Synergistic tumoricidal effect of combined hMUC1 vaccination and hNIS radioiodine gene therapy

Protective efficacy of a plasmid DNA vaccine against transgene-specific tumors by Th1 cellular immune responses after intradermal injection

With DNA vaccines, it is important to monitor the movement of transfectants and to overcome immune deviations. We used a pCMV-LacZ plasmid (expressing β-galactosidase) and a pcDNA-hNIS plasmid (expressing the human sodium/iodide symporter [hNIS] gene) as non-secreted visual-imaging markers. Transfectants carrying the hNIS or LacZ gene migrated to peripheral lymphoid tissues. hNIS-expressing cells were observed specifically in the LNs and spleen. Anti-β-galactosidase was detected in LacZ DNA immunized mice after boosting twice, suggestive of Th2 humoral immune responses. Antibody isotyping defined the humoral immune response. A dominant IgG2a type occurred in hNIS-immunized mice in ELISAs. IgG2a/IgG1 ratios increased after hNIS DNA vaccination. High levels of INF-γ-secreting cells were identified in ELISpot and increased IFN-γ levels were found in cytokine ELISAs. Tumor growth decreased in hNIS DNA-immunized mice. In conclusion, humoral immune responses switched to the Th1 cellular immune response, even though we administered plasmid DNA by intra dermal injection.

The combination of ANT2 shRNA and hNIS radioiodine gene therapy increases CTL cytotoxic activity through the phenotypic modulation of cancer cells: combination treatment with ANT2 shRNA and I-131

BACKGROUND

It is important to simultaneously induce strong cell death and antitumor immunity in cancer patients for successful cancer treatment. Here, we investigated the cytotoxic and phenotypic modulation effects of the combination of ANT2 shRNA and human sodium iodide symporter (hNIS) radioiodine gene therapy in vitro and in vivo and visualized the antitumor effects in an immunocompromised mouse colon cancer model.

METHODS

A mouse colon cancer cell line co-expressing hNIS and the luciferase gene (CT26/hNIS-Fluc, named CT26/NF) was established. CT26/NF cells and tumor-bearing mice were treated with HBSS, scramble, ANT2 shRNA, I-131, and ANT2 shRNA + I-131. The apoptotic rates (%) and MHC class I and Fas gene expression levels were determined in treated CT26/NF cells using flow cytometry. Concurrently, the level of caspase-3 activation was determined in treated cells in vitro. For in vivo therapy, tumor-bearing mice were treated with scramble, ANT2 shRNA, I-131, and the combination therapy, and the anti-tumor effects were monitored using bioluminescence. The killing activity of cytotoxic T cells (CTLs) was measured with a lactate dehydrogenase (LDH) assay.

RESULTS

For the in vitro experiments, the combination of ANT2 shRNA and I-131 resulted in a higher apoptotic cell death rate compared with ANT2 shRNA or I-131 alone, and the levels of MHC class I and Fas-expressing cancer cells were highest in the cells receiving combination treatment, while single treatment modestly increased the level of MHC class I and Fas gene expression. The combination of ANT2 shRNA and I-131 resulted in a higher caspase-3 activation than single treatments. Interestingly, in vivo combination treatment led to increased gene expression of MHC class I and Fas than the respective mono-therapies; furthermore, bioluminescence showed increased antitumor effects after combination treatment than monotherapies. The LDH assay revealed that the CTL killing activity against CT26/NF cells was most effective after combination therapy.

CONCLUSIONS

Increased cell death and phenotypic modulation of cancer cells in vitro and in vivo were achieved simultaneously after combination therapy with ANT2 shRNA and I-131, and this combination therapy induced remarkable antitumor outcomes through improvements in CTL immunity against CT26/NF. Our results suggest that combination therapy can be used as a new therapeutic strategy for cancer patients who show resistance to single therapy such as radiation or immunotherapy.

Combined E7-dendritic cell-based immunotherapy and human sodium/iodide symporter radioiodine gene therapy with monitoring of antitumor effects by bioluminescent imaging in a mouse model of uterine cervical cancer

Using a uterine cervical cancer cell line expressing human papillomavirus (HPV) 16 E7 antigen and bioluminescent imaging (BLI), we evaluated the therapeutic potential of combined immunotherapy using transfected dendritic cells (DC-E7) and human sodium/iodide symporter (hNIS) radioiodine gene therapy in a xenograft animal cancer model. Dendritic cells expressing either E7 antigen (DC-E7) or no-insert (DC-no insert) were made for immunization materials, and murine uterine cervical cancer cell line coexpressing E7, firefly luciferase, hNIS, and EGFP genes (TC-1/FNG) were prepared for the animal tumor model. C57BL/6 mice were divided into five therapy groups (phosphate-buffered saline [PBS], DC-no insert, DC-E7, I-131, and DC-E7+I-131 groups). Single therapy with either DC-E7 or I-131 induced greater retardation in tumor growth compared with PBS or DC-no insert groups, and it resulted in some tumor-free mice (DC-E7 and I-131 groups, 40% and 20%, respectively). Combination therapy with DC-E7 and I-131 dramatically inhibited tumor growth, thus causing complete disappearance of tumors in all mice, and these effects were further confirmed by BLI in vivo. In conclusion, complete disappearance of the tumor was achieved with combined DC-E7 vaccination and hNIS radioiodine gene therapy in a mouse model with E7-expressing uterine cervical cancer, and serial BLIs successfully demonstrated antitumor effects in vivo.

