Normal Human Kidney Cells Research Articles

Calmodulin-sensitive adenylyl cyclases mediate AVP-dependent cAMP production and Cl−secretion by human autosomal dominant polycystic kidney cells

In autosomal dominant polycystic kidney disease (ADPKD), binding of AVP to the V2 receptor (V2R) increases cAMP and accelerates cyst growth by stimulating cell proliferation and Cl(-)-dependent fluid secretion. Basal cAMP is elevated in human ADPKD cells compared with normal human kidney (NHK) cells. V2R mRNA levels are elevated in ADPKD cells; however, AVP caused a greater increase in global cAMP in NHK cells, suggesting an intrinsic difference in cAMP regulation. Expression, regulatory properties, and receptor coupling of specific adenylyl cyclases (ACs) provide temporal and spatial regulation of the cAMP signal. ADPKD and NHK cells express mRNAs for all nine ACs. Ca(2+)-inhibited ACs 5 and 6 are increased in ADPKD cells, while Ca(2+)/CaM-stimulated ACs 1 and 3 are downregulated. ACs 1, 3, 5, and 6 were detected in cyst cells in situ, and codistribution with aquaporin-2 suggests that these cysts were derived from collecting ducts. To determine the contribution of CaM-sensitive ACs to AVP signaling, cells were treated with W-7, a CaM inhibitor. W-7 decreased AVP-induced cAMP production and Cl(-) secretion by ADPKD cells. CaMKII inhibition increased AVP-induced cAMP, suggesting that cAMP synthesis is mediated by AC3. In contrast, CaM and CaMKII inhibition in NHK cells did not affect AVP-induced cAMP production. Restriction of intracellular Ca(2+) switched the response in NHK cells, such that CaM inhibition decreased AVP-induced cAMP production. We suggest that a compensatory response to decreased Ca(2+) in ADPKD cells switches V2R coupling from Ca(2+)-inhibited ACs 5/6 to Ca(2+)/CaM-stimulated AC3, to mitigate high cAMP levels in response to continuous AVP stimulation.

Endogenous concentrations of ouabain act as a cofactor to stimulate fluid secretion and cyst growth of in vitro ADPKD models via cAMP and EGFR-Src-MEK pathways

In autosomal-dominant polycystic kidney disease (ADPKD), renal cysts develop by aberrant epithelial cell proliferation and transepithelial fluid secretion. We previously showed that ouabain increases proliferation of cultured human ADPKD cells via stimulation of the EGF receptor (EGFR)-Src-MEK/ERK signaling pathway. We examined whether ouabain affects fluid secretion and in vitro cyst growth of human ADPKD cell monolayers, ADPKD cell microcysts cultured in a three-dimensional collagen matrix, and metanephric organ cultures from Pkd1(m1Bei) mice. Physiological concentrations of ouabain alone did not affect net transepithelial basal-to-apical fluid transport in ADPKD monolayers or growth of cultured ADPKD microcysts. In contrast, in the presence of forskolin or 8-bromo-cAMP, ouabain significantly enhanced ADPKD fluid secretion and microcyst expansion. Ouabain exerted this effect by enhancing cAMP-dependent Cl(-) secretion via the CFTR. Similarly, ouabain accelerated cAMP-dependent cyst enlargement in Pkd1(m1Bei) mice metanephroi, with a more prominent response in homozygous than heterozygous mice. Ouabain had no effect on fluid secretion and cystogenesis of normal human kidney cells and caused only slight cystic dilations in wild-type mouse kidneys. The effects of ouabain in ADPKD cells and Pkd1(m1Bei) metanephroi were prevented by inhibitors of EGFR (AG1478), Src (PP2), and MEK (U0126). Together, our results show that ouabain, used in physiological concentrations, has synergistic effects on cAMP-mediated fluid secretion and cyst growth, via activation of the EGFR-Src-MEK pathway. These data provide important evidence for the role of ouabain as an endogenous hormone that exacerbates ADPKD cyst progression.

