In vivo screening models of cisplatin-resistant human lung cancer cell lines using SCID mice

Nedaplatin concurrent with three-dimensional conformal radiotherapy for treatment of locally advanced esophageal carcinoma

AIM: To evaluate the efficacy and toxicity of nedaplatin (NDP) concurrent with radiotherapy in the treatment of locally advanced esophageal carcinoma.

METHODS: Sixty-eight patients with locally advanced esophageal carcinoma were randomized into either a NDP group (n = 34) or a cisplatin (DDP) group (n = 34). The NDP group received NDP 80-100 mg/m²iv on day 1 + leucovorin (CF) 100 mg/m²iv on days 1-5 + 5-fluorouracil (5-FU) 500 mg/m²iv on days 1-5. The DDP group received DDP 30 mg/m²iv on days 1-3 + CF 100 mg/m² on days 1-5 + 5-FU 500 mg/m²iv on days 1-5. The treatment was repeated every 4 wk in both groups. Concurrent radiotherapy [60-66 Gy/(30-33 f)/(6-7 wk)] was given during chemotherapy.

RESULTS: There was no significant difference in the short-term response rate between the NDP group and DDP group (90.9% vs 81.3%, P = 0.528). Although the 1- and 2-year survival rates were higher in the NDP group than in the DDP group (75.8% vs 68.8%, 57.6% vs 50.0%), the difference in the overall survival rate was not statistically significant between the two groups (P = 0.540). The incidences of nausea, vomiting and nephrotoxicity were significantly lower in the NDP group than in the DDP group (17.6% vs 50.0%, P = 0.031; 11.8% vs 47.1%, P = 0.016; 8.8% vs 38.2%, P = 0.039). There was no significant difference in the incidence of myelosuppression, radiation-induced esophagitis or radiation-induced pneumonia between the two groups.

CONCLUSION: NDP-based concurrent chemoradiotherapy is effective and well-tolerated in patients with locally advanced esophageal carcinoma. NDP-based regimen has comparable efficacy to DDP-based regimen but is associated with lower incidences of gastrointestinal and renal toxicity.

Validation of intratracheal instillation of lung tumour cells in mice using single photon emission computed tomography/computed tomography imaging

In search of better predictive animal models for evaluating treatment response in lung cancer, orthotopic lung tumour models are a great step forward over traditional subcutaneous models. Crucial in the development of such orthotopic models is a reliable and reproducible instillation method. Because cells are instilled inside the thorax, the accuracy of the instillation and visualization of tumour growth demands the use of non-invasive imaging methods. We used a minimally invasive intratracheal intubation method to instill bioluminescent lung tumour cells in the lung parenchyma. Adaptation of the cell containing medium provides the possibility of tracing the exact location of the injection by means of single photon emission computed tomography/computed tomography (CT) imaging. The transplantation medium was also optimized to prevent migration of the injected substance. This results in the outgrowth of single and well-defined lung tumours at the instillation site. Finally, tumour growth was validated and longitudinally monitored with a combination of CT and bioluminescence imaging. The reported transplantation procedure enables the assessment of injection accuracy and provides a good approach for the generation of orthotopic lung tumour models for future response imaging studies.

Bcl-2 antisense oligonucleotides (G3139) inhibit Merkel cell carcinoma growth in SCID mice

