[Legal regulation of clinical application of artificial intelligence].

With the wide application of artificial intelligence (AI) technology in clinical practice, more and more legal problems need to be solved. At present, although the legal status of AI is still controversial in academic and practical circles, its infringement risk in clinical diagnosis and surgery cannot be avoided. On the basis of the distinction between strong and weak AI liability subjects, those who meet the requirements of infringement, damage consequence, causal relationship, subjective fault, etc., can constitute tort liability, but the existence of exemption causes can also exempt liability. In addition to the ex post accountability of tort liability, it is also necessary to establish a complete administrative legal regulation system. At present, China needs to explore and establish the classification registration system, compulsory insurance system and reserve system of AI as soon as possible, so as to strengthen the legal regulation of the whole process of AI clinical application before, during and after the event.

Long non-coding RNA OR3A4 facilitates cell proliferation and migration in colorectal cancer through the Wnt/ß-catenin signaling pathway.

Since this article has been suspected of research misconduct and the corresponding authors did not respond to our request to prove originality of data and figures, "Long non-coding RNA OR3A4 facilitates cell proliferation and migration in colorectal cancer through the Wnt/ß-catenin signaling pathway, by W. Sun, G.-R. Chen, J. Wang, X.-Y. Yu, X.-F. Hao, M.-Y. Hu, published in Eur Rev Med Pharmacol Sci 2020; 24 (10): 5360-5366-DOI: 10.26355/eurrev_202005_21319-PMID: 32495870" has been withdrawn. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/21319.

[The proatherogenic effect of high salt diet combined with focal hypoperfusion on spontaneous hypertension rat].

Objective: To explore the histopathology, monocytes phenotypes and brain mRNA transcription of angiogenic and atherogenic factors preliminarily in spontaneous hypertensive rats (SHRs) fed with high salt diet and subjected to chronic focal hypoperfusion. Methods: A total of 21 SHRs were randomly assigned into SHR with normal diet (SHR-ND group, n=7), SHR fed with high salt (8%) chows (SHR-HSD group, n=14) groups. After induction of high salt diet for 20 weeks, unilateral carotid artery occlusion was applied to one half of SHR-HSD (SHR-HSD-UCAO, n=7) group for 10 weeks to mimic chronic focal cerebral hypoperfusion. The neuropathology, monocytes phenotypes and brain transcription of fibroblast growth factor (FGF-b), platelet-derived endothelial cell growth factor (PD-ECGF), angiogenin (ANG), transforming growth factor-ß (TGF-ß) and vascular endothelial growth factor A (VEGF-A) among three groups were compared. Results: The systolic blood pressure ((246±12) mmHg vs (220±16) mmHg, P=0.0291, 1 mmHg=0.133 kPa) and diastolic blood pressure ((189±15) mmHg vs (164±12) mmHg, P=0.0143) of SHR-HSD group were elevated significantly compared with those of SHR-ND group. Compared with normotensive Wistar-Kyoto (WKY), SHR-ND, SHR-HSD and SHR-HSD-UCAO groups demonstrated lipohyalinosis, vessel wall thickening, lumen narrowing and multiple enlarged perivascular space and diffuse disarrangement of nerve fiber and myelin vacuolation in corpus callosum pathologically. The ratio of CD11b(+) CD68(+) monocytes in peripheral blood of SHR-HSD group was higher compared with both SHR-ND and SHR-HSD-UCAO groups (P=0.000 8). The mean inflorescence index (MFI) of CD86 and CD206 showd considerable decline in SHR-HSD-UCAO group compared with those of SHR-HSD group (P=0.018 7 and 0.016 8, respectively). The CD86 MFI of CD11b+CD68+ monocytes in SHR-HSD-UCAO group was remarkably higher than that of SHR-ND and SHR-HSD groups (P=0.000 5). Compared with SHR-ND and SHR-HSD groups, the brain mRNA transcription of angiogenic factors including PD-ECGF and ANG were down-regulated (P=0.004 6 and 0.000 2, respectively), while the atherogenic factors including TGF-ß and VEGF-A were up-regulated in SHR-HSD-UCAO group (P<0.000 1 and P=0.045, respectively). Conclusion: SHR-HSD-UCAO group shares the pathophysiological characteristics with advanced stage arteriosclerotic cerebral small vessel disease (aCSVD), including neuropathology, imbalanced circulating monocytes phenotypes and down-regulated angiogenic factors.

