Tobacco, air pollution, environmental carcinogenesis, and thoughts on conquering strategies of lung cancer

Each year there will be an estimated 2.1 million new lung cancer cases and 1.8 million lung cancer deaths worldwide.Tobacco smoke is the No.1 risk factors of lung cancer,accounting for>85%lung cancer deaths.Air pollution,or haze,comprises ambient air pollution and household air pollution,which are reported to cause 252,000 and 304,000 lung cancer deaths each year,respectively.Tobacco smoke and haze(hereafter,smohaze)contain fine particles originated from insufficient combustion of biomass or coal,have quite similar carcinogens,and cause similar diseases.Smohaze exert hazardous effects on exposed populations,including induction of a large amount of mutations in the genome,alternative splicing of mRNAs,abnormalities in epigenomics,initiation of tumor-promoting chronic inflammation,and facilitating immune escape of transformed cells.Tackling smohaze and development of multi-targets-based preventive and therapeutic approaches targeting smohaze-induced carcinogenesis are the key to conquer lung cancer in the future.

Identification of a potential tumor suppressor gene, UBL3, in non-small cell lung cancer

Objective: Oncogenes have been shown to be drivers of non-small cell lung cancer(NSCLC), yet the tumor suppressing genes involved in lung carcinogenesis remain to be systematically investigated. This study aimed to identify tumor suppressing ubiquitin pathway genes(UPGs) that were critical to lung tumorigenesis.Methods: The 696 UPGs were silenced by an siRNA screening in NSCLC cells;the potential tumor suppressing UPGs were analyzed, and their clinical significance was investigated.Results: We reported that silencing of 11 UPGs resulted in enhanced proliferation of NSCLC cells, and four UPGs(UBL3, TRIM22, UBE2 G2, and MARCH1) were significantly downregulated in tumor samples compared to that in normal lung tissues and their expression levels were positively associated with overall survival(OS) of NSCLC patients. Among these genes, UBL3 was the most significant one. UBL3 expression was decreased in tumor samples compared to that in paired normal lung tissues in 59/86(68.6%) NSCLCs, was correlated with TNM stage and sex of NSCLC patients, and was significantly higher in non-smoking patients than in smoking patients. Silencing UBL3 accelerated cell proliferation and ectopic expression of UBL3 suppressed NSCLC in vitro and in vivo.Conclusions: These results showed that UBL3 represented a tumor suppressor in NSCLC and may have potential for use in therapeutics and for the prediction of clinical outcome of patients.

High frequency of alternative splicing variants of the oncogene Focal Adhesion Kinase in neuroendocrine tumors of the pancreas and breast

The characteristic genetic abnormality of neuroendocrine neoplasms(NENs),a heterogeneous group of tumors found in various organs,remains to be identified.Here,based on the analysis of the splicing variants of an oncogene Focal Adhesion Kinase(FAK)in The Cancer Genome Atlas datasets that contain 9193 patients of 33 cancer subtypes,we found that Box 6/Box 7-containing FAK variants(FAK^(6/7))were observed in 7(87.5%)of 8 pancreatic neuroendocrine carcinomas and 20(11.76%)of 170 pancreatic ductal adenocarcinomas(PDACs).We tested FAK variants in 157 tumor samples collected from Chinese patients with pancreatic tumors,and found that FAK^(6/7)was positive in 34(75.6%)of 45 pancreatic NENs,19(47.5%)of 40 pancreatic solid pseudopapillary neoplasms,and 2(2.9%)of 69 PDACs.We further tested FAK splicing variants in breast neuroendocrine carcinoma(BrNECs),and found that FAK^(6/7)was positive in 14(93.3%)of 15 BrNECs but 0 in 23 non-NEC breast cancers.We explored the underlying mechanisms and found that a splicing factor serine/arginine repetitive matrix protein 4(SRRM4)was overexpressed in FAK^(6/7)-positive pancreatic tumors and breast tumors,which promoted the formation of FAK^(6/7)in cells.These results suggested that FAK^(6/7)could be a biomarker of NENs and represent a potential therapeutic target for these orphan diseases.

Revisiting China’s response to coronavirus disease 2019

“The rolling Yangtze River flows eastward,washingaway the heroes in its waves.”These words were written by a poet,Shen Yang,500years ago in his poem Immortal by the River.“Countlessevents of the past and present are all turned into laughterand conversation of the white-haired fishermen andwoodcutters.”

Advances in COVID-19:the virus,the pathogenesis,and evidence-based control and therapeutic strategies

Since the outbreak of the COVID-19 pandemic in early December 2019,81174 confirmed cases and 3242 deaths have been reported in China as of March 19,2020.The Chinese people and government have contributed huge efforts to combat this disease,resulting in significant improvement of the situation,with 58 new cases(34 were imported cases)and 11 new deaths reported on March 19,2020.However,as of March 19,2020,the COVID-19 pandemic continues to develop in 167 countries/territories outside of China,and 128665 confirmed cases and 5536 deaths have been reported,with 16498 new cases and 817 new deaths occurring in last 24 hours.Therefore,the world should work together to fight against this pandemic.Here,we review the recent advances in COVID-19,including the insights in the virus,the responses of the host cells,the cytokine release syndrome,and the therapeutic approaches to inhibit the virus and alleviate the cytokine storm.By sharing knowledge and deepening our understanding of the virus and the disease pathogenesis,we believe that the community can efficiently develop effective vaccines and drugs,and the mankind will eventually win this battle against this pandemic.

