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Effects of antiplatelet agents on pulmonary metastases
Abstract:
The role of platelets in cancer metastasis was studied by investigating the effects of the antiplatelet agents ticlopidine, diltiazem, dipyridamole and trapidil on artificial and spontaneous pulmonary metastases in mice. These agents were tested at their optimal inhibitory doses on adenosine diphosphate-induced platelet aggregation; namely, 100 mg/kg for ticlopidine, 2 mg/kg for diltiazem, 180 mg/kg for trapidil and 60 mg/kg for dipyridamole. At these doses, trapidil caused moderate inhibition of thrombin-induced platelet aggregation in mice, but the other agents had only slight effects. Artificial pulmonary metastasis was produced by inoculation of Lewis lung carcinoma (LLC) or B16 melanoma (B16) cells into C57BL/6 mice. For induction of spontaneous pulmonary metastases, these tumor cells were implanted subcutaneously into the footpads of mice. The resulting primary tumors of LLC and B16 were removed 9-10 and 17 days later, respectively. Artificial pulmonary metastases were inhibited significantly by all the antiplatelet agents tested. Spontaneous pulmonary metastases were markedly reduced only when these agents were given after removal of the primary tumor. The role of platelets is discussed with respect to thrombus formation in the lodgement of tumor cells and the participation of platelet-derived growth factor in the growth of metastatic foci.
Insights
Antiplatelet agents significantly inhibited artificial lung metastasis in mice. Spontaneous metastasis reduction was observed only when agents were administered post-primary tumor removal, highlighting platelets' role in cancer spread.
Area of Science:
- Oncology
- Hematology
- Pharmacology
Background:
- Platelets play a crucial role in cancer metastasis.
- Understanding the mechanisms of platelet involvement is key to developing anti-metastatic therapies.
Purpose of the Study:
- To investigate the efficacy of antiplatelet agents in inhibiting both artificial and spontaneous pulmonary metastases in mice.
- To elucidate the role of platelets in tumor cell lodgement and metastatic growth.
Main Methods:
- Tested ticlopidine, diltiazem, dipyridamole, and trapidil at optimal inhibitory doses for adenosine diphosphate-induced platelet aggregation.
- Induced artificial pulmonary metastases by inoculating Lewis lung carcinoma (LLC) or B16 melanoma (B16) cells.
- Induced spontaneous pulmonary metastases by implanting LLC and B16 cells subcutaneously and removing primary tumors post-initiation.
Main Results:
- All tested antiplatelet agents significantly inhibited artificial pulmonary metastases.
- Spontaneous pulmonary metastases were markedly reduced only when antiplatelet agents were administered after primary tumor removal.
- T বিক্রidia caused moderate inhibition of thrombin-induced platelet aggregation, while others had slight effects.
Conclusions:
- Platelets are significantly involved in the process of cancer metastasis.
- Antiplatelet therapy shows promise in reducing metastasis, particularly when initiated after primary tumor resection.
- Platelet-derived growth factor may contribute to the growth of metastatic foci.