The association of psoriasis and hypertension: focusing on anti-inflammatory therapies and immunological mechanisms.

Psoriasis is a chronic skin disease characterized by recurrent inflammation, and is increasingly being recognized as a systemic inflammatory disorder, which is associated with cardiovascular events, metabolic syndrome, diabetes, obesity and hypertension. Recent findings have suggested a greater risk of hypertension, particularly difficult-to-control hypertension, in patients with severe psoriasis. Additionally, abnormal activation of immune cells with overexpression of pathogenic cytokines in psoriasis, leading to immune cascade, oxidative injury and collagen deposition in arteries, may further contribute to vascular stiffening and hypertension. However, studies have demonstrated beneficial effects of antipsoriatic drugs on blood pressure and the cardiovascular system, including immunosuppressants and biological reagents targeting tumour necrosis factor-α, interleukin (IL)-17A and the IL-12/23 p40 subunit. This review summarizes the mechanisms underlying the impact of systemic inflammation on skin and arteries, and assesses the epidemiological and clinical links between psoriasis and hypertension.

Long non-coding RNA OR3A4 facilitates cell proliferation and migration in colorectal cancer through the Wnt/ß-catenin signaling pathway.

OBJECTIVE: Colorectal cancer (CRC) remains one of the most ordinary cancers worldwide. Recently, researches have suggested the important role of long noncoding RNAs (lncRNAs) in the progression of tumorigenesis. This study aims to identify how lncRNA OR3A4 functions in the development of CRC. PATIENTS AND METHODS: OR3A4 expressions in 54 paired CRC tissues and CRC cell lines were detected by Real Time-quantitative Polymerase Chain Reaction (RT-qPCR). Moreover, the in vitro functions of OR3A4 in CRC cells were identified by performing proliferation assay, wound healing assay, and transwell assay. Besides, the underlying mechanism of OR3A4 in CRC development was explored through Western blot and RT-qPCR. RESULTS: OR3A4 expression was significantly higher in CRC tissues than adjacent normal ones. Cell proliferation, migration, and CRC were inhibited after OR3A4 was knocked down in vitro, which were promoted after upregulation of OR3A4. Moreover, OR3A4 could activate the Wnt/ß-catenin pathway, thus influencing phenotypes of CRC cells. CONCLUSIONS: OR3A4 enhances CRC cell proliferation and migration by activating the Wnt/ß-catenin signaling pathway.

Effect of abaloparatide on vertebral, nonvertebral, major osteoporotic, and clinical fractures in a subset of postmenopausal women at increased risk of fracture by FRAX probability.

We evaluated the efficacy of abaloparatide in women who were at increased risk for fracture, based on CHMP recommended risk thresholds, at the Abaloparatide Comparator Trial In Vertebral Endpoints (ACTIVE) study baseline. Among patients at high risk based on FRAX probabilities, 18 months of abaloparatide significantly decreased risk for all fracture endpoints compared with placebo. PURPOSE: Abaloparatide, a novel anabolic agent for the treatment of postmenopausal osteoporosis, significantly reduced the risk of vertebral and nonvertebral fractures in the ACTIVE study compared with placebo. In this post hoc analysis, we evaluated abaloparatide's efficacy in a subset of women in the study at an increased risk of fracture at baseline, based on the Committee for Medicinal Products for Human Use (CHMP) recommended risk thresholds for inclusion in clinical trials. METHODS: Women with a baseline 10-year risk of major osteoporotic fracture ≥ 10% or hip fracture ≥ 5%, assessed using the FRAX® tool (including femoral neck bone mineral density), were included in the analysis. The proportion with one or more events of new morphometric vertebral fractures was calculated. Event rates for nonvertebral, major osteoporotic, and all clinical fractures were estimated using Kaplan-Meier analysis. RESULTS: Following 18 months of treatment, abaloparatide significantly reduced incident vertebral fractures compared with placebo (relative risk reduction = 91%; 0.5% versus 5.6%; p < 0.001). Abaloparatide treatment was also associated with significantly fewer nonvertebral, major osteoporotic, and clinical fractures compared with placebo: 2.7% versus 5.8%, p = 0.036; 1.3% versus 6.0%, p < 0.001; and 3.5% versus 8.2%, p = 0.006, respectively. The effect of abaloparatide on major osteoporotic fractures (78% reduction) was significantly greater than that seen with teriparatide (23% reduction, p = 0.007). CONCLUSION: In a subset of postmenopausal women at increased risk of fracture as judged by CHMP guidance, abaloparatide significantly decreased the risk of all fracture endpoints compared with placebo.

