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  • In this study for the first time we demonstrated that

    2020-02-13

    In this UK 356618 study, for the first time, we demonstrated that herb-derived LFS-01 induces concomitant mitophagy and apoptosis in lymphoma cells. Through various biochemical studies, we showed that LFS-01 directly targets the sulfhydryl (-SH) group of a conserved cysteine in the nuclear export signal (NES)-binding groove of CRM1 protein and leads to the nuclear retention of Nrf2, which consequently upregulates p62, an essential structural component of the autophagosomes towards mitophagic clearance. Our RNA-seq experiments also confirmed that p62/SQSTM1 was significantly overexpressed upon LFS-01 exposure. Furthermore, we showed that LFS-01 treatment activates AMPK/mTOR pathway and leads to mitophagic signaling in lymphoma cells. We revealed that LFS-01 administration can significantly suppress tumor growth in a xenograft model with minimal toxicity. Our findings establish a critical role for mitophagy in mediating the biological effects of LFS-01 and suggest that LFS-01 could be used as a prototype for the development of next-generation cancer therapeutics targeting on mitophagy.
    Materials and methods
    Results
    Discussion Although enormous efforts have been made towards developing immunotherapies for liquid tumors, lymphoma especially non-Hodgkin lymphomas (NHL) still represent as a serious threat to human health. Particularly, patients with aggressive forms of NHL such as diffuse large B cell lymphoma (DLBCL) and Burkitt\'s lymphoma usually have a poor prognosis with limited treatment options [32]. In this respect, for the first time, we report that traditional Chinese medicine-derived LFS-01 exerts its biological effects by triggering a concomitant mitophagy and apoptosis in lymphoma cells. We showed that LFS-01 displayed strong in vitro and in vivo anti-neoplastic properties against NHL with minimal toxicity in normal cells, suggesting possible weak adverse effects of this compound. Thus far, three types of programmed cellular death have been described, namely apoptosis, autophagy and necrosis. Herein, the relationship between apoptosis and autophagy is rather complex and largely dependent on cell type and stimuli. Nevertheless, mounting evidences suggest that apoptosis (self-killing) and autophagy (self-eating) are mechanistically linked. Interestingly, it has been suggested that therapeutic strategies that can trigger both apoptosis and autophagy in tumor cells may be advantageous such that non-specific toxicity can be avoided [33]. Moreover, synergistic effects of autophagy and apoptosis may contribute to the selective killing of tumor cells [34,35]. To date, several naturally-derived compounds have been reported to induce both autophagy and apoptosis in tumor cells such as arsenic trioxide [36], vitamin K2 [37], and resveratrol [38]. Notably, arsenic trioxide is also derived from traditional Chinese medicine and has been used in clinical practice for treating acute myeloid leukemia (AML) [39]. In this study, we found that LFS-01 treatment of NHL cell lines (Raji and U2932) pretreated with either z-VAD (a caspase inhibitor) or 3-MA (an autophagy inhibitor) resulted in a significant reduction of cytotoxicity against tumor cells. Further, we observed that the killing of tumor cells by LFS-01 was nearly blocked when the lymphoma cells were simultaneously pretreated with both z-VAD and 3-MA. This strongly suggests that LFS-01 kills lymphoma cells through the activation of both mitophagy and apoptosis. Interestingly, we UK 356618 examined that LFS-01 has minimal cytotoxicity against normal lymphocytes from healthy donors, clearly demonstrating its selective eradication of lymphoma cells. We subsequently assessed the in vivo antitumor activities of LFS-01 in xenograft model. LFS-01 was able to significantly reduce the tumor volume in SCID mice that received a subcutaneous injection of lymphoma cells. Moreover, histopathological analysis revealed that cleaved PARP and caspase 3 were elevated after LFS-01 treatment. On the other hand, both ratios of LC3-I/LC3-II and p-mTOR/mTOR were significantly decreased upon LFS-01 administration, supporting the in vitro results that LFS-01 exerts therapeutic effects through triggering dual mitophagy and apoptosis.