Human Tumor Xenograft Mouse Model Research Articles

Synergistic and selective inhibition of NSCLC cell growth via a caspase-independent cell death pathway by tumor suppressor 101F6 nanoparticles plus vitamin C in vitro and in vivo

13086 Background: 101F6 is a candidate tumor suppressor gene on chromosome 3p21.3, a site of allele loss and genomic alterations were frequently found in many human cancers. We previously showed that enforced expression of wt-101F6 by adenoviral virus significantly inhibited tumor cell growth in 3p21.3-deficient NSCLC cells in vitro and in vivo. How 101F6 exerts this effect is largely unknown. Using a computer-aided structural and functional modeling, we recently identified 101F6 as a member of cytochrome b-561 protein family, which is involved in the regeneration of vitamin C. We hypothesized that under normal physiologic conditions, 101F6 protects cells from oxidative damage by regenerating antioxidant vitamin C and that in 101F6-deficient tumor cells, exogenous 101F6 facilitates vitamin C-mediated cytotoxic H2O2 formation. Methods and Results: We examined endogenous 101F6 expression in human NSCLC cell lines and tissue samples. All normal lung bronchial epithelial cells and fibroblasts but few lung cancers expressed 101F6. We investigated the combined effect of 101F6 and vitamin C on the cell growth: a nanoparticle-mediated wt-101F6 gene transfer plus a sub-pharmacologic concentration of vitamin C synergistically inhibited 3p21.3-deficient NSCLC cell growth but did not affect normal cell growth. We also used a human NSCLC H322 orthotopic lung tumor xenograft mouse model to evaluate the therapeutic efficacy of systemic injection of 101F6 nanoparticles and intraperitoneal injection of vitamin C. The growth of lung tumors was synergistically inhibited by the combination treatment (p<0.001). Furthermore, exogenous 101F6 promoted intracellular vitamin C uptake, leading to the vitamin C-mediated accumulation of H2O2 in the tumor cells, and these two agents synergistically killed the cells through caspase-independent apoptosis and autophagy cell death pathways. Conclusions: The synergistic and selective antitumor effect of 101F6 nanoparticles plus vitamin C may offer a useful tool for lung cancer prevention and intervention. This abstract is supported by grants from NCI (SPORE P50CA70907) and DOD (TARGET, DAMD17002–1-0706). No significant financial relationships to disclose.

Anti-proliferative and anti-tumor effects of antisense oligonucleotide GTI-2601 targeted against human thioredoxin

Human thioredoxin has been implicated in cancer as a growth stimulator through regulation of DNA replication and growth factor activity, as a modulator of transcription factor activity, and as an inhibitor of apoptosis. In the present study, the steady-state level of thioredoxin protein was examined in a number of cancer cell lines. Interestingly, thioredoxin expression is elevated in a variety of human tumor cell lines compared with normal cell lines. The altered expression of thioredoxin in tumor cells suggests it may be a target in the development of novel therapeutic agents for the treatment and prevention of cancer. Further to this possibility, 26 phosphorothioate antisense oligodeoxynucleotides (PS-AS-ODNs) were evaluated for the ability to inhibit thioredoxin expression in cell culture. One PS-AS-ODN, GTI-2601, specifically reduced the levels of thioredoxin mRNA and protein, exhibited potent anti-proliferative effects on colony formation in vitro, and had anti-tumor effects in human tumor xenograft mouse models in vivo. Sequence-specific decreases in thioredoxin expression levels were accompanied by significant suppression of tumor growth in mice. Taken together, these data suggest that thioredoxin may be a useful target for developing PS-AS-ODNs as drug candidates against human cancer.

In vivo antitumor activity by 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone in a solid human carcinoma xenograft model

Previously we have shown that 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC), which is isolated from the buds of Cleistocalyx operculatus, significantly inhibits the growth of human liver cancer SMMC-7721 cells and is able to induce apoptosis of SMMC-7721 cells in vitro. Here we report the antitumor effects of DMC in vivo, using a solid human tumor xenograft mouse model using human liver cancer SMMC-7721 cells. The average tumor weights in the control group and in mice injected with 150 mg/kg DMC were 1.42+/-0.11 g and 0.59+/-0.12 g, respectively. Flow cytometric analysis of the tumor cell population demonstrated an aneuploid peak (representing 33.60+/-0.80% of the total in mice injected with 150 mg/kg DMC). To our knowledge, this is the first time that chalcone compounds have been applied to a human tumor xenograft model.

