Liver Graft MicroRNAs Expression in Different Etiology of Acute Jaundice after Living Donor Liver Transplantation.

Background: Acute jaundice remains a critical problem following liver transplantation. MicroRNAs (miRNAs) are involved in regulating gene expression related to various disease phenotypes and statuses. Aims: To differentiate acute jaundice etiology after living donor liver transplantation (LDLT), we examined the hepatic miRNA expression patterns in several liver graft pathologies. Methods: Eighty liver transplant recipients undergoing post-LDLT graft biopsy for the evaluation of acute jaundice were enrolled in this 1-year prospective study. Using a real-time quantitative reverse transcription-polymerase chain reaction profiling assay, we identified hepatic miRNA (miRNA-122, miRNA-301, miRNA-133a, and miRNA-21) signatures in various allografts pathologies. Results: Pathologic findings of the 80 recipients were as follows: acute cholangitis (AC), 37 (46%); acute rejection (AR), 20 (25%); recurrent hepatitis (RH), 12 (15%); non-specific pathological change, 6 (8%); and fatty change (FC), 5 (6%). None of these identified hepatic miRNAs expression pattern was significantly correlated with serum parameters, including neutrophil-lymphocyte ratio. In AC, hepatic miRNA-122, miRNA-301, miRNA-133a, and miRNA-21 expression was significantly downregulated (p < 0.05). MicroRNA-122 expression was elevated in cases of AR and RH (p < 0.05); miRNA-301 and miRNA-21 expression was higher in RH than in AC (p < 0.05); and miRNA-133a expression was higher in FC than in AR (p < 0.05). Conclusions: Our study suggests that specific hepatic miRNA expression patterns as a checklist may be useful for differential diagnosis of acute jaundice following liver transplantation.

Liver Graft Pathology and Low Serum 25-Hydroxyvitamin D after Living Donor Liver Transplantation.

BACKGROUND: Most cases of advanced liver diseases are associated with low serum 25-hydroxyvitamin D and vitamin D deficiency. This phenomenon may occur in living donor liver transplantation (LDLT). AIMS: We conducted this study to explore the interplay between VDR and CYP2R1 in liver graft and compared our findings with the pathological interpretation of serum 25(OH)D concentration. METHODS: In total, 60 patients received liver graft biopsy after LDLT and were separated (1:1) into two groups: graft rejection group and graft non-rejection group. We extracted both of the recipients' and donors' serum DNA to investigate the vitamin D receptor (VDR) rs2228530 and CYP2R1 rs10741657 single nucleotide polymorphisms (SNPs) using real-time polymerase chain reaction. We also extracted DNA from liver graft tissues to explore the genetic alleles of VDR rs2228530 and CYP2R1 rs10741657 after LDLT. Serum biochemistry profile and 25(OH)D concentrations were measured before and after LDLT. RESULTS: There were no significant differences in serum VDR rs2228530 and CYP2R1 rs10741657 genetic alleles between recipients and donors. The percentage of genetic modification was 33.4% (10/30) for the rejection and non-rejection groups in VDR rs2228530, and 66.7% (20/30) for both groups in CYP2R1 rs10741657. Serum 25(OH)D concentrations were significantly lower after LDLT D30 than that before LDLT in the rejection (p = 0.0001) and non-rejection graft pathology (p = 0.0017) groups. CONCLUSIONS: The presence of low serum 25(OH)D concentrations after LDLT suggested that post-transplant low serum 25(OH)D concentrations may develop with the homogenous phenomenon of VDR rs2228530 and CYP2R1 rs10741657 genetic modifications in recipients regardless of graft pathology.

Characterization of Androgen Receptor Complex Associated Protein (ARCAP) in hepatocellular carcinoma and liver.