Human sodium iodide symporter added to multidrug resistance 1 small hairpin RNA in a single gene construct enhances the therapeutic effects of radioiodine in a nude mouse model of multidrug resistant colon cancer

The objective of this study was to investigate the therapeutic potential of ¹³¹I added to doxorubicin therapy in multidrug resistance (MDR) mouse colon cancer coexpressing the MDR1 small hairpin RNA (shRNA) and human sodium iodide symporter (hNIS) gene in a single gene construct and to visualize the antitumor effects using molecular nuclear imaging. HCT-15 coexpressing shRNA for MDR1 gene (MDR1 shRNA) and hNIS gene with a single construct was established (referred to as MN61 cell). Inhibition of P-gp function by MDR1 shRNA and functional activity of hNIS gene was assessed using a ⁹⁹(m)Tc sestamibi uptake and ¹²⁵I uptake, respectively. Cytotoxic effects by a combination of doxorubicin and ¹³¹I were determined in parental (HCT-15) or MN61 cells using an in vitro clonogenic assay. Therapeutic effect of either combination therapy (doxorubicin and ¹³¹I) or single therapy (doxorubicin or ¹³¹I alone) was evaluated by tumor volume measurement. ⁹⁹(m)Tc-sestamibi, ¹²³I, and ⁹⁹(m)Tc-pertechnetate images of mice were acquired to evaluate functional assessment in vivo. Cellular uptake of ⁹⁹(m)Tc-sestamibi and ¹²⁵I was approximately 2-fold and 100-fold higher in MN61 cells than in parental cells, respectively. Combination of ¹³¹I and doxorubicin resulted in higher cytotoxcity in MN61 cells as compared with parental cells. Scintigraphic imaging showed higher uptake of ⁹⁹(m)Tc-sestamibi and ¹²³I in MN61 tumor as compared with parental tumor. In mice treated with doxorubicin, there was a slight delay in tumor growth in the MN61 tumor but not in the parental tumor. Cancer treatment with ¹³¹I or doxorubicin induced a rapid reduction of tumor volume in the MN61 tumor but not in the parental tumor. Combination therapy further generated a rapid reduction of tumor volume as compared with ¹³¹I therapy alone (p < 0.05). A combination hNIS mediated radioiodine gene therapy added to MDR1 shRNA treatment improved the effects of cancer treatment in a MDR cancer model and could enable visualization of the antitumor effects with nuclear imaging.

Treatment with mANT2 shRNA enhances antitumor therapeutic effects induced by MUC1 DNA vaccination

In this study, we developed a combination therapy (pcDNA3/hMUC1+mANT2 shRNA) to enhance the efficiency of MUC1 DNA vaccination by combining it with mANT2 short hairpin RNA (shRNA) treatment in immunocompetent mice. mANT2 shRNA treatment alone increased the apoptosis of BMF cells (B16F1 murine melanoma cell line coexpressing an MUC1 and Fluc gene) and rendered BMF tumor cells more susceptible to lysis by MUC1-associated CD8(+) T cells. Furthermore, combined therapy enhanced MUC1 associated T-cell immune response and antitumor effects, and resulted in a higher cure rate than either treatment alone (pcDNA3/hMUC1 or mANT2 shRNA therapy alone). Human MUC1 (hMUC1)-loaded CD11c(+) cells in the draining lymph nodes of BMF-bearing mice treated with the combined treatment were found to be most effective at generating hMUC1-associated CD8(+)IFNγ(+) T cells. Furthermore, the in vitro killing activities of hMUC1-associated cytotoxic T cells (CTLs) in the combined therapy were greater than in the respective monotherapies. Cured animals treated with the combined treatment rejected a rechallenge by BMF cells, but not a rechallenge by B16F1-Fluc cells at 14 days after treatment, and showed MUC1 antigen-associated immune responses. These results suggest that combined therapy enhances antitumor activity, and that it offers an effective antitumor strategy for treating melanoma.

CpG Oligodeoxynucleotides Enhance the Activities of CD8+ Cytotoxic T-Lymphocytes Generated by Combined hMUC1 Vaccination and hNIS Radioiodine Gene Therapy

PURPOSE

The authors evaluated whether the cytotoxicity of CD8+CTLs generated by combined hMUC1 vaccination and hNIS radioiodine gene therapy was enhanced in the presence of CpG in an established tumor model.

METHODS

CMNF cells (CT26 cells expressing hMUC1, hNIS and Firefly luciferase) were transplanted into BALB/c mice. Four and 10 days later, tumor-bearing mice were immunized intramuscularly with pcDNA3.1 or pcDNA-hMUC1 or pcDNA-hMUC1+CpG, and subsequently administered PBS or (131)I [five groups (seven mice/group): referred to as the pcDNA3.1+PBS, phMUC1+PBS, pcDNA3.1+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG groups]. The number of CD8+IFNr+ T cells of splenocytes as well as the number of CD8+IFNr+ T cells of splenocytes re-stimulated with CD11c+ cells was determined using FACS analysis. The activities of cytotoxic T cells (CTLs) from splenocytes were investigated.

