Qiong Wang

Attenuation of TNFSF10/TRAIL-induced apoptosis by an autophagic survival pathway involving TRAF2- and RIPK1/RIP1-mediated MAPK8/JNK activation

Although it is known that tumor necrosis factor-related apoptosis-inducing ligand (TNFSF10/TRAIL) induces autophagy, the mechanism by which autophagy is activated by TNFSF10 is still elusive. In this report, we show evidence that TRAF2- and RIPK1-mediated MAPK8/JNK activation is required for TNFSF10-induced cytoprotective autophagy. TNFSF10 activated autophagy rapidly in cancer cell lines derived from lung, bladder and prostate tumors. Blocking autophagy with either pharmacological inhibitors or siRNAs targeting the key autophagy factors BECN1/Beclin 1 or ATG7 effectively increased TNFSF10-induced apoptotic cytotoxicity, substantiating a cytoprotective role for TNFSF10-induced autophagy. Blocking MAPK8 but not NFκB effectively blocked autophagy, suggesting that MAPK8 is the main pathway for TNFSF10-induced autophagy. In addition, blocking MAPK8 effectively inhibited degradation of BCL2L1/Bcl-xL and reduction of the autophagy-suppressing BCL2L1–BECN1complex. Knockdown of TRAF2 or RIPK1 effectively suppressed TNFSF10-induced MAPK8 activation and autophagy. Furthermore, suppressing autophagy inhibited expression of antiapoptosis factors BIRC2/cIAP1, BIRC3/cIAP2, XIAP and CFLAR/c-FLIP and increased the formation of TNFSF10-induced death-inducing signaling complex (DISC). These results reveal a critical role for the MAPK8 activation pathway through TRAF2 and RIPK1 for TNFSF10-induced autophagy that blunts apoptosis in cancer cells. Thus, suppression of MAPK8-mediated autophagy could be utilized for sensitizing cancer cells to therapy with TNFSF10.

Receptor-interacting Protein 1 Increases Chemoresistance by Maintaining Inhibitor of Apoptosis Protein Levels and Reducing Reactive Oxygen Species through a microRNA-146a-mediated Catalase Pathway

Background: Whether RIP1 directly contributes to chemotherapy response in cancer has not been determined. Results: RIP1 knockdown resulted in miR-146a-mediated catalase reduction, ROS induction, IAP degradation, and increased cisplatin cytotoxicity. Conclusion: RIP1 blunts the anticancer activity of cisplatin by releasing miR-146a-mediated catalase suppression. Significance: Our results establish a chemoresistant role for RIP1, and intervention within the RIP1-mediated pathway may be exploited for chemosensitization. Although receptor-interacting protein 1 (RIP1) is well known as a key mediator in cell survival and death signaling, whether RIP1 directly contributes to chemotherapy response in cancer has not been determined. In this report, we found that, in human lung cancer cells, knockdown of RIP1 substantially increased cytotoxicity induced by the frontline anticancer therapeutic drug cisplatin, which has been associated with robust cellular reactive oxygen species (ROS) accumulation and enhanced apoptosis. Scavenging ROS dramatically protected RIP1 knockdown cells against cisplatin-induced cytotoxicity. Furthermore, we found that, in RIP1 knockdown cells, the expression of the hydrogen peroxide-reducing enzyme catalase was dramatically reduced, which was associated with increased miR-146a expression. Inhibition of microRNA-146a restored catalase expression, suppressed ROS induction, and protected against cytotoxicity in cisplatin-treated RIP1 knockdown cells, suggesting that RIP1 maintains catalase expression to restrain ROS levels in therapy response in cancer cells. Additionally, cisplatin significantly triggered the proteasomal degradation of cellular inhibitor of apoptosis protein 1 and 2 (c-IAP1 and c-IAP2), and X-linked inhibitor of apoptosis (XIAP) in a ROS-dependent manner, and in RIP1 knockdown cells, ectopic expression of c-IAP2 attenuated cisplatin-induced cytotoxicity. Thus, our results establish a chemoresistant role for RIP1 that maintains inhibitor of apoptosis protein (IAP) expression by release of microRNA-146a-mediated catalase suppression, where intervention within this pathway may be exploited for chemosensitization.

