Parasites have been shown to have both pro- and antitumor effects. Malaria parasites ( Plasmodium spp) are among those known to have this possible “bidirectional role” in carcinogenesis, say researchers from Aix-Marseille Université in France. They reviewed the current thinking on whether malaria—a worldwide killer—can be useful in cancer prevention and treatment.
Positive relationships between malaria and virus-associated cancers are relatively well documented, the researchers say. Evidence suggests that malaria can alter immune responses by modulating both humoral and cell-mediated immunity. Plasmodium -related cancers are primarily lymphoproliferative, vulnerable to virus reactivation. Epstein-Barr virus (EBV), for example, has been observed in lymphatic and hematologic tumors such as Hodgkin disease and T cell lymphoma, and malaria can reactivate EBV.
In animal studies, malarial infection with Plasmodium berghei ( P berghei ) increased the rate of spontaneous leukemia. In one study, concurrent infection with P berghei increased the incidence of malignant lymphoma in mice injected with Moloney leukemogenic virus.
On the other hand, Plasmodium spp also produces proteins that demonstrate certain anti-oncogenic effects, they note. The researchers suggest that using proteins in cancer treatment should be explored, adding that it’s a “safer approach than the inoculation of wild type Plasmodium.” Positive parasite-induced effects against cancers of the hematopoietic and lymphoid tissues are mentioned only for 2 species and those only in a decades-old study. Based on current knowledge, the researchers say, the antitumor effects observed are attributable to modifications to the host immune response. Thus, their characteristics and locations within the host can be highly diverse.
All in all, the researchers conclude, the growing evidence is opening intriguing pathways for using one ill to cure another.
Source:
Faure E. Parasitology. 2016;143(14):1811-1823.
