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The G protein-coupled receptor proteinase-activated receptor 2 (PAR2) has been implicated
in various aspects of cellular physiology including inflammation, obesity and cancer. In cancer,
it usually acts as a driver of cancer progression in various tumor types by promoting invasion and
metastasis in response to activation by serine proteinases. Recently, we discovered another mode
through which PAR2 may enhance tumorigenesis: crosstalk with transforming growth factor-β
(TGF-β) signaling to promote TGF-β1-induced cell migration/invasion and invasion-associated gene
expression in ductal pancreatic adenocarcinoma (PDAC) cells. In this chapter, we review what is
known about the cellular TGF-β responses and signaling pathways affected by PAR2 expression,
the signaling activities of PAR2 required for promoting TGF-β signaling, and the potential molecular
mechanism(s) that underlie(s) the TGF-β signaling–promoting effect. Since PAR2 is activated through
various serine proteinases and biased agonists, it may couple TGF-β signaling to a diverse range of
other physiological processes that may or may not predispose cells to cancer development such as
local inflammation, systemic coagulation and pathogen infection.
Renal drug transporters such as the organic cation transporters (OCTs), organic anion
transporters (OATs) and multidrug resistance proteins (MRPs) play an important role in the tubular
secretion of many drugs influencing their efficacy and safety. However, only little is known about
the distinct protein abundance of these transporters in human kidneys, and about the impact of
age and gender as potential factors of inter-subject variability in their expression and function.
The aim of this study was to determine the protein abundance of MDR1, MRP1-4, BCRP, OAT1-3,
OCT2-3, MATE1, PEPT1/2, and ORCTL2 by liquid chromatography-tandem mass spectrometry-based
targeted proteomics in a set of 36 human cortex kidney samples (20 males, 16 females; median age
53 and 55 years, respectively). OAT1 and 3, OCT2 and ORCTL2 were found to be most abundant
renal SLC transporters while MDR1, MRP1 and MRP4 were the dominating ABC transporters.
Only the expression levels of MDR1 and ORCTL2 were significantly higher abundant in older donors.
Moreover, we found several significant correlations between different transporters, which may
indicate their functional interplay in renal vectorial transport processes. Our data may contribute to
a better understanding of the molecular processes determining renal excretion of drugs.
Background: Recently, the expression of proteinase-activated receptor 2 (PAR2) has been
shown to be essential for activin receptor-like kinase 5 (ALK5)/SMAD-mediated signaling and cell
migration by transforming growth factor (TGF)-β1. However, it is not known whether activation
of non-SMAD TGF-β signaling (e.g., RAS–RAF–MEK–extracellular signal-regulated kinase (ERK)
signaling) is required for cell migration and whether it is also dependent on PAR2. Methods: RNA
interference was used to deplete cells of PAR2, followed by xCELLigence technology to measure
cell migration, phospho-immunoblotting to assess ERK1/2 activation, and co-immunoprecipitation
to detect a PAR2–ALK5 physical interaction. Results: Inhibition of ERK signaling with the MEK
inhibitor U0126 blunted the ability of TGF-β1 to induce migration in pancreatic cancer Panc1 cells.
ERK activation in response to PAR2 agonistic peptide (PAR2–AP) was strong and rapid, while it was
moderate and delayed in response to TGF-β1. Basal and TGF-β1-dependent ERK, but not SMAD
activation, was blocked by U0126 in Panc1 and other cell types indicating that ERK activation is
downstream or independent of SMAD signaling. Moreover, cellular depletion of PAR2 in HaCaT
cells strongly inhibited TGF-β1-induced ERK activation, while the biased PAR2 agonist GB88 at 10
and 100 µM potentiated TGF-β1-dependent ERK activation and cell migration. Finally, we provide
evidence for a physical interaction between PAR2 and ALK5. Our data show that both PAR2–APand TGF-β1-induced cell migration depend on ERK activation, that PAR2 expression is crucial for
TGF-β1-induced ERK activation, and that the functional cooperation of PAR2 and TGF-β1 involves a
physical interaction between PAR2 and ALK5
The multifunctional sphingosine-1-phosphate (S1P) is a lipid signaling molecule and central
regulator in the development of several cancer types. In recent years, intriguing information has
become available regarding the role of S1P in the progression of Glioblastoma multiforme (GBM),
the most aggressive and common brain tumor in adults. S1P modulates numerous cellular processes
in GBM, such as oncogenesis, proliferation and survival, invasion, migration, metastasis and stem cell
behavior. These processes are regulated via a family of five G-protein-coupled S1P receptors (S1PR1-5)
and may involve mainly unknown intracellular targets. Distinct expression patterns and multiple
intracellular signaling pathways of each S1PR subtype enable S1P to exert its pleiotropic cellular
actions. Several studies have demonstrated alterations in S1P levels, the involvement of S1PRs
and S1P metabolizing enzymes in GBM pathophysiology. While the tumorigenic actions of S1P
involve the activation of several kinases and transcription factors, the specific G-protein (Gi, Gq,
and G12/13)-coupled signaling pathways and downstream mediated effects in GBM remain to be
elucidated in detail. This review summarizes the recent findings concerning the role of S1P and its
receptors in GBM. We further highlight the current insights into the signaling pathways considered
fundamental for regulating the cellular processes in GMB and ultimately patient prognosis.
