Emerging trends in management of long COVID with a focus on pulmonary rehabilitation: A review.

Long COVID, or post-acute sequelae of COVID-19 (PASC), represents a complex condition with persistent symptoms following SARS-Cov-2 infection. The symptoms include fatigue, dyspnoea, cognitive impairment, decreased quality of life in variable levels of severity. Potential mechanisms behind long COVID include vascular damage, immune dysregulation and viral persistence. Diagnosing long COVID involves medical evaluation by multidisciplinary team and assessment of persistent symptoms with scoring systems in development. Treatment strategies are symptom-focused, encompassing multidisciplinary care, rehabilitation and tailored exercise programmes. Pulmonary rehabilitation, an effective and critical component of long COVID management, has shown promise, particularly for patients with respiratory symptoms such as dyspnoea. These programmes, which combine exercise, breathing techniques, education and psychological support, improve symptoms, quality of life and overall recovery. Innovative technologies, such as telemedicine, wearable devices, telerehabilitation, are transforming long COVID management. Telemedicine facilitates consultations and interventions, eliminating healthcare access barriers. Wearable devices enable remote and continuous monitoring of patients during their rehabilitation activities. Telerehabilitation has proven to be safe and feasible and to have high potential for COVID-19 recovery. This review provides a concise overview of long COVID, encompassing its definition, prevalence, mechanisms, clinical manifestations, diagnosis and management approaches. It emphasizes the significance of multidisciplinary approach in diagnosis and treatment of long COVID, with focus on pulmonary rehabilitation and innovative technology advances to effectively address the management of long COVID.

Computational simulation of JAK/STAT signaling in somatic versus germline stem cells.

BACKGROUND: The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway regulates a variety of cellular processes. A major activation event in this pathway involves the phosphorylation of a tyrosine of STAT, converting unphosphorylated STAT (uSTAT) to phosphorylated STAT (pSTAT), an active transcription factor. In a noncanonical role, uSTAT contributes to the maintenance of heterochromatin stability. As such, an increase in pSTAT concurrently reduces uSTAT, resulting in heterochromatin loss, as observed in Drosophila somatic tissues. Paradoxically, an opposing phenomenon occurs in Drosophila male germline stem cells (GSCs), where the JAK/STAT pathway remains persistently active due to a continuous supply of ligands. Here, computational simulations were employed to dissect JAK/STAT pathway activation under different cellular contexts, mimicking somatic and germline cells. In these simulations, ordinary differential equations were leveraged to replicate the chemical reactions governing JAK/STAT signaling under different conditions. RESULTS: The outcomes indicate that transient ligand stimulation, typical in somatic tissues, led to a momentary reduction in uSTAT levels. Conversely, sustained ligand stimulation, a characteristic feature of the GSC niche, resulted in elevated uSTAT levels at equilibrium. CONCLUSION: The simulation suggests that the duration of ligand exposure could explain the observed opposite effects of JAK/STAT activation on heterochromatin in somatic versus GSCs.

Simulation of STAT and HP1 interaction by molecular docking.

Heterochromatin Protein 1 (HP1) is a major component of heterochromatin. Multiple proteins have been shown to interact with HP1 with the HP1-binding motif PxVxL/I, thereby affecting heterochromatin stability. The HP1-interacting proteins include the signal transducer and activator of transcription (STAT) protein, which can be regulated by phosphorylation on a tyrosine around amino acid 700 in the carboxyl terminus. Previous research has shown that unphosphorylated STAT (uSTAT) binds to HP1 via a PxVxI HP1-binding motif and maintains the stability of heterochromatin, while phosphorylated STAT (pSTAT) dissociates from HP1, resulting in heterochromatin disruption. To understand the theoretical basis of the biochemical observations, we employed computational modeling to investigate STAT-HP1 binding configurations and the effect of STAT phosphorylation on their interaction. Using STAT3 and HP1α protein structures for molecular docking and thermodynamic calculations, our computations predict that uSTAT homodimers have a higher affinity for HP1 and a lower affinity for DNA than pSTAT homodimers, and that phosphorylation induces a conformational change in STAT, shifting its binding preference from HP1 to DNA. The results of our modeling studies support the idea that phosphorylation drives STAT from HP1-binding to DNA-binding, suggesting a potential role for uSTAT in both maintaining and initiating heterochromatin formation.

