Characterization of Plasma Membrane Localization and Phosphorylation Status of Organic Anion Transporting Polypeptide (OATP) 1B1 c.521 T>C Nonsynonymous Single-Nucleotide Polymorphism

Human uncultured adipose-derived stromal vascular fraction shows therapeutic potential against osteoarthritis in immunodeficient rats via direct effects of transplanted M2 macrophages

BACKGROUND

The uncultured adipose-derived stromal vascular fraction (SVF), consisting of adipose-derived stromal cells (ADSCs), M2 macrophages (M2Φ) and others, has shown therapeutic potential against osteoarthritis (OA), however, the mechanisms underlying its therapeutic effects remain unclear. Therefore, this study investigated the effects of the SVF on OA in a human-immunodeficient rat xenotransplantation model.

METHODS

OA model was induced in the knees of female immunodeficient rats by destabilization of the medial meniscus. Immediately after the surgery, human SVF (1 × 105), ADSCs (1 × 104), or phosphate buffered saline as a control group were transplanted into the knees. At 4 and 8 weeks postoperatively, OA progression and synovitis were analyzed by macroscopic and histological analyses, and the expression of collagen II, SOX9, MMP-13, ADAMTS-5, F4/80, CD86 (M1), CD163 (M2), and human nuclear antigen (hNA) were evaluated immunohistochemically. In vitro, flow cytometry was performed to collect CD163-positive cells as M2Φ from the SVF. Chondrocyte pellets (1 × 105) were co-cultured with SVF (1 × 105), M2Φ (1 × 104), and ADSCs (1 × 104) or alone as a control group, and the pellet size was compared. TGF-β, IL-10 and MMP-13 concentrations in the medium were evaluated using enzyme-linked immunosorbent assay.

RESULTS

In comparison with the control and ADSC groups, the SVF group showed significantly slower OA progression and less synovitis with higher expression of collagen II and SOX9, lower expression of MMP-13 and ADAMTS-5, and lower F4/80 and M1/M2 ratio in the synovium. Only the SVF group showed partial expression of hNA-, CD163-, and F4/80-positive cells in the rat synovium. In vitro, the SVF, M2Φ, ADSC and control groups, in that order, showed larger pellet sizes, higher TGF-β and IL-10, and lower MMP-13 concentrations.

CONCLUSIONS

The M2Φ in the transplanted SVF directly affected recipient tissue, enhancing the secretion of growth factors and chondrocyte-protecting cytokines, and partially improving chondrocytes and joint homeostasis. These findings indicate that the SVF is as an effective option for regenerative therapy for OA, with mechanisms different from those of ADSCs.

Subcellular Fractionation and Metaproteogenomic Identification and Validation of Key Differentially Expressed Molecular Targets for Keloid Disease

Keloid disease (KD) is a common connective tissue disorder of unknown aetiopathogenesis with ill-defined treatment. Keloid scars present as exophytic fibroproliferative reticular lesions postcutaneous injury, and even though KD remains neoplastically benign, keloid lesions behave locally aggressive, invasive and expansive. To date, there is limited understanding and validation of biomarkers identified through combined proteomic and genomic evaluation of KD. Therefore, the aim in this study was to identify putative causative candidates in KD by performing a comprehensive proteomics analysis of subcellular fractions as well as the whole cell, coupled with transcriptomics data analysis of normal compared with KD fibroblasts. We then applied novel integrative bioinformatics analysis to demonstrate that NF-kB-p65 (RELA) from the cytosolic fraction and CAPN2 from the whole-cell lysate were statistically significantly upregulated in KD and associated with alterations in relevant key signaling pathways, including apoptosis. Our findings were further confirmed by showing upregulation of both RELA and CAPN2 in KD using flow cytometry and immunohistochemistry. Moreover, functional evaluation using real-time cell analysis and flow cytometry demonstrated that both omeprazole and dexamethasone inhibited the growth of KD fibroblasts by enhancing the rate of apoptosis. In conclusion, subcellular fractionation and metaproteogenomic analyses have identified, to our knowledge, 2 previously unreported biomarkers of significant relevance to keloid diagnostics and therapeutics.

Impact of genetic variants in the solute carrier (SLC) genes encoding drug uptake transporters on the response to anticancer chemotherapy

Cancer drug resistance constitutes a severe limitation for the satisfactory outcome of these patients. This is a complex problem due to the co-existence in cancer cells of multiple and synergistic mechanisms of chemoresistance (MOC). These mechanisms are accounted for by the expression of a set of genes included in the so-called resistome, whose effectiveness often leads to a lack of response to pharmacological treatment. Additionally, genetic variants affecting these genes further increase the complexity of the question. This review focuses on a set of genes encoding members of the transportome involved in drug uptake, which have been classified into the MOC-1A subgroup of the resistome. These proteins belong to the solute carrier (SLC) superfamily. More precisely, we have considered here several members of families SLC2, SLC7, SLC19, SLC22, SLCO, SLC28, SLC29, SLC31, SLC46, and SLC47 due to the impact of their expression and genetic variants in anticancer drug uptake by tumor cells or, in some cases, general bioavailability. Changes in their expression levels and the appearance of genetic variants can contribute to the Darwinian selection of more resistant clones and, hence, to the development of a more malignant phenotype. Accordingly, to address this issue in future personalized medicine, it is necessary to characterize both changes in resistome genes that can affect their function. It is also essential to consider the time-dependent dimension of these features, as the genetic expression and the appearance of genetic variants can change during tumor progression and in response to treatment.

