Potential therapeutic effects of natural extracts in multiple myeloma

Multiple myeloma (MM) is the second most commonly hematologic malignancy characterized by proliferation of monoclonal plasmas cells in bone marrow. Despite the availability of new drugs targeting the neoplastic clone and its microenvironment, MM is still an incurable disease, with patients experiencing subsequent phases of remission and relapse, eventually leading to disease resistance and patient death. In the past decades, natural products have attracted increasing attention in the field of anti-myeloma treatment by virtue of their multiple bioactivities and lower toxicity. This review focuses on the research progress and mechanisms through which these natural extracts inhibit tumor cell proliferation and normalize microenvironment in multiple myeloma. These include the induction of apoptosis, inhibition of bone injury and angiogenesis, and reversion of multidrug resistance.