Bone mineral density response rates are greater in patients treated with abaloparatide compared with those treated with placebo or teriparatide: Results from the ACTIVE phase 3 trial.

BACKGROUND: Abaloparatide is a 34-amino acid peptide that selectively binds to the RG conformation of the parathyroid hormone receptor type 1. It was developed for the treatment of women with postmenopausal osteoporosis at high risk of fracture. In ACTIVE, an 18-month phase 3 study (NCT01343004), abaloparatide increased bone mineral density (BMD), decreased the risk of vertebral and nonvertebral fractures compared with placebo, and decreased the risk of major osteoporotic fractures compared with placebo and teriparatide. Here, we report a prospective, exploratory BMD responder analysis from ACTIVE. METHODS: Proportions of patients experiencing BMD gains from baseline of >0%, >3%, and >6% at the total hip, femoral neck, and lumbar spine at 6, 12, and 18 months of treatment were compared among the placebo, abaloparatide, and teriparatide groups in ACTIVE. Responders were defined prospectively as patients experiencing BMD gains at all 3 anatomic sites. RESULTS: At months 6, 12, and 18, there were significantly more >3% BMD responders in the abaloparatide group compared with placebo and teriparatide: month 6, 19.1% vs 0.9% for placebo and 6.5% for teriparatide; month 12, 33.2% vs 1.5% and 19.8%; month 18, 44.5% vs 1.9% and 32.0% (P < 0.001 for all comparisons of abaloparatide to placebo and to teriparatide). Findings were similar for the >0% and >6% responder thresholds. CONCLUSIONS: In postmenopausal women with osteoporosis, a significantly greater proportion of patients treated with abaloparatide experienced increases in BMD than did those treated with placebo or teriparatide.

[Clinical and pathological features and mutational types of WT1 mutation-associated nephropathy].

Objective: To explore the clinical and pathological features and mutational types and their relations with WT1 mutation-associated nephropathy (WT1MAN). Methods: The clinical and pathological data and the results of WT1 mutation analysis of the cases from Nanfang Hospital of Southern Medical University, Sun Yat-sen Memorial Hospital and The First Affiliated Hospital of Sun Yat-sen University whom we recruited recently and reported during the last ten years were analyzed. Results: Totally, 20 cases (6 males and 14 females), included 5 newly diagnosed cases, were recruited. (1) Ten children were diagnosed with Denys-Drash syndrome (DDS): The median onset age of proteinuria was 1 year and 7 months. Diffuse mesangial sclerosis (DMS) were revealed in 3 cases, minimal lesions (MCD) in 4 cases, and focal segmental glomerulosclerosis (FSGS) in 1 case; renal pathology was not available in the other 2 cases. Glomerular basement membrane (GBM) thickening was observed in 2 cases. Calcineurin inhibitors (CNIs) were administered in 5 cases, complete remission of proteinuria was observed in 3 cases, partial remission in the other 2 cases. Genetic analysis revealed that six cases had WT1 missense mutation, 3 had nonsense mutation, and 1 had frameshift mutation. (2) Two cases were diagnosed with Frasier syndrome (FS): proteinuria was observed at 1 year and 1 month of age and 1 year and 9 months of age, respectively. FSGS with GBM layering were observed in both cases. They progressed to ESRD at 1 year and 6 months of age and 6 years and 6 months of age, respectively. CNI was tried in 1 case with partial proteinuria remission. Both patients were detected to have WT1 splice mutation. (3) Isolated nephropathy (IN) was observed in 8 cases: three had splice mutation, 5 had missense mutation. Of the 3 patients with splice mutation, one was found to have nephropathy and renal failure at the age of 5 months. The other two cases (1 was FSGS and another MCD), both had GBM layering. CNIs were tried on both of them, one got partial remission with normal renal function at the age of fourteen years, the other one had no response and entered ESRD at the age of 6 years and 9 months. Of the 5 cases with missense mutation, 3 had DMS, 2 of them entered ESRD within 6 months of age, another case had DMS entered ESRD at 9 years of age. One case with FSGS, was treated with CNIs and got complete remission. Conclusions: Slow progression (7/10) nephropathy was observed in DDS patients. Missense mutation (11/20) was the most common type of WT1 variants, followed by splice mutation (5/20) in this group of patients. Early onset nephropathy (4/5), rapid progression (4/5) and GBM layering (4/4) wereobserved in patients with splice mutation. CNI was effective in reducing or even eliminating proteinuria in WT1 MAN patients (8/9).

