradiated at Tehran Research Reactor. The diameter and surface morphologies were characterized by particle sizer and scanning electron microscopy before and after irradiation. The complex stability, radiochemical purity, and in vivo biodistribiotion were checked in the final solution up to 3 days. In this study, (166)Ho-PLLA spherical particles with a smooth surface and diameter of 20-40 µm were obtained, which were stable in vitro and in vivo studies. Neutron irradiation did not damage the particles. The ease with which the PLLA spheres could be made in the optimal size range for later irradiation and their ability to retain the (166)Ho provided good evidence for their potential use in radioembolization.

Iodine-131 radiolabeling of poly ethylene glycol-coated gold nanorods for in vivo imaging.

Gold nanorods (GNRs) can be used in various biomedical applications; however, very little is known about their in vivo tissue distribution by radiolabeling. Here, we have developed a rapid and simple method with high yield and without disturbing their optical properties for radiolabeling of gold rods with iodine-131 in order to track in vivo tissue uptake of GNRs after systemic administration by biodistribution analysis and γ-imaging. Following intravenous injection into rat, PEGylated GNRs have much longer blood circulation times.

SiRNA-mediated IGF-1R inhibition sensitizes human colon cancer SW480 cells to radiation.

PURPOSE: Insulin like growth factor receptor 1 (IGF-1R) is well-documented to play a key role in radiation response and tumor radiosensitivity, thus offering an attractive clinic drug target to enhance tumor sensitivity to anti-cancer radiotherapy. MATERIAL AND METHODS: Human colon carcinoma SW480 cells were transfected with the specific small interference RNA (siRNA) expression vector (pkD-shRNA-IGF-1R-V2) designed to target IGF-1R mRNA. The expression of IGF-1R mRNA and its protein among the transfected and untransfected cells were detected by semi-quantitative RT-PCR and ELISA assay. The changes in cell radiosensitivity were examined by MTT assay. RESULTS: Transfection of mammalian expression vector pkD containing IGF-1R siRNA was shown to reduce IGF-1R mRNA levels by up to 95%. ELISA assay detected a similar inhibition of IGF-1R protein levels in cells transfected with IGF-1R siRNA. SW480 cells transfected with the expression vector for siRNA significantly rendered cells more sensitive to radiation and the highest radiation enhancement ratio was 2.02 +/- 0.08. CONCLUSION: These data provide the first evidence that specific siRNA fragment (pkD-shRNA-IGF-1R-V2) targeting human IGF-1R mRNA is able to enhance colon cancer radiosensitivity. Also results indicated that, combining IGF-1R siRNA and radiation significantly enhances antitumor efficacy compared with either modality alone.

Downregulation of IGF-IR expression by RNAi inhibits proliferation and enhances chemosensitization of human colon cancer cells.

PURPOSE: Colon cancer is the second leading cause of cancer death worldwide. Elevated expression of insulin-like growth factor-I receptor (IGF-IR) is a frequent genetic abnormality seen in this malignancy. For a better understanding of its role in maintaining the malignant phenotype, we used RNA interference (RNAi) directed against IGF-IR in our study. The aim of this study was to examine the anti-proliferation and chemosensitization effects elicited by a decrease in the transcription and protein levels of IGF-IR by RNAi in SW480 colon cancer cells. METHODS: A plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting IGF-IR to reduce its expression in SW480 cells. Western blot analysis was used to measure the protein level of IGF-IR. We assessed the effects of IGF-IR silencing on cancer cell growth by a cell growth curve. The effect of the 5-fluorouracil (5-FU)-induced cell death by knockdown of IGF-IR was also investigated by methyl thiazolyl tetrazolium assay. RESULTS: Transfection of siRNA targeting IGF-IR was shown to reduce IGF-IR messenger RNA levels by 95%. Western blotting detected a similar inhibition of IGF-IR protein levels in those cells. The cells transfected with PKD-short hairpin RNA-IGF-IR-V2 significantly decreased cell growth and rendered cells more sensitive to chemotherapy. The highest proliferation inhibitory and chemosensitization ratios were 53 +/- 2% and 1.78, respectively. CONCLUSION: This study indicates that downregulation of IGF-IR results in significant inhibition of tumor growth in vitro. It also provides a promising strategy to chemotherapy efficacy in human tumors and forming a basis for future in vivo trials.

1484insG polymorphism of the PTPN1 gene is associated with insulin resistance in an Iranian population.

