RECK and TIMP-2 mediate inhibition of MMP-2 and MMP-9 by Annona muricata

Up-regulation of MMP-2 and MMP-9 plays a significant role in promoting cancer progression by degradingthe components of the extracellular matrix, thereby enhancing the migration of tumor cells. Although the antiproliferative and apoptotic effect of Annona muricata is well established, its effect on MMP-2 and MMP-9, amajor target in several types of cancers, has not been studied. Powdered samples of various parts of A.muricata like fruit, stem, seed, and twig extracted using aqueous methanol showed significant dose-dependentinhibition of MMP-2 and MMP-9 in a highly metastatic fibrosarcoma cell line, HT1080. Additionally, theseextracts also up-regulated the expression of several endogenous inhibitors of MMP-2 and MMP-9 likeREversion-inducing Cysteine-rich protein with Kazal motifs (RECK) and Tissue Inhibitor of Metalloproteinase-2 (TIMP-2). Furthermore, primary cells developed from tumor tissues obtained from patients notexposed to chemotherapy, also exhibited similar results. Remarkably, the inhibition of MMP-2 and MMP-9observed was tumor specific, with the A. muricata fruit extract showing only 2% inhibition in cells obtainedfrom normal tissues, when compared to 60% inhibition observed in cells obtained from tumor samples. Thepresent study elucidates a novel mechanism by which A. muricata extracts selectively exhibit their anti-canceractivity in tumor cells by down-regulating MMP-2 and MMP-9 that are important biomarkers in cancer.

Hypopituitarism following snake bite.

A patient who developed hypopituitarism after viperine envenomation is described. Thrombosis as a part of disseminated intravascular coagulation may have been the cause. Hypopituitarism should be suspected in such cases especially when there is associated acute renal failure.