KrasG12D-LOH promotes malignant biological behavior and energy metabolism of pancreatic ductal adenocarcinoma cells through the mTOR signaling pathway.

Oncogenic Kras with loss of heterozygosity (LOH) is frequently detected in various tumours. However, the exact function and mechanism by which KrasG12D-LOH operates remain unclear. Therefore, the current study investigated the effect of KrasG12D-LOH on the malignant phenotype of pancreatic ductal adenocarcinoma (PDAC) cells. Our investigation revealed that KrasG12D-LOH is associated with increased proliferation, invasion and reduced apoptosis in PDAC cells. The results also exhibited enhanced glycolytic phenotype of KrasG12D-LOH PDAC cells. Hyperactive mTOR plays a significant role in the initiation and maintenance of tumors. To investigate the correlation between KrasG12D-LOH and mTOR, the mTOR signaling pathway was detected by western blot analysis. We found that KrasG12D-LOH up-regulated Akt, AMPK, REDD1 and mTOR in PDAC cells. In summary, our results demonstrated that KrasG12D-LOH promotes oncogenic Kras-induced PDAC by regulating energy metabolism and mTOR signaling pathway. These data may provide novel therapeutic perspectives for PDAC.

Vibrational dynamics (IR, Raman, NRVS) and a DFT study of a new antitumor tetranuclearstannoxane cluster, Sn(iv)-oxo-{di-o-vanillin} dimethyl dichloride.

The vibrational dynamics of a newly synthesized tetrastannoxane was characterized with a combination of experimental (Raman, IR and tin-based nuclear resonance vibrational spectroscopy) and computational (DFT/B3LYP) methods, with an emphasis on the vibrations of the tin sites. The cytotoxic activity revealed a significant regression selectively against the human pancreatic cell lines.

Importance of CD44 on umbilical cord mesenchymal stem cells for expansion of hematopoietic cells.

Human umbilical cord mesenchymal stem cells (hUCMSCs) have important functions on the expansion of hematopoietic stem cells (HSCs) through providing the essential microenvironment for hematopoiesis. In order to test whether CD44 on hUCMSCs could have a key function for the ability of hUCMSCs to expand human HSCs, the soluble anti—CD44 antibody was added to the co—cultures of hUCMSCs and cord blood (CB) CD34+ cells, which blocked the ability of hUCMSCs to expand CB CD34+ cells significantly. Long—term culture initiating cell (LTC—IC) assay revealed that the ability of multipotent differentiation of CB CD34+ cells co—cultured with CD44 knockdown hUCMSCs could only retain lasting at most for 5 weeks in vitro. In vivo assay, based on non—obese diabetic/severe combined immunodeficient disease (NOD/SCID) mice, revealed that the hematopoietic reconstitution potential of CB CD34+ cells co—cultured with CD44 knockdown hUCMSCs is significantly reduced. The hematopoietic supporting ability of hUCMSCs in vivo and in vitro is reduced upon the knockdown of CD44. CD44 has important functions on the ability of hUCMSCs to expand human HSCs in the cell— extrinsic control.