BACKGROUND: Protein tyrosine phosphatase 1B (PTP1B), encoded by the PTPN1 gene, efficiently dephosphorylates the insulin receptor, and attenuates insulin signaling. Recently, a 1484insG variant of the PTPN1 gene has been associated with an increased risk of metabolic syndrome in an Italian population that has not been confirmed in the subsequent studies. The purpose of this study was to investigate the association of 1484insG polymorphism of the PTPN1 with obesity, insulin resistance, type 2 diabetes and other cardiovascular-related traits in an Iranian population. METHODS: The genotypes of 1484insG variant were determined by PCR-RFLP method in 696 unrelated subjects including 412 subjects with normal glucose tolerance and normal fasting glucose and 284 type 2 diabetic patients. RESULTS: The allelic frequency of 1484insG polymorphism among type 2 diabetic patients and non-diabetic subjects was 4.9 and 4.1%, respectively (p = 0.475). In type 2 diabetic patients, among quantitative traits, no significant difference in anthropometric and biochemical parameters was seen between the wild-type and heterozygous 1484insG genotypes in male and female groups and in non-diabetic subjects, male carriers of 1484insG allele had significantly higher fasting insulin (p = 0.003), cholesterol (p = 0.012), LDL-C (p = 0.037), apo B (p = 0.015), and HOMA-IR (p = 0.011) levels compared to the individuals carrying the wild-type genotype. Among non-diabetic female individuals, only body mass index was significantly higher in 1484insG subjects compared to the wild-type individuals (p = 0.007). CONCLUSIONS: Our results from a sample of Iranian type 2 diabetes cases and controls provide evidence that the 1484insG genotype of the PTPN1 gene may be associated with insulin resistance and other cardiovascular risk factors in non-diabetic male subjects.

Imaging, biodistribution and in vitro study of smart 99mTc-PAMAM G4 dendrimer as novel nano-complex.

Overexpression of folic acid receptor in various human tumors cells makes it as good candidate for targeting delivery of chemotherapeutic and radiopharmaceutical agents. In this research, FA used for functionalization of PEG modified PAMAM G4 dendrimer as a smart delivery of 5-FU and 99mTc for the breast carcinoma in order to chemotherapeutic and imaging goals. One aim of this research was assess the FA-mediated cell viability assay of PEG-PAMAM G4-FA-5FU-99mTc and in vitro uptake of PEG-PAMAM G4-FA-99mTc as the novel nano-complex determined on C2Cl2 (normal cell) and MCF-7 (breast cancer cell) cell lines. Other main goals were studied. Morover, an investigation in to in vivo imaging and biodistribution was carried out via a novel radio tracer by which tumor accumulation and site were obviously detected. The targeted tumor images taken by tail intravenous injection demonstrated that nano-complex can be smartly used in imaging study of the clinical practices. Also, the biodistribution of this nano-complex was investigated and the organ predestination of 99mTc labeled nano-complex (%ID/g) was ascertained.

In vitro Cytotoxicity Effects of 197Au/PAMAMG4 and 198Au/PAMAMG4 Nanocomposites Against MCF7 and 4T1 Breast Cancer Cell Lines.

Purpose: Study on gold based therapeutic agents for cancer cells deracination has become under scrutiny in recent years owing to effective treatments are not available for rapidly progressive cancers. The aim of present study was to examine efficiency of radioactive 198Au/PAMAMG4 and non-radioactive 197Au/PAMAMG4 nancomposites against 4T1 and MCF7 breast cancer cell lines. Methods: The PAMAMG4 dendrimer was treated with the gold anions and then, the mixture was chemically reduced by NaBH4. Prepared 197Au/PAMAMG4 was bombarded by thermal neutrons in the Tehran Research Reactor to 198Au/PAMAMG4 be produced. Prepared nanocomposites were characterized by means of FT-IR, 1H NMR, Zeta-potential measurements, TEM and EDX analyses. The radionuclidic purity of the 198Au/PAMAMG4 solution was determined using purity germanium (HPGe) spectroscopy and its stability in the presence of human serum was studied. In vitro studies were carried out to compare toxicity of PAMAMG4, 197Au/PAMAMG4 and 198Au/PAMAMG4 towards 4T1 and MCF7 cancerous cells and C2C12 normal cell lines. Results: Characterization results exhibited that invitro agents, 197Au/PAMAMG4 and 198Au/PAMAMG4, were synthesized successfully. Cells viability after 24 h, 48 h, and 72 h incubation, using MTT assay showed that the toxicity of 198Au/PAMAMG4 is significantly superior in comparison with 197Au/PAMAMG4 and PAMAMG4. Furthermore, the toxicity of 198Au/PAMAMG4 was higher on cancerous cells especially in higher level of concentrations after 72 hours (P<0.05). Conclusion: In the current study, the preparation of 197Au/PAMAMG4 and 198Au/PAMAMG4 is described and the cytotoxic properties of them against the MCF7, 4T1 cancerous cells and C2C12 normal cells were evaluated using MTT assay.