Major basic protein is a useful marker to distinguish eosinophilic esophagitis from IBD-associated eosinophilia in children

OBJECTIVES

The incidence of eosinophilic esophagitis (EoE) is 3-5 times greater in patients with inflammatory bowel disease (IBD) compared with the general population. This study aimed to differentiate true EoE from esophageal eosinophilia in IBD patients by evaluating expression of major basic protein (MBP) and interleukin-13 (IL-13) in esophageal biopsies.

METHODS

This retrospective study included subjects who had an esophagogastroduodenoscopy with esophageal biopsies for IBD work up or suspicion for EoE. Patients were classified into 5 groups: EoE with ≥15 eosinophils per high power field (eos/hpf), EoE-IBD with ≥15 eos/hpf, IBD eosinophilia with 1-14 eos/hpf, IBD and control groups. Biopsies were stained with MBP and IL-13 antibodies and the results (% staining/total tissue area), demographic, and clinical findings were compared among the groups.

RESULTS

The median for MBP staining levels in EoE-IBD was 3.8 (interquartile range 1.3-23), significantly lower than in EoE at 52.8 (8.3-113.2), but higher than in IBD eosinophilia at 0.2 (0-0.9; p < 0.001) and negligible in the IBD and control groups. IL-13 expression in EoE was significantly higher only compared with IBD and controls not with EoE-IBD or IBD eosinophilia. MBP predicted EoE with 100% sensitivity and 99% specificity while IL-13 had 83% sensitivity and 90% specificity using cutoff point from the cohort without EoE-IBD patients. Based on MBP cutoff point that distinguished EoE from non EoE, 56% in EoE-IBD were MBP-positive whereas 100% in EoE group (p < 0.05).

CONCLUSIONS

MBP may be an excellent marker in distinguishing true EoE from eosinophilia caused by IBD. Our data implied that MBP together with endoscopic and histologic changes can assist EoE diagnosis in IBD patients.

Assessing Trans-Inhibition of OATP1B1 and OATP1B3 by Calcineurin and/or PPIase Inhibitors and Global Identification of OATP1B1/3-Associated Proteins

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are key determinants of drug-drug interactions (DDIs). Various drugs including the calcineurin inhibitor (CNI) cyclosporine A (CsA) exert preincubation-induced trans-inhibitory effects upon OATP1B1 and/or OATP1B3 (abbreviated as OATP1B1/3) by unknown mechanism(s). OATP1B1/3 are phosphoproteins; calcineurin, which dephosphorylates and regulates numerous phosphoproteins, has not previously been investigated in the context of preincubation-induced trans-inhibition of OATP1B1/3. Herein, we compare the trans-inhibitory effects exerted on OATP1B1 and OATP1B3 by CsA, the non-analogous CNI tacrolimus, and the non-CNI CsA analogue SCY-635 in transporter-overexpressing human embryonic kidney (HEK) 293 stable cell lines. Preincubation (10-60 min) with tacrolimus (1-10 µM) rapidly and significantly reduces OATP1B1- and OATP1B3-mediated transport up to 0.18 ± 0.03- and 0.20 ± 0.02-fold compared to the control, respectively. Both CsA and SCY-635 can trans-inhibit OATP1B1, with the inhibitory effects progressively increasing over a 60 min preincubation time. At each equivalent preincubation time, CsA has greater trans-inhibitory effects toward OATP1B1 than SCY-635. Preincubation with SCY-635 for 60 min yielded IC50 of 2.2 ± 1.4 µM against OATP1B1, which is ~18 fold greater than that of CsA (0.12 ± 0.04 µM). Furthermore, a proteomics-based screening for protein interactors was used to examine possible proteins and processes contributing to OATP1B1/3 regulation and preincubation-induced inhibition by CNIs and other drugs. A total of 861 and 357 proteins were identified as specifically associated with OATP1B1 and OATP1B3, respectively, including various protein kinases, ubiquitin-related enzymes, the tacrolimus (FK506)-binding proteins FKBP5 and FKBP8, and several known regulatory targets of calcineurin. The current study reports several novel findings that expand our understanding of impaired OATP1B1/3 function; these include preincubation-induced trans-inhibition of OATP1B1/3 by the CNI tacrolimus, greater preincubation-induced inhibition by CsA compared to its non-CNI analogue SCY-635, and association of OATP1B1/3 with various proteins relevant to established and candidate OATP1B1/3 regulatory processes.