Cloning and functional identification of a novel BCA3 splice.

The human breast cancer-associated gene (BCA3) was first discovered in breast and prostate cancer cells lines. In vivo studies have shown that BCA3 is mainly expressed in breast tumor cells and not in normal breast and prostate tissues. To date, 3 splice variants of BCA3 have been reported: a double-absent variant lacking exon 3 and exon 5 (BCA3-1), an exon 3-absent variant (BCA3-2), and full-length BCA3. In this study, we investigated whether a novel BCA3 splice variant exists that lacks only the exon 5-encoding sequence. BCA3 variant splices were subcloned and sequenced using reverse transcription-polymerase chain reaction. The preliminary biological functions of the splices were identified using confocal microscopy and a luciferase assay. The absence of exon 3 and exon 5 influenced the subcellular localization of BCA3 and nuclear factor kappa B (NF-kB)-dependent gene expression. Exon 3 and exon 5 of BCA3 may function together to provide a nuclear localization signal or transport sequence to enter the nucleus, and exon 3 may contain specific sequence(s) or domain(s) that influence the NF-κB signal cascade. The discovery of novel BCA3 splicing indicates a new cancer research area, which may increase the understanding of cancer generation and development.

Cloning and characterization of three chemosensory proteins from Spodoptera exigua and effects of gene silencing on female survival and reproduction.

Insect chemosensory proteins (CSPs) are supposed to transport hydrophobic chemicals to receptors on sensory neurons. However, CSPs are broadly expressed in various insect tissues, suggesting their involvement in the physiological processes beyond chemoreception. So, the exact physiological roles of CSPs in insects still need to be unraveled. In this study, three full-length of CSP genes from Spodoptera exigua have been cloned and characterized. The deduced amino acid sequences of SexiCSP1, SexiCSP2 and SexiCSP3 revealed open reading frames of 128, 128 and 126 amino acids, respectively, with four conserved cysteine residues. The expression patterns of the three SexiCSPs were further investigated by real-time PCR. Three SexiCSPs were expressed in antennae, heads, legs, wings, thoraxes, abdomens, testes and ovaries, with the highest expression level in female and male antennae. Furthermore, all three SexiCSPs mRNA were distributed extensively in the tested development stages with the highest expression level in pupae. RNAi-based gene silencing study resulted in a dramatic reduction of corresponding mRNA in female S. exigua after injection with dsRNA of all three SexiCSPs. Consequentially, 42.5% of mortalities, 68.3% (compare to DEPC water injected control) and 71.4% (compare to uninjected control) oviposition inhibition, and significantly effected egg hatching were observed in the female S. exigua injected with dsSexiCSP3 as compared to control treatments. On the other hand, dsSexiCSP1 and dsSexiCSP2 injected female adults did not show effects on survival and reproduction. Our study confirms the utility of RNAi approach to functional characterization of CSP genes in S. exigua and provides a starting point for further studies on female survival and reproduction in this insect. It also reveals the potential pest controlling method, as insect behavior regulation agent that disrupts the expression of chemosensory proteins.

Absence of magnetism in hcp iron-nickel at 11 K.

Synchrotron Mössbauer spectroscopy (SMS) was performed on an hcp-phase alloy of composition Fe92Ni8 at a pressure of 21 GPa and a temperature of 11 K. Density functional theoretical calculations predict antiferromagnetism in both hcp Fe and hcp Fe-Ni. For hcp Fe, these calculations predict no hyperfine magnetic field, consistent with previous experiments. For hcp Fe-Ni, however, substantial hyperfine magnetic fields are predicted, but these were not observed in the SMS spectra. Two possible explanations are suggested. First, small but significant errors in the generalized gradient approximation density functional may lead to an erroneous prediction of magnetic order or of erroneous hyperfine magnetic fields in antiferromagnetic hcp Fe-Ni. Alternately, quantum fluctuations with periods much shorter than the lifetime of the nuclear excited state would prohibit the detection of moments by SMS.

