PARP inhibitor exerts an anti-tumor effect via LMO2 and synergizes with cisplatin in natural killer/T cell lymphoma.

BACKGROUND: PARP inhibitor (PARPi), as a kind of DNA damage repair inhibitor, has been shown to be effective in various solid tumors and hematologic malignancies. Natural killer/T cell lymphoma (NKTCL) is a highly aggressive malignancy, the treatment of which has long been a major challenge in the clinic. Here, we investigated the efficacy and mechanism of PARPi, and the therapeutic value of PARPi combined with cisplatin in NKTCL. METHODS: The cell proliferation, cell apoptosis, and cell cycle of NKTCL cells were detected respectively by CCK-8 and flow cytometry. The changes of mRNA expression and protein level were measured respectively by mRNA-sequencing, quantitative real-time PCR, western blotting, and immunofluorescence. LMO2 expression was detected by immunohistochemistry and western blotting. Targeted knockdown of LMO2 was conducted by short hairpin RNA. The tumor xenograft models were established to evaluate the efficacy of drugs in vivo. RESULTS: PARPi inhibited cell proliferation, promoted cell apoptosis, and induced S-phase cell cycle arrest in NKTCL cells. PARPi led to the accumulation of DNA damage by blocking DNA repair and DNA replication. Additionally, LMO2 deficiency reduced the sensitivity of NKTCL cells to PARPi. Finally, the combination of PARPi and cisplatin exhibited significant synergistic effects both in vitro and in vivo. CONCLUSIONS: In summary, we found that PARPi exerted an anti-tumor effect via LMO2 and synergized with cisplatin in NKTCL, which provides the theoretical basis for the clinical application of PARPi.

CAR-T cells targeting CD38 and LMP1 exhibit robust antitumour activity against NK/T cell lymphoma.

BACKGROUND: Natural killer/T cell lymphoma (NKTCL) is an aggressive lymphoma with a poor prognosis. Chimeric antigen receptor-transduced T (CAR-T) cell therapy has become a promising immunotherapeutic strategy against haematologic malignancies. METHODS: In this study, four CAR-T cell lines (CD38-CAR, LMP1-CAR, CD38-LMP1 tandem CAR 1 and CD38-LMP1 tandem CAR 2) were generated. The effect of CAR-T cells against NKTCL cells was evaluated both in vitro and in vivo. Expression of T cell activation markers and cytokines produced by CAR-T cells were detected by flow cytometry. RESULTS: The four CAR-T cell lines could effectively eliminate malignant NKTCL cells. They could be activated and produce inflammatory cytokines in a target-dependent manner. In vivo tests showed that the CAR-T cells exhibited significant antitumour effects in a xenotransplanted NKTCL mouse model. CONCLUSIONS: In summary, four CAR-T cell lines exhibited significant cytotoxicity against NKTCL cells both in vitro and in vivo. These results indicated the effective therapeutic promise of CD38 and LMP1 CAR-T cells in NKTCL.

Enhanced efficacy of combined fluzoparib and chidamide targeting in natural killer/T-cell lymphoma.

The treatment of natural killer/T-cell lymphoma (NKTCL) presents an onerous challenge, and a search for new therapeutic targets is urgently needed. Poly ADP-ribose polymerase inhibitors (PARPi) were initially used to treat breast and ovarian cancers with BRCA1/2 mutations. Their excellent antitumor efficacy led to a series of clinical trials conducted in other malignancies. However, the exploration of PARPi and their potential use in combination treatments for NKTCL remains unexplored. We treated NKTCL cell lines with fluzoparib (a novel inhibitor of PARP) and chidamide (a classical inhibitor of HDACs) to explore their cytotoxic effects in vitro. Then, their antitumor efficacy in vivo was confirmed in YT-luciferin xenograft mouse models. Fluzoparib or chidamide alone inhibited NKTCL cell proliferation in a dose-dependent manner. Cotreatment with both drugs synergistically induced excessive accumulation of DNA double-strand breaks and massive apoptotic cell death by inhibiting the DNA damage repair pathway, as shown by the decreased protein levels of p-ATM, p-BRCA1, p-ATR, and Rad51. Moreover, the combination treatment apparently increased the level of intracellular reactive oxygen species (ROS) to enhance apoptosis, and pretreatment with an ROS scavenger reduced the proapoptotic effect by 30-60% in NKTCL cell lines. In vivo, this combined regimen also showed synergistic antitumor effects in xenograft mouse models. The combination of fluzoparib and chidamide showed synergistic effects against NKTCL both in vitro and in vivo and deserves further exploration in clinical trials.

LMP1 enhances aerobic glycolysis in natural killer/T cell lymphoma.

Natural killer/T cell lymphoma (NKTCL) exhibits highly aggressive clinical behavior, and the outcomes for relapsed/refractory patients are still poor. Recently, the mechanism underlying the effect of Epstein-Barr virus (EBV) infection, which has not been fully defined in NKTCL, has attracted great attention. We explored how LMP1 promoted aerobic glycolysis via metabolic sequencing combined with mRNA sequencing and immunoprecipitation coupled to mass spectrometry. Experimental assays were used to determine the effects of LMP1 and its downstream pathway on the function and glucose metabolism of NKTCL cells. The correlations between LMP1 expression in patients and their clinical features, treatment response, and prognosis were analyzed. Results show that LMP1 enhances NKTCL cell proliferation in vitro and in vivo, inhibits apoptosis, and decreases gemcitabine sensitivity. In addition, LMP1 also enhances aerobic glycolysis in NKTCL cells, as indicated by increases in glucose uptake, lactate production, and extracellular acidification rate. Clinically, LMP1 expression is correlated with risk stratification, treatment response, and prognosis, and higher LMP1 expression indicates greater SUVmax for NKTCL patients. Mechanistically, LMP1 competitively binds to TRAF3 to promote cell proliferation and aerobic glycolysis by regulating the noncanonical NF-κB pathway. The application of an NF-κB pathway inhibitor or reactivation of the NF-κB pathway affects aerobic glycolysis and the biological function of NKTCL cells. In summary, this study is the first to describe and define in detail how LMP1 affects glucose metabolism in NKTCL and might provide a novel perspective for further treatment.

A second-generation CD38-CAR-T cell for the treatment of multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is an aggressive plasma cell malignancy, causing a number of deaths worldwide every year. Chimeric antigen receptor (CAR) transduced T-cell therapy has been a promising immunotherapy against hematological malignancies. METHODS: In this study, we developed a second-generation CAR construct and generated CAR-T cells targeting CD38 molecule. Then effects of CAR-T cells against MM cell lines were evaluated. RESULTS: CD38-CAR-T cells showed higher cytotoxicity to MM cell lines and primary MM cells than that of control T cells in vitro. Over 50% MM1.s and RPMI8226 cells were killed by CAR-T cells even at effector to target ratio of 1:100. CAR-T cells also showed an enhanced cytotoxicity against primary MM cells. CAR-T cells could be activated and produced a variety of cytokines in a target-dependent manner. In vivo test indicated that CAR-T cells also showed significant antitumor effect on xenograft mice models. CONCLUSION: These results indicated a promising therapeutic strategy of CD38-CAR-T cells against MM.