Citation Details

Journal Article

4T1-luc2, 4T1, Bioware, IVIS

Sunitinib is a potent and clinically approved tyrosine kinase inhibitor that can suppress tumour growth by inhibiting angiogenesis. However, conflicting data exist regarding the effects of this drug on the growth of metastases in preclinical models. Here we use 4T1 and RENCA tumour cells, which both form lung metastases in Balb/c mice, to re-address the effects of sunitinib on the progression of metastatic disease in mice. We show that treatment of mice with sunitinib prior to intravenous injection of tumour cells can promote the seeding and growth of 4T1 lung metastases, but not RENCA lung metastases, showing that this effect is cell line dependent. However, increased metastasis occurred only upon administration of a very high sunitinib dose, but not when lower, clinically relevant doses were used. Mechanistically, high dose sunitinib led to a pericyte depletion effect in the lung vasculature that correlated with increased seeding of metastasis. By administering sunitinib to mice after intravenous injection of tumour cells, we demonstrate that while sunitinib does not inhibit the growth of 4T1 lung tumour nodules, it does block the growth of RENCA lung tumour nodules. This contrasting response was correlated with increased myeloid cell recruitment and persistent vascularisation in 4T1 tumours, whereas RENCA tumours recruited less myeloid cells and were more profoundly devascularised upon sunitinib treatment. Finally, we show that progression of 4T1 tumours in sunitinib treated mice results in increased hypoxia and increased glucose metabolism in these tumours and that this is associated with a poor outcome. Taken together, these data suggest that the effects of sunitinib on tumour progression are dose-dependent and tumour model-dependent. These findings have relevance for understanding how anti-angiogenic agents may influence disease progression when used in the adjuvant or metastatic setting in cancer patients.

Journal Article

PC-3-luc2, Prostate Cancer, Bioware, IVIS

Several in vitro and in vivo models have revealed the key role of CXCR4/CXCL12 axis in tumor-stroma interactions. Stromal cells present in the tumor microenvironment express high levels of CXCL12 protein, directly stimulating proliferation and migration of CXCR4-expressing cancer cells. This specific prosurvival influence of stromal cells on tumor cells is thought to protect them from cytotoxic chemotherapy and is postulated as a possible explanation for the minimal residual disease in hematological and solid cancers. Therefore, CXCR4/CXCL12 signaling is an attractive therapeutic target in cancer, as proven in preclinical leukemia mouse models, where CXCR4 inhibition sensitized cancer cells to conventional chemotherapy. This study investigates whether inhibition of CXCR4 with the specific inhibitor AMD3100 sensitizes human prostate cancer cells to docetaxel. We showed that both mouse and human stromal cell lines have a protective effect on PC3-luc cells by promoting their survival after chemotherapy. Furthermore, we demonstrated that AMD3100 sensitizes PC3-luc cells to docetaxel. In a subcutaneous xenograft mouse model of human prostate carcinoma, we showed that a combination of docetaxel and AMD3100 exerts increased antitumor effect compared with docetaxel alone. We concluded that CXCR4 inhibition chemosensitizes prostate cancer cells, both in vitro and in vivo. To explore the relevance of these findings, we analyzed CXCR4 expression levels in human prostate cancer samples. We found that cancer cells present in bone metastatic lesions express higher CXCR4 levels relative to the cells present in primary tumors and lymph node metastatic lesions. These findings underscore the potential of CXCR4 inhibitors as chemosensitizing agents.