Heterogeneous Cells as well as Adipose-Derived Stromal Cells in Stromal Vascular Fraction Contribute to Enhance Anabolic and Inhibit Catabolic Factors in Osteoarthritis

The stromal-vascular fraction (SVF), comprising heterogeneous cell populations and adipose-derived stromal cells (ADSCs), has therapeutic potential against osteoarthritis (OA); however, the underlying mechanism remains elusive. This study aimed to investigate the therapeutic effects of heterogeneous cells in rabbit SVF on rabbit chondrocytes. Rabbit SVF and ADSCs were autografted into knees at OA onset. The SVF (1 × 105) and low-dose ADSCs (lADSC; 1 × 104) groups adjusted for their stromal cell content were compared. Animals were euthanized 8 and 12 weeks after OA onset for macroscopic and histological analyses of OA progression and synovitis. Immunohistochemical and real-time polymerase chain reaction assessments were conducted. In vitro, immune-fluorescent double staining was performed for SVF to stain macrophages with F4/80, CD86(M1), and CD163(M2). OA progression was markedly suppressed, and synovitis was reduced in the SVF groups (OARSI histological score 8 W: 6.8 ± 0.75 vs. 3.8 ± 0.75, p = 0.001; 12 W: 8.8 ± 0.4 vs. 5.4 ± 0.49, p = 0.0002). The SVF groups had higher expression of collagen II and SOX9 in cartilage and TGF-β and IL-10 in the synovium, lower expression of MMP-13, and lower macrophage M1/M2 ratio than the lADSC groups. Immunofluorescent double staining revealed a markedly higher number of M2 than that of M1 macrophages in the SVF. The therapeutic effects of SVF on chondrocytes were superior than those of lADSCs, with enhanced anabolic and inhibited catabolic factors. Heterogeneous cells, mainly M2 macrophages in the SVF, enhanced growth factor secretion and chondrocyte-protective cytokines, thus benefiting chondrocytes and knee joint homeostasis. Overall, the SVF is a safe, relatively simple, and a useful treatment option for OA.

Human liver single nuclear RNA sequencing implicates BMPR2, GDF15, arginine, and estrogen in portopulmonary hypertension

Portopulmonary hypertension (PoPH) is a type of pulmonary vascular disease due to portal hypertension that exhibits high morbidity and mortality. The mechanisms driving disease are unknown, and transcriptional characteristics unique to the PoPH liver remain unexplored. Here, we apply single nuclear RNA sequencing to compare cirrhotic livers from patients with and without PoPH. We identify characteristics unique to PoPH in cells surrounding the central hepatic vein, including increased growth differentiation factor signaling, enrichment of the arginine biosynthesis pathway, and differential expression of the bone morphogenic protein type II receptor and estrogen receptor type I genes. These results provide insight into the transcriptomic characteristics of the PoPH liver and mechanisms by which PoPH cellular dysfunction might contribute to pulmonary vascular remodeling.

Hemolytic iron regulation in traumatic brain injury and alcohol use

Hemorrhage is a major component of traumatic brain injury (TBI). Red blood cells, accumulated at the hemorrhagic site, undergo hemolysis upon energy depletion and release free iron into the central nervous system. This iron must be managed to prevent iron neurotoxicity and ferroptosis. As prior alcohol consumption is often associated with TBI, we examined iron regulation in a rat model of chronic alcohol feeding subjected to fluid percussion-induced TBI. We found that alcohol consumption prior to TBI altered the expression profiles of the lipocalin 2/heme oxygenase 1/ferritin iron management system. Notably, unlike TBI alone, TBI following chronic alcohol consumption sustained the expression of all three regulatory proteins for 1, 3, and 7 days post-injury. In addition, alcohol significantly affected TBI-induced expression of ferritin light chain at 3 days post-injury. We also found that alcohol exacerbated TBI-induced activation of microglia at 7 days post-injury. Finally, we propose that microglia may also play a role in iron management through red blood cell clearance.

Nitrogen transporters along the intestinal spiral valve of cloudy catshark (Scyliorhinus torazame): Rhp2, Rhbg, UT

As part of their osmoregulatory strategy, marine elasmobranchs retain large quantities of urea to balance the osmotic pressure of the marine environment. The main source of nitrogen used to synthesize urea comes from the digestion and absorption of food across the gastrointestinal tract. In this study we investigated possible mechanisms of nitrogen movement across the spiral valve of the cloudy catshark (Scyliorhinus torazame) through the molecular identification of two Rhesus glycoprotein ammonia transporters (Rhp2 and Rhbg) and a urea transporter (UT). We used immunohistochemistry to determine the cellular localizations of Rhp2 and UT. Within the spiral valve, Rhp2 was expressed along the apical brush-border membrane, and UT was expressed along the basolateral membrane and the blood vessels. The mRNA abundance of Rhp2 was significantly higher in all regions of the spiral valve of fasted catsharks compared to fed catsharks. The mRNA abundance of UT was significantly higher in the anterior spiral valve of fasted catsharks compared to fed. The mRNA transcript of four ornithine urea cycle (OUC) enzymes were detected along the length of the spiral valve and in the renal tissue, indicating the synthesis of urea via the OUC occurs in these tissues. The presence of Rhp2, Rhbg, and UT along the length of the spiral valve highlights the importance of ammonia and urea movement across the intestinal tissues, and increases our understanding of the mechanisms involved in maintaining whole-body nitrogen homeostasis in the cloudy catshark.