Expression and prognostic role of STAT5a across cancer types.

Studies examining the role of signal transducer and activator of transcription 5 (STAT5) in various cancers have produced controversial results. To address this controversy, we examined the prognostic role of STAT5a in cancer patients across multiple cancers. Transcription levels of STAT5a between tumors and normal tissues, obtained from public databases, were analyzed for statistical differences using Cox regression analysis with the outcome as overall survival and covariate of interest as high STAT5a expression. Meta-analysis was then conducted to summarize the hazard ratio estimate from the Cox regression analyses. We found that STAT5a was significantly under-expressed in breast, lung, and ovarian cancers, while STAT5a was significantly overexpressed in lymphoid neoplasm diffuse large B-cell lymphoma, glioblastoma, and glioma. High STAT5a expression was significantly associated with favorable survival in bladder cancer (lnHR = -0.8689 [-1.4087, -0.3292], P-value = 0.0016), breast cancer (lnHR = -0.7805 [-1.1394, -0.4215], P-value < 0.0001) and lung cancer (lnHR = -0.3255 [-0.6427, -0.0083], P-value = 0.0443). After adjusting for clinicopathological factors, high STAT5a expression remained significantly associated with favorable survival in breast cancer (lnHR = -0.6091 [-1.0810, -0.1372], P-value = 0.0114). These results suggest that higher STAT5a expression is associated with favorable overall survival in breast cancer, and therefore might have protective effects, and that STAT5a expression could be a potential prognostic biomarker, especially in breast cancer. However, the prognostic role of STAT5a is dependent on cancer type.

Canonical and non-canonical functions of STAT in germline stem cell maintenance.

BACKGROUND: Maintenance of the Drosophila male germline stem cells (GSCs) requires activation of the Janus kinase/signal transducer and activators of transcription (JAK/STAT) pathway by niche signals. The precise role of JAK/STAT signaling in GSC maintenance, however, remains incompletely understood. RESULTS: Here, we show that, GSC maintenance requires both canonical and non-canonical JAK/STAT signaling, in which unphosphorylated STAT (uSTAT) maintains heterochromatin stability by binding to heterochromatin protein 1 (HP1). We found that GSC-specific overexpressing STAT, or even the transcriptionally inactive mutant STAT, increases GSC number and partially rescues the GSC-loss mutant phenotype due to reduced JAK activity. Furthermore, we found that both HP1 and STAT are transcriptional targets of the canonical JAK/STAT pathway in GSCs, and that GSCs exhibit higher heterochromatin content. CONCLUSIONS: These results suggest that persistent JAK/STAT activation by niche signals leads to the accumulation of HP1 and uSTAT in GSCs, which promote heterochromatin formation important for maintaining GSC identity. Thus, the maintenance of Drosophila GSCs requires both canonical and non-canonical STAT functions within GSCs for heterochromatin regulation.

Inpatient use of metformin and acarbose is associated with reduced mortality of COVID-19 patients with type 2 diabetes mellitus.

AIMS: Type 2 diabetes mellitus (T2DM) is a strong risk factor for complications of coronavirus disease 2019 (COVID-19). The effect of T2DM medications on COVID-19 outcomes remains unclear. In a retrospective analysis of a cohort of 131 patients with T2DM hospitalized for COVID-19 in Wuhan, we have previously found that metformin use prior to hospitalization is associated with reduced mortality. The current study aims to investigate the effects of inpatient use of T2DM medications, including metformin, acarbose, insulin and sulfonylureas, on the mortality of COVID-19 patients with T2DM during hospitalization. METHODS: We continue to carry out a retrospective analysis of a cohort of 131 patients with T2DM hospitalized for COVID-19 and treated with different combinations of diabetes medications. RESULTS: We found that patients using metformin (p = .02) and acarbose (p = .04), alone or both together (p = .03), after admission were significantly more likely to survive than those who did not use either metformin or acarbose. 37 patients continued to take metformin after admission and 35 (94.6%) survived. Among the 57 patients who used acarbose after admission, 52 survived (91.2%). A total of 20 patients used both metformin and acarbose, while 57 used neither. Of the 20 dual-use patients, 19 (95.0%) survived. CONCLUSION: Our analyses suggest that inpatient use of metformin and acarbose together or alone during hospitalization should be studied in randomized trials.