Journal Article

MDA-MB-231-luc-D3H2Ln, D3H2Ln, IVIS, Breast cancer, Bioware

Statins and bisphosphonates are two distinct classes of isoprenoid pathway inhibitors targeting downstream enzyme to HMG-CoA reductase (upstream enzyme) and farnesyl-pyrophosphate synthase, respectively. Here, we studied fluvastatin (Fluva) and zoledronate (Zol), representative molecules of each class, respectively. In vivo metastatic potentials of both molecules were assessed. For the first time, we observed a significant reduction in progression of established metastases with Fluva treatment. Treatment with both Zol at 100 mug/kg and Fluva at 15 mg/kg inhibited 80% of the metastasis bioluminescence signal and increased survival of mice. The Zol and Fluva transcriptomic profiles of treated MDA-MB-231 cells revealed analogous patterns of affected genes, but each of them reached with different kinetics. The observable changes in gene expression started after 24 h for Fluva IC(50 72 h) and only after 48 h for Zol IC(50 72 h). To obtain early changes in gene expression of Zol-treated cells, a 3 times higher dose of Zol IC(50 72 h) had to be applied. Combining Fluva and Zol in vivo showed no synergy, but a benefit of several days in survival of mice. This study demonstrated that Zol or Fluva is of potential clinical use for the treatment of established metastasis.

Journal Article

MDA-MB-231-D3H1, MDA-MB-231-luc-D3H1, IVIS, Bioware, Breast Cancer

Abstract Purpose: This study uses a three-dimensional cell culture model to investigate lethal bystander effects in human breast cancer cell cultures (MCF-7, MDA-MB-231) treated with (125)I-labeled 5-iodo-2 -deoxyuridine ((125)IdU). These breast cancer cell lines respectively form metastatic xenografts in nude mice in an estrogen-dependent and independent manner. Materials and methods: In the present study, these cells were cultured in loosely-packed three-dimensional architecture in a Cytomatrix carbon scaffold. Cultures were pulse-labeled for 3 h with (125)IdU to selectively irradiate a minor fraction of cells, and simultaneously co-pulse-labeled with 0.04 mM 5-ethynyl-2'-deoxyuridine (EdU) to identify the radiolabeled cells using Click-iT((R)) EdU and flow cytometry. The cultures were then washed and incubated for 48 h. The cells were then harvested, serially diluted, and seeded for colony formation. Aliquots of cells were subjected to flow cytometry to determine the percentage of cells labeled with (125)IdU/EdU. Additional aliquots were used to determine the mean (125)I activity per labeled cell. The percentage of labeled cells was about 15% and 10% for MCF-7 and MDA cells, respectively. This created irradiation conditions wherein the cross-dose to unlabeled cells was small relative to the self-dose to labeled cells. The surviving fraction relative to EdU-treated controls was measured. Results: Survival curves indicated significant lethal bystander effect in MCF-7 cells, however, no significant lethal bystander effect was observed in MDA-MB-231 cells. Conclusions: These studies demonstrate the capacity of (125)IdU to induce lethal bystander effects in human breast cancer cells and suggest that the response depends on phenotype.

Journal Article

MDA-MB-231-D3H1, MDA-MB-231-luc-D3H1, IVIS, Bioware, Breast Cancer

The present study was undertaken to determine the anticancer efficacy of zerumbone (ZER), a sesquiterpene from subtropical ginger, against human breast cancer cells in vitro and in vivo. ZER treatment caused a dose-dependent decrease in viability of MCF-7 and MDA-MB-231 human breast cancer cells in association with G(2)/M phase cell cycle arrest and apoptosis induction. ZER-mediated cell cycle arrest was associated with downregulation of cyclin B1, cyclin-dependent kinase 1, Cdc25C, and Cdc25B. Even though ZER treatment caused stabilization of p53 and induction of PUMA, these proteins were dispensable for ZER-induced cell cycle arrest and/or apoptosis. Exposure of MDA-MB-231 and MCF-7 cells to ZER resulted in downregulation of Bcl-2 but its ectopic expression failed to confer protection against ZER-induced apoptosis. On the other hand, the SV40 immortalized mouse embryonic fibroblasts derived from Bax and Bak double knockout mice were significantly more resistant to ZER-induced apoptosis. ZER-treated MDA-MB-231 and MCF-7 cells exhibited a robust activation of both Bax and Bak. In vivo growth of orthotopic MDA-MB-231 xenografts was significantly retarded by ZER administration in association with apoptosis induction and suppression of cell proliferation (Ki-67 expression). These results indicate that ZER causes G(2)/M phase cell cycle arrest and Bax/Bak-mediated apoptosis in human breast cancer cells, and retards growth of MDA-MB-231 xenografts in vivo.