Dysregulation of the mTOR pathway by mechlorethamine

Mechlorethamine (HN2) is a derivative of the chemical warfare agent sulfur mustard (SM) and cutaneous exposure to HN2 is associated with dermal-epidermal junction (DEJ) disruption (vesication). The primary purpose of the present study was to investigate the effect of HN2 on the mammalian target of rapamycin (mTOR) signaling pathway using an in vivo mouse ear vesicant model (MEVM). To this end, the ears of male C57BL/ 6 J mice were exposed to a single topical dose of HN2 (100 mM) or vehicle control (DMSO). Mice were then euthanized 30 min, 1 h or 24 h following exposure. Mouse ear skin exposed to HN2 and biopsied 24 h thereafter exhibited increased tissue expression of Raptor, an important member of the mTORC1 complex, relative to vehicle treated samples. HN2 reduced the downstream effectors phospho S6 (Ser 240/244) ribosomal protein and phospho 4E-BP1 (Thr 37/46) of the mTOR pathway in the epidermis at 30 min, 1 h and 24 h following HN2 exposure but not in the dermis. These results support the hypothesis that HN2-mediated cutaneous toxicity involves dysregulation of the mTOR signaling pathway in the epidermis.

Effects of the SLCO1B1 A388G single nucleotide polymorphism on the development, clinical parameters, treatment, and survival of multiple myeloma cases in a Polish population

BACKGROUND

Multiple myeloma is one of the most common hematological malignancies worldwide. Genetic alterations may lead to the progression from monoclonal gammopathy to multiple myeloma. Additionally, the genetic background of the disease might influence therapy outcomes, including survival time. SLCO1B1, belonging to the OATPs family, is a membrane protein that mediates the uptake of a wide range of endogenous and exogenous (including drugs) compounds.

METHODS AND RESULTS

In this study, the A388G single nucleotide polymorphism in the SLCO1B1 gene in Polish multiple myeloma patients was determined. This polymorphism affects the amino acid change of the protein, so it may be responsible for treatment effectiveness or risk of disease development. A388G was evaluated by the PCR-RFLP method. The presented study showed a statistically significant association between the GG genotype with longer survival of patients with multiple myeloma with Melphalan-Prednisone therapy compared to other treatment regimens (p = 0.0271). There was no statistically significant association in the frequency of genotypes (p = 0.8211) and alleles: allele A (p = 0.5442); allele G (p = 0.8020) between multiple myeloma patients and a control group.

CONCLUSIONS

The A388G polymorphism does not seem to affect the increased risk of the development of multiple myeloma. However, the occurrence of the GG genotype may prolong of patients overall survival in the case of Melphalan-Prednisone therapy.

Mouse Syngeneic Melanoma Model with Human Epidermal Growth Factor Receptor Expression

The development of epidermal growth factor receptor (EGFR)-targeting agents for the treatment of malignant melanoma requires cheap and easy animal tumor models for high-throughput in vivo screening. Thus, the aim of this study was to develop mouse syngeneic melanoma model that expresses human EGFR. Cloudman S91 clone M3 mouse melanoma cells were transduced with lentiviral particles carrying the human EGFR gene followed by a multistep selection process. The resulting M3-EGFR has been tested for EGFR expression and functionality in vitro and in vivo. Radioligand assay confirmed the presence of 13,900 ± 1500 EGF binding sites per cell at a dissociation constant of 5.3 ± 1.4 nM. M3-EGFR demonstrated the ability to bind and internalize specifically and provide the anticipated intracellular nuclear import of three different EGFR-targeted modular nanotransporters designed for specific anti-cancer drug delivery. Introduction of the human EGFR gene did not alter the tumorigenicity of the offspring M3-EGFR cells in host immunocompetent DBA/2J mice. Preservation of the expression of EGFR in vivo was confirmed by immunohistochemistry. To sum up, we successfully developed the first mouse syngeneic melanoma model with preserved in vivo expression of human EGFR.

Tofacitinib Inhibits STAT Phosphorylation and Matrix Metalloproteinase-3, -9 and -13 Production by C28/I2 Human Juvenile Chondrocytes

Purpose

This in vitro study was designed to determine the effect of the pan-Janus kinase inhibitor, Tofacitinib, on basal and interleukin-6 (IL-6)-induced signal transducers and activators of transcription (STAT) phosphorylation and matrix metalloproteinase (MMP) gene expression and MMP production by C28/I2 human chondrocytes.

Methods

C28/I2 chondrocytes were grown to a confluent high-density and treated either with recombinant human IL-6 (rhIL-6; 10-20ng/mL) or maintained in the basal state for up to 60 min. MMP gene expression was determined using RT-PCR and MMP production by semi-quantitative immunohistochemistry. The effect of IL-6 with or without Tofacitinib on activation of STAT proteins was determined from quantitative Western blots.

Results

C28/I2 chondrocytes produced STAT1, STAT3 and STAT5AB which were phosphorylated (p) following treatment with rhIL-6 for 30 min. Tofacitinib (2.5nM-100nM) decreased rhIL-6-induced activation of STAT1, STAT3, and STAT5AB as well as decreasing the expression of MMP3 and MMP13 but not MMP9, MMP1 or MMP2. In addition, Tofacitinib (50nM) reduced the number of rhIL-6-induced MMP3-, and MMP13- antibody-positive C28/I2 chondrocytes. However, Tofacitinib did decrease the number of MMP9-antibody-positive C28/I2 chondrocytes.

Conclusion

Taken together, these data showed that Tofacitinib, a pan-JAK small molecule inhibitor employed for the medical therapy of rheumatoid arthritis was a potent inhibitor of rhIL-6-induced STAT phosphorylation that appeared to be coupled to the inhibition of MMP-3, -9 and -13 production by C28/I2 chondrocytes.