Back to the spring of 2020: facts and hope of COVID-19 outbreak

Since December 2019,an atypical pneumonia has occurred in Wuhan,a beautiful city located at the center of China(Fig.1),and the whole country.The origin of the disease remains unclear and the suspected Huanan Seafood Wholesale Market was closed on January 1,2020.Very rapidly,a novel coronavirus was isolated and named first the 2019 novel coronavirus(2019-nCoV)[1]and subsequently severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)[2],and is suggested to be named as human coronavirus 2019(HCoV-19)[3].Meanwhile,the disease is chronologically called pneumonia of unknown origin,novel coronavirus pneumonia(NCP),and coronavirus disease-2019(COVID-19)(Fig.2).Superspreading events of this virus have also taken place on the Diamond Princess cruise off the coast of Yokohama,Japan[4].The Chinese central[5]and local governments[6]have been endeavoring unprecedented efforts to constrain the outbreak,and more than 30000 medical professionals especially doctors and nurses outside Wuhan have been joining the local ones to handle this emergency.

Identification of an E3 ligase-encoding gene RFWD3 in non-small cell lung cancer

In order to unveil ubiquitin pathway genes (UPGs) that are essential for non-small cell lung cancer (NSCLC) cell proliferation,we recently conducted a siRNA screening experiment to knockdown the expression of 696 UPGs found in the human genome in A549 and H1975 NSCLC cells.We found that silencing of one of the candidates,RFWD3 that encodes an E3 ubiquitin ligase essential for the repair of DNA interstrand cross-links inresponse to DNA damage,led to dramatic inhibition of NSCLC cell proliferation with significant Z-scores.Knockdown of RFWD3 suppressed colony forming activity of NSCLC cells.We further evaluated the significance of RFWD3 in NSCLCs and found that this gene was more elevated in tumor samples than in paired normal lung tissues and was inversely associated with the clinical outcome of patients with NSCLC.Moreover,RFWD3 expression was significantly higher in smokers than in non-smokers.These results show for the first time that RFWD3 is required for NSCLC cell proliferation and may have an important role in lung carcinogenesis.

Genomic variations in the counterpart normal controls of lung squamous cell carcinomas

Lung squamous cell carcinoma （LUSC） causes approximately 400 000 deaths each year worldwide. The occurrence of LUSC is attributed to exposure to cigarette smoke, which induces the development of numerous genomic abnormalities. However, few studies have investigated the genomic variations that occur only in normal tissues that have been similarly exposed to tobacco smoke as tumor tissues. In this study, we sequenced the whole genomes of three normal lung tissue samples and their paired adjacent squamous cell carcinomas. We then called genomic variations specific to the normal lung tissues through filtering the genomic sequence of the normal lung tissues against that of the paired tumors, the reference human genome, the dbSNP138 common germline variants, and the variations derived from sequencing artifacts. To expand these observations, the whole exome sequences of 478 counterpart normal controls （CNCs） and paired LUSCs of The Cancer Genome Atlas （TCGA） dataset were analyzed. Sixteen genomic variations were called in the three normal lung tissues. These variations were confirmed by Sanger capillary sequencing. A mean of 0.5661 exonic variations/Mb and 7.7887 altered genes per sample were identified in the CNC genome sequences of TCGA. In these CNCs, C：G→T：A transitions, which are the genomic signatures of tobacco carcinogen N-methyl-N-nitro-N-nitrosoguanidine, were the predominant nucleotide changes. Twenty five genes in CNCs had a variation rate that exceeded 2%, including ARSD （18.62%）, MUC4 （8.79%）, and RBMX（7.11%）. CNC variations in CTAGE5 and USP17L7were associated with the poor prognosis of patients with LUSC. Our results uncovered previously unreported genomic variations in CNCs, rather than LUSCs, that may be involved in the develooment of LUSC.

Innate immune checkpoint Siglec10 in cancers:mining of comprehensive omics data and validation in patient samples

Sialic acid binding Ig-like lectin 10(Siglec10)is a member of innate immune checkpoints that inhibits the activation of immune cells through the interaction with its ligand CD24 on tumor cells.Here,by analyzing public databases containing 64517 patients of 33 cancer types,we found that the expression of Siglec10 was altered in 18 types of cancers and was associated with the clinical outcomes of 11 cancer types.In particular,Siglec10 was upregulated in patients with kidney renal clear cell carcinoma(KIRC)and was inversely associated with the prognosis of the patients.In 131 KIRC patients of our settings,Siglec10 was elevated in the tumor tissues of 83(63.4%)patients compared with that in their counterpart normal kidney tissues.Moreover,higher level of Siglec10 was associated with advanced disease(stages III and IV)and worse prognosis.Silencing of CD24 in KIRC cells significantly increased the number of Siglec10-expressing macrophages phagocytosing KIRC cells.In addition,luciferase activity assays suggested that Siglec10 was a potential target of the transcription factors c-FOS and GATA1,which were identified by data mining.These results demonstrate that Siglec10 may have important oncogenic functions in KIRC,and represents a novel target for the development of immunotherapies.