BACKGROUND: Hepatocellular carcinoma (HCC) ranks many tasks in clinical oncology due to possibly developing a general tumor in men and, usually lead to malignant to death within years. Researches had reported about major factors for being HCC was male sex and HCC associated with cirrhosis in childhood was found more common in males than females. In certain mouse strains as studied, breeding with testosterone significantly increases the development of HCC. Furthermore, castration of male mice diminished the frequency of the development of liver tumors. Meanwhile male hepatitis B virus transgenic mice have a greater occurrence of HCC than females. METHODS: We apply degenerate priming PCR to observe the expression of various steroid receptors in livers. Yeast-two hybrid screening to search a novel RNA fragment helps to find a new full-length gene by RACE experiment. RT-PCR is applied to detect various expressions in tissues and cell lines. In situ hybridization detects DNA in Chromosome mapping. GFP-constructs transfection proves the gene localization in cells. Immunoprecipitation pulldown assay verifies protein interaction. Gene transfection followed with luciferase assay demonstrates the interaction of genes within cellular signaling. Genomic alignment analysis for observing sequences data perform from NCBI database website (http://www.ncbi.nim.nih.gov/genebank/). RESULTS: The androgen receptor (AR) expression level is found at the highest level among the steroid receptors families detected in liver tumors. By yeast-two hybrid screening, we cloned an Androgen Receptor Complex Associated Protein (ARCAP), of 95 Kd in molecular weight and its cDNA. ARCAP locates at Chromosome 1. Our findings indicate ARCAP is highly expressed in hepatoma cell lines and liver tumors and their adjacent tumors as observed. Yeast two-hybrid assay and in vitro immunoprecipitation assays demonstrated an interaction between AR and ARCAP. CONCLUSION: We aim to search for different types and levels of steroid receptors expressed within human HCCs and in the adjacent liver tissues. To verify possible molecular mechanisms by which AR might affect hepatoma cells, we had characterized a novel protein ARCAP which functions as a coregulator to interact with AR within liver. The ligand-dependent AR with its cofactor, ARCAP, can induce a signal cascade by transactivation.

HCV RNA in serum and liver samples of patients undergoing living donor liver transplantation.

OBJECTIVE: To compare hepatitis C virus (HCV) RNA levels from serum and explanted native liver samples from patients undergoing living donor liver transplantation (LDLT). METHODS: This was a prospective observational study. Serum and liver samples were collected from consecutive serum anti-HCV-positive transplant recipients between February 2016 to August 2019. HCV RNA was extracted from liver samples and subjected to one-step reverse-transcription qPCR. using the TopScript One Step qRT-PCR Probe Kit with HCV qPCR probe assay and human GAPDH qPCR probe assay on a ViiA7 Real-Time PCR System. RESULTS: Among the 80 patients, 36% (29/80) were HCV RNA positive in serum and 85% (68/80) had positive hepatic HCV RNA. Post-liver transplantation, 4% (3/80) patients were serum positive. CONCLUSIONS: Our study suggests that pre-transplant serum HCV RNA levels may give an underestimate of the number of positive HCV RNA cases and that hepatic HCV RNA data may be more accurate.

The Perioperatively Altered Neutrophil-to-Lymphocyte Ratio Associates with Impaired DNA Damage Response in Liver Transplantation Recipients with Hepatocellular Carcinoma.

Increasing evidence has suggested that elevated systemic inflammation with a high neutrophil-lymphocyte ratio (NLR) is associated with poor prognosis after liver transplantation (LT). The ongoing molecular events involved in poor survival remain unclear. This retrospective study evaluated LT recipients whose data was collected at Kaohsiung Chang Gung Memorial Hospital between 2005 and 2014. Clinical records of 347 patients with hepatocellular carcinoma from seven days before LT to 30 days after LT illustrated that longitudinal values of lymphocytes, RBC, and hemoglobin were persistently low in patients with peritransplant high NLR (PTH-NLR, pre-LT ≥ 4 and post-LT ≥ 5), which indicated a significantly worse survival rate in association with increased RDW-CV and pancytopenia when compared to other patients (p = 0.008). We further found that PTH-NLR patients had decreased DNA damage response (DDR) genes and detoxifying enzymes of ADH and ALDH families, and increased mitochondrial stress response genes in their liver tissues. Reduced lineage markers of liver progenitor cells were also observed in PTH-NLR patients signifying the presence of unresolved impairments after LT. Our results demonstrate the association between hematopoietic deficiencies and lack of protection against DDR with PTH-NLR in LDLT recipients with HCC and may imply abnormal hematological and organismal defects in those patients.

Emerging Roles of Calcium Signaling in the Development of Non-Alcoholic Fatty Liver Disease.

