PRKD2: A two-pronged kinase crucial for the tumor-supporting activity of HSP90

Multifaceted Functions of Protein Kinase D in Pathological Processes and Human Diseases

Protein kinase D (PKD) is a family of serine/threonine protein kinases operating in the signaling network of the second messenger diacylglycerol. The three family members, PKD1, PKD2, and PKD3, are activated by a variety of extracellular stimuli and transduce cell signals affecting many aspects of basic cell functions including secretion, migration, proliferation, survival, angiogenesis, and immune response. Dysregulation of PKD in expression and activity has been detected in many human diseases. Further loss- or gain-of-function studies at cellular levels and in animal models provide strong support for crucial roles of PKD in many pathological conditions, including cancer, metabolic disorders, cardiac diseases, central nervous system disorders, inflammatory diseases, and immune dysregulation. Complexity in enzymatic regulation and function is evident as PKD isoforms may act differently in different biological systems and disease models, and understanding the molecular mechanisms underlying these differences and their biological significance in vivo is essential for the development of safer and more effective PKD-targeted therapies. In this review, to provide a global understanding of PKD function, we present an overview of the PKD family in several major human diseases with more focus on cancer-associated biological processes.

Effects of NRP1 on angiogenesis and vascular maturity in endothelial cells are dependent on the expression of SEMA4D

Angiogenesis and vascular maturation play important roles in tumorigenesis and tumor development. The expression of neuropilin 1 (NRP1) is closely associated with angiogenesis in tumors; however, the molecular mechanisms of action in angiogenesis and tumor maturation, as well as the potential clinical value of NRP1 remain unclear. The importance of NRP1 expression in tumor progression was determined using The Cancer Genome Atlas (TCGA) database analysis. Gain- and loss-of-function experiments of NRP1 were performed in vascular endothelial cells (ECs) to investigate the functions in angiogenesis. CCK-8, flow cytometry, Transwell experiments and a series of in vitro experiments were used to detect cell functions. A combination of angiogenesis antibody arrays and RNA-Seq analyses were performed to reveal the proangiogenic mechanisms of action. The function of semaphorin 4D (SEMA4D) was also investigated separately. NRP1 mRNA levels were significantly increased in primary tumors compared with normal tissues based on TCGA data (P<0.01) and were associated with tumor development in patients. Gain- and loss-of-function experiments highlighted the function of NRP1 in promoting EC proliferation, motility and capillary-like tube formation and in reducing apoptosis. NRP1 overexpression led to significantly decreased EC markers (PECAM-1, angiogenin, PIGF and MMP-9) expression levels and reduced the vascular maturity. MAPK7, TPM1, RRBP1, PTPRK, HSP90A, PRKD2, PFKFB3, RGS4 and SPARC were revealed to play important roles in this process. SEMA4D was revealed to be a key protein associated with NRP1 in ECs. These data indicated that NRP1-promoted angiogenesis may be induced at the cost of reducing maturity of the ECs. NRP1 may also be a therapeutic target for antiangiogenic strategies and a candidate prognostic marker for tumors.

HSP90 and Co-chaperones: Impact on Tumor Progression and Prospects for Molecular-Targeted Cancer Therapy

Heat shock protein 90 (HSP90), a highly and unique chaperone, presents as a double-edged sword. It plays an essential role in many physiological and pathological processes, including tumor development. The current review highlights a recent understanding of the roles of HSP90 in molecular mechanisms underlying cancer survival and progression. HSP90 and its client proteins through the regulation of oncoproteins including signaling proteins, receptors, and transcriptional factors involved in tumorigenesis. It also has potential clinical application as diagnostic and prognostic biomarkers for assessing cancer progression. In this way, using HSP90 to develop new anticancer therapeutic agents including HSP90 inhibitors, anti-HSP90 antibody, and HSP90-based vaccines has been promising.

PRKD2 Promotes Progression and Chemoresistance of AML via Regulating Notch1 Pathway

Introduction

Progression and chemoresistance of acute myeloid leukemia (AML) contribute to most of the treatment failure. Notch pathway has been proven to be involved in many biological processes and diseases, especially AML. In this study, we aimed to explore genes correlated with Notch1 pathway in AML and determine their roles in the regulation of AML progression and chemoresistance.

Methods

TCGA database was used to explore Notch1 associated genes. Kaplan-Meier survival analysis was performed to evaluate the prognostic significance of genes. Quantitative RT-PCR (qRT-PCR) and Western blot were performed to examine the expression of genes. The expression of PRKD2 was up-regulated or knocked down in AML cell lines by lentivirus or siRNAs. CCK-8 and flow cytometry were used to analyze the effect of PRKD2 on cell proliferation and chemoresistance.

Results

Based on TCGA database, PRKD2 was found to be positively correlated with Notch1 expression, cytogenetic risk status and poorer prognosis in AML. Moreover, the expression level of PRKD2 was higher in AML chemo-resistant cells than in chemo-sensitive cells. Functionally, knockdown of PRKD2-induced apoptosis and increased chemosensitivity of AML cells. PRKD2 overexpression promoted proliferation and chemoresistance of AML cells. Furthermore, we found PRKD2 could regulate Notch1 pathway. Besides, high PRKD2 expression was correlated with higher risk group of AML patients which indicated that PRKD2 was an independent prognostic marker for AML.

Conclusion

Taken together, our results showed that PRKD2 could promote the proliferation and chemoresistance of AML cells by regulating Notch1 pathway. The study broadened our insights into the underlying mechanisms in chemoresistance and proliferation of AML, and provided a new prognostic marker and treatment target for AML.

Differential expression of genes associated with T lymphocytes function in septic patients with hypoxemia challenge

Background

This study aimed to assess gene expression alterations related to T lymphocytes function and explore their potential association with hypoxemia among septic patients.

Methods

This is a retrospective cohort clinical study with laboratory investigations. We studied patients enrolled in sepsis biological specimen bank from Department of Critical Care Medicine, Zhongda Hospital, fulfilling consensus criteria for sepsis without any documented immune comorbidity admitted in ICU within 48 h after onset with whole blood samples drawn within 24 h of admission. Whole genome expression by microarray assay (Human LncRNA Microarray V4.0) was compared in hypoxemia cohort versus without. Differentially expressed (DE) genes with >1 log₂[fold change (FC)] and false discovery rate (FDR) <0.20 that enriched in T cell related biological process entered the adjusted analysis to identify the candidate genes. The correlation analysis within candidate genes or with clinical parameters were performed. We assessed candidate expression ex vivo in co-culture system with RAW246.7 cells and validated genes identified in prior studies of sepsis-ARDS/hypoxemia within our present study.

Results

Septic patients (n=9) with hypoxemic phenotype held higher illness severity, serum lactate and creatine, and incidence of lymphopenia compared with non-hypoxemic group (n=6). Several gene signatures related to apoptosis, inhibitory receptors, T cell immunoreceptor, transcriptions factors, toll-like receptors and cytokine and effector molecules were upregulated in hypoxemic group. Candidate genes were identified after adjustment for age, sex and presence of lymphopenia with significantly negative correlations with partial pressure of O₂ in an arterial blood (PaO₂) and fraction of inspiration O₂ (FiO₂) ratio, among which NLRP3, SOS1, ELF1 and STAT3 held an increasing expression in ex vivo validation while the others, PSMA5, CLEC4D, CD300A, PRKD2 and PSMA2 showed the opposite alteration from those in vivo.

Conclusions

Higher illness severity and incidence of lymphopenia was observed following hypoxemia in sepsis and T cell-related gene signatures were associated with hypoxemia during sepsis.