Antisense oligonucleotide therapy for urologic tumors

Depletion of telomerase RNA inhibits growth of gastrointestinal tumors transplanted in mice

AIM: To explore effects of telomerase RNA-targeting phosphorothioate antisense oligodeoxynucleotides (PS-ASODN) on growth of human gastrointestinal stromal tumors transplanted in mice.

METHODS: A SCID mouse model for transplantation of human gastrointestinal stromal tumors (GISTs) was established using tumor cells from a patient who was diagnosed with GIST and consequently had been treated with imatinib. GIST cells cultured for 10 passages were used for inoculation into mice. Transfection of PS-ASODN was carried out with Lipotap Liposomal Transfection Reagent. GISTs that subsequently developed in SCID mice were subjected to intra-tumoral injection once daily from day 7 to day 28 post-inoculation, and mice were divided into the following four groups according to treatment: PS-ASODN group (5.00 μmoL/L of oligonucleotide, each mouse received 0.2 mL once daily); imatinib group (0.1 mg/g body weight); liposome negative control group (0.01 mL/g); and saline group (0.01 mL/g). On day 28, the mice were sacrificed, and tumor attributes including weight and longest and shortest diameters were measured. Tumor growth was compared between treatment groups, and telomerase activity was measured by enzyme-linked immunosorbent assay. Apoptosis was examined by flow cytometry. Real-time polymerase chain reaction was used to detect expression of the mRNA encoding the apoptosis inhibition B-cell leukemia/lymphoma 2 (bcl-2) gene.

RESULTS: In the PS-ASODN group, tumor growth was inhibited by 59.437%, which was markedly higher than in the imatinib group (11.071%) and liposome negative control group (2.759%) [tumor inhibition = (mean tumor weight of control group - mean tumor weight of treatment group)/(mean tumor weight of control group) × 100%]. Telomerase activity was significantly lower (P < 0.01) in the PS-ASODN group (0.689 ± 0.158) compared with the imatinib group (1.838 ± 0.241), liposome negative control group (2.013 ± 0.273), and saline group (2.004 ± 0.163). Flow cytometry revealed that the apoptosis rate of tumor cells treated with PS-ASODN was 20.751% ± 0.789%, which was higher (P < 0.01) than that of the imatinib group (1.163% ± 0.469%), liposome negative control group (1.212% ± 0.310%), and saline group (1.172% ± 0.403%). Expression of bcl-2 mRNA in the transplanted GISTs was markedly downregulated (P < 0.01) in the PS-ASODN group (7.245 ± 0.739) compared with the imatinib group (14.153 ± 1.618) and liposome negative control group (16.396 ± 1.351).

CONCLUSION: PS-ASODN can repress GIST growth, mediated perhaps by inhibition of telomerase activity and downregulation of bcl-2 expression.

Optimizing chemotherapy for transitional cell carcinoma by application of bcl-2 and bcl-xL antisense oligodeoxynucleotides

OBJECTIVE

Therapy failure after intravesical and systemic chemotherapy for transitional cell carcinoma (TCC) is still high. Antiapoptotic proteins such as Bcl-2 and Bcl-xL have been reported to promote chemoresistance in TCC. Targeting bcl-2 and bcl-xL messenger ribonucleic acid with antisense oligodeoxynucleotides (AS-ODNs) may enhance the cytotoxic effects of chemotherapeutic agents. Therefore, we investigated the effects of bcl-2 and bcl-xL AS-ODNs in combined treatment with conventional and new chemotherapeutic agents to evaluate the cytotoxic effects in comparison to monotreatment.

METHODS AND MATERIALS

Western blot analysis or immunohistochemistry verified Bcl-2 and Bcl-xL expression in a panel of human TCC cell lines that had been monotreated with cisplatin, gemcitabine, mitomycin C, and paclitaxel. In addition, bcl-2 or bcl-xL AS-ODNs were applied in combination with each chemotherapeutic agent. Cell viability was determined using a standard MTT assay and Neubauer hemocytometry.

RESULTS

All cell lines responded to chemotherapeutic monotreatment in a dose-dependent manner. Maximum cell death rates after monotreatment were 47.4% (cisplatin), 39.0% (gemcitabine), 83.4% (mitomycin C), and 54.8% (paclitaxel). After combined treatment with chemotherapy and bcl-2 or bcl-xL AS-ODNs, cell death rates were significantly higher (e.g., 30.3% vs. 87.2% in HT 1197 cells for monotreatment vs. the combination of paclitaxel and bcl-xL AS-ODNs). Three-way analysis of variance revealed that combined treatment had a significant effect on all cell lines.

CONCLUSIONS

Our study confirms that the addition of bcl-2 and bcl-xL AS-ODNs enhances the cytotoxic potential of chemotherapeutic agents in TCC cell lines as a result of combined effects. Further trials in ex vivo and in vivo models have to be performed to promote clinical application in patients.

[Regenerative medicine in andrology: tissue engineering and gene therapy as potential treatment options for penile deformations and erectile dysfunction]

Tissue engineering and gene therapy are currently investigated in animal studies for reconstructing penile tissue or treating erectile dysfunction. This review aims to ecamine these experimental efforts from the last years and tries to give a brief introduction to the basic methodology of these new techniques from the field of regenerative medicine.

IL-2 gene and antisense TGF-beta1 strategies counteract HSV-2 transformed tumor progression

The H238 tumor cells are Herpes simplex virus type 2-transformed BALB/c mouse fibroblasts that constitutively express transforming growth factor (TGF-beta1). TGF-beta can diminish immune capacity, whereas interleukin 2 (IL-2) is stimulatory to the immune system and can counteract the negative effects of TGF-beta1. The H238-BALB/c system provides a syngeneic model to evaluate new strategies with the potential to ameliorate tumor-induced immune depression. Plasmids expressing either antisense TGF-beta1 or murine Il-2 were constructed and stably transformed cells generated (masH238 and H238-IL2, respectively). In vitro measurements (ELISA and RT-PCR) demonstrated a >70% decrease in TGF-beta1 secretion by the masH238 tumor cells, and significant levels of IL-2 production by the H238-IL2 transfected cells when compared to wild type and control plasmid-transfected H238 cells. BALB/c mice injected subcutaneously with the masH238 cells developed significantly smaller tumors than the controls. Mice injected with H238-IL-2 cells developed tumors that failed to progress relative to control tumor growth. The differences in tumor growth in the mice were associated with enhanced immune reactivity and an increased response to T lymphocyte mitogens. Significant differences were also noted in lymphocyte populations and expression of CD25 and CD71 activation markers in the blood and spleens of mice receiving transfected tumor cells. Collectively, the data demonstrate that strategies employing antisense TGF-beta1 and IL-2 expression by transfected tumor cells can counteract the progression of a TGF-beta1-secreting tumor and enhance immune function involving modulation of T lymphocyte populations.