The liver plays a central role in energy metabolism. Dysregulated hepatic lipid metabolism is a major cause of non-alcoholic fatty liver disease (NAFLD), a chronic liver disorder closely linked to obesity and insulin resistance. NAFLD is rapidly emerging as a global health problem with currently no approved therapy. While early stages of NAFLD are often considered benign, the disease can progress to an advanced stage that involves chronic inflammation, with increased risk for developing end-stage disease including fibrosis and liver cancer. Hence, there is an urgent need to identify potential pharmacological targets. Ca2+ is an essential signaling molecule involved in a myriad of cellular processes. Intracellular Ca2+ is intricately compartmentalized, and the Ca2+ flow is tightly controlled by a network of Ca2+ transport and buffering proteins. Impaired Ca2+ signaling is strongly associated with endoplasmic reticulum stress, mitochondrial dysfunction and autophagic defects, all of which are etiological factors of NAFLD. In this review, we describe the recent advances that underscore the critical role of dysregulated Ca2+ homeostasis in lipid metabolic abnormalities and discuss the feasibility of targeting Ca2+ signaling as a potential therapeutic approach.

MicroRNA-301a inhibition enhances the immunomodulatory functions of adipose-derived mesenchymal stem cells by induction of macrophage M2 polarization.

MicroRNAs (miRNAs) are a class of short non-coding RNAs that play a significant role in biological processes in various cell types, including mesenchymal stem cells (MSCs). However, how miRNAs regulate the immunomodulatory functions of adipose-derived MSCs (AD-MSCs) remains unknown. Here, we showed that modulation of miR-301a in AD-MSCs altered macrophage polarization. Bone marrow (BM)-derived macrophages were stimulated with LPS (1 µg/ml) and co-cultured with miRNA transfected AD-MSCs for 24 h. The expression of M1 and M2 markers in macrophages was analyzed. Inhibition of miR-301a induced M2 macrophage with arginase-1, CD163, CD206, and IL-10 upregulation. Additionally, toll-like receptor (TLR)-4 mRNA expression in macrophages was downregulated in co-cultures with AD-MSCs transfected with a miR-301a inhibitor. Nitric oxide (NO) in the supernatant of AD-MSC/macrophage co-culture was also suppressed by inhibition of miR-301a in AD-MSCs. We further found that suppression of miR-301a in AD-MSCs increased prostaglandin E2 (PGE2) concentration in the conditioned medium of the co-culture. Taken together, the results of our study indicate that miR-301a can modulate the immunoregulatory functions of AD-MSCs that favor the applicability as a potential immunotherapeutic agent.

Decreased PEDF Promotes Hepatic Fatty Acid Uptake and Lipid Droplet Formation in the Pathogenesis of NAFLD.

Non-alcoholic fatty liver disease (NAFLD), the leading cause of chronic liver diseases worldwide, ranges from simple steatosis to steatohepatitis, with the risk for progressive fibrosis or even cirrhosis. While simple steatosis is a relatively benign condition, the buildup of toxic lipid metabolites can induce chronic inflammation, ultimately triggering disease progression. Pigment epithelium-derived factor (PEDF) is a secreted, multifunctional glycoprotein with lipid metabolic activities. PEDF promotes lipolysis through binding to adipose triglyceride lipase (ATGL), a key enzyme for triglyceride breakdown. In the current study, we aimed to delineate how changes in PEDF expression affect hepatic lipid accumulation. Our data revealed that hepatic PEDF was downregulated in a mouse NAFLD model. We further showed that decreased PEDF levels in hepatocytes in vitro resulted in elevated fatty acid uptake and lipid droplet formation, with concomitant upregulation of fatty acid transport proteins CD36 and fatty acid binding protein 1 (FABP1). RNA sequencing analysis of PEDF knocked down hepatocytes revealed an alteration in gene expression profile toward lipid accumulation. Additionally, decreased PEDF promotes mobilization of fatty acids, an observation distinct from blocking ATGL activity. Taken together, our data suggest that hepatic PEDF downregulation causes molecular changes that favor triglyceride accumulation, which may further lead to NAFLD progression.

What Is Hot and New in Basic and Translational Science in Liver Transplantation in 2019? Report of the Basic and Translational Research Committee of the International Liver Transplantation Society.

