CDK1 Acts as a Prognostic Biomarker Associated with Immune Infiltration in Pan-Cancer, Especially in Gastrointestinal Tumors.

OBJECTIVE: Cyclin-dependent kinase 1 (CDK1) regulates the cell cycle and is highly expressed in most tumors. CDK1 expression has been associated with poor disease prognosis. This study aimed to identify the prognostic value of CDK1 in pan-cancer and investigate the association between CDK1 expression and immune cell infiltration. METHODS: CDK1 expression and its correlation with prognosis in pan-cancer were analyzed using online databases. Immune infiltration was assessed by ESTIMATE and CIBERSORT algorithms. We then evaluated the relationship between CDK1 expression and tumor mutational burden (TMB), microsatellite instability (MSI), or tumor-infiltrating immune cells. In addition, we performed the co-expression analysis of immune-related genes and GO analysis with CDK1 expression in pan-cancer. Finally, we compared the CDK1 expression profile with the immune-related genes in 30 pairs of clinical gastrointestinal tumor samples. RESULTS: Our analysis demonstrated overexpression of CDK1 in most tumor tissues, especially in gastrointestinal tumors. The high expression of CDK1 was associated with poor overall survival, disease-specific survival, disease-free interval, and progression-free interval in kidney renal papillary cell carcinoma (KIRP), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), pancreatic adenocarcinoma (PAAD), prostate adenocarcinoma (PRAD), and sarcoma (SARC). Besides, CDK1 expression was significantly associated with TMB in 22 cancer types and MSI in 8 cancer types as well as greater frequencies of MSI-high (MSI-H) status and high tumor mutational burden (TMB-H) in uterine corpus endometrial carcinoma (UCEC), stomach adenocarcinoma (STAD), sarcoma (SARC), rectum adenocarcinoma (READ), mesothelioma (MESO), head and neck squamous cell carcinoma (HNSC), and colon adenocarcinoma (COAD). In addition, CDK1 expression correlated with immune cell infiltrating levels, such as M0, M1, or M2 macrophages, memory CD4 T cells, T follicular helper cells, and naive B cells. Our data showed that CDK1 was remarkably correlated with 47 immune-related and immune checkpoint genes in many cancer types. Furthermore, CDK1 was up-regulated in gastrointestinal tumor samples, especially in gastric cancer and intestinal cancer. CDK1 was positively correlated with IDO1 in gastric cancer and PD-1 in intestinal cancer. CONCLUSION: Taken together, our data demonstrated the roles of CDK1 in oncogenesis and metastasis in pan-cancer. Thus, CDK1 is a potential prognostic biomarker and a target for tumor immunotherapy.

Effects of Naphtho[2,1-a]pyrene Exposure on CYP1A1 Expression: An in Vivo and in Vitro Mechanistic Study Exploring the Role of m6A Posttranscriptional Modification.

BACKGROUND: Currently, many emerging polycyclic aromatic hydrocarbons (PAHs) have been found to be widely present in the environment. However, little has been reported about their toxicity, particularly in relation to CYP1A1. OBJECTIVES: This study aimed to explore the toxicity of naphtho[2,1-a]pyrene (N21aP) and elucidate the mechanism underlying N21aP-induced expression of CYP1A1. METHODS: The concentration and sources of N21aP were detected and analyzed by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) and diagnostic ratio analysis. Then the effects of CYP1A1 on the toxicity of N21aP were conducted in male wild-type (WT) and Cyp1a1 knockout mice exposed to N21aP (0.02, 0.2, and 2mg/kg) through intratracheal instillation. Further, the aryl hydrocarbon receptor (AhR) pathway was examined through luciferase and chromatin immunoprecipitation (ChIP) assays. N6-methyladenosine (m6A) modification levels were measured on global RNA and specifically on CYP1A1 mRNA using dot blotting and methylated RNA immunoprecipitation-quantitative real-time polymerase chain reaction (MeRIP qRT-PCR), with validation by m6A inhibitors, DAA and SAH. m6A sites on CYP1A1 were identified by bioinformatics and luciferase assays, and CYP1A1 mRNA's interaction with IGF2BP3 was confirmed by RNA pull-down, luciferase, and RNA binding protein immunoprecipitation (RIP) assays. RESULTS: N21aP was of the same environmental origin as benzo[a]pyrene (BaP) but was more stably present in the environment. N21aP could be metabolically activated by CYP1A1 to produce epoxides, causing DNA damage and further leading to lung inflammation. Importantly, in addition to the classical AhR pathway (i.e., BaP), N21aP also induced CYP1A1 expression with a posttranscriptional modification of m6A in CYP1A1 mRNA via the METTL14-IGF2BP3-CYP1A1 axis. Specifically, in the two recognition sites of METTL14 on the CYP1A1 mRNA transcript (position at 2700 and 5218), a methylation site (position at 5218) in the 3'-untranslated region (UTR) was recognized by IGF2BP3, enhanced the stability of CYP1A1 mRNA, and finally resulted in an increase in CYP1A1 expression. DISCUSSION: This study systematically demonstrated that in addition to AhR-mediated transcriptional regulation, N21aP, had a new additional mechanism of m6A-mediated posttranscriptional modification, jointly contributing to CYP1A1 expression. Given that PAHs are the metabolic substrates of CYP1A1, this study not only helps to understand the significance of environment-genetic interactions for the toxicity of PAHs but also helps to better understand the health risks of the emerging PAHs at environmental exposure levels. https://doi.org/10.1289/EHP14055.

Construction, expression and antiviral activity analysis of recombinant adenovirus expressing human IFITM3 in vitro.

Interferon-inducible transmembrane protein 3 (IFITM3) inhibits the replication of multiple pathogenic viruses by blocking their entry. In this study, we constructed a shuttle plasmid, harboring human IFITM3. Thereafter, recombinant adenovirus rAd5-IFITM3 was obtained by co-transfection of the linearized viral backbone vector pAd5 and the shuttle plasmid. The results showed that human IFITM3 did not affect the assembly and morphogenesis of progeny adenovirus. Human IFITM3 can be expressed in both A549 and MDCK cells in a time dependent manner. Furthermore, cells infected with rAd5-IFITM3 at a multiplicity of infection (MOI) of 100 for 24 h were challenged with avian influenza virus (AIV) H5N1 at an MOI of 1 for 6, 12 and 24 h. Rates of H5N1 infection in rAd5-IFITM3 cells were significantly decreased at 24 h post-infection (hpi), in a time dependent manner, compared with that of wild type wtAd5-infected cells. The expressions of viral genes were significantly inhibited at transcriptional and translational levels at 6 and 12 hpi. These results suggest that IFITM3 can suppress H5N1 replication in the early stage of the infection, which may be used as a promise agent against H5N1 infection in vivo.