A Superoxide-Mediated Mitogen-Activated Protein Kinase Phosphatase-1 Degradation and c-Jun NH2-Terminal Kinase Activation Pathway for Luteolin-Induced Lung Cancer Cytotoxicity

Although luteolin is identified as a potential cancer therapeutic and preventive agent because of its potent cancer cell-killing activity, the molecular mechanisms by which its cancer cell cytotoxicity is achieved have not been well elucidated. In this report, luteolin-induced cellular signaling was systematically investigated, and a novel pathway for luteolins lung cancer killing was identified. The results show that induction of superoxide is an early and crucial step for luteolin-induced apoptotic and nonapoptotic death in lung cancer cells. The c-Jun N-terminal kinase (JNK) was potently activated after superoxide accumulation. Suppression of superoxide completely blocked luteolin-induced JNK activation, which was well correlated to alleviation of luteolins cytotoxicity. Although luteolin slightly stimulated the JNK-activating kinase mitogen-activated protein kinase kinase 7, the latter was not dependent on superoxide. We further found that luteolin triggers a superoxide-dependent rapid degradation of the JNK-inactivating phosphatase mitogen-activated protein kinase phosphatase-1 (MKP-1). Introduction of a degradation-resistant MKP-1 mutant effectively attenuated luteolin-induced JNK activation and cytotoxicity, suggesting that inhibition of the JNK suppressor MKP-1 plays a major role in luteolin-induced lung cancer cell death. Taken together, our results unveil a novel pathway consisting of superoxide, MKP-1, and JNK for luteolins cytotoxicity in lung cancer cells, and manipulation of this pathway could be a useful approach for applying luteolin for lung cancer prevention and therapy.

Abstract B27: RIP1 maintains DNA integrity and cell proliferation by regulating PGC-1α-mediated mitochondrial oxidative phosphorylation and glycolysis

In the presence of ample oxygen, cancer cells prefer glycolysis to mitochondrial respiration for energy supply. This metabolic alteration, known as the Warburg effect or aerobic glycolysis, has been shown to contribute to cancer cell proliferation. However, how this glucose metabolism pathway is precisely regulated remains elusive. Receptor-interacting protein 1 (RIP1) is an important cellular signaling molecule that plays a pivotal role in the regulation of cell death, survival and proliferation. However, the role of RIP1 in cell metabolism is unclear. To investigate the function of RIP1 in lung cancer cell proliferation, we established stable RIP1 knockdown lung cancer cell lines using lentivius-mediated shRNA expression. RIP1 knockdown inhibited the proliferation of lung cancer cells, which was associated with DNA damage-induced p53 activation. Compared with control cells, the RIP1 knockdown cells had higher glucose consumption and lactate production, indicating a higher glycolytic rate. The increased glycolysis lowered the cellular level of nicotinamide adenine dinucleotide (NAD+), a cofactor essential for DNA damage repair. By microarray profiling and promoter reporter assays, we determined that RIP1 positively regulates the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a key factor involved in the regulation of mitochondrial function. The downregulation of PGC-1α reduced the expression of components of electron transfer chain that impaired oxidative phosphorylation, which underlays the increased glycolysis in RIP1 knockdown cells. Moreover, RIP1 knockdown cells were more sensitive to both DNA damage anticancer agents and glycolysis inhibitors. Our data suggest that while aerobic glycolysis within a certain range favors cancer cell proliferation, excessive glycolysis may cause cytostasis. Thus, maintenance of glycolysis by RIP1 is critical to cancer cell energy homeostasis and DNA integrity, which may be exploited for anticancer therapy. Citation Format: Wenshu Chen, Qiong Wang, Lang Bai, Weijie Chen, Xia Wang, Carmen S. Tellez, Shuguang Leng, Mabel T. Padilla, Toru Nyunoya, Steven A. Belinsky, Yong Lin. RIP1 maintains DNA integrity and cell proliferation by regulating PGC-1α-mediated mitochondrial oxidative phosphorylation and glycolysis. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B27.