Next-Generation Sequencing and Proteomics of Cerebrospinal Fluid From COVID-19 Patients With Neurological Manifestations.

The SARS-CoV-2 and its variants are still hitting the world. Ever since the outbreak, neurological involvements as headache, ageusia, and anosmia in COVID-19 patients have been emphasized and reported. But the pathogenesis of these new-onset neurological manifestations in COVID-19 patients is still obscure and controversial. As difficulty always lay in the diagnosis of neurological infection, current reports to validate the presence of SARS-CoV-2 in cerebrospinal fluid (CSF) almost relied on the basic methods and warranted improvement. Here we reported a case series of 8 patients with prominent new-onset neurological manifestations, who were screened out from a patch of 304 COVID-19 confirmed patients. Next-generation sequencing (NGS) and proteomics were conducted in the simultaneously obtained CSF and serum samples of the selected patients, with three non-COVID-19 patients with matched demographic features used as the controls for proteomic analysis. SARS-CoV-2 RNA was detected in the CSF of four COVID-19 patients and was suspicious in the rest four remaining patients by NGS, but was negative in all serum samples. Proteomic analysis revealed that 185 and 59 proteins were differentially expressed in CSF and serum samples, respectively, and that only 20 proteins were shared, indicating that the proteomic changes in CSF were highly specific. Further proteomic annotation highlighted the involvement of complement system, PI3K-Akt signaling pathway, enhanced cellular interaction, and macrophages in the CSF proteomic alterations. This study, equipped with NGS and proteomics, reported a high detection rate of SARS-CoV-2 in the CSF of COVID-19 patients and the proteomic alteration of CSF, which would provide insights into understanding the pathological mechanism of SARS-CoV-2 CNS infection.

Worldwide inverse correlation between Bacille Calmette-Guérin (BCG) immunization and COVID-19 mortality.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has spread to all countries in the world, and different countries have been impacted differently. The study aims to understand what factors contribute to different COVID-19 impacts at the country level. METHODS: Multivariate statistical analyses were used to evaluate COVID-19 deaths and cases relative to nine other demographic and socioeconomic factors in all countries and regions of the world using data as of August 1, 2020. The factors analyzed in the study include a country's total COVID-19 deaths and cases per million population, per capita gross domestic product (GDP), population density, virus tests per million population, median age, government response stringency index, hospital beds availability per thousand population, extreme poverty rate, Bacille Calmette-Guérin (BCG) vaccination rate, and diphtheria-tetanus-pertussis (DTP3) immunization rate. RESULTS: The study reveals that COVID-19 deaths per million population in a country most significantly correlates, inversely, with the country's BCG vaccination rate (r = - 0.50, p = 5.3e-5), and also significantly correlates a country's per capita GDP (r = 0.39, p = 7.4e-3) and median age (r = 0.30, p = 0.042), while COVID-19 cases per million population significantly correlate with per capita GDP and tests per thousand population. To control for possible confounding effects of age, the correlation was assessed in countries propensity score matched for age. The inverse correlation between BCG vaccination rates and COVID-19 case (r = - 0.30, p = 0.02) and death (r = - 0.42, p = 0.0007) remained significant among the top 61 countries with the highest median age. CONCLUSION: This study contributes to a growing body of evidence supporting the notion that BCG vaccination may be protective against COVID-19 mortality.

Drosophila SERTAD domain protein Taranis is required in somatic cells for maintenance of male germline stem cells.