The International Liver Transplantation Society (ILTS) 2019 Annual Congress was held in Toronto, Canada, in May 2019. Members of the ILTS Basic and Translational Research Committee attended all sessions of the meeting and selected the most promising, innovative, and novel research presented. A total of 900 abstracts were presented at the meeting. The percentage of abstracts presented at the ILTS Congress that contains basic or translational research continues to increase, accounting for 15% of all the abstracts in 2019, up from 10% in 2018. Here, we summarize the "what's hot what's new" in 5 main themes: liver immunobiology and tolerance, ischemia/reperfusion injury and organ preservation, bioengineering and liver regeneration, hepatic primary tumor biology, and pathophysiology of liver failure.

Circulating exosomal miR-92b: Its role for cancer immunoediting and clinical value for prediction of posttransplant hepatocellular carcinoma recurrence.

A recurrence of hepatocellular carcinoma (HCC) after living donor liver transplantation (LDLT) is one of the major concerns reflecting the higher mortality of HCC. This study aimed to explore the impact of circulating exosomes on HCC development and recurrence. One-shot transfusion of hepatoma serum to naïve rats induced liver cancer development with gradual elevation of alpha-fetoprotein (AFP), but exosome-free hepatoma serum failed to induce AFP elevation. The microarray analysis revealed miR-92b as one of the highly expressing microribonucleic acids in hepatoma serum exosomes. Overexpression of miR-92b enhanced the migration ability of liver cancer cell lines with active release of exosomal miR-92b. The hepatoma-derived exosomal miR-92b transferred to natural killer (NK) cells, resulting in the downregulation of CD69 and NK cell-mediated cytotoxicity. Furthermore, higher expression of miR-92b in serum exosomes was confirmed in HCC patients before LDLT, and its value at 1 month after LDLT was maintained at a higher level in the patients with posttransplant HCC recurrence. In summary, we demonstrated the impact of circulating exosomes on liver cancer development, partly through the suppression of CD69 on NK cells by hepatoma-derived exosomal miR-92b. The value of circulating exosomal miR-92b may predict the risk of posttransplant HCC recurrence.

Coagulation factor VII gene polymorphisms are not associated with the occurrence or the survival of hepatocellular carcinoma: a report of 37 cases.

OBJECTIVE: : Coagulation factor VII (FVII) triggers the extrinsic pathway of blood coagulation. In our previous study, we showed that FVII plays an important role in tumorigenesis of hepatocellular carcinoma (HCC). However, the role of FVII polymorphism in HCC is still unknown. The present study aimed to investigate the relationship between HCC carcinogenesis and single nucleotide polymorphism of FVII. METHODS: : Thirty-seven HCC patients and 30 healthy donors were recruited in this study. Four common FVII gene polymorphisms - a decanucleotide insertion at position -323 (-323ins10-bp), a G to T substitution at position -401 (-401G/T), a G to A substitution at position -402 (-402G/A), and a T to C substitution at position -122 (-122T/C) - were analyzed by sequencing or commercialized assays using genomic DNA isolated from blood samples. Clinicopathological parameters between control and HCC subjects were compared according to the specific genotypes. RESULTS: : The most common nucleotide variation was -402G/A. However, no statistically significant difference was observed between healthy controls and HCC subjects for all four polymorphisms in terms of genotype distribution and allele frequencies, indicating that these polymorphisms may not affect HCC tumorigenesis. Furthermore, no association was found between -402G/A polymorphisms and tumor stage, recurrence, and overall survival. CONCLUSIONS: : Our results indicate that FVII polymorphisms may not be a key factor that clinically impact tumorigenesis and outcomes of HCC, although further investigations should be conducted to confirm our findings.

Tumor microenvironment mediated by suppression of autophagic flux drives liver malignancy.

The physiological role of autophagy in the catabolic process of the body involves protein synthesis and degradation in homeostasis under normal and stressed conditions. In hepatocellular carcinoma (HCC), the role of tumor microenvironment (TME) has been concerned as the main issue in fighting against this deadly malignancy. During the last decade, the crosstalk between tumor cells and their TME in HCC extensively accumulated. However, a deeper knowledge for the actual function of autophagy in this interconnection which involved in supporting tumor development, progression and chemoresistance in HCC is needed but still largely unknown. Recent studies have shown that coagulants tissue factor (TF) and factor VII (FVII) has a pathological role in promoting tumor growth by activating protease-activated receptor 2 (PAR2). Autophagy-associated LC3A/B-II formation was selectively suppressed by FVII/PAR2 signaling which mediated by mTOR activation through Atg7 but not Atg5/Atg12 axis. The coagulant-derived autophagic suppression seemed potentiate a vicious circle of malignancy in producing more FVII and PAR2 which facilitate in vivo and in vitro tumor progression of HCC and the investigations are consistent with the clinical observations. In this review, we briefly summarize the current understanding of autophagy and discuss recent evidence for its role in HCC malignancy.

