Epithelial-mesenchymal transition and H2O2 signaling – a driver of disease progression and a vulnerability in cancers

Mutation-selective drugs constitute a great advancement in personalized anticancer treatment with increased quality of life and overall survival in cancers. However, the high adaptability and evasiveness of cancers can lead to disease progression and the development of drug resistance, which cause recurrence and metastasis. A common characteristic in advanced neoplastic cancers is the epithelial-mesenchymal transition (EMT) which is strongly interconnected with H2O2 signaling, increased motility and invasiveness. H2O2 relays its signal through the installation of oxidative posttranslational modifications on cysteines. The increased H2O2 levels that are associated with an EMT confer a heightened sensitivity towards the induction of ferroptosis as a recently discovered vulnerability.

Application of RtcB ligase to monitor self-cleaving ribozyme activity by RNA-seq

Self-cleaving ribozymes are catalytic RNAs and can be found in all domains of life. They catalyze a site-specific cleavage that results in a 5′ fragment with a 2′,3′ cyclic phosphate (2′,3′ cP) and a 3′ fragment with a 5′ hydroxyl (5′ OH) end. Recently, several strategies to enrich self-cleaving ribozymes by targeted biochemical methods have been introduced by us and others. Here, we develop an alternative strategy in which 5ʹ OH RNAs are specifically ligated by RtcB ligase, which first guanylates the 3′ phosphate of the adapter and then ligates it directly to RNAs with 5′ OH ends. Our results demonstrate that adapter ligation to highly structured ribozyme fragments is much more efficient using the thermostable RtcB ligase from Pyrococcus horikoshii than the broadly applied Escherichia coli enzyme. Moreover, we investigated DNA, RNA and modified RNA adapters for their suitability in RtcB ligation reactions. We used the optimized RtcB-mediated ligation to produce RNA-seq libraries and captured a spiked 3ʹ twister ribozyme fragment from E. coli total RNA. This RNA-seq-based method is applicable to detect ribozyme fragments as well as other cellular RNAs with 5ʹ OH termini from total RNA.

SRPK1 promotes cell proliferation and tumor growth of osteosarcoma through activation of the NF-κB signaling pathway

To explore the expression and the functions of SRPK1 in osteosarcoma, we retrieved transcription profiling dataset by array of human bone specimens from patients with osteosarcoma from ArrayExpress (accession E-MEXP-3628) and from Gene Expression Omnibus (accession GSE16102) and analyzed expression level of SRPK1 and prognostic value in human osteosarcoma. Then we examined the effect of differential SRPK1 expression levels on the progression of osteosarcoma, including cell proliferation, cell cycle, apoptosis, and investigated its underlying molecular mechanism using in vitro osteosarcoma cell lines and in vivo nude mouse xenograft models. High expression level of SRPK1 was found in human osteosarcoma tissues and cell lines as compared to the normal bone tissues and osteoblast cells, and predicted poor prognosis of human osteosarcoma. Overexpression of SRPK1 in osteosarcoma U2OS cells led to cell proliferation but inhibition of apoptosis. In contrast, knockdown of SRPK1 in HOS cells impeded cell viability and induction of apoptosis. Moreover, silencing SRPK1 inhibited osteosarcoma tumor growth in nude mice. Mechanistic studies revealed that SRPK1 promoted cell cycle transition in osteosarcoma cells and activation of NF-κB is required for SRPK1 expression and its pro-survival signaling. SRPK1 promoted human osteosarcoma cell proliferation and tumor growth by regulating NF-κB signaling pathway.

Infection, inflammation and thrombosis: a review of potential mechanisms mediating arterial thrombosis associated with influenza and severe acute respiratory syndrome coronavirus 2

Thrombosis has long been reported as a potentially deadly complication of respiratory viral infections and has recently received much attention during the global coronavirus disease 2019 pandemic. Increased risk of myocardial infarction has been reported during active infections with respiratory viruses, including influenza and severe acute respiratory syndrome coronavirus 2, which persists even after the virus has cleared. These clinical observations suggest an ongoing interaction between these respiratory viruses with the host’s coagulation and immune systems that is initiated at the time of infection but may continue long after the virus has been cleared. In this review, we discuss the epidemiology of viral-associated myocardial infarction, highlight recent clinical studies supporting a causal connection, and detail how the virus’ interaction with the host’s coagulation and immune systems can potentially mediate arterial thrombosis.

