Search

Background: Control of SARS-CoV-2 (SCV-2) transmission requires understanding SCV-2 replication dynamics.Methods: We developed a multiplexed droplet digital PCR (ddPCR) assay to quantify SCV-2 subgenomic RNAs (sgRNAs), which are only produced during active viral replication, and discriminate them from genomic RNAs (gRNAs). We applied the assay to specimens from 144 people with single nasopharyngeal samples and 27 people with >1 sample. Results were compared to qPCR and viral culture.Results: sgRNAs were quantifiable across a range of qPCR cycle threshold (Ct) values and correlated with Ct values. The ratio of sgRNA:gRNA was stable across a wide range of Ct values, whereas adjusted amounts of N sgRNA to a human housekeeping gene declined with higher Ct values. Adjusted sgRNA and gRNA amounts were quantifiable in culture-negative samples, although levels were significantly lower than in culture-positive samples. Daily testing of 6 persons revealed that sgRNA is concordant with culture results during the first week of infection but may be discordant with culture later in infection. Further, sgRNA:gRNA is constant during infection despite changes in viral culture.Conclusions: Ct values from qPCR correlate with active viral replication. More work is needed to understand why some cultures are negative despite presence of sgRNA. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase 8 (CA8), a member of the carbonic anhydrase family, is one of the three isozymes that do not catalyze the reversible hydration of carbon dioxide due to the lack of one important histidine. In the present study, we observed increased expression of CA8 in more aggressive types of human osteosarcoma (OS) cells and found that CA8 expression is correlated with disease stages, such that more intense expression occurs in the disease late stage. We also demonstrated that overexpression of CA8 in human OS (HOS) cells significantly increased cell proliferation both in vitro and in vivo. Downregulated CA8 sensitized cells to apoptotic stress induced by staurosporine and cisplatin, suggesting a specific role of CA8 to protect cells from stresses. In addition, downregulation of CA8 in HOS cells reduced cell invasion and colony formation ability in soft agar and further decreased matrix metalloproteinase 9 and focal adhesion kinase expression, indicating that CA8 might facilitate cancer cell invasion via the activation of FAK-MMP9 signaling. Interestingly, HOS cells with CA8 knockdown showed a significant decrease in glycolytic activity and cell death under glucose withdrawal, further indicating that CA8 may be involved in regulating aerobic glycolysis and enhancing cell viability. Knockdown of CA8 significantly decreased phosphorylated Akt expression suggesting that the oncogenic role of CA8 may be mediated by the regulation of Akt activation through p-Akt induction. Importantly, the inhibition of glycolysis by 2-deoxyglucose sensitized CA8 HOS-CA8-myc cells to cisplatin treatment under low glucose condition, highlighting a new therapeutic option for OS cancer. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase 8 (CA8), a member of the carbonic anhydrase family, is one of the three isozymes that do not catalyze the reversible hydration of carbon dioxide due to the lack of one important histidine. In the present study, we observed increased expression of CA8 in more aggressive types of human osteosarcoma (OS) cells and found that CA8 expression is correlated with disease stages, such that more intense expression occurs in the disease late stage. We also demonstrated that overexpression of CA8 in human OS (HOS) cells significantly increased cell proliferation both in vitro and in vivo. Downregulated CA8 sensitized cells to apoptotic stress induced by staurosporine and cisplatin, suggesting a specific role of CA8 to protect cells from stresses. In addition, downregulation of CA8 in HOS cells reduced cell invasion and colony formation ability in soft agar and further decreased matrix metalloproteinase 9 and focal adhesion kinase expression, indicating that CA8 might facilitate cancer cell invasion via the activation of FAK-MMP9 signaling. Interestingly, HOS cells with CA8 knockdown showed a significant decrease in glycolytic activity and cell death under glucose withdrawal, further indicating that CA8 may be involved in regulating aerobic glycolysis and enhancing cell viability. Knockdown of CA8 significantly decreased phosphorylated Akt expression suggesting that the oncogenic role of CA8 may be mediated by the regulation of Akt activation through p-Akt induction. Importantly, the inhibition of glycolysis by 2-deoxyglucose sensitized CA8 HOS-CA8-myc cells to cisplatin treatment under low glucose condition, highlighting a new therapeutic option for OS cancer.