Preferential role of iron in heme degradation of hemoglobin upon gamma irradiation.

It is usually believed that γ-ray interaction with biomolecules is intermediately performed by reactive oxygen species (ROS) produced from radiolysis of water. Hemoglobin (Hb) as one of the most abundant biomolecule in blood and well-studied endogenously affected by ROS, was a good candidate for study. Adult human Hb was extracted and irradiated using four distinct 20, 60, 90 and 170Gy doses from Co-60 γ-ray source. UV-vis, fluorescence and FT-IR spectroscopies were used to study the whole conformational changes and partial degradation of heme. Hb species calculated using Benesch equations indicated that the concentration of oxy-Hb was decreased from 9.97µM to 6.56µM, while the total metastable met and deoxy-Hb concentration were just increased 2.39µM and about 8.4% of total heme was diminished. Heme degradation was studied using fluorescence spectra at two 321 and 460nm excitation wavelengths as fully and partially degradation of heme respectively. Inverse behavior of these two fluorescence spectra suggested a new mechanism of heme degradation in which γ-ray preferably absorbed by heme without any intermediary effects of water. It was confirmed by FT-IR spectra at 900-1000cm-1 where the FeN and NH of porphyrin indicate their own stretching vibrational bands. Thermal stability justified that the gamma radiation induced the conformational changes of Hb which is appeared during thermal unfolding. First derivative of thermal spectra indicated that the Tm of 170Gy dose irradiated sample is 2°C lowered and total concentration of Hb was decreased 14%.

Synthesis of a stabilized 177Lu-siRNA complex and evaluation of its stability and RNAi activity.

PURPOSE: Serum and intracellular instability limits the therapeutic applications of short interfering RNA (siRNA) as a radiopharmaceutical. Chemical modifications like phosphorothioate (PS) substitution and 2'-O-methoxy (2'-O-Me) modifications could eliminate such limitations. In this study, the effects of PS and 2'-O-Me modifications at the backbone of siRNA on serum stability and RNA interference activity were investigated. MATERIALS AND METHODS: Fully PS and 2'-O-Me-modified type 1 insulin-like growth factor receptor (IGF-1R) siRNA was radiolabeled with lutetium-177 ((177)Lu) through p-SCN-Bn-DTPA as a chelator. After purification with Vivaspin and PD-10 columns, the radiolabs were examined for stability in serum by instant thin-layer chromatography and polyacrylamide gel electrophoresis. The level of IGF-1R in response to the modified and labeled IGF-1R siRNA was examined using RT-PCR and ELISA assay in colon cancer cells. The effects of such siRNA on the prevention of proliferation of colon cancer cells and its apoptosis were investigated using MTT assay and Annexin-V/propidium iodide double staining, respectively. Cellular accumulation quantities of the labeled and modified IGF-1R siRNA were determined using a γ-counter by taking advantage of (177)Lu as a γ-emitter. RESULTS: Both the modified (177)Lu-siRNA complex and the modified nonlabeled siRNA showed significant stability in serum. The levels of IGF-1R mRNA and protein significantly decreased with both the labeled and nonlabeled IGF-1R siRNAs, but no such reduction in IGF-1R was observed with luciferase siRNA (P<0.01). Proliferation decreased significantly and apoptosis increased in the cells treated with modified (177)Lu-IGF-1R siRNA in comparison with either (177)Lu or labeled luciferase siRNA (P<0.001). CONCLUSION: Uniform chemically modified siRNAs can form stable complexes with Lu that pronounce its cytotoxic effect through apoptosis in colon cancer cells.

Preparation and radiolabeling of a lyophilized (kit) formulation of DOTA-rituximab with 9°Y and ¹¹¹In for domestic radioimmunotherapy and radioscintigraphy of non-Hodgkin's lymphoma.