Salivary glands provide secretory functions, including secretion of xenobiotics and among
them drugs. However, there is no published information about protein abundance of drug transporters
measured using reliable protein quantification methods. Therefore, mRNA expression and absolute
protein content of clinically relevant ABC (n = 6) and SLC (n = 15) family member transporters in the
human parotid gland, using the qRT-PCR and liquid chromatography-tandem mass spectrometry
(LC−MS/MS) method, were studied. The abundance of nearly all measured proteins ranged between
0.04 and 0.45 pmol/mg (OCT3 > MRP1 > PEPT2 > MRP4 > MATE1 > BCRP). mRNAs of ABCB1,
ABCC2, ABCC3, SLC10A1, SLC10A2, SLC22A1, SLC22A5, SLC22A6, SLC22A7, SLC22A8, SLCO1A2,
SLCO1B1, SLCO1B3 and SLCO2B1 were not detected. The present study provides, for the first time,
information about the protein abundance of membrane transporters in the human parotid gland,
which could further be used to define salivary bidirectional transport (absorption and secretion)
mechanisms of endogenous compounds and xenobiotics.
Exogenous glucocorticoids increase the risk for osteoporosis, but the role of endogenous glucocorticoids remains elusive. Here, we describe the generation and validation of a loss- and a gain-of-function model of the cortisol producing enzyme 11β-HSD1 (HSD11B1) to modulate the endogenous glucocorticoid conversion in SCP-1 cells — a model for human mesenchymal stem cells capable of adipogenic and osteogenic differentiation. CRISPR-Cas9 was successfully used to generate a cell line carrying a single base duplication and a 5 bp deletion in exon 5, leading to missense amino acid sequences after codon 146. These inactivating genomic alterations were validated by deep sequencing and by cloning with subsequent capillary sequencing. 11β-HSD1 protein levels were reduced by 70% in the knockout cells and cortisol production was not detectable. Targeted chromosomal integration was used to stably overexpress HSD11B1. Compared to wildtype cells, HSD11B1 overexpression resulted in a 7.9-fold increase in HSD11B1 mRNA expression, a 5-fold increase in 11β-HSD1 protein expression and 3.3-fold increase in extracellular cortisol levels under adipogenic differentiation. The generated cells were used to address the effects of 11β-HSD1 expression on adipogenic and osteogenic differentiation. Compared to the wildtype, HSD11B1 overexpression led to a 3.7-fold increase in mRNA expression of lipoprotein lipase (LPL) and 2.5-fold increase in lipid production under adipogenic differentiation. Under osteogenic differentiation, HSD11B1 knockout led to enhanced alkaline phosphatase (ALP) activity and mRNA expression, and HSD11B1 overexpression resulted in a 4.6-fold and 11.7-fold increase in mRNA expression of Dickkopf-related protein 1 (DKK1) and LPL, respectively. Here we describe a HSD11B1 loss- and gain-of-function model in SCP-1 cells at genetic, molecular and functional levels. We used these models to study the effects of endogenous cortisol production on mesenchymal stem cell differentiation and demonstrate an 11β-HSD1 dependent switch from osteogenic to adipogenic differentiation. These results might help to better understand the role of endogenous cortisol production in osteoporosis on a molecular and cellular level.
Previous studies have reported the fundamental role of immunoregulatory
proteins in the clinical phenotype and outcome of sepsis. This study investigated two functional single
nucleotide polymorphisms (SNPs) of T cell immunoglobulin and mucin domain-containing protein 3
(TIM-3), which has a negative stimulatory function in the T cell immune response. Methods: Patients
with sepsis (n = 712) were prospectively enrolled from three intensive care units (ICUs) at the University
Medical Center Goettingen since 2012. All patients were genotyped for the TIM-3 SNPs rs1036199 and
rs10515746. The primary outcome was 28-day mortality. Disease severity and microbiological findings
were secondary endpoints. Results: Kaplan–Meier survival analysis demonstrated a significantly
lower 28-day mortality for TIM-3 rs1036199 AA homozygous patients compared to C-allele carriers
(18% vs. 27%, p = 0.0099) and TIM-3 rs10515746 CC homozygous patients compared to A-allele
carriers (18% vs. 26%, p = 0.0202). The TIM-3 rs1036199 AA genotype and rs10515746 CC genotype
remained significant predictors for 28-day mortality in the multivariate Cox regression analysis after
adjustment for relevant confounders (adjusted hazard ratios: 0.67 and 0.70). Additionally, patients
carrying the rs1036199 AA genotype presented more Gram-positive and Staphylococcus epidermidis
infections, and rs10515746 CC homozygotes presented more Staphylococcus epidermidis infections.