Evaluation of selective inhibitors of nuclear export (SINE) CRM1 inhibitors for the treatment of renal cell carcinoma (RCC).

4634 Background: For the ~30% of patients who present with RCC at the metastatic stage, multi-kinase inhibitors have been used with moderate success: progression-free survival remains at only one to two years, and thus it is imperative to discover novel therapeutic approaches for metastatic disease. We asked whether (1) SINE inhibitors of chromosome region maintenance protein 1 (CRM1) attenuate key cell cycle regulatory and apoptotic molecules and whether these compounds exert salutary effects in a human RCC xenograft mouse model. Methods: Four RCC cell lines (ACHN, Caki-1, 786-O, and A498) with distinct genotypes, and primary normal human kidney (NHK) cell lines, were used in this study. The cells were treated with the chemically related SINE CRM1 inhibitors KPT-185 or 251 and MTT assays were performed. In addition, cell cycle analyses, immunofluorescence for p53 and p21, and immunoblotting for CRM1, p53, p21, p27, and p-MDM2 were performed for all cell lines. RCC mice with Caki-1 xenografts were treated with vehicle, the orally-available CRM1 inhibitor KPT-251, or sorafenib for 26 days. Tumor volume was measured over several days. Results: Both KPT185 and 251 specifically reduced CRM1 protein levels in RCC cells. KPT-185 caused dose-dependent cytotoxicity in RCC cells, which was greater than sorafenib in RCC cell lines but less in NHK cells, suggesting a possible clinical advantage of KPT-185 over sorafenib. By FACS analysis, we showed that KPT-185 arrests the cell cycle in both G2/M and G1, and increased the sub-G0 cell population. KPT-185 and 251 both increased p53 and p21 in RCC cells, and KPT-185 confined these proteins to the nucleus. In vivo, KPT-251 inhibited Caki-1 xenografts in mice compared to both vehicle and sorafenib without obvious systemic adverse effects. Conclusions: We introduce a completely novel therapeutic approach to the treatment of RCC based on inhibition of the nuclear export of key cell cycle regulatory proteins. Inhibition of CRM1 leads to forced nuclear retention, and thereby activation, of several key p53-pathway proteins, leading to cell cycle arrest and apoptosis in RCC cell lines in vitro and tumor growth inhibition in vivo.

Characterization of Differential Protein Tethering at the Plasma Membrane in Response to Epidermal Growth Factor Signaling

Physical tethering of membrane proteins to the cortical actin cytoskeleton provides functional organization to the plasma membrane and contributes to diverse cellular processes including cell signaling, vesicular trafficking, endocytosis, and migration. For these processes to occur, membrane protein tethering must be dynamically regulated in response to environmental cues. In this study, we describe a novel biochemical scheme for isolating the complement of plasma membrane proteins that are physically tethered to the actin cytoskeleton. We utilized this method in combination with tandem liquid chromatography/mass spectrometry (LC-MS/MS) to demonstrate that cytoskeletal tethering of membrane proteins is acutely regulated by epidermal growth factor (EGF) in normal human kidney (HK2) cells. Our results indicate that several proteins known to be involved in EGF signaling, as well as other proteins not traditionally associated with this pathway, are tethered to the cytoskeleton in dynamic fashion. Further analysis of one hit from our proteomic survey, the receptor phosphotyrosine phosphatase PTPRS, revealed a correlation between cytoskeletal tethering and endosomal trafficking in response to EGF. This finding parallels previous indications that PTPRS is involved in the desensitization of EGFR and provides a potential mechanism to coordinate localization of these two membrane proteins in the same compartment upon EGFR activation.