BACKGROUND: On the basis of results of our previous investigations on 90Y-DTPA-rituximab and in order to fulfil national demands to radioimmunoconjugates for radioscintigraphy and radioimmunotherapy of Non-Hodgkin's Lymphoma (NHL), preparation and radiolabeling of a lyophilized formulation (kit) of DOTA-rituximab with 111In and 90Y was investigated. METHODS: 111In and 90Y with high radiochemical and radionuclide purity were prepared by 112Cd (p,2n)111In nuclear reaction and a locally developed 90Sr/90Y generator, respectively. DOTA-rituximab immunoconjugates were prepared by the reaction of solutions of p-SCN-Bz-DOTA and rituximab in carbonate buffer (pH = 9.5) and the number of DOTA per molecule of conjugates were determined by transchelation reaction between DOTA and arsenaso yttrium(III) complex. DOTA-rituximab immunoconjugates were labeled with 111In and 90Y and radioimmunoconjugates were checked for radiochemical purity by chromatography methods and for immunoreactivity by cell-binding assay using Raji cell line. The stability of radiolabeled conjugate with the approximate number of 7 DOTA molecules per one rituximab molecule which was prepared in moderate yield and showed moderate immunoreactivity, compared to two other prepared radioimmunoconjugates, was determined at different time intervals and against EDTA and human serum by chromatography methods and reducing SDS-polyacrylamide gel electrophoresis, respectively. The biodistribution of the selected radioimmunoconjugate in rats was determined by measurement of the radioactivity of different organs after sacrificing the animals by ether asphyxiation. RESULTS: The radioimmunoconjugate with approximate DOTA/rituximab molar ratio of 7 showed stability after 24 h at room temperature, after 96 h at 4°C, as the lyophilized formulation after six months storage and against EDTA and human serum. This radioimmunoconjugate had a biodistribution profile similar to that of 90Y-ibritumomab, which is approved by FDA for radioimmunotherapy of NHL, and showed low brain and lung uptakes and low yttrium deposition into bone. CONCLUSION: Findings of this study suggest that further investigations may result in a lyophilized (kit) formulation of DOTA-rituximab which could be easily radiolabeled with 90Y and 111In in order to be used for radioimmunotherapy and radioscintigraphy of B-cell lymphoma in Iran.

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

PURPOSE: The radiolabeling of targeting biomolecules with gamma emitter radionuclides for tracing and beta emitters for therapy involves the conjugation of such biomolecules to the chelating agents to form complexes with the radionuclide of interest. In this study, radioconjugate of IGF-1R siRNA with lutetium-177 ((177)Lu) was produced, and the anti-proliferation and apoptosis effects elicited by this (177)Lu-siRNA complex in the SW480 colon cancer cells were evaluated. METHODS: IGF-1R and Luciferase siRNAs were conjugated with p-SCN-Bn-DTPA, and then radiolabeled with (177)Lu. The effects of labeled and non-labeled IGF-1R siRNAs on IGF-1R expression were assessed with RT-PCR analysis and ELISA assay. IGF-1R siRNAs induced cell death and apoptosis were investigated using MTT assay and Annexin-V/propidium iodide (PI) double staining, respectively. RESULTS: Combined purification using Vivaspin and PD-10 columns resulted in a radiochemical purity of 97.32% ± 1.97%. Knockdown effect of the labeled IGF-1R siRNA was not significantly different from the non-labeled duplex of the same sequence (P<0.05), but it was significant compared to the Luciferase siRNAs (P<0.001). Proliferation decreased significantly, but apoptosis increased in the cells treated with the (177)Lu-IGF-1R siRNA in comparison with either (177)Lu or IGF-1R siRNA (P<0.001). CONCLUSION: Radioconjugate of IGF-1R siRNA, p-SCN-Bn-DTPA and (177)Lu was successfully produced and characterized as radiopharmaceutical. The present study demonstrates the involvement of (177)Lu-labeled IGF-1R siRNA in the inhibition of cell growth and induction of apoptosis in colon cancer cells.

Knockdown of IGF-IR by RNAi inhibits SW480 colon cancer cells growth in vitro.

BACKGROUND AND AIMS: Colon cancer is the second leading cause of death due to cancer worldwide. Elevated expression of IGF-IR is a frequent genetic abnormality seen in this malignancy. The aim of the study was to examine the anti-growth effects elicited by a decrease in the protein level of IGF-IR by RNA interference (RNAi) in SW480 cells. METHODS: A plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting IGF-IR to reduce its expression in SW480 cells. The expression of IGF-1R protein was detected by Western blot. We assessed the effects of IGF-IR silencing on cancer cell growth by a growth curve. RESULTS: We prepared a type of IGF-IR short hairpin RNA (shRNA) expression vector that could efficiently inhibit the expression of IGF-IR in SW480 cells. At 48 h after transfection, the expression inhibition rate was 92 +/- 2% at mRNA level detected by RT-PCR analysis. Western blotting detected a similar inhibition of IGF-IR protein levels in cells transfected with pkD-shRNA-IGF-IR-V2. Downregulation of IGF-IR resulted in significant inhibition of cancer cell growth in vitro. The cell growth inhibition rates at 24, 48, and 72 h after pkD-shRNA-IGF-IR-V2 transfection were 32.06, 47.61, and 35.36%, respectively. CONCLUSIONS: Our data show that decreasing the IGF-IR protein level in SW480 cells by RNAi could significantly inhibit tumor growth in vitro, implying the therapeutic potential of RNAi on the treatment of colon cancer by targeting overexpression oncogenes such as IGF-IR. IGF-IR may be a potential therapeutic target for human colon cancer.