RESULTS

Marked tumor growth inhibition was observed in the phMUC1+(131)I and phMUC1+(131)I+CpG groups, but not in the other three single therapy groups. Particularly the number of CD8+IFN-γ+ T cells of splenocytes was more increased in the phMUC1+(131)I+CpG group than in the phMUC1+(131)I group. The number of CD8+IFN-γ+ T cells of splenocytes stimulated with CD11c+ cells was the most enhanced in the phMUC1+(131)I+CpG group among the five groups. Concurrently, the activities of hMUC1-associated CTLs obtained from splenocytes in the phMUC1+(131)I+CpG group were significantly greater than in the other four groups (pcDNA+PBS, phMUC1+PBS, pcDNA+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG, 16 ± 2%, 20 ± 1%, 30 ± 2%, 60 ± 2%, and 87 ± 2%, respectively, P < 0.01).

CONCLUSION

Our data suggest that adjuvant CpG ODNs can increase the killing activities of CTLs generated by combined hMUC1 DNA vaccination and hNIS radioiodine gene therapy.

Enhanced anti-tumor effects of combined MDR1 RNA interference and human sodium/iodide symporter (NIS) radioiodine gene therapy using an adenoviral system in a colon cancer model

Using an adenoviral system as a delivery mediator of therapeutic gene, we investigated the therapeutic effects of the use of combined MDR1 shRNA and human NIS (hNIS) radioiodine gene therapy in a mouse colon xenograft model. In vitro uptake of Tc-99m sestamibi was increased approximately two-fold in cells infected with an adenovirus vector that expressed MDR1 shRNA (Ad-shMDR1) and I-125 uptake was 25-fold higher in cells infected with an adenovirus vector that expressed human NIS (Ad-hNIS) as compared with control cells. As compared with doxorubicin or I-131 treatment alone, the combination of doxorubicin and I-131 resulted in enhanced cytotoxicity for both Ad-shMDR1- and Ad-hNIS-infected cells, but not for control cells. In vivo uptake of Tc-99m sestamibi and Tc-99m pertechnetate was twofold and 10-fold higher for Ad-shMDR1 and Ad-hNIS-infected tumors as compared with tumors infected with a control adenovirus construct that expressed β-galactrosidase (Ad-LacZ), respectively. In mice treated with either doxorubicin or I-131 alone, there was a slight delay in tumor growth as compared to mice treated with Ad-LacZ. However, combination therapy with doxorubicin and I-131 induced further significant inhibition of tumor growth as compared with mice treated with Ad-LacZ. We have shown successful therapeutic efficacy of combined MDR shRNA and hNIS radioiodine gene therapy using an adenoviral vector system in a mouse colon cancer model. Adenovirus-mediated cancer gene therapy using MDR1 shRNA and hNIS would be a useful tool for the treatment of cancer cells expressing multi-drug resistant genes.

Human sodium/iodide symporter-mediated radioiodine gene therapy enhances the killing activities of CTLs in a mouse tumor model

We examined whether human sodium/iodide symporter (hNIS) radioiodine gene therapy can modulate the phenotype of cancer cells and enhance the killing activities of CTLs in a mouse tumor model. Various doses of I-131 (75, 300, 600, 1,200, and 2,400 microCi/5 mL) were incubated with hNIS-expressing colon cancer (CT26/hNIS) and parental cells (CT26), and numbers of MHC class I and Fas-expressing cells were determined by fluorescence-activated cell sorting (FACS). In addition, CT26/hNIS or CT26 tumor-bearing mice were treated with 1,200 microCi of I-131, and percentages of MHC class I and Fas-expressing tumor cells were determined by FACS. The levels of tumor-infiltrating CD8+IFNgamma+ and CD11c+CD86+ cells and CTL killing activities were measured in CT26/hNIS tumor-bearing mice (treated with PBS or 1,200 microCi of I-131) by FACS and lactate dehydrogenase assay, respectively. MHC class I and Fas gene expressions were markedly upregulated in CT26/hNIS cells, but not in CT26 cells, in an I-131 dose-dependent manner. The level of MHC class I and Fas-expressing cancer cell were 4.5-fold and 2.1-fold higher in CT26/hNIS tumors than in CT26 tumors, respectively (P < 0.01). Interestingly, numbers of tumor-infiltrating CD8+IFNgamma+ cells and CD11c+CD86+ cells were 5-fold and 2.5-fold higher in I-131-treated tumors than in PBS tumors, respectively (P < 0.001). Furthermore, CTL assays showed significantly more specific tumor cell lysis in I-131 tumors than in PBS tumors (P < 0.01). Our findings suggest that hNIS radioiodine gene therapy can generate tumor-associated immunity in tumor microenvironments and enhance the killing activities of CTLs.