Long non-coding RNA FAM66C regulates glioma growth via the miRNA/LATS1 signaling pathway

Glioma is one of the most common primary intracranial carcinomas and typically associated with a dismal prognosis and poor quality of life. The identification of novel oncogenes is clinically valuable for early screening and prevention. Recently, the studies have revealed that long non-coding RNAs (lncRNAs) play important roles in the development and progression of cancers including glioma. The expression of lncRNA FAM66C is reduced in glioma cell lines and clinical samples compared to non-tumor samples. Knockdown of FAM66C in U87 and U251 cells significantly promoted cell proliferation and migration, respectively. Furthermore, the correlation between FAM66C and Hippo pathway regulators YAP1 and LATS1, along with the alteration of their protein expression level indicated that FAM66C regulated cell growth through this pathway. Moreover, luciferase assay demonstrated that another two noncoding RNAs, miR15a/miR15b, directly bonded to the 3′UTR of LATS1 to facilitated its transcriptional expression and inhibited cell growth. In addition, the luciferase activity of FAM66C was block by miR15a/miR15b, and the promotion of cell growth effects caused by FAM66C deficiency was attenuated by miR15a/miR15b mimics, further proved that FAM66C functioned as a competing endogenous RNA to regulate glioma growth via the miRNA/LATS1 signaling pathway.

Evolutionary adaptation of DHFR via expression of enzyme isoforms with various binding properties and dynamics behavior: a bioinformatics and computational study

We compared the binding properties and dynamics of three experimentally reviewed isoforms of human dihydrofolate reductase (DHFR). The cytoplasmic variants including isoforms1 and 2 (iso1 and iso2) are produced by alternative splicing; while the mitochondrial form is located in the mitochondria. The iso1 as the canonical sequence contains 187 residues, and iso2 differs from the iso1, where it has 1–52 residues missing at the N-terminus of canonical sequence. Here, the structural models of the iso2 and mitochondrial forms were constructed by the MODELLER program using the crystal structure of the iso1 as the template. Bioinformatics analysis on ligand-bearing structures demonstrates that mitochondrial variant forms more stable complex with ligands compared with iso1 and 2, indicating their different binding properties. The root mean square fluctuation (RMSF) data suggest that C-terminus of iso1 contains two representative highly flexible fragments, while iso2 contains a highly flexible fragment at N-terminus end. Interestingly, both ends of mitochondrial variant have a degree of rigidity. Finally, the observation of differences in structural dynamics and binding properties predicts that the simultaneous existence of enzyme isoforms is a way to increase the speed of the enzyme maneuver in response to various environmental conditions. This prediction needs to be tested experimentally.

The phytochemical plumbagin reciprocally modulates osteoblasts and osteoclasts

Bone metabolism is essential for maintaining bone mineral density and bone strength through a balance between bone formation and bone resorption. Bone formation is associated with osteoblast activity whereas bone resorption is linked to osteoclast differentiation. Osteoblast progenitors give rise to the formation of mature osteoblasts whereas monocytes are the precursors for multi-nucleated osteoclasts. Chronic inflammation, auto-inflammation, hormonal changes or adiposity have the potential to disturb the balance between bone formation and bone loss. Several plant-derived components are described to modulate bone metabolism and alleviate osteoporosis by enhancing bone formation and inhibiting bone resorption. The plant-derived naphthoquinone plumbagin is a bioactive compound that can be isolated from the roots of the Plumbago genus. It has been used as traditional medicine for treating infectious diseases, rheumatoid arthritis and dermatological diseases. Reportedly, plumbagin exerts its biological activities primarily through induction of reactive oxygen species and triggers osteoblast-mediated bone formation. It is plausible that plumbagin’s reciprocal actions – inhibiting or inducing death in osteoclasts but promoting survival or growth of osteoblasts – are a function of the synergy with bone-metabolizing hormones calcitonin, Parathormone and vitamin D. Herein, we develop a framework for plausible molecular modus operandi of plumbagin in bone metabolism.

Characterization of a fluorescent 1,8-naphthalimide-functionalized PAMAM dendrimer and its Cu(ii) complexes as cytotoxic drugs: EPR and biological studies in myeloid tumor cells

The activity and interacting ability of a polyamidoamine (PAMAM) dendrimer modified with 4-N-methylpiperazine-1,8-naphthalimide units (termed D) and complexed by Cu(ii) ions, towards healthy and cancer cells were studied. Comparative electron paramagnetic resonance (EPR) studies of the Cu(ii)-D complex are presented: coordination mode, chemical structure, flexibility and stability of these complexes, in the absence and presence of myeloid cancer cells and peripheral blood mononuclear cells (PBMC). The interactions of Cu(ii) ions in the biological media at different equilibrium times were studied, highlighting different stability and interacting conditions with the cells. Furthermore, flow cytometry and confocal analysis, trace the peculiar properties of the dendrimers in PBMC and U937 cells. Indeed, a new probe (Fly) was used as a potential fluorescent tool for biological imaging of Cu(ii). The study highlights that dendrimer and, mainly, the Cu(ii) metallodendrimer are cytotoxic agents for the cells, specifically for U937 tumor cells, inducing mitochondrial dysfunction, ROS increase and lysosome involvement. The metallodendrimer shows antitumor selectivity, fewer affecting healthy PBMC, inducing a massive apoptotic cell death on U937 cells, in line with the high stability of this complex, as verified by EPR studies. The results underline the potentiality of this metallodendrimer to be used as anticancer drug.