Transforming growth factor-β inhibits cystogenesis in human autosomal dominant polycystic kidney epithelial cells

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of kidney failure and characterized by the formation of multiple fluid-filled cysts in the kidneys. It is believed that environmental factors may play an important role in the disease progression. However, the molecular identity of autocrine/paracrine factors influencing cyst formation is largely unknown. In this study, we identified transforming growth factor-β2 (TGF-β2) secreted by normal human kidney (NHK) and ADPKD cells as an inhibitor of cystogenesis in 3D culture system using ADPKD cells from human kidneys. TGF-β2 was identified in conditioned media (CM) of NHK and ADPKD cells as a latent factor activated by heat in vitro. While all TGF-β isoforms recombinant proteins (TGF-β1, -β2, or -β3) displayed a similar inhibitory effect on cyst formation, TGF-β2 was the predominant isoform detected in CM. The involvement of TGF-β2 in the suppression of cyst formation was demonstrated by using a TGF-β2 specific blocking antibody and a TGF-β receptor I kinase inhibitor. TGF-β2 inhibited cyst formation by a mechanism other than activation of p38 mitogen-activated protein (MAP) kinase that mediated cell death in ADPKD cells. Further, we found that TGF-β2 modulated expression of various genes involved in cell–cell and cell–matrix interactions and extracellular matrix proteins that may play a role in the regulation of cystogenesis. Collectively, our results suggest that TGF-β2 secreted by renal epithelial cells may be an inhibitor of cystogenesis influencing the progression of ADPKD.

Abstract 2591: Folate receptor alpha: A promoter of cancer cell proliferation that is independent of folate

Abstract Folate receptor alpha (FRα) is over-expressed in malignant tumors of epithelial origin, particularly in ovarian cancer, but largely absent in normal tissue. High levels of protein expression in tumor cells are associated with increased proliferative capacity and enhanced chemo-resistance to Cisplatinum (CP). However, the underlying mechanism remains unclear. We sought to evaluate the biological function of FRα in CP-resistant cancer and hypothesized that alterations of FRα expression levels in drug CP-resistant cancers would result in the re-sensitization of tumor cells to CP. We first developed a human ovarian cancer cell line, IGROV-1, with increased CP resistance and found that these cells also showed an increase in FRα expression over parental IGROV-1 cells. Then, we used FOLR1 specific siRNA to completely knock-down FRα expression. Surprisingly, ablation of FRα expression did not restore sensitivity to CP but had a substantial negative impact on proliferation in both parental and CP-resistant cells. Similar phenomena were also observed when FRα was knocked-down in 786-0 cells, a human renal carcinoma line that expresses robust levels of FRα. In contrast, when we applied FRα knock-down to the normal human kidney cells HK-2 (FRα+), we observed no impairment on proliferation. One explanation of these results is that removal of FRα in cancer cells impairs the ability of these cells to uptake reduced folates, a requirement for nucleic acid synthesis and other methylation reactions. However, even pharmacological concentrations of 5-methyltetrahydrofolate, provided only partial restoration of proliferation in these cells. Taken together, these results suggest that FRα plays an essential role in the proliferation of tumor cells, but not in normal cells via a yet undefined pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2591. doi:10.1158/1538-7445.AM2011-2591

Bone morphogenetic proteins -2, -4, -6, -7 and their receptors are expressed in normal human kidney and renal cell carcinoma