Merkel cell carcinoma was first described in 1972 by Toker and is an aggressive neuroendocrine skin tumor with a high metastatic potential. Merkel cell carcinoma is thought to derive from the neuroendocrine (Merkel) cells of the skin, although in contrast to fetal and especially adult Merkel cells, Merkel cell carcinomas express high levels of the Bcl-2 oncoprotein. Bcl-2 is capable of blocking programmed cell death and has been shown to play an important role in normal cell turnover, tumor biology, and chemoresistance. High Bcl-2 expression leading to prolonged survival of cells may therefore be of importance in the biological and clinical characteristics of Merkel cell carcinoma. In a SCID mouse xenotransplantation model for human Merkel cell carcinoma, we investigated the influence of the bcl-2 antisense oligonucleotide G3139 (Genta) on tumor growth in comparison with control oligonucleotides or cisplatin. Bcl-2 antisense treatment, targeting the first six codons of the bcl-2 mRNA, resulted in either a dramatic reduction of tumor growth or complete remission, whereas reverse sequence and two-base mismatch control oligonucleotides or cisplatin had no significant antitumor effects compared with saline-treated controls. Apoptosis was enhanced 2.4-fold in the bcl-2 antisense treated tumors compared with the saline-treated group, and no other treatment showed a comparable increase in apoptosis. Our findings suggest that bcl-2 antisense treatment may be a novel approach to improve treatment outcome of human Merkel cell carcinoma.

Interleukin-2 gene transduction into freshly isolated lung adenocarcinoma cells with adenoviral vectors

We evaluated the efficiency of gene transduction and of gene expression by adenoviral vectors in human lung adenocarcinoma cells. Freshly isolated cancer cells were collected from pleural effusions in adenocarcinoma patients by centrifugation with a Percoll gradient. Adenoviral vectors resulted in effective gene transduction into human lung cancer cell lines and into freshly isolated lung adenocarcinoma cells. In an experiment using the beta-galactosidase (LacZ) gene, the Adex1CA vector with a regulatory sequence of chicken beta-actin as promoter and an enhancer derived from cytomegalovirus produced a higher transduction ratio and greater expression levels than adenoviral vectors with other promoter systems. Transduction with Adex1CA vectors containing the human interleukin-2 (IL-2) gene (Adex1CAhIL-2) resulted in enhanced secretion of IL-2 from gene-modified lung cancer cells. Treatment with normal human serum inhibited gene transduction by Adex1CAhIL-2 but did not inhibit gene expression after transduction by Adex1CAhIL-2. The secretion of IL-2 from the gene-modified cells, which were irradiated at 100 Gy before transduction, continued for 8 days. In a mouse model, the intrapleural injection of IL-2 gene-modified 3LL cells transduced by Adex1CAhIL-2 could cure the pre-existing lung tumours with malignant pleural effusions to induce tumor-specific immunity. But these therapies did not show any therapeutic benefit on the pre-existing tumor in subcutaneous region. These data suggest a potentially useful but limited clinical role of Adex1CAhIL-2 in gene therapy for lung cancer patients.

In vitro and in vivo modulation by rhizoxin of non-P-glycoprotein-mediated vindesine resistance

Rhizoxin is an antineoplastic drug that inhibits tubulin polymerization. In this study, we demonstrated that rhizoxin was approximately twice as active in vitro against a human small-cell lung cancer cell line with non-P-glycoprotein-mediated resistance to vindesine, H69/VDS, as against its parental line, H69. Tubulin polymerization in H69/VDS, demonstrated by Western blot analysis, was inhibited markedly by rhizoxin compared with that in H69, in a concentration-dependent manner. A drug-accumulation study showed that the intracellular rhizoxin level in H69/VDS was 15% lower than that in H69, whereas efflux from H69/VDS was enhanced slightly. These results indicate that enhanced inhibition of tubulin polymerization rather than increased intracellular drug concentration accounted for the higher sensitivity of H69/VDS to rhizoxin. In an experiment using mice with severe combined immunodeficiency and inoculated subcutaneously with H69/VDS, in vivo tumor growth was reduced markedly by three intermittent intraperitoneal doses of rhizoxin compared with that in mice inoculated with H69. Three weeks after the last rhizoxin dose, the relative treated/untreated tumor volumes were 0.29 for H69, but only 0.06 for H69/VDS, indicating that H69/VDS regrowth was minimal even after a 3-week treatment-free period. In conclusion, rhizoxin conquers vindesine resistance of a human small-cell lung cancer cell line in vitro and in vivo.