Exploiting Dependence of Castration-Resistant Prostate Cancer on the Arginine Vasopressin Signaling Axis by Repurposing Vaptans

Men with advanced prostate cancer are treated by androgen deprivation therapy but the disease recurs as incurable castration-resistant prostate cancer (CRPC), requiring new treatment options. We previously demonstrated that the G protein-coupled receptor (GPCR) arginine vasopressin receptor type1A (AVPR1A) is expressed in CRPC and promotes castration-resistant growth in vitro and in vivo. AVPR1A is part of a family of GPCR's including arginine vasopressin receptor type 2 (AVPR2). Interrogation of prostate cancer patient sample data revealed that coexpression of AVPR1A and AVPR2 is highly correlated with disease progression. Stimulation of AVPR2 with a selective agonist desmopressin promoted CRPC cell proliferation through cAMP/protein kinase A signaling, consistent with AVPR2 coupling to the G protein subunit alpha s. In contrast, blocking AVPR2 with a selective FDA-approved antagonist, tolvaptan, reduced cell growth. In CRPC xenografts, antagonizing AVPR2, AVPR1A, or both significantly reduced CRPC tumor growth as well as decreased on-target markers of tumor burden. Combinatorial use of AVPR1A and AVPR2 antagonists promoted apoptosis synergistically in CRPC cells. Furthermore, we found that castration-resistant cells produced AVP, the endogenous ligand for arginine vasopressin receptors, and knockout of AVP in CRPC cells significantly reduced proliferation suggesting possible AVP autocrine signaling. These data indicate that the AVP/arginine vasopressin receptor signaling axis represents a promising and clinically actionable target for CRPC.

IMPLICATIONS

The arginine vasopressin signaling axis in CRPC provides a therapeutic window that is targetable through repurposing safe and effective AVPR1A and AVPR2 antagonists.

Regulation of Drug Transport Proteins-From Mechanisms to Clinical Impact: A White Paper on Behalf of the International Transporter Consortium

Membrane transport proteins are involved in the absorption, disposition, efficacy, and/or toxicity of many drugs. Numerous mechanisms (e.g., nuclear receptors, epigenetic gene regulation, microRNAs, alternative splicing, post‐translational modifications, and trafficking) regulate transport protein levels, localization, and function. Various factors associated with disease, medications, and dietary constituents, for example, may alter the regulation and activity of transport proteins in the intestine, liver, kidneys, brain, lungs, placenta, and other important sites, such as tumor tissue. This white paper reviews key mechanisms and regulatory factors that alter the function of clinically relevant transport proteins involved in drug disposition. Current considerations with in vitro and in vivo models that are used to investigate transporter regulation are discussed, including strengths, limitations, and the inherent challenges in predicting the impact of changes due to regulation of one transporter on compensatory pathways and overall drug disposition. In addition, translation and scaling of in vitro observations to in vivo outcomes are considered. The importance of incorporating altered transporter regulation in modeling and simulation approaches to predict the clinical impact on drug disposition is also discussed. Regulation of transporters is highly complex and, therefore, identification of knowledge gaps will aid in directing future research to expand our understanding of clinically relevant molecular mechanisms of transporter regulation. This information is critical to the development of tools and approaches to improve therapeutic outcomes by predicting more accurately the impact of regulation‐mediated changes in transporter function on drug disposition and response.

PARP inhibitors chemopotentiate and synergize with cisplatin to inhibit bladder cancer cell survival and tumor growth

Background

Management of bladder cancer (BLCA) has not changed significantly in the past few decades, with platinum agent chemotherapy being used in most cases. Chemotherapy reduces tumor recurrence after resection, but debilitating toxicities render a large percentage of patients ineligible. Recently approved immunotherapy can improve outcomes in only a third of metastatic BLCA patients. Therefore, more options for therapy are needed. In this study, we explored the efficacy of PARP inhibitors (PARPi) as single agents or as combinations with platinum therapy.

Methods

We treated BLCA cells with PARPi (olaparib, niraparib, rucaparib, veliparib, or talazoparib) alone or as the combination of cisplatin with PARPi. We then measured their survival, proliferation, apoptosis, as well as their ability to form colonies. BLCA xenografts in male SCID mice were treated similarly, followed by the assessment of their growth, proliferation, and apoptosis.

Results

PARPi niraparib and talazoparib were effective in reducing BLCA cell survival as single agents. Combinations of Cisplatin with talazoparib and niraparib effectively reduced the survival of BLCA cells, while veliparib was not effective even at high concentrations. In vivo, the combinations of cisplatin with niraparib, rucaparib, or talazoparib reduced BLCA xenograft growth significantly.

Conclusions

We provide evidence that PARPi can be effective against BLCA as single agents or as combinatorial therapy with cisplatin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09376-9.