Bone morphogenetic proteins (BMPs) are multifunctional cytokines with important role in cell proliferation, differentiation and embryonic pattern formation. The role of BMPs in the tumor biology is under investigation. These molecules have inhibitory and stimulatory effect on growth of different cancer cells. Renal cell carcinoma (RCC) is the most lethal tumor of all urogenital cancers with increasing incidence. Because BMPs have significant influence on the renal development and pathophysiology of renal diseases it is expected that they have role in the renal cell carcinoma too. Aim of our study was to present mRNA expression of different BMPs and their receptors in RCC compared to healthy kidney tissue. We examined expression of mRNA BMP-2, mRNA BMP-4, mRNA BMP-6, mRNA BMP-7, and mRNA of their receptors (BMPR-IA, BMPR-IB, BMPR-II) in 45 RCC and 15 normal kidney tissue samples obtained by nephrectomy. Their expressions were measured by using reverse transcriptase polymerase chain reaction (RT-PCR). Relative mRNA expression were calculated by dividing the ligand or receptor expression level by the expression of GPDH and multiplied by one hundred. mRNA expression were compared between normal and neoplastic tissue and correlated with clinicopathological parameters as histological subtype, nuclear grade, TNM stage, ECOG status, gender and age. Expression of all mRNA BMP ligands and their receptors were increased in RCC specimens compared to normal kidney but these differences were not statisticaly significant. Patients with RCC were divided in two groups: clear cell (CC-RCC) and non clear cell (NCC-RCC) group. There was not differences in BMPs expression between these two groups. Expression of BMPs compared to different nuclear grade, TNM stage, ECOG status and gender was similar between investigated groups. We found higher expression of mRNA BMPR-IB in patients older than 60 years when compared with those younger than 60 years (p=0, 036). Multivariate analysis showed that expression of mRNA BMPR-IA was higher in female patients with CC-RCC (p=0, 003). These results showed that mRNA of different BMPs ligands and their receptors are present in normal human kidney cells and in tumor cells of both RCC subtypes but higher expression was noticed in tumor cells. Also their expression was not in correlation with most important clinicopathological parameters as TNM stage, nuclear grade and histological subtype.

Microarray analysis reveals the inhibition of nuclear factor-kappa B signaling by aristolochic acid in normal human kidney (HK-2) cells

To study the molecular mechanism underlying the effect of aristolochic acid (AA), a major active component of plants from the Aristolochiaceae family using microarray analysis. Human kidney (HK-2) cells were treated with AA (0, 10, 30, and 90 micromol/L) for 24 h, and the cell viability was measured by a 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay. Complementary DNA microarrays were used to investigate the gene expression pattern of HK-2 cells exposed to AA in triplicate. A quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) assay was used to verify the microarray data for selected nuclear factor kappa B (NF-kappaB)-regulated genes. Furthermore, the subcellular localization of NF-kappaB p65 was visualized by immunofluorescence confocal microscopy in HK-2 cells. The NF-kappaB activity was examined by a luciferase reporter assay in HK-2/NF-kappaB transgenic cells. AA exhibited a dose-dependent cytotoxic effect in HK-2 cells and induced alterations in the gene expression profiles related to the DNA damage response, DNA repair, macromolecule metabolic process, carbohydrate metabolic process, DNA metabolic process, apoptosis, cell cycle, and transcription. In addition, 9 biological pathways associated with immunomodulatory functions were down-regulated in AA-treated HK-2 cells. A network analysis revealed that NF-kappaB played a central role in the network topology. Among NF-kappaB-regulated genes, 8 differentially expressed genes were verified by qRT-PCR. The inhibition of NF-kappaB activity by AA was further confirmed by immunofluorescence confocal microscopy and by NF-kappaB luciferase reporter assay. Our data revealed that AA could suppress NF-kappaB activity in normal human cells, perhaps partially accounting for the reported anti-inflammatory effects of some plants from the genus Aristolochia.

Overexpression of AEG-1 in renal cell carcinoma and its correlation with tumor nuclear grade and progression

The study was aimed at detecting the expression of a newly found oncogene, astrocyte elevated gene-1 (AEG-1), in renal cell carcinoma (RCC) and its correlation with histopathologic features and the survival of patients. Real-time reverse transcription-PCR and Western blot showed markedly higher expression of AEG-1 in 8 cases of RCC tissue compared with the paired normal tissue from the same patient. The expression level of AEG-1 was also increased in four RCC cell lines in contrast with normal tubular epithelial human kidney cells 2 (HK-2) at both mRNA and protein levels. Furthermore, immunohistochemistry analysis showed highly expressed AEG-1 in 96 of 102 (94.1%) cases of paraffin-embedded archival RCC tissue. Statistical analysis showed a significant correlation of AEG-1 expression with tumor grade (P <0.001), clinical staging (P = 0.003), T classification (P = 0.003) as well as metastasis classification (P=0.032). The means for survival time of low AEG-1 expression group was 76.98m<br />while high AEG-1expression group was 60.94m. Our results suggest that AEG-1 protein is overexpressed in RCC and plays an important role in tumor differentiation and progression. <br />High AEG-1 expression is closely associated with poor prognosis. Astrocyte elevated gene-1, AEG-1, renal cell carcinoma, prognosis.