Factor VII-Induced MicroRNA-135a Inhibits Autophagy and Is Associated with Poor Prognosis in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common and aggressive malignancies worldwide. Treatment outcomes remain poor mainly due to lack of good diagnostic/prognostic markers and limited therapeutic strategies. We previously characterized aberrant activation of the TF/FVII/PAR2 pathway, which subsequently results in decreased autophagy, as a crucial event in malignant progression of HCC. Here, we identified miR-135a as a highly upregulated miRNA in HCC in response to TF/FVII/PAR2 activation. Analyzing 103 HCC patient specimens, we confirmed that miR-135a was frequently elevated in HCC tissues with higher FVII expression compared to adjacent non-cancerous counterparts. Increased miR-135a levels in HCC were also associated with tumor staging, recurrence, microvascular invasion, and decreased disease-free survival. We subsequently identified Atg14, a key component that regulates the formation of autophagosome as a direct target of miR-135a. Ectopic expression of miR-135a suppressed Atg14 levels and inhibited the autophagic processes. Our results indicate strong positive correlations between miR-135a levels and malignant behaviors in HCC patients and also suggest novel functions of miR-135a in regulation of autophagy, which could be useful as a potential target for prognostic and therapeutic uses.

Hormonal and Growth Regulation of Epithelial and Stromal Cells From the Normal and Malignant Endometrium by Pigment Epithelium-Derived Factor.

We discovered that pigment epithelium-derived factor (PEDF)-null mice have endometrial hyperplasia, the precursor to human type I endometrial cancer (ECA), which is etiologically linked to unopposed estrogen (E2), suggesting that this potent antiangiogenic factor might contribute to dysregulated growth and the development of type I ECA. Treatment of both ECA cell lines and primary ECA cells with recombinant PEDF dose dependently decreased cellular proliferation via an autocrine mechanism by blocking cells in G1 and G2 phases of the cell cycle. Consistent with the known opposing effects of E2 and progesterone (Pg) on endometrial proliferation, Pg increases PEDF protein synthesis and release, whereas E2 has the converse effect. Using PEDF luciferase promoter constructs containing two Pg and one E2 response elements, E2 reduced and Pg increased promoter activity due to distal response elements. Furthermore, E2 decreases and Pg increases PEDF secretion into conditioned media (CM) by both normal endometrial stromal fibroblasts (ESFs) and cancer-associated fibroblasts (CAFs), but only CM from ESFs mediated growth-inhibitory activity of primary endometrial epithelial cells (EECs). In addition, in cocultures with primary EECs, Pg-induced growth inhibition is mediated by ESFs, but not CAFs. This is consistent with reduced levels of Pg receptors on CAFs surrounding human malignant glands in vivo. Taken together, the data suggest that PEDF is a hormone-regulated negative autocrine mediator of endometrial proliferation, and that paracrine growth inhibition by soluble factors, possibly PEDF, released by ESFs in response to Pg, but not CAFs, exemplifies a tumor microenvironment that contributes to the pathogenesis of ECA.

Overexpression of Insig-2 inhibits atypical antipsychotic-induced adipogenic differentiation and lipid biosynthesis in adipose-derived stem cells.