Expression of hepatocyte-like phenotypes in bone marrow stromal cells after HGF induction.

Bone marrow comprises heterogeneous cell populations, of which certain progenitors have demonstrated the ability to differentiate into multiple mesenchymal cell lineages. This study demonstrates the bone marrow stromal cells (BMSCs) with intrinsic plasticity to differentiate into hepatocyte-like phenotypes under in vitro induction of hepatocyte growth factor (HGF). BMSCs isolated from rat femurs and tibias were cultured and passaged 3-4 times in the presence of HGF. Cells were harvested on days 0, 10, and 20 and subjected to examination of any hepatocyte characteristics by flow cytometry, RT-PCR, Western blot, and immunocytochemistry. Expression of albumin and alpha-fetoprotein at both mRNA and protein levels was detectable on day 10. By contrast, c-Met mRNA was significantly decreased in BMSC in the course of HGF induction. Here BMSC was shown to differentiate into hepatocyte-like phenotypes given the HGF induction, as an alternative source for adult stem cell transplantation in liver repair.

Phonon density of states of iron up to 153 gigapascals.

We report phonon densities of states (DOS) of iron measured by nuclear resonant inelastic x-ray scattering to 153 gigapascals and calculated from ab initio theory. Qualitatively, they are in agreement, but the theory predicts density at higher energies. From the DOS, we derive elastic and thermodynamic parameters of iron, including shear modulus, compressional and shear velocities, heat capacity, entropy, kinetic energy, zero-point energy, and Debye temperature. In comparison to the compressional and shear velocities from the preliminary reference Earth model (PREM) seismic model, our results suggest that Earth's inner core has a mean atomic number equal to or higher than pure iron, which is consistent with an iron-nickel alloy.

SF/HGF-c-Met autocrine and paracrine promote metastasis of hepatocellular carcinoma.

AIM: To explore the role of SF/HGF-Met autocrine and paracrine in metastasis of hepatocellular carcinoma (HCC). METHODS: SF/HGF and c-met transcription and protein expression in HCC were examined by RT-PCR and Western Blot in 4 HCC cell lines, including HepG2, Hep3B, SMMC7721 and MHCC-1, the last cell line had a higher potential of metastasis. sf/hgf cDNA was transfected by the method of Lipofectin into SMMC7721. SF/HGF and c-met antibody were used to stimulate and block SF/HGF-c-met signal transduction. Cell morphology, mobility, and proliferation were respectively compared by microscopic observation, wound healing assay and cell growth curve. RESULTS: HCC malignancy appeared to be relative to its met-SF/HGF expression. In MHCC-1, c-met expression was much stronger than that in other cell lines with lower potential of metastasis and only SF/HGF autocrine existed in MHCC-1. After sf/hgf cDNA transfection or conditioned medium of MHCC-1 stimulation, SMMC7721 changed into elongated morphology, and the abilities of proliferation (P < 0.05) and mobility increased. Such bio-activity could be blocked by c-met antibody (P < 0.05). CONCLUSION: The system of SF/HGF-c-met autocrine and paracrine played an important role in development and metastasis potential of HCC. Inhibition of SF/HGF-c-met signal transduction system may reduce the growth and metastasis of HCC.

Improving follow-up after an abnormal pap smear: results from a quasi-experimental intervention study.

