ACOX1 destabilizes p73 to suppress intrinsic apoptosis pathway and regulates sensitivity to doxorubicin in lymphoma cells.

Lymphoma is one of the most curable types of cancer. However, drug resistance is the main challenge faced in lymphoma treatment. Peroxisomal acyl-CoA oxidase 1 (ACOX1) is the rate-limiting enzyme in fatty acid ß-oxidation. Deregulation of ACOX1 has been linked to peroxisomal disorders and carcinogenesis in the liver. Currently, there is no information about the function of ACOX1 in lymphoma. In this study, we found that upregulation of ACOX1 promoted proliferation in lymphoma cells, while downregulation of ACOX1 inhibited proliferation and induced apoptosis. Additionally, overexpression of ACOX1 increased resistance to doxorubicin, while suppression of ACOX1 expression markedly potentiated doxorubicin-induced apoptosis. Interestingly, downregulation of ACOX1 promoted mitochondrial location of Bad, reduced mitochondrial membrane potential and provoked apoptosis by activating caspase-9 and caspase-3 related apoptotic pathway. Overexpression of ACOX1 alleviated doxorubicin-induced activation of caspase-9 and caspase-3 and decrease of mitochondrial membrane potential. Importantly, downregulation of ACOX1 increased p73, but not p53, expression. p73 expression was critical for apoptosis induction induced by ACOX1 downregulation. Also, overexpression of ACOX1 significantly reduced stability of p73 protein thereby reducing p73 expression. Thus, our study indicated that suppression of ACOX1 could be a novel and effective approach for treatment of lymphoma. [BMB Reports 2019; 52(9): 566-571].

ß-Asarone increases doxorubicin sensitivity by suppressing NF-κB signaling and abolishes doxorubicin-induced enrichment of stem-like population by destabilizing Bmi1.

BACKGROUND: Lymphoma is one of the most common hematologic malignancy. Drug resistance is the main obstacle faced in lymphoma treatment. Cancer stem cells are considered as the source of tumor recurrence, metastasis and drug resistance. The ß-Asarone, a low-toxicity compound from the traditional medical herb Acorus calamus, has been shown to act as an anti-cancer reagent in various cancer types. However, the anti-cancer activities of ß-Asarone in lymphoma have not been shown. METHODS: Cell counting assay was used to evaluate Raji cell proliferation. CCK8 assay was used to evaluate the cell viability. Annexin-V/PI staining and flow cytometry analysis were used to evaluate apoptosis. ALDEFLUOR assay was used to evaluate the stem-like population. Luciferase reporter assay was used to examine the activation of NF-κB signaling. Western blot and polymerase chain reaction (PCR) were used to determine the expression of interested genes. RESULTS: We showed that ß-Asarone inhibited proliferation and induced apoptosis in Raji lymphoma cells in a dose-dependent manner. Additionally, ß-Asarone functioned as a sensitizer of doxorubicin and resulted in synergistic effects on inhibition of proliferation and induction of apoptosis when combined with doxorubicin treatment. Interestingly, we found that ß-Asarone also reduced the stem-like population of Raji lymphoma cells in a dose-dependent manner, and suppressed the expression of c-Myc and Bmi1. Importantly, ß-Asarone abolished doxorubicin-induced enrichment of the stem-like population. In the mechanism study, we revealed that ß-Asarone suppressed not only basal NF-κB activity but also Tumor necrosis factor α (TNF-α) induced NF-κB activity. Moreover, blocking NF-κB signaling inactivation was critical for ß-Asarone induced apoptosis and inhibition of proliferation, but not for the effect on ß-Asarone reduced stem-like population. In fact, ß-Asarone suppressed stem-like population by destabilizing Bmi1 via a proteasome-mediated mechanism. CONCLUSIONS: Our data suggested the application of ß-Asarone to lower the toxic effect of doxorubicin and increase the sensitivity of doxorubicin in clinical treatment. More importantly, our data revealed a novel role of ß-Asarone which could be used to eliminate stem-like population in lymphoma, implying that ß-Asarone might reduce relapse and drug resistance.

[Alteration of serum lipids in patients with acute leukemia and its clinical significance].

To explore the clinical significance on alteration of serum lipids in acute leukemia (AL) patients, the level of serum lipids was monitored in 86 AL cases by using of automatic biochemical analyzer. The results showed that TG was significantly higher (P < 0.05) while TC, LDL-C and HDL-C were obviously lower (P < 0.05) in AL patients than those in normal controls. After chemotherapy, TG decreased but TC, LDL-C and HDL-C were still higher (P < 0.05) as comparing to pre-treatment in complete remission cases. There were no changes of those parameters in non-remission patients. It is concluded that determination of serum lipids level in AL patients is a simple and important accessory index to evaluate curative effect and monitor patient's condition.