Background: Haematological malignancies are the fifth commonest cancer in the UK, with an average 5-year survival rate of
70.5%. Drug resistance and recurrence affect many patients with blood cancers. The anticancer properties of Cannabis constituents,
Delta-9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), in a variety of neoplastic cell lines, including those of the breast, skin,
lung, and prostate, have been previously reported. This research investigated the cytostaticity and cytotoxicity of CBD and THC,
synergism between CBD and THC, and chemosensitisation with Hydroxyurea (HU) in two haematological malignancy cell lines,
Jurkat and U937.
Methods: U937 and Jurkat were incubated with various concentrations and combinations of CBD, THC, and HU for 24, 48, and
72 hours, then their effects on cell viability and proliferation were evaluated.
Results: Both CBD and THC reduced viability and proliferation in Jurkat and U937 in a time- and dose-dependent manner. CBD
and THC demonstrated synergism in both cell lines. Combinations of cannabinoids and HU resulted in greater growth inhibition and
cytotoxicity in both cell lines, than when any agent was used individually.
Conclusion: These findings suggest CBD and THC may be useful for treating haematological malignancies and warrant further
in vitro studies.