Atypical antipsychotics (AAPs) are considered to possess superior efficacy for treating both the positive and negative symptoms of schizophrenia; however, AAP use often causes excessive weight gain and metabolic abnormalities. Recently, several reports have demonstrated that AAPs activate sterol regulatory element-binding protein (SREBP). SREBP, SREBP cleavage-activating protein (SCAP) and insulin-induced gene (Insig) regulate downstream cholesterol and fatty acid biosynthesis. In this study, we explored the effects of clozapine, olanzapine and risperidone on SREBP signaling and downstream lipid biosynthesis genes in the early events of adipogenic differentiation in adipose-derived stem cells (ASCs). After the induction of adipogenic differentiation for 2 days, all AAPs, notably clozapine treatment for 3 and 7 days, enhanced the expression of SREBP-1 and its downstream lipid biosynthesis genes without dexamethasone and insulin supplementation. Simultaneously, protein level of SREBP-1 was significantly enhanced via inhibition of Insig-2 expression. By contrast, SREBP-1 activation was suppressed when Insig-2 expression was upregulated by transfection with Insig-2 plasmid DNA. In summary, our results indicate that AAP treatment, notably clozapine treatment, induces early-stage lipid biosynthesis in ASCs. Such abnormal lipogenesis can be reversed when Insig-2 expression was increased, suggesting that Insig/SCAP/SREBP signaling may be a therapeutic target for AAP-induced weight gain and metabolic abnormalities.

Blockade of estrogen-stimulated proliferation by a constitutively-active prolactin receptor having lower expression in invasive ductal carcinoma.

A comprehensive understanding of prolactin's (PRL's) role in breast cancer is complicated by disparate roles for alternatively-spliced PRL receptors (PRLR) and crosstalk between PRL and estrogen signaling. Among PRLRs, the short form 1b (SF1b) inhibits PRL-stimulated cell proliferation. In addition to ligand-dependent PRLRs, constitutively-active varieties, missing the S2 region of the extracellular domain (ΔS2), naturally occur. Expression analysis of the ΔS2 version of SF1b (ΔS2SF1b) showed higher expression in histologically-normal contiguous tissue versus invasive ductal carcinoma. To determine the function of ΔS2SF1b, a T47D breast cancer line with inducible expression was produced. Induction of ΔS2SF1b blocked estrogen-stimulated cell proliferation. Unlike intact SF1b, induction of ΔS2SF1b had no effect on PRL-mediated activation of Stat5a. However induction inhibited estrogen's stimulatory effects on serine-118 phosphorylation of estrogen receptor α, serine-473 phosphorylation of Akt, serine-9 phosphorylation of GSK3ß, and c-myc expression. In addition, induction of ΔS2SF1b increased expression of the cell cycle-inhibiting protein, p21. Thus, increased expression of ΔS2SF1b, such as we demonstrate occurs with the selective PRLR modulator, S179D PRL, would create a physiological state in which estrogen-stimulated proliferation was inhibited, but differentiative responses to PRL were maintained.

Inhibitors of SCF-Skp2/Cks1 E3 ligase block estrogen-induced growth stimulation and degradation of nuclear p27kip1: therapeutic potential for endometrial cancer.

In many human cancers, the tumor suppressor, p27(kip1) (p27), a cyclin-dependent kinase inhibitor critical to cell cycle arrest, undergoes perpetual ubiquitin-mediated proteasomal degradation by the E3 ligase complex SCF-Skp2/Cks1 and/or cytoplasmic mislocalization. Lack of nuclear p27 causes aberrant cell cycle progression, and cytoplasmic p27 mediates cell migration/metastasis. We previously showed that mitogenic 17-ß-estradiol (E2) induces degradation of p27 by the E3 ligase Skp1-Cullin1-F-Box- S phase kinase-associated protein2/cyclin dependent kinase regulatory subunit 1 in primary endometrial epithelial cells and endometrial carcinoma (ECA) cell lines, suggesting a pathogenic mechanism for type I ECA, an E2-induced cancer. The current studies show that treatment of endometrial carcinoma cells-1 (ECC-1) with small molecule inhibitors of Skp2/Cks1 E3 ligase activity (Skp2E3LIs) stabilizes p27 in the nucleus, decreases p27 in the cytoplasm, and prevents E2-induced proliferation and degradation of p27 in endometrial carcinoma cells-1 and primary ECA cells. Furthermore, Skp2E3LIs increase p27 half-life by 6 hours, inhibit cell proliferation (IC50, 14.3µM), block retinoblastoma protein (pRB) phosphorylation, induce G1 phase block, and are not cytotoxic. Similarly, using super resolution fluorescence localization microscopy and quantification, Skp2E3LIs increase p27 protein in the nucleus by 1.8-fold. In vivo, injection of Skp2E3LIs significantly increases nuclear p27 and reduces proliferation of endometrial epithelial cells by 42%-62% in ovariectomized E2-primed mice. Skp2E3LIs are specific inhibitors of proteolytic degradation that pharmacologically target the binding interaction between the E3 ligase, SCF-Skp2/Cks1, and p27 to stabilize nuclear p27 and prevent cell cycle progression. These targeted inhibitors have the potential to be an important therapeutic advance over general proteasome inhibitors for cancers characterized by SCF-Skp2/Cks1-mediated destruction of nuclear p27.

