The effect of host immune status on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains unknown. Here, we report the first case of coronavirus disease 2019 (COVID-19) with human immunodeficiency virus type 1 (HIV-1)/hepatitis C virus coinfection, who showed a persistently negative SARS-CoV-2 RNA test but delayed antibody response in the plasma. This case highlights the influence of HIV-1–induced immune dysfunction on early SARS-CoV-2 clearance.

Protein tyrosine phosphatase receptor-type T (PTPRT) is the most frequently mutated tyrosine phosphatase in human cancers. However, the cell signaling pathways regulated by PTPRT largely remain to be elucidated. Here, we show that paxillin is a direct substrate of PTPRT and that PTPRT specifically regulates paxillin phosphorylation at tyrosine residue 88 (Y88) in colorectal cancer (CRC) cells. We engineered CRC cells homozygous for a paxillin Y88F knock-in mutant and found that these cells exhibit significantly reduced cell migration and impaired anchorage-independent growth, fail to form xenograft tumors in nude mice, and have decreased phosphorylation of p130CAS, SHP2, and AKT. PTPRT knockout mice that we generated exhibit increased levels of colonic paxillin phosphorylation at residue Y88 and are highly susceptible to carcinogen azoxymethane-induced colon tumor, providing critical in vivo evidence that PTPRT normally functions as a tumor suppressor. Moreover, similarly increased paxillin pY88 is also found as a common feature of human colon cancers. These studies reveal an important signaling pathway that plays a critical role in colorectal tumorigenesis.colorectal cancer R eversible tyrosine phosphorylation, which is coordinately controlled by protein tyrosine kinases (PTKs) and phosphatases (PTPs), governs numerous signaling pathways that regulate cell proliferation, apoptosis, adhesion, and migration. Over the last two decades, many PTKs have been found to be mutated in a variety of different tumor types (reviewed in ref. 1). In contrast to PTKs, the role of PTPs in tumorigenesis is underexplored. To systematically evaluate possible roles of PTPs in tumorigenesis, we used a high throughput molecular and bioinformatics approach to detect genetic alterations of the tyrosine phosphatase gene family in colorectal cancers (CRCs) (2). Among the six mutated PTPs that we identified, protein tyrosine phosphatase receptor-type T (PTPRT), also known as PTPρ, was the most frequently mutated (2). In addition, we and others found that PTPRT is also mutated in lung, stomach, and skin cancers (2, 3). The spectrum of mutations, which includes nonsense mutations and frameshifts, suggested that these mutations were inactivating (2). Biochemical analyses demonstrated that missense mutations in the catalytic domains of PTPRT diminished its phosphatase activity, whereas overexpression of PTPRT inhibited CRC cell growth (2). Taken together, these studies suggest that PTPRT normally acts as a tumor suppressor gene. In light of these data, it is important to identify the functionally significant substrates of PTPRT as well as to elucidate the signal transduction pathways regulated by this phosphatase. Here, we report that paxillin, an adaptor protein involved in cell adhesion, migration, proliferation, and apoptosis (4, 5), is a direct substrate of PTPRT and that phospho-paxillin has oncogenic properties. We further demonstrate that in an in vivo model, PTPRT is both a potent tumor suppressor gene and a key regulator of colonic ph...

High-risk human papillomavirus (HPV) infections are necessary but insufficient causes of cervical cancers. Other risk factors for cervical cancer (e.g., pregnancy, smoking, infections causing inflammation) can lead to high and sustained nitric oxide (NO) concentrations in the cervix, and high NO levels are related to carcinogenesis through DNA damage and mutation. However, the effects of NO exposure in HPV-infected cells have not been investigated. In this study, we used the NO donor DETA-NO to model NO exposure to cervical epithelium. In cell culture media, 24-hour exposure to 0.25 to 0.5 mmol/L DETA-NO yielded a pathologically relevant NO concentration. Exposure of cells maintaining episomal high-risk HPV genomes to NO increased HPV early transcript levels 2- to 4-fold but did not increase viral DNA replication. Accompanying increased E6 and E7 mRNA levels were significant decreases in p53 and pRb protein levels, lower apoptotic indices, increased DNA double-strand breaks, and higher mutation frequencies when compared with HPV-negative cells. We propose that NO is a molecular cofactor with HPV infection in cervical carcinogenesis, and that modifying local NO cervical concentrations may constitute a strategy whereby HPV-related cancer can be reduced.

Background Asymptomatic carriers contribute to the spread of Coronavirus Disease 2019 (COVID-19), but their clinical characteristics, viral kinetics, and antibody responses remain unclear. Methods A total of 56 COVID-19 patients without symptoms at admission and 19 age-matched symptomatic patients were enrolled. RNA of SARS-CoV-2 was tested using transcriptase quantitative PCR, and the total antibodies (Ab), IgG, IgA and IgM against the SARS-CoV-2 were tested using Chemiluminescence Microparticle Immuno Assay. Results Among 56 patients without symptoms at admission, 33 cases displayed symptoms and 23 remained asymptomatic throughout the follow-up period. 43.8% of the asymptomatic carriers were children and none of the asymptomatic cases had recognizable changes in C-reactive protein or interleukin-6, except one 64-year-old patient. The initial threshold cycle value of nasopharyngeal SARS-CoV-2 in asymptomatic carriers was similar to that in pre-symptomatic and symptomatic patients, but the communicable period of asymptomatic carriers (9.63 days) was shorter than pre-symptomatic patients (13.6 days). There was no obvious differences of the seropositive conversion rate of total Ab, IgG, and IgA among the three groups, though the rates of IgM varied largely. The average peak IgG and IgM COI of asymptomatic cases was 3.5 and 0.8, respectively, which is also lower than those in symptomatic patients with peaked IgG and IgM COI of 4.5 and 2.4 (p <0.05). Conclusion Young COVID-19 patients seem to be asymptomatic cases with early clearance of SARS-CoV-2 and low levels of IgM generation but high total Ab, IgG and IgA. Our findings provide empirical information for viral clearance and antibody kinetics of asymptomatic COVID-19 patients.