BACKGROUND: Polycomb proteins are essential for maintaining stem cell identity across different stem cell niches. However, how they function to maintain stem cell niches is not fully understood. RESULTS: Here we show that the SERTAD protein Taranis (Tara), which is a Polycomb-trithorax group protein, is expressed in the adult testis niche and plays a role in its maintenance in Drosophila. We found that tara is expressed in early cyst cells, likely including somatic cyst stem cells (CySCs) of Drosophila male testis tip region, which houses both germline and somatic cyst stem cells along with the hub cells, forming the stem cell niche. Consistent with its expression, we found that, while loss of tara in germline cells only had minimal effects, tara knockdown in all cells or only in somatic cells of the niche reduced the number of not only somatic cells, but also germline stem cells (GSCs). We further found that Tara might antagonize Notch signaling in CySCs to maintain the stem cell niche. CONCLUSIONS: Our studies suggest that Tara might function in somatic CySCs for GSC maintenance in the Drosophila testis.

Worldwide inverse correlation between Bacille Calmette-Guérin immunization and COVID-19 mortality.

The coronavirus disease 2019 (COVID-19) pandemic has spread to all countries in the world after more than half a year since it was first reported in late 2019, and different countries have been impacted differently. Multivariate statistical analyses were used to evaluate COVID-19 deaths and cases relative to nine other demographic and socioeconomic factors in all countries and regions of the world using data as of August 1, 2020. The factors analyzed in the study include a country's total COVID-19 deaths and cases per million population, per capita gross domestic product (GDP), population density, virus tests per million population, median age, government response stringency index, hospital beds availability per thousand population, extreme poverty rate, Bacille Calmette-Guérin (BCG) vaccination rate, and diphtheria-tetanus-pertussis (DTP3) immunization rate. The study reveals that COVID-19 deaths per million population in a country most significantly correlates, inversely, with the country's BCG vaccination rate, and also significantly correlates a country's per capita GDP and median age, while COVID-19 cases per million population significantly correlate with per capita GDP and tests per thousand population. This study contributes to a growing body of evidence supporting the notion that BCG vaccination may be protective against COVID-19 mortality.

A Screening Method for Identification of Heterochromatin-Promoting Drugs Using Drosophila.

Drosophila is an excellent model organism that can be used to screen compounds that might be useful for cancer therapy. The method described here is a cost-effective in vivo method to identify heterochromatin-promoting compounds by using Drosophila. The Drosophila's DX1 strain, having a variegated eye color phenotype that reflects the extents of heterochromatin formation, thereby providing a tool for a heterochromatin-promoting drug screen. In this screening method, eye variegation is quantified based on the surface area of red pigmentation occupying parts of the eye and is scored on a scale from 1 to 5. The screening method is straightforward and sensitive and allows for testing compounds in vivo. Drug screening using this method provides a fast and inexpensive way for identifying heterochromatin-promoting drugs that could have beneficial effects in cancer therapeutics. Identifying compounds that promote the formation of heterochromatin could also lead to the discovery of epigenetic mechanisms of cancer development.

Unphosphorylated STAT3 in heterochromatin formation and tumor suppression in lung cancer.

BACKGROUND: Aberrant JAK/STAT activation has been detected in many types of human cancers. The role of JAK/STAT activation in cancer has been mostly attributed to direct transcriptional regulation of target genes by phosphorylated STAT (pSTAT), while the unphosphorylated STAT (uSTAT) is believed to be dormant and reside in the cytoplasm. However, several studies have shown that uSTATs can be found in the nucleus. In addition, it has been shown that tissue-specific loss of STAT3 or STAT5 in mice promotes cancer growth in certain tissues, and thus these STAT proteins can act as tumor suppressors. However, no unifying mechanism has been shown for the tumor suppressor function of STATs to date. We have previously demonstrated a non-canonical mode of JAK/STAT signaling for Drosophila STAT and human STAT5A, where a fraction of uSTAT is in the nucleus and associated with Heterochromatin Protein 1 (HP1); STAT activation (by phosphorylation) causes its dispersal, leading to HP1 delocalization and heterochromatin loss. METHODS: We used a combination of imaging, cell biological assays, and mouse xenografts to investigate the role of STAT3 in lung cancer development. RESULTS: We found that uSTAT3 has a function in promoting heterochromatin formation in lung cancer cells, suppressing cell proliferation in vitro, and suppressing tumor growth in mouse xenografts. CONCLUSIONS: Thus, uSTAT3 possesses noncanonical function in promoting heterochromatin formation, and the tumor suppressor function of STAT3 is likely attributable to the heterochromatin-promoting activity of uSTAT3 in the non-canonical JAK/STAT pathway.