Quantification of tumor tissue populations by multispectral analysis.

Tumor heterogeneity complicates the quantification of a therapeutic response by MRI. To address this issue, a novel approach has been developed that combines MR diffusion imaging with multispectral (MS) analysis to quantify tumor tissue populations. K-means (KM) clustering of the apparent diffusion coefficient (ADC), T2, and proton density (M0) was employed to estimate the volumes of viable tumor tissue, necrosis, and neighboring subcutaneous adipose tissue in a human colorectal tumor xenograft mouse model. In a second set of experiments, the temporal evolution of the MS tissue classes in response to therapeutic intervention Apo2L/TRAIL and CPT-11 was observed. The multiple parameters played complementary roles in identifying the various tissues. The ADC was the dominant parameter for identifying regions of necrosis, whereas T2 identified two necrotic subpopulations, and M0 contributed to the differentiation of viable tumor from subcutaneous adipose tissue. MS viable tumor estimates (mean volume = 275 +/- 147 mm(3)) were highly correlated (r = 0.81, P < 0.01) with histological estimates (117 +/- 51 mm(3)). In the treatment study, MS viable tumor volume (at day 10) was 77 +/- 67 mm(3) for the Apo2L/TRAIL+CPT-11 group, and was significantly reduced relative to the control group (292 +/- 127 mm(3), P < 0.01). This method shows promise as a means of detecting an early therapeutic response in vivo.

Antitumor activity of a phosphorothioate antisense oligodeoxynucleotide targeted against C-raf kinase

Substantial evidence exists supporting a direct role for raf kinases in the development and maintenance of certain human malignancies. Here we test the potential of phosphorothioate antisense oligodeoxynucleotides targeted against human C-raf-1 kinase to specifically inhibit C-raf-1 kinase gene expression and tumor progression in cell culture and in vivo, using human tumor xenograft mouse models. Treatment of human tumor cells with appropriate phosphorothioate antisense oligodeoxynucleotides led to specific inhibition of C-raf kinase gene expression in cell culture and in vivo at well-tolerated doses. Moreover, oligodeoxynucleotide treatment resulted in potent antiproliferative effects in cell culture and potent antitumor effects in vivo against a variety of tumor types that were highly consistent with an antisense mechanism of action for these compounds. These studies strongly suggest that antisense inhibitors targeted against C-raf-1 kinase may be of considerable value as antineoplastic agents that display activity against a wide spectrum of tumor types at well-tolerated doses.

Evaluation of Marine Sponge Metabolites for Cytotoxicity and Signal Transduction Activity

Twenty-four metabolites derived from marine sponges were evaluated for their cytotoxicities against two human tumor cell lines, non-small cell lung carcinoma A549 and colon adenocarcinoma HT-29, and against one murine leukemia cell line, P-388, and evaluated for their ability to effect signal transduction in a newly developed cell adhesion assay using an EL-4 cell line. The compounds included latrunculin A [1], batzelline A [2], chondrillin [3], aureol [4], epihippuristanol, theonellamine B, discorhabdins A and C, kabiramide C, dercitin, meridine, manzamines A, B, and C, 8,15-diisocyano-11(20)-amphilectene and the corresponding C-15 formamide, a 20-carbon acetylenic alcohol, 4,5-dihydro-6"-deoxybromotopsentin, epispongiadiol, isospongiadiol, puupehenone, reiswigin A, and demethyl- and demethyloxyaaptamine. Latrunculin A [1], batzelline A [2], chondrillin [3], and aureol [4] expressed the desired profile of a greater than five-fold level of cytotoxicity against A549 relative to P-388, and an effect in the cell adhesion assay. In this group of compounds, cytotoxicity toward A549 was equal to or more pronounced than against HT-29. Latrunculin A was evaluated in an sc-implanted human A549 lung tumor xenograft mouse model and yielded a T/C of 146%. Batzelline A was evaluated in the cancer cell line panel at the National Cancer Institute and found to express selective cytotoxicity against several melanoma cancer cell lines.