Estrogen and progesterone regulate p27kip1 levels via the ubiquitin-proteasome system: pathogenic and therapeutic implications for endometrial cancer.

The levels of proteins that control the cell cycle are regulated by ubiquitin-mediated degradation via the ubiquitin-proteasome system (UPS) by substrate-specific E3 ubiquitin ligases. The cyclin-dependent kinase inhibitor, p27kip1 (p27), that blocks the cell cycle in G1, is ubiquitylated by the E3 ligase SCF-Skp2/Cks1 for degradation by the UPS. In turn, Skp2 and Cks1 are ubiquitylated by the E3 ligase complex APC/Cdh1 for destruction thereby maintaining abundant levels of nuclear p27. We previously showed that perpetual proteasomal degradation of p27 is an early event in Type I endometrial carcinogenesis (ECA), an estrogen (E2)-induced cancer. The present studies demonstrate that E2 stimulates growth of ECA cell lines and normal primary endometrial epithelial cells (EECs) and induces MAPK-ERK1/2-dependent phosphorylation of p27 on Thr187, a prerequisite for p27 ubiquitylation by nuclear SCF-Skp2/Cks1 and subsequent degradation. In addition, E2 decreases the E3 ligase [APC]Cdh1 leaving Skp2 and Cks1 intact to cause p27 degradation. Furthermore, knocking-down Skp2 prevents E2-induced p27 degradation and growth stimulation suggesting that the pathogenesis of E2-induced ECA is dependent on Skp2-mediated degradation of p27. Conversely, progesterone (Pg) as an inhibitor of endometrial proliferation increases nuclear p27 and Cdh1 in primary EECs and ECA cells. Pg, also increases Cdh1 binding to APC to form the active E3ligase. Knocking-down Cdh1 obviates Pg-induced stabilization of p27 and growth inhibition. Notably, neither E2 nor Pg affected transcription of Cdh1, Skp2, Cks1 nor p27. These studies provide new insights into hormone regulation of cell proliferation through the UPS. The data implicates that preventing nuclear p27 degradation by blocking Skp2/Cks1-mediated degradation of p27 or increasing Cdh1 to mediate degradation of Skp2-Cks1 are potential strategies for the prevention and treatment of ECA.

Long term increased expression of the short form 1b prolactin receptor in PC-3 human prostate cancer cells decreases cell growth and migration, and causes multiple changes in gene expression consistent with reduced invasive capacity.

BACKGROUND: We have shown that treatment of human prostate cancer cells with the selective prolactin (PRL) receptor modulator, S179D PRL, inhibits growth in vitro, and the initiation and growth of xenografts in vivo. S179D PRL treatment also upregulates expression of the short form 1b (SF1b) PRL receptor, activation of which upregulates expression of the cell cycle-regulating protein, p21. METHODS: We examined the consequences of long term increased expression and activation of SF1b, at levels comparable to those resulting from treatment with S179D PRL, by creating PC-3-derived stable cell lines expressing a constitutively active form of SF1b, DeltaS2 SF1b. RESULTS: Increased expression of DeltaS2 SF1b decreased growth and migration of the cells. This was accompanied by an increase in cell-matrix interactions, and cell-cell aggregation when cells were plated on basement membrane components. Real-time PCR evaluated the expression of genes related to invasive capacity. Of particular interest was decreased expression of the protease, urokinase-type plaminogen activator, and its receptor, uPAR, and increased expression of its inhibitors, PAI-1 and 2. Also decreased in cells with increased expression of DeltaS2 SF1b was expression of basic fibroblast growth factor and vascular endothelial growth factor. CONCLUSION: We conclude that at least part of the beneficial effects of S179D PRL is the result of increased expression of SF1b, and that the effects of increased expression and activation of SF1b continue to be of potential benefit in the long term.