Engineered Bacteria Enhance Immunotherapy and Targeted Therapy through Stromal Remodeling of Tumors

Desmoplastic solid tumors are characterized by the rapid build-up of extracellular matrix (ECM) macromolecules, such as hyaluronic acid (HA). The resulting physiological barrier prevents the infiltration of immune cells and also impedes the delivery of anticancer agents. The development of a hypervesiculating Escherichia coli Nissle (ΔECHy) based tumor targeting bacterial system capable of distributing a fusion peptide, cytolysin A (ClyA)-hyaluronidase (Hy) via outer membrane vesicles (OMVs) is reported. The capability of targeting hypoxic tumors, manufacturing recombinant proteins in situ and the added advantage of an on-site OMV based distribution system makes the engineered bacterial vector a unique candidate for peptide delivery. The HA degrading potential of Hy for stromal modulation is combined with the cytolytic activity of ClyA followed by testing it within syngeneic cancer models. ΔECHy is combined with immune checkpoint antibodies and tyrosine kinase inhibitors (TKIs) to demonstrate that remodeling the tumor stroma results in the improvement of immunotherapy outcomes and enhancing the efficacy of biological signaling inhibitors. The biocompatibility of ΔECHy is also investigated to show that the engineered bacteria are effectively cleared, elicit minimal inflammatory and immune responses, and therefore could be a reliable candidate as a live biotherapeutic.

The Effect of Single Nucleotide Variations in the Transmembrane Domain of OATP1B1 on in vitro Functionality

Purpose

Organic Anion Transporting Polypeptide 1B1 (OATP1B1) mediates hepatic influx and clearance of many drugs, including statins. The SLCO1B1 gene is highly polymorphic and its function-impairing variants can predispose patients to adverse effects. The effects of rare genetic variants of SLCO1B1 are mainly unexplored. We examined the impact of eight naturally occurring rare variants and the well-known SLCO1B1 c.521C > T (V174A) variant on in vitro transport activity, cellular localization and abundance.

Methods

Transport of rosuvastatin and 2,7-dichlorofluorescein (DCF) in OATP1B1 expressing HEK293 cells was measured to assess changes in activity of the variants. Immunofluorescence and confocal microscopy determined the cellular localization of OATP1B1 and LC–MS/MS based quantitative targeted absolute proteomics analysis quantified the amount of OATP1B1 in crude membrane fractions.

Results

All studied variants, with the exception of P336R, reduced protein abundance to varying degree. V174A reduced protein abundance the most, over 90% compared to wild type. Transport function was lost in G76E, V174A, L193R and R580Q variants. R181C decreased activity significantly, while T345M and L543W retained most of wild type OATP1B1 activity. P336R showed increased activity and H575L decreased the transport of DCF significantly, but not of rosuvastatin. Decreased activity was interrelated with lower absolute protein abundance in the studied variants.

Conclusions

Transmembrane helices 2, 4 and 11 appear to be crucial for proper membrane localization and function of OATP1B1. Four of the studied variants were identified as loss-of-function variants and as such could make the individual harboring these variants susceptible to altered pharmacokinetics and adverse effects of substrate drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-021-03107-8.

Pre-incubation with OATP1B1 and OATP1B3 inhibitors potentiates inhibitory effects in physiologically relevant sandwich-cultured primary human hepatocytes

Organic anion transporting polypeptides (OATP)1B1 and OATP1B3 are liver-specific transport proteins that express on the basolateral membrane of human hepatocytes and mediate hepatic uptake of many drugs, including statins. They are important determinants of transporter-mediated drug-drug interactions (DDIs). It has been reported that pre-incubation with some OATP1B1 and OATP1B3 inhibitors potentiates the inhibitory effects, yielding reduced IC50 values. The US FDA draft guidance has recently recommended to use the lower IC50 values after inhibitor-preincubation to assess OATP1B1 and OATP1B3-mediated DDIs. However, it remains unknown whether the potentiation effects of inhibitor-preincubation on IC50 values occur in a physiologically relevant cell model. The current study was designed to determine the IC50 values of OATP1B1 and OATP1B3 inhibitors everolimus (EVR), sirolimus (SIR), and dasatinib against OATP1B substrates in physiologically relevant primary human hepatocytes with or without inhibitor-preincubation and to compare the OATP-mediated DDI prediction using data from primary human hepatocytes and that reported previously in transporter-expressing cell lines. Primary human hepatocytes were cultured in a sandwich configuration. Accumulation of [3H]-CCK-8 (1 µM, 1.5 min), [3H]-rosuvastatin (0.5 µM, 2 min) and [3H]-pitavastatin (1 µM, 0.5 min) was determined in human sandwich-cultured hepatocytes (SCH) in the presence of vehicle control or an inhibitor with or without inhibitor-preincubation at designated concentrations, and was utilized to determine the IC50 values for these inhibitors. R-value models were used to predict OATP-mediated DDIs. Pre-incubation with EVR at a clinically relevant concentration of 0.2 µM significantly reduced accumulation of [3H]-CCK-8 and [3H]-rosuvastatin even after washing. Reduced IC50 values following inhibitor pre-incubation were observed for all three inhibitors using [3H]-CCK-8 and [3H]-rosuvastatin as substrates in human SCH. The IC50 values after inhibitor-preincubation were lower or comparable in transporter-expressing cell lines compared with that in human SCH. For dasatinib, R-values from both cell lines and human SCH were greater than the US FDA cut-off value of 1.1. For EVR, R values from cell lines were 1.23 and were lowered to near 1.1 (1.08-1.09) in human SCH. For SIR, R values from either cell type were less than the cut-off values of 1.1. In conclusion, the current study is the first to report that pre-incubation with OATP1B inhibitors potentiates inhibitory effects in physiologically relevant primary human hepatocytes, supporting the rationale of the current US FDA draft guidance of including an inhibitor-preincubation step when assessing OATP-mediated DDIs in vitro. IC50 values after inhibitor-preincubation in transporter-expressing cell lines may be used for DDI prediction for the purpose of mitigating false-negative OATP-mediated DDI prediction.