Streptonigrin at low concentration promotes heterochromatin formation.

Heterochromatin is essential for regulating global gene transcription and protecting genome stability, and may play a role in tumor suppression. Drugs promoting heterochromatin are potential cancer therapeutics but very few are known. In order to identify drugs that can promote heterochromatin, we used a cell-based method and screened NCI drug libraries consisting of oncology drugs and natural compounds. Since heterochromatin is originally defined as intensely stained chromatin in the nucleus, we estimated heterochromatin contents of cells treated with different drugs by quantifying the fluorescence intensity of nuclei stained with Hoechst DNA dye. We used HeLa cells and screened 231 FDA-approved oncology and natural substance drugs included in two NCI drug libraries representing a variety of chemical structures. Among these drugs, streptonigrin most prominently caused an increase in Hoechst-stained nuclear fluorescence intensity. We further show that streptonigrin treated cells exhibit compacted DNA foci in the nucleus that co-localize with Heterochromatin Protein 1 alpha (HP1α), and exhibit an increase in total levels of the heterochromatin mark, H3K9me3. Interestingly, we found that streptonigrin promotes heterochromatin at a concentration as low as one nanomolar, and at this concentration there were no detectable effects on cell proliferation or viability. Finally, in line with a previous report, we found that streptonigrin inhibits STAT3 phosphorylation, raising the possibility that non-canonical STAT function may contribute to the effects of streptonigrin on heterochromatin. These results suggest that, at low concentrations, streptonigrin may primarily enhance heterochromatin formation with little toxic effects on cells, and therefore might be a good candidate for epigenetic cancer therapy.

Endogenous IL-33 and Its Autoamplification of IL-33/ST2 Pathway Play an Important Role in Asthma.

IL-33 and its receptor ST2 are contributing factors to airway inflammation and asthma exacerbation. The IL-33/ST2 signaling pathway is involved in both the onset and the acute exacerbations of asthma. In this study, we address the role of endogenous IL-33 and its autoamplification of the IL-33/ST2 pathway in Ag-dependent and Ag-independent asthma-like models. Wild-type, IL-33 knockout, ST2 knockout mice were either intratracheally administrated with 500 ng of rIL-33 per day for four consecutive days or were sensitized and challenged with OVA over 21 d. In wild-type mice, IL-33 or OVA induced similar airway hyperresponsiveness and eosinophilic airway inflammation. IL-33 induced its own mRNA and ST2L mRNA expression in the lung. IL-33 autoamplified itself and ST2 protein expression in airway epithelial cells. OVA also induced IL-33 and ST2 protein expression. In IL-33 knockout mice, the IL-33- and OVA-induced airway hyperresponsiveness and eosinophilic airway inflammation were both significantly attenuated, whereas IL-33-induced ST2L mRNA expression was preserved, although no autoamplification of IL-33/ST2 pathway was observed. In ST2 knockout mice, IL-33 and OVA induced airway hyperresponsiveness and eosinophilic airway inflammation were both completely diminished, and no IL-33/ST2 autoamplification was observed. These results suggest that endogenous IL-33 and its autoamplification of IL-33/ST2 pathway play an important role in the induction of asthma-like phenotype. Thus an intact IL-33/ST2 pathway is necessary for both Ag-dependent and Ag-independent asthma-like mouse models.

Aging mechanisms-A perspective mostly from Drosophila.