Abstract A06: Combination of TRAIL and Chal-24 synergistically induces autophagy-mediated apoptosis in lung cancer cells

Combination chemotherapy is an effective strategy for increasing anticancer efficacy, reducing side effects and alleviating drug resistance. Here we report that combination of the recently identified novel chalcone derivative, chalcone-24 (Chal-24), and TNF-related apoptosis-inducing ligand (TRAIL) significantly increases cytotoxicity in lung cancer cells. Chal-24 treatment significantly enhanced TRAIL-induced activation of caspase-8 and caspase-3, and the cytotoxicity induced by combination of these agents was effectively suppressed by the pan-caspase inhibitor z-VAD-fmk. Chal-24 and TRAIL combination suppressed expression of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein large (c-FLIPL) and cellular inhibitor of apoptosis proteins (c-IAPs), and ectopic expression of c-FLIPL and c-IAPs inhibited the potentiated cytotoxicity. In addition, TRAIL and Chal-24 cooperatively activated autophagy. Suppression of autophagy effectively attenuated cytotoxicity induced by the combination of Chal-24 and TRAIL, which was associated with attenuation of c-FLIPL and c-IAPs degradation. Altogether, these results suggest that Chal-24 potentiates the anticancer activity of TRAIL through autophagy-mediated degradation of c-FLIPL and c-IAPs, and that combination of Chal-24 and TRAIL could be an effective approach in improving chemotherapy efficacy. Citation Format: Xiuling Xu, Jennings Xu, Shaoqing Shi, Qiong Wang, Bryanna Saxton, Chengguo Xing, Yong Lin. Combination of TRAIL and Chal-24 synergistically induces autophagy-mediated apoptosis in lung cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Targeting the Vulnerabilities of Cancer; May 16-19, 2016; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(1_Suppl):Abstract nr A06.

Abstract 2910: Suppressing excessive reactive oxygen species accumulation by RIP1 potentiates BPDE-induced transformation of human bronchial epithelial cells.

Cell survival signaling is important for the malignant phenotypes of cancer cells. Although the role of receptor-interacting protein 1 (RIP1) in cell survival signaling is well documented, whether RIP1 is directly involved in cancer development has never been studied. In this report, we found that RIP1 expression is substantially increased in human non-small cell lung cancer (NSCLC) tissues and cell lines. RIP1 expression in human bronchial epithelial cells (HBECs) was significantly induced by cigarette smoke extract (CSE) or benzo[a]pyrene diol epoxide (BPDE), the active form of the tobacco-specific carcinogen benzo (a) pyrene (BaP). In RIP1 knockdown HBECs, BPDE-induced cytotoxicity was significantly increased, which was associated with induction of cellular reactive oxygen species (ROS), mainly hydrogen peroxide (H 2 O 2 ), and activation of mitogen-activated protein kinases (MAPKs) including JNK, ERK and p38. Scavenging ROS suppressed BPDE-induced MAPK activation and inhibiting ROS or MAPKs substantially blocked BPDE-induced cytotoxicity, suggesting ROS-mediated MAPK activation is involved in BPDE-induced cell death. The H 2 O 2 -reducing enzyme catalase is destabilized in an ERK- and JNK-dependent manner in RIP1 knockdown HBECs and application of catalase effectively blocked BPDE-induced H 2 O 2 accumulation and cytotoxicity. Importantly, BPDE-induced transformation of HBECs was significantly reduced when RIP1 expression was suppressed. Altogether, these results strongly suggest an oncogenic role for RIP1, which promotes malignant transformation through protecting DNA-damaged cells against carcinogen-induced cytotoxicity associated with excessive ROS production. Citation Format: Qiong Wang, Wenshu Chen, Xiuling Xu, Bilan Li, Weiyang He, Mabel T. Padilla. Suppressing excessive reactive oxygen species accumulation by RIP1 potentiates BPDE-induced transformation of human bronchial epithelial cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2910. doi:10.1158/1538-7445.AM2013-2910