Susceptibility of cyclin-dependent kinase inhibitor 1-deficient mice to rheumatoid arthritis arising from interleukin-1β-induced inflammation

We recently reported that cyclin-dependent kinase inhibitor 1 (p21) deficiency induces osteoarthritis susceptibility. Here, we determined the mechanism underlying the effect of p21 in synovial and cartilage tissues in RA. The knee joints of p21-knockout (p21^-/-) (n = 16) and wild type C57BL/6 (p21^+/+) mice (n = 16) served as in vivo models of collagen antibody-induced arthritis (CAIA). Arthritis severity was evaluated by immunological and histological analyses. The response of p21 small-interfering RNA (siRNA)-treated human RA FLSs (n = 5 per group) to interleukin (IL)-1β stimulation was determined in vitro. Arthritis scores were higher in p21^-/- mice than in p21^+/+ mice. More severe synovitis, earlier loss of Safranin-O staining, and cartilage destruction were observed in p21^-/- mice compared to p21^+/+ mice. p21^-/- mice expressed higher levels of IL-1β, TNF-α, F4/80, CD86, p-IKKα/β, and matrix metalloproteinases (MMPs) in cartilage and synovial tissues via IL-1β-induced NF-kB signaling. IL-1β stimulation significantly increased IL-6, IL-8, and MMP expression, and enhanced IKKα/β and IκBα phosphorylation in human FLSs. p21-deficient CAIA mice are susceptible to RA phenotype alterations, including joint cartilage destruction and severe synovitis. Therefore, p21 may have a regulatory role in inflammatory cytokine production including IL-1β, IL-6, and TNF-α.

Regulation of OATP1B1 Function by Tyrosine Kinase-mediated Phosphorylation

PURPOSE

OATP1B1 (SLCO1B1) is the most abundant and pharmacologically relevant uptake transporter in the liver and a key mediator of xenobiotic clearance. However, the regulatory mechanisms that determine OATP1B1 activity remain uncertain, and as a result, unexpected drug-drug interactions involving OATP1B1 substrates continue to be reported, including several involving tyrosine kinase inhibitors (TKI).

EXPERIMENTAL DESIGN

OATP1B1-mediated activity in overexpressing HEK293 cells and hepatocytes was assessed in the presence of FDA-approved TKIs, while rosuvastatin pharmacokinetics in the presence of an OATP1B1 inhibiting TKI were measured in vivo. Tyrosine phosphorylation of OATP1B1 was determined by LC/MS-MS-based proteomics and transport function was measured following exposure to siRNAs targeting 779 different kinases.

RESULTS

Twenty-nine of 46 FDA-approved TKIs studied significantly inhibit OATP1B1 function. Inhibition of OATP1B1 by TKIs, such as nilotinib, is predominantly noncompetitive, can increase systemic concentrations of rosuvastatin in vivo, and is associated with reduced phosphorylation of OATP1B1 at tyrosine residue 645. Using genetic screens and functional validation studies, the Src kinase LYN was identified as a potential regulator of OATP1B1 activity that is highly sensitive to inhibition by various TKIs at clinically relevant concentrations.

CONCLUSIONS

A novel kinase-dependent posttranslational mechanism of OATP1B1 activation was identified and interference with this process by TKIs can influence the elimination of a broad range of xenobiotic substrates.

Post-translational regulation of the major drug transporters in the families of organic anion transporters and organic anion-transporting polypeptides

The organic anion transporters (OATs) and organic anion-transporting polypeptides (OATPs) belong to the solute carrier (SLC) transporter superfamily and play important roles in handling various endogenous and exogenous compounds of anionic charge. The OATs and OATPs are often implicated in drug therapy by impacting the pharmacokinetics of clinically important drugs and, thereby, drug exposure in the target organs or cells. Various mechanisms (e.g. genetic, environmental, and disease-related factors, drug-drug interactions, and food-drug interactions) can lead to variations in the expression and activity of the anion drug-transporting proteins of OATs and OATPs, possibly impacting the therapeutic outcomes. Previous investigations mainly focused on the regulation at the transcriptional level and drug-drug interactions as competing substrates or inhibitors. Recently, evidence has accumulated that cellular trafficking, post-translational modification, and degradation mechanisms serve as another important layer for the mechanisms underlying the variations in the OATs and OATPs. This review will provide a brief overview of the major OATs and OATPs implicated in drug therapy and summarize recent progress in our understanding of the post-translational modifications, in particular ubiquitination and degradation pathways of the individual OATs and OATPs implicated in drug therapy.