The success of cervical cancer control programs depends on regular screening with the Pap smear test and prompt and appropriate treatment of early neoplastic lesions. Recognizing the potentially grave consequences of lack of follow-up for abnormal Pap smears, numerous intervention studies have tested the impact of a variety of strategies to increase return for follow-up. The majority of these studies were evaluated under controlled experimental conditions. Despite the encouraging findings of these trials, the next step in the research continuum requires that the effectiveness of these interventions be demonstrated in real world settings before full implementation is initiated. We report the results of an evaluation study assessing the combined effectiveness of three intervention modalities found effective in prior randomized studies: a tracking follow-up protocol, transportation incentives, and financial incentives. This study used a before-after, nonequivalent control group design to assess the impact of a multifaceted intervention that included a computerized tracking protocol with transportation and financial incentives. The study was implemented at two major hospitals, two comprehensive health centers (CHC), and nine public health centers (PHC) under the jurisdiction of the Los Angeles County Department of Health Services. One hospital, one CHC, and the four PHC located in the catchment area of the CHC were selected as experimental sites. The control sites - one hospital, one CHC, and five PHC - provided usual care. All women with an abnormal Pap smear at the intervention and control sites were included in the study. The study consisted of a 1-year period of baseline data collection (September 1989-August 1990), followed by a 2(1/2)-year intervention period (September 1990-February 1993). During the intervention period, the intervention protocol was implemented at the experimental sites, and the control sites provided usual care. Overall, we found that the rates of receipt of follow-up care were consistent with those found in similar studies. In contrast to results obtained in these prior randomized trials, we did not find strong and consistent evidence for intervention effects. Significant findings emerged only at the CHC and hospital levels and only for selected years. Results underscore the importance of testing interventions in real world conditions before large-scale implementation is initiated. In addition, this study highlights the challenge of detecting intervention effects in large-scale studies because of the greater measurement difficulties in field studies as compared with controlled experiments.

Regulation of cyclin-dependent kinase inhibitor p21(WAF1/Cip1/Sdi1) gene expression in hepatic regeneration.

WAF1/Cip1/Sdi1 (p21) is the prototype of a family of proteins that inhibit cyclin-dependent kinases and regulate cell cycle progression in eukaryotic cells. In addition to normal cell cycle progression, p21 is involved in growth suppression mediated by p53 and transforming growth factor beta (TGFbeta), differentiation, and apoptosis. To gain insight into the possible involvement of p21 in liver cell growth, the expression and regulation of the p21 gene was evaluated in rodent models of liver regeneration and specimens of human liver diseases. Little p21 mRNA was detected in normal liver tissue. After growth stimulation in vivo by 70% partial hepatectomy (PH), the p21 transcript was upregulated in a biphasic manner, with enhanced expression during G1 phase and following S phase. The induction of p21 after PH was regulated primarily at the post-transcriptional level and was due to enhanced mRNA stability. Inhibition of protein synthesis with cycloheximide rapidly induced p21 expression, primarily by post-transcriptional stabilization of the transcript. Hepatic p21 mRNA was also induced by dietary protein deprivation in normal mice. Expression of the p21 gene after PH was similar in p53-deficient (p53 -/-) and wild-type mice, but was p53-dependent following protein deprivation. Primary hepatocytes in culture demonstrated increased p21 expression after treatment with hepatocyte growth factor, TGFbeta, and activin A. p21 mRNA was upregulated in human liver diseases, suggesting a possible role in hepatic growth regulation in pathologic states. The present study demonstrates that p21 is regulated by p53-dependent and -independent pathways in the liver, and is influenced by both mitogenic and growth inhibitory stimuli.

Distinct patterns of cyclin D1 regulation in models of liver regeneration and human liver.

The expression of cyclin D1 and associated cdks was examined in models of liver regeneration and human liver specimens. In mouse liver after 70% partial hepatectomy, there was > 20-fold induction of cyclin D1 mRNA and protein, beginning prior to peak DNA synthesis. In normal rat liver, basal levels of cyclin D1 protein were significantly higher than in the mouse. After hepatectomy in the rat, cyclin D1 mRNA was induced 6- to 10-fold, while the protein levels changed < 2-fold and did not parallel changes in the mRNA. Cyclin D1 protein was detected in freshly isolated rat hepatocytes, but this diminished within 6 hours in culture. After growth stimulation with HGF, cyclin D1 mRNA was induced 3- to 5-fold and its protein > 20-fold in rat hepatocytes. Immunoprecipitation of cyclin D1 demonstrated its association with cdk4 but not cdk5 in regenerating liver. In human liver biopsy specimens, cyclin D1 protein was detectable in normal liver and induced 2- to 10-fold in mitotically active liver following transplantation. These results suggest that the regulation of cyclin D1 protein in human liver may more closely parallel the mouse than the rat hepatectomy model. Furthermore, cyclin expression in primary cells in culture may differ significantly from that observed in vivo.