Conclusion: The studied TIM-3 genetic variants are associated with altered 28-day mortality and
susceptibility to Gram-positive infections in sepsis.
Membrane monocarboxylate transporter 1 (SLC16A1/MCT1) plays an important role in
hepatocyte homeostasis, as well as drug handling. However, there is no available information
about the impact of liver pathology on the transporter levels and function. The study was aimed to
quantify SLC16A1 mRNA (qRT-PCR) and MCT1 protein abundance (liquid chromatography–tandem
mass spectrometry (LC¬¬–MS/MS)) in the livers of patients diagnosed, according to the standard
clinical criteria, with hepatitis C, primary biliary cirrhosis, primary sclerosing hepatitis, alcoholic liver
disease (ALD), and autoimmune hepatitis. The stage of liver dysfunction was classified according to
Child–Pugh score. Downregulation of SLC16A1/MCT1 levels was observed in all liver pathology
states, significantly for ALD. The progression of liver dysfunction, from Child–Pugh class A to C,
involved the gradual decline in SLC16A1 mRNA and MCT1 protein abundance, reaching a clinically
significant decrease in class C livers. Reduced levels of MCT1 were associated with significant
intracellular lactate accumulation. The MCT1 transcript and protein did not demonstrate significant
correlations regardless of the liver pathology analyzed, as well as the disease stage, suggesting
posttranscriptional regulation, and several microRNAs were found as potential regulators of MCT1
abundance. MCT1 membrane immunolocalization without cytoplasmic retention was observed in all
studied liver pathologies. Overall, the study demonstrates that SLC16A1/MCT1 is involved in liver
pathology, especially in ALD
PIM1 Inhibition Affects Glioblastoma Stem Cell Behavior and Kills Glioblastoma Stem-like Cells
(2021)
Despite comprehensive therapy and extensive research, glioblastoma (GBM) still represents the most aggressive brain tumor in adults. Glioma stem cells (GSCs) are thought to play a major role in tumor progression and resistance of GBM cells to radiochemotherapy. The PIM1 kinase has become a focus in cancer research. We have previously demonstrated that PIM1 is involved in survival of GBM cells and in GBM growth in a mouse model. However, little is known about the importance of PIM1 in cancer stem cells. Here, we report on the role of PIM1 in GBM stem cell behavior and killing. PIM1 inhibition negatively regulates the protein expression of the stem cell markers CD133 and Nestin in GBM cells (LN-18, U-87 MG). In contrast, CD44 and the astrocytic differentiation marker GFAP were up-regulated. Furthermore, PIM1 expression was increased in neurospheres as a model of GBM stem-like cells. Treatment of neurospheres with PIM1 inhibitors (TCS PIM1-1, Quercetagetin, and LY294002) diminished the cell viability associated with reduced DNA synthesis rate, increased caspase 3 activity, decreased PCNA protein expression, and reduced neurosphere formation. Our results indicate that PIM1 affects the glioblastoma stem cell behavior, and its inhibition kills glioblastoma stem-like cells, pointing to PIM1 targeting as a potential anti-glioblastoma therapy.
Doxorubicin is a frequently used anticancer drug to treat many types of tumors, such as breast cancer or bronchial carcinoma. The clinical use of doxorubicin is limited by its poorly predictable cardiotoxicity, the reasons of which are so far not fully understood. The drug is a substrate of several efflux transporters such as P-gp or BCRP and was recently reported to be a substrate of cation uptake transporters. To evaluate the potential role of transporter proteins in the accumulation of doxorubicin at its site of action (e.g., mammary carcinoma cells) or adverse effects (e.g., heart muscle cells), we studied the expression of important uptake and efflux transporters in human breast cancer and cardiac tissue, and investigated the affinity of doxorubicin to the identified transporters. The cellular uptake studies on doxorubicin were performed with OATP1A2*1, OATP1A2*2, and OATP1A2*3-overexpressing HEK293 cells, as well as OCT1-, OCT2-, and OCT3- overexpressing MDCKII cells. To assess the contribution of transporters to the cytotoxic effect of doxorubicin, we determined the cell viability in the presence and absence of transporter inhibitors in different cell lines. Several transporters, including P-gp, BCRP, OCT1, OCT3, and OATP1A2 were expressed in human heart and/or breast cancer tissue. Doxorubicin could be identified as a substrate of OCT1, OCT2, OCT3, and OATP1A2. The cellular uptake into cells expressing genetic OATP1A2 variants was markedly reduced and correlated well with the increased cellular viability. Inhibition of OATP1A2 (naringin) and OCT transporters (1-methyl-4-phenylpyridinium) resulted in a significant decrease of doxorubicin-mediated cytotoxicity in cell lines expressing the respective transporters. Similarly, the excipient Cremophor EL significantly inhibited the OCT1-3- and OATP1A2-mediated cellular uptake and attenuated the cytotoxicity of doxorubicin. In conclusion, genetic and environmental-related variability in the expression and function of these transporters may contribute to the substantial variability seen in terms of doxorubicin efficacy and toxicity.