Abstract 2277: Autophagy-associated necroptosis contributes to cancer cell cytotoxicity induced by the chalcone compound SBC2

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Chalcone-based compounds are potential agents for cancer chemoprevention and chemotherapy. The recently developed chalcone-based compound SBC2 suppresses xenograft tumor growth in nude mice, however, the mechanisms by which SBC2 kills cancer cells are elusive. In this study, we have investigated the cellular signaling pathways involved in SBC2s cytotoxicity in cancer cells derived from lung and bladder tumors. SBC2 potently killed different cancer cells, which was effectively blocked by the necroptosis inhibitor Necrostatin-1 and knockdown of the necroptosis pathway components RIP1 and RIP3, suggesting that SBC2-induced cytotoxicity is associated with necroptosis. SBC2 robustly activated JNK and ERK through activation of their upstream activating kinases MEKK1 and MKK7. Blocking JNK and ERK effectively blocked SBC2-induced cytotoxicity, implying an important role of these MAPKs in SBC2-induced cancer cell death. In addition, SBC2 strongly induced autophagy, which was suppressed when JNK was blocked. Furthermore, SBC2 triggered BCL-XL phosphorylation that was dependent on JNK. Importantly, suppression of autophagy with either pharmacological inhibitors or a siRNA targeting the essential autophagy component ATG7 effectively attenuated SBC2-induced cell death. These results suggest that SBC2 kills cancer cells through activating JNK-mediated and autophagy-associated necroptosis. Taken together, our observations substantiate SBC2 as a potential anticancer therapeutic and identify a novel pathway for cancer cell killing by SBC2 that involves autophagy and necroptosis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2277. doi:1538-7445.AM2012-2277

Abstract 385: Potentiating MUC1 expression in human bronchial epithelial cells by cigarette smoke carcinogens through induction of TNF-α secretion from macrophages

Although an important role of inflammation in the development of lung cancer has been recognized, how inflammation promotes lung epithelial cell transformation and lung cancer development has not been well elucidated. Cigarette smoke (CS), the major cause of lung cancers, potently elicits chronic pulmonary inflammation. Our recent studies have found that CS significantly induces Muc1 (MUC1 for human and Muc1 for nonhuman species) expression in mouse bronchial epithelial cells and macrophages, and MUC1 facilitates Benzo(a)pyrene diolepoxide (BPDE)-induced human lung epithelial cell transformation. In this study, we investigated the role of inflammatory cells in regulating CS carcinogen-induced MUC1 expression in bronchial epithelial cells. BPDE and N-Nitroso-N-methylurea (MNU), an active CS carcinogen and a mimic, strongly induced tumor necrosis factor-alpha (TNF-α) secretion from human macrophages. The TNF-α induction was effectively blocked when ERK, JNK, and NF-κB were blocked, suggesting these pathways are involved in the induction of TNF-α from macrophages by BPDE and MNU. Interestingly, knockdown of MUC1 in macrophages suppressed BPDE- or MNU-induced TNF-α secretion, suggesting MUC1 plays a role in modulating carcinogen-induced and macrophage-mediated inflammatory responses. Conditioned media from BPDE- or MNU-treated macrophages potently induced MUC1 expression in human bronchial epithelial cells (HBECs), which was inhibited by a TNF-α neutralizing antibody, suggesting that TNF-α derived from macrophages contributes to CS carcinogen-induced MUC1 expression in HBECs. Thus, our results establish a dual role of MUC1 in CS-induced and inflammation-associated lung cancer development: to facilitate TNF-α secretion from macrophages and to potentiate transformation of HBECs. Note: This work is supported by NIH/NIEHS grant 1R01ES017328. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 385. doi:1538-7445.AM2012-385