A mechanistic understanding of the natural aging process, which is distinct from aging-related disease mechanisms, is essential for developing interventions to extend lifespan or healthspan. Here, we discuss current trends in aging research and address conceptual and experimental challenges in the field. We examine various molecular markers implicated in aging with an emphasis on the role of heterochromatin and epigenetic changes. Studies in model organisms have been advantageous in elucidating conserved genetic and epigenetic mechanisms and assessing interventions that affect aging. We highlight the use of Drosophila, which allows controlled studies for evaluating genetic and environmental contributors to aging conveniently. Finally, we propose the use of novel methodologies and future strategies using Drosophila in aging research.

Metformin Use in Diabetes Prior to Hospitalization: Effects on Mortality in Covid-19.

OBJECTIVE: Although type 2 diabetes mellitus (T2DM) has been reported as a risk factor for coronavirus disease 2019 (COVID-19), the effect of pharmacologic agents used to treat T2DM, such as metformin, on COVID-19 outcomes remains unclear. Metformin increases the expression of angiotensin converting enzyme 2, a known receptor for severe acute respiratory syndrome coronavirus 2. Data from people with T2DM hospitalized for COVID-19 were used to test the hypothesis that metformin use is associated with improved survival in this population. METHODS: Retrospective analyses were performed on de-identified clinical data from a major hospital in Wuhan, China, that included patients with T2DM hospitalized for COVID-19 during the recent epidemic. One hundred and thirty-one patients diagnosed with COVID-19 and T2DM were used in this study. The primary outcome was mortality. Demographic, clinical characteristics, laboratory data, diabetes medications, and respiratory therapy data were also included in the analysis. RESULTS: Of these 131 patients, 37 used metformin with or without other antidiabetes medications. Among the 37 metformin-taking patients, 35 (94.6%) survived and 2 (5.4%) did not survive. The mortality rates in the metformin-taking group versus the non-metformin group were 5.4% (2/37) versus 22.3% (21/94). Using multivariate analysis, metformin was found to be an independent predictor of survival in this cohort (P = .02). CONCLUSION: This study reveals a significant association between metformin use and survival in people with T2DM diagnosed with COVID-19. These clinical data are consistent with potential benefits of the use of metformin for COVID-19 patients with T2DM.

Identification of methotrexate as a heterochromatin-promoting drug.

Heterochromatin is a tightly packed form of DNA involved in gene silencing, chromosome segregation, and protection of genome stability. Heterochromatin is becoming more recognized in tumor suppression and may thus serve as a potential target for cancer therapy. However, to date there are no drugs that are well established to specifically promote heterochromatin formation. Here, we describe a screening method using Drosophila to identify small molecule compounds that promote heterochromatin formation, with the purpose of developing epigenetic cancer therapeutics. We took advantage of a Drosophila strain with a variegated eye color phenotype that is sensitive to heterochromatin levels, and screened a library of 97 FDA approved oncology drugs. This screen identified methotrexate as the most potent small molecule drug, among the 97 oncology drugs screened, in promoting heterochromatin formation. Interestingly, methotrexate has been identified as a JAK/STAT inhibitor in a functional screen, causing reduced phosphorylation of STAT proteins. These findings are in line with our previous observation that unphosphorylated STAT (uSTAT) promotes heterochromatin formation in both Drosophila and human cells and suppresses tumor growth in mouse xenografts. Thus, Drosophila with variegated eye color phenotypes could be an effective tool for screening heterochromatin-promoting compounds that could be candidates as cancer therapeutics.

Genome-wide Kdm4 histone demethylase transcriptional regulation in Drosophila.

