Xiangqian Zheng

Rab1 in cell signaling, cancer and other diseases

The endoplasmic reticulum (ER) and Golgi membrane system have major roles in cell signaling and regulation of the biosynthesis/transport of proteins and lipids in response to environmental cues such as amino acid and cholesterol levels. Rab1 is the founding member of the Rab small GTPase family, which is known to mediate dynamic membrane trafficking between ER and Golgi. Growing evidence indicate that Rab1 proteins have important functions beyond their classical vesicular transport functions, including nutrient sensing and signaling, cell migration and presentation of cell-surface receptors. Moreover, deregulation of RAB1 expression has been linked to a myriad of human diseases such as cancer, cardiomyopathy and Parkinson’s disease. Further investigating these new physiological and pathological functions of Rab1 should provide new opportunities for better understanding of the disease processes and may lead to more effective therapeutic interventions.

Genetic and clinical characteristics of head and neck paragangliomas in a chinese population

Head and neck paragangliomas (PGLs) are rare and frequently associated with germline mutations of the succinate dehydrogenase (SDH) genes, especially for familial cases. The purpose of the study was to explore genetic and clinical characteristics of head and neck PGLs in a Chinese population.

Targeted DNA Sequencing Detects Mutations Related to Susceptibility among Familial Non-medullary Thyroid Cancer.

Some studies have demonstrated that familial non-medullary thyroid cancer (FNMTC) has a more aggressive clinical behavior compared to sporadic NMTC (SNMTC). However, FNMTC is difficult to differentiate from SNMTC by the morphology and immunohistochemistry. Although genes responsible for FNMTC were unclear, screening for rare germline mutations on known important tumor suppressor genes might offer more insights on predicting susceptibility to FNMTC. Here, a customized panel was designed to capture all exons of 31 cancer susceptive genes possibly related to FNMTC. Using next-generation sequencing we performed deep sequencing to achieve 500× coverage of the targeted regions. At the end 45 variants were identified in 29 of 47 familial patients and 6 of 16 sporadic patients. Notably, several germline mutations were found matching between paired FNMTC patients from the same family, including APC L292F and A2778S, BRAF D22N, MSH6 G355S and A36V, MSH2 L719F, MEN1 G508D, BRCA1 SS955S, BRCA2 G2508S, and a GNAS inframe insertion. We demonstrated a novel approach to help diagnose and elucidate the genetic cause of the FNMTC patients, and assess whether their family members are exposed to a higher genetic risk. The findings would also provide insights on monitoring the potential second cancers for thyroid cancer patients.

Aurora-A-mediated phosphorylation of LKB1 compromises LKB1/AMPK signaling axis to facilitate NSCLC growth and migration

Deletion or loss-of-function mutation of LKB1, frequently occurring in non-small cell lung cancers (NSCLCs), is a predominant caution of NSCLC initiation and progression. However, the upstream signaling pathways governing LKB1 activation are largely unknown. Here, we report that LKB1 undergoes Aurora kinase A (AURKA)-mediated phosphorylation, which largely compromises the LKB1/AMPK signaling axis, in turn leading to the elevation of NSCLC cell proliferation, invasion and migration. Mechanically, AURKA-mediated phosphorylation of LKB1 impairs LKB1 interaction with and phosphorylation of its downstream target AMPKα, which has critical roles in governing cancer cell energy metabolic homeostasis and tumorigenesis. Clinically, AURKA displays high levels in NSCLC patients, and correlates with poor outcome of patients with lung adenocarcinoma. Pathologically, the amplification or activation of AURKA-induced impairment of the LKB1/AMPK signaling pathway contributes to NSCLC initiation and progression, highlighting AURKA as a potential therapeutic target for combatting hyperactive AURKA-driven NSCLCs.