더덕 추출물의 항돌연변이 및 항종양 효과

This study was carried out to investigate the mutagenic, antimutagenic, cytotoxicity and antitumor effect of Codonopsis lanceolata (CL). CL was extracted with 70% ethanol and then further fractionated to hexane, chloroform, ethyl acetate, butanol and water. Antimutagenic, cytotoxicity and antitumor effects of CL extracts were measured by using Ames test, SRB method, and the tumor growth inhibition test. CL extracts did not show any mutagenicity in the Ames test; however, 70% ethanol extracts and its fractions had strong antimutagenic effects against mutation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 4-nitroquinoline-1-oxide (4NQO). The ethyl acetate fraction of CL (200 ㎍/plate) showed approximately 72.1% inhibitory effect on the mutagenesis induced by 4NQO against TA98 strain, whereas 69.6% and 67.0% inhibitions were observed on the mutagenesis induced by MNNG and 4NQO against TA100 strain. In anticancer effects, the cytotoxicity of CL extract and its fractions against cancer cell lines including human cervical adenocarcinoma (HeLa), human hepatocellular carcinoma (HepG2), human breast adenocarcinoma (MCF-7), human lung carcinoma (A549) and transformed primary human embryo kidney (293) were investigated. The treatment of 1 ㎎/mL CL ethyl acetate fraction had the highest cytotoxicity of 74.5%, 70.7% and 80.3% against HeLa, MCF-7 and A549 cells, respectively. In contrast, the extract and its fractions showed only 2∼31% cytotoxicity for a normal human kidney cell line (293). In vivo anticancer effect of CL extract was tested using Balb/c mice transplanted sarcoma-180 cells. CL ethyl acetate fraction showed the highest inhibition rate of 56.4% at the 50 ㎎/㎏ concentration.

고로쇠 수피 초고압 추출물의 항암활성 증진

본 연구에서는 초고압 공정을 통하여 기존의 일반 열수추출공정과 비교함으로써 초고압 공정에 의한 항산화 활성 증진 및 항암활성 증진 효과를 확인하였다. 기존의 추출공정과 비교하여 높은 압력 하에서 추출수율이 증가한 것은 시료의 세포막이 비가역적으로 분해되어 막 투과성이 증가되어 물질 이동이 용이하게 되어 용매가 세포 안으로 들어가 보다 많은 성분이 세포 밖으로 쉽게 용출되어 나오는 결과라고 추정된다. DPPH radical 소거활성을 측정한 결과, 네 가지의 추출물 중 15분간 초고압 처리한 추출물의 활성이 1.0㎎/mL의 농도에서 94.56%로 가장 높은 활성을 보였고, 또한 BHA의 93.24%보다 높은 활성을 보였다. SOD 유사활성 결과를 살펴보면 15분간 초고압 처리를 한 추출물의 활성이 모든 농도에서 대조군으로 비교한 BHA의 활성보다 높았고, 열수추출의 활성보다 높은 결과를 나타내었다. 인간의 정상폐 세포인 HEL299를 이용한 세포 독성은 초음파 공정을 15분간 처리한 추출물 1.0 ㎎/mL의 농도에서 20.12%로, 일반 열수 추출물의 24.53%보다 낮은 세포독성을 나타내어 초고압 공정을 통한 세포독성 저감 효과를 확인할 수 있었다. 또한 인간 정상 신장 세포인 HEK293을 이용한 세포 독성실험에서도 1.0 ㎎/mL의 농도에서 초고압 처리를 15분 동안 한 추출물이 23.54%를 나타내어 일반 열수 추출물보다 약 3% 낮은 독성을 보였다. 암세포 억제활성 측정은 AGS, A549, MCF-7, Hep3B, Caco-2의 세포를 이용하여 실험을 하였다. 위의 4가지 암세포에서 1.0 ㎎/mL의 농도에서 70% 이상의 높은 암세포 억제 활성을 보였고, 암세포의 생육활성에 대한 정상 세포의 세포독성의 비로 나타낸 선택적사멸도는 1.0 ㎎/mL의 농도에서 4 정도로 나타났으며, 초고압 공정에 의한 추출물의 사멸도가 높게 나타났다. 본 실험 결과를 통하여 기존의 일반 열수 추출에 비해 초고압 공정을 통한 추출물의 수율향상 및 세포독성 저감 효과를 확인할 수 있었는데, 이는 초고압에 의한 고로쇠 수피 표면조직의 파괴와 성분 변화로 인한 유용물질 및 신물질의 대량 용출과 함께 독성물질이 파괴되거나 변성되어 나타난 결과라고 생각된다. 또한 항산화 활성 및 항암활성 증진효과를 확인할 수 있었는데 이를 통해 고로쇠나무의 항산화제 및 항암 신소재로의 가능성을 확인할 수 있었다. 더 나아가 초고압 공정에 의해 용출된 성분의 분리 및 성분 분석에 관한 연구가 더 필요할 것으로 사료된다.