The histone lysine demethylase 4 (Kdm4/Jmjd2/Jhdm3) family is highly conserved across species and reverses di- and tri-methylation of histone H3 lysine 9 (H3K9) and lysine 36 (H3K36) at the N-terminal tail of the core histone H3 in various metazoan species including Drosophila, C.elegans, zebrafish, mice and humans. Previous studies have shown that the Kdm4 family plays a wide variety of important biological roles in different species, including development, oncogenesis and longevity by regulating transcription, DNA damage response and apoptosis. Only two functional Kdm4 family members have been identified in Drosophila, compared to five in mammals, thus providing a simple model system. Drosophila Kdm4 loss-of-function mutants do not survive past the early 2nd instar larvae stage and display a molting defect phenotype associated with deregulated ecdysone hormone receptor signaling. To further characterize and identify additional targets of Kdm4, we employed a genome-wide approach to investigate transcriptome alterations in Kdm4 mutants versus wild-type during early development. We found evidence of increased deregulated transcripts, presumably associated with a progressive accumulation of H3K9 and H3K36 methylation through development. Gene ontology analyses found significant enrichment of terms related to the ecdysteroid hormone signaling pathway important in development, as expected, and additionally previously unidentified potential targets that warrant further investigation. Since Kdm4 is highly conserved across species, our results may be applicable more widely to other organisms and our genome-wide dataset may serve as a useful resource for further studies.

Tumour cell-intrinsic CTLA4 regulates PD-L1 expression in non-small cell lung cancer.

Cytotoxic T lymphocyte antigen 4 (CTLA4) and programmed cell death protein 1 (PD-1) are immune checkpoint proteins expressed in T cells. Although CTLA4 expression was found in multiple tumours including non-small cell lung cancer (NSCLC) tissues and cells, its function in tumour cells is unknown. Recently, PD-1 was found to be expressed in melanoma cells and to promote tumorigenesis. We found that CTLA4 was expressed in a subset of NSCLC cell lines and in a subgroup of cancer cells within the lung cancer tissues. We further found that in NSCLC cells, anti-CTLA4 antibody can induce PD-L1 expression, which is mediated by CTLA4 and the EGFR pathway involving phosphorylation of MEK and ERK. In CTLA4 knockout cells, EGFR knockout cells or in the presence of an EGFR tyrosine kinase inhibitor, anti-CTLA4 antibody was not able to induce PD-L1 expression in NSCLC cells. Moreover, anti-CTLA4 antibody promoted NSCLC cell proliferation in vitro and tumour growth in vivo in the absence of adaptive immunity. These results suggest that tumour cell-intrinsic CTLA4 can regulate PD-L1 expression and cell proliferation, and that anti-CTLA4 antibody, by binding to the tumour cell-intrinsic CTLA4, may result in the activation of the EGFR pathway in cancer cells.

Canonical and non-canonical JAK/STAT transcriptional targets may be involved in distinct and overlapping cellular processes.

BACKGROUND: The Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway has been well-characterized as a crucial signal transduction cascade that regulates vital biological responses including development, immunity and oncogenesis. Additionally to its canonical pathway that uses the phosphorylated form of the STAT transcription factor, recently the non-canonical pathway involving heterochromatin formation by unphosphorylated STAT was recently uncovered. Considering the significant role of the JAK/STAT pathway, we used the simple Drosophila system in which the non-canonical pathway was initially characterized, to compare putative canonical versus non-canonical transcriptional targets across the genome. We analyzed microarray expression patterns of wildtype, Jak gain- and loss-of-function mutants, as well as the Stat loss-of-function mutant during embryogenesis, since the contribution of the canonical signal transduction pathway has been well-characterized in these contexts. Previous studies have also demonstrated that Jak gain-of-function and Stat mutants counter heterochromatin silencing to de-repress target genes by the non-canonical pathway. RESULTS: Compared to canonical target genomic loci, non-canonical targets were significantly more associated with sites enriched with heterochromatin-related factors (p = 0.004). Furthermore, putative canonical and non-canonical transcriptional targets identified displayed some differences in biological pathways they regulate, as determined by Gene Ontology (GO) enrichment analyses. Canonical targets were enriched mainly with genes relevant to development and immunity, as expected, whereas the non-canonical target gene set mainly showed enrichment of genes for various metabolic responses and stress response, highlighting the possibility that some differences may exist between the two loci. CONCLUSIONS: Canonical and non-canonical JAK/STAT genes may regulate distinct and overlapping sets of genes and may perform specific overall functions in physiology. Further studies at different developmental stages, or using distinct tissues may identify additional targets and provide insight into which gene targets are unique to the canonical or non-canonical pathway.