6-Hydroxyindole is an endogenous long-lasting OATP1B1 inhibitor elevated in renal failure patients

The hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1 is inhibited by some uremic toxins; however, direct inhibition can only partially explain the delayed systemic elimination of substrate drugs in renal failure patients. This study aimed to examine the long-lasting inhibition of OATP1B1 by uremic toxins and their metabolites. Preincubation of HEK293/OATP1B1 cells with 21 uremic toxins resulted in almost no change in the uptake of a typical substrate [³H]estrone-3-sulfate (E₁S), although some directly inhibited [³H]E₁S uptake. In contrast, preincubation with an indole metabolite, 6-hydroxyindole, reduced [³H]E₁S uptake, even after the inhibitor was washed out before [³H]E₁S incubation. Such long-lasting inhibition by 6-hydroxyindole was time-dependent and recovered after a 3-h incubation without 6-hydroxyindole. Preincubation with 6-hydroxyindole increased the Km for [³H]E₁S uptake with minimal change in Vmax. This was compatible with no change in the cell-surface expression of OATP1B1, as assessed by a biotinylation assay. Preincubation with 6-hydroxyindole reduced [³H]E₁S uptake in human hepatocytes without changes in OATP1B1 mRNA. Plasma concentration of 6-hydroxyindole in renal failure patients increased as renal function decreased, but might be insufficient to exhibit potent OATP1B1 inhibition. In conclusion, 6-hydroxyindole is an endogenous long-lasting OATP1B1 inhibitor with elevated plasma concentrations in renal failure patients.

Two common polymorphic variants of OATP4A1 as potential risk factors for colorectal cancer

Genetic variations in the organic-anion-transporting polypeptide (OATP)-encoding solute carrier of organic anions (SLCO) genes can promote cancer development and progression. The overexpression of solute carrier organic anion transporter family member 4A1 (OATP4A1), a transporter for steroid hormones, prostaglandins, and bile acids, has been previously associated with tumor recurrence and progression in colorectal cancer (CRC). Therefore, the present study aimed to investigate the association between 2 frequent single nucleotide polymorphisms (SNPs) in SLCO4A1 (rs34419428, R70Q; rs1047099G, V78I) and CRC predisposition. Following restriction fragment length polymorphism-PCR analysis in 178 patients with CRC [Union for International Cancer Control (UICC) stage I/II] and 65 healthy controls, no significant difference was observed in allele frequency and the number of heterozygous/homozygous individuals between the groups. Notably, the R70Q minor allele was identified to be associated with the V78I minor allele in the genome. Comparing of the individual genotypes of CRC patients to clinical data, including sex, UICC-stage and relapse revealed no increased risk for CRC. In addition, the OATP4A1 immunoreactivity assay in paraffin-embedded CRC and adjacent non-tumorous mucosa sections, examined using quantitative microscopy image analysis, did not reveal any association with these polymorphisms. No significant differences were observed in the expression levels, localization, and sodium fluorescein transport capacity among the OATP4A1 variants, which was studied using functional assays in Sf9-insect and A431 tumor cells overexpressing the 2 single and a double mutant OATP4A1 SNP variants. These results suggested that the 2 most frequent polymorphisms located in the first intracellular loop of OATP4A1 do not associate with CRC predisposition and tumor recurrence. They are unlikely to affect the outcome of CRC in patients.

Role of Genetic Variations in the Hepatic Handling of Drugs

The liver plays a pivotal role in drug handling due to its contribution to the processes of detoxification (phases 0 to 3). In addition, the liver is also an essential organ for the mechanism of action of many families of drugs, such as cholesterol-lowering, antidiabetic, antiviral, anticoagulant, and anticancer agents. Accordingly, the presence of genetic variants affecting a high number of genes expressed in hepatocytes has a critical clinical impact. The present review is not an exhaustive list but a general overview of the most relevant variants of genes involved in detoxification phases. The available information highlights the importance of defining the genomic profile responsible for the hepatic handling of drugs in many ways, such as (i) impaired uptake, (ii) enhanced export, (iii) altered metabolism due to decreased activation of prodrugs or enhanced inactivation of active compounds, and (iv) altered molecular targets located in the liver due to genetic changes or activation/downregulation of alternative/compensatory pathways. In conclusion, the advance in this field of modern pharmacology, which allows one to predict the outcome of the treatments and to develop more effective and selective agents able to overcome the lack of effect associated with the existence of some genetic variants, is required to step forward toward a more personalized medicine.

Semi-quantitative Determination of Protein Expression using Immunohistochemistry Staining and Analysis: An Integrated Protocol

Semi-quantitative IHC is a powerful method for investigating protein expression and localization within tissues. The semi-quantitative immunohistochemistry (IHC) involves using software such as free software ImageJ Fiji to conduct deconvolution and downstream analysis. Currently, there is lack of an integrated protocol that includes a detailed procedure of how to measure or compare protein expression. Publications that use semi-quantification methods to quantify protein expression often don't provide enough details in their methods section, which makes it difficult for the reader to reproduce their data. The current protocol for the first time provides a detailed, step-by-step instruction of conducting semi-quantitative analysis of IHC images using ImageJ Fiji software so that researchers would be able to follow this single protocol to conduct their research. The protocol uses semi-quantitative IHC of organic anion transporting polypeptide (OATP1B1) as an example, and gives detailed steps on how to deconvolute IHC images stained with hematoxylin and 3, 3 - diaminobenzidine (DAB) and how to quantify their expression using ImageJ Fiji. The protocol includes clear steps for a reader so that this method can be applied to many different proteins. We anticipate this method will provide a practical guidance to the reader and make semi-quantification of proteins an easier task to include in publications.