The DNMT1-PAS1-PH20 axis drives breast cancer growth and metastasis

PH20 is a member of the human hyaluronidase family that degrades hyaluronan in the extracellular matrix and controls tumor progression.Inhibition of DNA methyltransferases(DNMTs)leads to elevated hyaluronan levels;however,whether DNMT inhibitors control PH20 remains unclear.Here,we report that the DNMT1 inhibitor,decitabine,suppresses PH20 expression by activating the long non-coding RNA PHACTR2-AS1(PAS1).PAS1 forms a tripartite complex with the RNA-binding protein vigilin and histone methyltransferase SUV39H1.The interaction between PAS1 and vigilin maintains the stability of PAS1.Meanwhile,PAS1 recruits SUV39H1 to trigger the H3K9 methylation of PH20,resulting in its silencing.Functionally,PAS1 inhibits breast cancer growth and metastasis,at least partially,by suppressing PH20.Combination therapy of decitabine and PAS1-30nt-RNA,which directly binds to SUV39H1,effectively blocked breast cancer growth and metastasis in mice.Taken together,DNMT1,PAS1,and PH20 comprise a regulatory axis to control breast cancer growth and metastasis.These findings reveal that the DNMT1-PAS1-PH20 axis is a potential therapeutic target for breast cancer.

Carcinogens that induce the A：T 〉 T：A nucleotide substitutions in the genome

Recently, Ng et al. reported that the A：T 〉 T：A substitutions, proposed to be a signature of aristolochic acid （AA） exposure, were detected in 76/98 （78%） of patients with hepatocellular carcinoma （HCC） from the Taiwan Province of China, and 47% to 1.7% of HCCs from the Chinese mainland and other countries harbored the nucleotide changes. However, other carcinogens, e.g., tobacco carcinogens 4-aminobiphenyl and 1,3-butadiene, air toxic vinyl chloride and its reactive metabolites chloroethylene oxide, melphalan and chlorambucil, also cause this signature in the genome. Since tobacco smoke is a worldwide public health threat and vinyl chloride distributes globally and is an air pollutant in Taiwan Province, the estimation of the patients＇ exposure history is the key to determine the ＂culprit＂ of the A：T 〉 T：A mutations. Apparently, without estimation of the patients＇ exposure history, the conclusion of Ng et al, is unpersuasive and misleading.

Degradation of SARS-CoV-2 receptor ACE2 by the E3 ubiquitin ligase Skp2 in lung epithelial cells

An unexpected observation among the COVID-19 pandemic is that smokers constituted only 1.4%–18.5%of hospitalized adults,calling for an urgent investigation to determine the role of smoking in SARS-CoV-2 infection.Here,we show that cigarette smoke extract(CSE)and carcinogen benzo(a)pyrene(BaP)increase ACE2 mRNA but trigger ACE2 protein catabolism.BaP induces an aryl hydrocarbon receptor(AhR)-dependent upregulation of the ubiquitin E3 ligase Skp2 for ACE2 ubiquitination.ACE2 in lung tissues of non-smokers is higher than in smokers,consistent with the findings that tobacco carcinogens downregulate ACE2 in mice.Tobacco carcinogens inhibit SARS-CoV-2 spike protein pseudovirions infection of the cells.Given that tobacco smoke accounts for 8 million deaths including 2.1 million cancer deaths annually and Skp2 is an oncoprotein,tobacco use should not be recommended and cessation plan should be prepared for smokers in COVID-19 pandemic.

Ambient air pollution and lung disease in China： health effects, study design approaches and future research

Ambient air pollution in China has worsened following dramatic increases in industrialization, automobile use and energy consumption. Particularly bothersome is the increase in the PM2.5 fraction of pollutants. This fraction has been associated with increasing rates of cardio-respiratory disease in China and elsewhere. Ambient pollutant levels have been described in many of China＇s cities and are comparable to previous levels in southern California. Lung cancer mortality in China has increased since the 1970s and has been higher in men and in urban areas, the exact explanation for which has not been determined. The estimation of individual risk for Chinese citizens living in areas of air pollution will require further research. Occupational cohort and casecontrol designs each have unique attributes that could make them helpful to use in this setting. Other important future research considerations include detailed exposure assessment and the possible use of biomarkers as a means to better understand and manage the threat posed by air pollution in China.

Translating the power of TCM into patients＇ hope

In ancient times, Chinese medical practitioners tasted medicinal herbs to test the efficacy of these herbs in treating diseases, and from the practical experience the pioneers improved their medical skills. The unique system of traditional Chinese medicine （TCM）, which has evolved over thousands of years, therefore repre- sents one of the oldest paradigms of translational medicine in the world. TCM has been widely and successfully used to treat illnesses from inflammation to cancer and retains an important role in the healthcare system of China today. However, challenges in the development of TCM have become clear in recent years, and major efforts must be made to further improve the current TCM system.