All-optical Mechanobiology Interrogation of Yes-associated Protein in Human Cancer and Normal Cells using a Multi-functional System

Long-term multi-functional imaging and analysis of live cells require streamlined, functional coordination of various hardware and software platforms. ...

University of Florida

The utility of combining the vascular targeting agents 5,6-dimethyl-xanthenone-4 acetic acid (DMXAA) and combretastatin A-4 disodium phosphate (CA4DP) with the anticancer drugs cisplatin and cyclophosphamide (CP) was evaluated in experimental rodent (KHT sarcoma), human breast (SKBR3) and ovarian (OW-1) tumor models. Doses of the vascular targeting agents that led to rapid vascular shutdown and subsequent extensive central tumor necrosis were identified. Histologic evaluation showed morphologic damage of tumor cells within a few hours after treatment, followed by extensive hemorrhagic necrosis and dose-dependent neoplastic cell death as a result of prolonged ischemia. Whereas these effects were induced by a range of CA4DP doses (10-150 mg/kg), the dose response to DMXAA was extremely steep; doses < or = 15 mg/kg were ineffective and doses > or = 20 mg/kg were toxic. DMXAA also enhanced the tumor cell killing of cisplatin, but doses > 15 mg/kg were required. In contrast, CA4DP increased cisplatin-induced tumor cell killing at all doses studied. This enhancement of cisplatin efficacy was dependent on the sequence and interval between the agents. The greatest effects were achieved when the vascular targeting agents were administered 1-3 hr after cisplatin. When CA4DP (100 mg/kg) or DMXAA (17.5 mg/kg) were administered 1 hr after a range of doses of cisplatin or CP, the tumor cell kill was 10-500-fold greater than that seen with chemotherapy alone. In addition, the inclusion of the antivascular agents did not increase bone marrow stem cell toxicity associated with these anticancer drugs, thus giving rise to a therapeutic gain.

Vascular targeting agents enhance chemotherapeutic agent activities in solid tumor therapy.

Unlike normal blood vessels, the unique characteristics of an expanding, disorganized and leaky tumor vascular network can be targeted for therapeutic gain by vascular disrupting agents (VDAs), which promote rapid and selective collapse of tumor vessels, causing extensive secondary cancer cell death. A hallmark observation following VDA treatment is the survival of neoplastic cells at the tumor periphery. However, comparative studies with the second generation tubulin-binding VDA OXi4503 indicate that the viable rim of tumor tissue remaining following treatment with this agent is significantly smaller than that seen for the lead VDA, combretastatin. OXi4503 is the cis-isomer of CA1P and it has been speculated that this agent's increased antitumor efficacy may be due to its reported metabolism to orthoquinone intermediates leading to the formation of cytotoxic free radicals. To examine this possibility in situ, KHT sarcoma-bearing mice were treated with either the cis- or trans-isomer of CA1P. Since both isomers can form quinone intermediates but only the cis-isomer binds tubulin, such a comparison allows the effects of vascular collapse to be evaluated independently from those caused by the reactive hydroxyl groups. The results showed that the cis-isomer (OXi4503) significantly impaired tumor blood flow leading to secondary tumor cell death and >95% tumor necrosis 24h post drug exposure. Treatment with the trans-isomer had no effect on these parameters. However, the combination of the trans-isomer with combretastatin increased the antitumor efficacy of the latter agent to near that of OXi4503. These findings indicate that while the predominant in vivo effect of OXi4503 is clearly due to microtubule collapse and vascular shut-down, the formation of toxic free radicals likely contributes to its enhanced potency.

Support of a free radical mechanism for enhanced antitumor efficacy of the microtubule disruptor OXi4503.

SRC, a non-receptor tyrosine kinase, is frequently over-expressed and highly activated in blood as well as solid tumors in various organs, including prostate, and has been associated with aggressive disease and a poor patient prognosis. Prostate cancer patients with a high risk of developing metastases have few treatment options, none of which can result in a durable cure. Therefore, the aim of the present study was to examine the impact of a SRC inhibitor, dasatinib, on the ability of human prostate cancer cell to complete key steps in the metastatic process, including invasion and angiogenesis. Dasatinib treatment impaired the metastatic phenotypes of the human prostate cancer cell lines, PC-3, DU-145, and LNCaP, by significantly reducing migration and invasion in modified Boyden chambers. Inhibition of phosphorylation, and therefore enhanced activation, of SRC and key downstream signaling pathway elements, including FAK, STAT3, Paxillin, and Akt, as determined by Western blotting, also was observed. This suggests that dasatinib interferes with critical cell functions associated with the metastatic cascade. Dasatinib also had direct effects on the ability of microvascular endothelial cells to form tubes in vitro and impaired the ability of PC-3 cells to induce angiogenesis in vivo. In conclusion, the present findings suggest that SRC inhibition by dasatinib may have utility in reducing the metastatic spread of prostate cancer cells.

Impact of the SRC inhibitor dasatinib on the metastatic phenotype of human prostate cancer cells.

Aerobic exercise is receiving increased recognition in oncology for its multiple purported benefits. Exercise is known to induce physiologic adaptations that improve patient quality-of-life parameters as well as all-cause mortality. There also is a growing body of evidence that exercise may directly alter the tumor microenvironment to influence tumor growth, metastasis, and response to anticancer therapies. Furthermore, the physiologic adaptations to exercise in normal tissues may protect against treatment-associated toxicity and allow for greater treatment tolerance. However, the exercise prescription required to induce these beneficial tumor-related outcomes remains unclear. This study characterized the aerobic adaptations to voluntary wheel running in normal tissues and the tumor microenvironment. Female, retired breeder BALB/c mice and syngeneic breast adenocarcinoma cells were utilized in primary tumor and metastasis models. Aerobic exercise was found to induce numerous adaptations across various tissues in these mice, although primary tumor growth and metastasis were largely unaffected. However, intratumoral hypoxia and global metabolism were altered in the tumors of exercising hosts relative to non-wheel running controls. Doxorubicin chemotherapy also was found to be more efficacious at delaying tumor growth with adjuvant aerobic exercise. Additionally, doxorubicin-induced cardiac toxicity was ameliorated in exercising hosts relative to non-wheel running controls. Taken together, these data suggest that the normal tissue and tumor microenvironment adaptations to aerobic exercise can improve doxorubicin efficacy while simultaneously limiting its toxicity.

Normal tissue and tumor microenvironment adaptations to aerobic exercise enhance doxorubicin anti-tumor efficacy and ameliorate its cardiotoxicity in retired breeder mice.

Sharon Lepler

Department of Radiation Oncology,
College of Medicine,
UF Health Cancer Center,
Department of Radiation Oncology, College of Medicine

University of Florida

All-optical Mechanobiology Interrogation of Yes-associated Protein in Human Cancer and Normal Cells using a Multi-functional System

Sharon Lepler

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Radiation Oncology,College of Medicine,UF Health Cancer Center,Department of Radiation Oncology, College of Medicine

University of Florida

All-optical Mechanobiology Interrogation of Yes-associated Protein in Human Cancer and Normal Cells using a Multi-functional System

Department of Radiation Oncology,
College of Medicine,
UF Health Cancer Center,
Department of Radiation Oncology, College of Medicine