Suberoyl bis-hydroxamic acid activates Notch1 signaling and induces apoptosis in anaplastic thyroid carcinoma through p53

Anaplastic thyroid cancer (ATC), usually derived from well-differentiated thyroid cancers is one of the most lethal human endocrine malignancies. In the present study, we report that in human ATC tumor tissue samples exist undetectable Notch1 and the active Notch1 intracellular domain could not be detected in ATC-CAL-62 cells. Interesting, suberoyl bis-hydroxamic acid (SBHA) administration could induce Notch1 intracellular domain levels in a dose-dependent manner, coupled with the increase of p53 and p21. Furthermore, ectopic expression of Notch1 or deletion of p53 with small-interfering RNA was able to abolish the effects of SBHA to elevation of Notch1 and p53 in ATC cells. As a result, SBHA treatment efficiently induced ATC cell apoptosis. These results indicate that SBHA may play antitumor functions via regulating Notch1/p53 signals, and highlight that SBHA could have clinical potential to benefit the therapy of ATC patients.

Abstract 4456: Aurora-A is a downstream target of RAS and forms a positive feedback regulation loop with NF-κB in non-small cell lung cancer

Previous studies have shown that inhibition of Aurora-A reduces mutant RAS oncogenic activity and that both Aurora-A and RAS activate NF-κB pathway through phosphorylation of IkBa and upregulation of GSKa, respectively. Here we show that Aurora-A expression and kinase activity are regulated by activating mutation of KRAS. Blockage of NF-κB by IκB-S32/36A abrogated KRAS-induced Aurora-A expression and kinase activity. Furthermore, we demonstrated that NF-κB directly bound to Aurora-A promoter and induces Aurora-A transcription. In addition, depletion of Aurora-A by siRNA and pharmacological inhibitor MLN8237 suppresses RAS-induced NF-κB activity and selectively induces cell death in KRAS mutant NSCLC cells. We also show that Aurora-A is induced by nicotine and is frequently overexpressed in NSCLCs. Overexpression of Aurora-A is associated with tobacco smoke and poor prognosis in lung adenocarcinoma but not squamous lung cancer. These data suggest that Aurora-A is regulated by RAS through NF-κB and that the feedback regulation loop between Aurora-A and NF-κB could play a pivotal role in NSCLC. Citation Format: Donghwa Kim, Masayuki Kanai, Xiangqian Zheng, Dali Zheng, Domenico Coppola, Jin Q. Cheng. Aurora-A is a downstream target of RAS and forms a positive feedback regulation loop with NF-κB in non-small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4456. doi:10.1158/1538-7445.AM2014-4456

Abstract 515: Aurora-A is a determinant of tamoxifen resistance by phosphorylation and activation of ERα in breast cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Aurora-A kinase is frequently overexpressed/activated in various types of human malignancy including breast cancer. In this study, we demonstrated that Aurora-A induces estrogen receptor α (ERα) transactivation activity in the presence and absence of estrogen. Aurora-A also interacts with and phosphorylates ERα at serine-167 and -305 in vitro and in vivo. As a result, Aurora-A induces ERα transcriptional activity, enhances ERα binding to DNA and transcriptionally up-regulates its targeting genes such as CCDN1 in a phospho-ERα-Ser-167/305 dependent manners. Further, overexpression of Aurora-A decreases whereas depletion of Aurora-A enhances tamoxifen sensitivity in ERα-positive breast cancer cells. Significantly, Aurora-A inhibitor synergized with tamoxifen and overcame tamoxifen-resistance in vitro and in animal model. These data suggest that ERα is a bona fide substrate of Aurora-A and that Aurora-A plays a pivotal role in tamoxifen resistance. Thus, Aurora-A represents a critical therapeutic target in breast cancer endocrine-therapy. Citation Format: Xiangqian Zheng, Jianping Guo, Hua Yang, Lili He, Masayuki Kanai, Domenico Coppola, Ming Gao, Xiubao Ren, Jin Q. Cheng. Aurora-A is a determinant of tamoxifen resistance by phosphorylation and activation of ERα in breast cancer. [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 515. doi:10.1158/1538-7445.AM2013-515