Biological Activities of Fractions from Methanolic Extract of Picrasma quassioides

Antioxidant, antidiabetes, and anticancer activities of fractions (water, hexane, EtOAc, and BuOH) from methanolic (MeOH) extract of Picrasma quassioides were evaluated in vitro. Among the four fractions, BuOH fraction showed cytotoxic activity on the human stomach carcinoma cells (NCI-N87) without cytotoxic effect on the human normal kidney cells (293) by MTT assay. Considering these results, we adapted BuOH fraction of MeOH extract to the assessment of apoptosis by flow cytometry and mRNA expression levels of established apoptotic-related genes on NCI-N87 cells. The experiments showed that BuOH fraction could induce apoptosis on NCI-N87 cells significantly. Take together these results, P. quassioides showed that it could be used for potential pharmaceutical products.

잔대 추출물들의 항돌연변이 및 항종양 효과

본 연구는 잔대의 돌연변이원성, 항돌연변이원성, 세포독성, 항종양 효과를 조사하기 위해서 수행되었다. 잔대를 70% 에탄올로 추출하여 추출용매에 따라 핵산, 클로로포름, 에틸아세테이트, 부탄올과 물층으로 분획하였다. Ames test, SRB assay와 종양 억제실험 방법을 사용하여 실험하였다. Ames test결과, 잔대 에탄올 추출물과 그 분획물들은 돌연변이원성을 나타내지 않았을 뿐만 아니라, MNNG와 4NQO로 돌연변이를 일으켰을 때 높은 항돌연변이 효과를 나타내었다. 잔대 에틸아세테이트 분획물은 S. Typhimurium TA98를 4NQO로 돌연변이를 유도하였을 때 66.5%의 억제율을 나타내었으며, S. Typhimurium TA100에서 MNNG와 4NQO로 돌연변이를 유도했을 때는 83.3%와 75.1%의 억제율을 나타내었다. 잔대 추출물 및 그 분획물들의 암세포 성장 억제효과를 살펴보기 위해 인간 자궁암세포(HeLa), 인간 간암세포(Hep3B), 인간 유방암세포(MCF-7), 인간 위암세포(AGS), 인간 폐암세포(A549)와 인간 신장정상세포(293)를 사용하였다. 잔대 에틸아세테이트 분획물을 1 ㎎/mL를 처리하였을 때 각각 79.9%(HeLa), 74.9%(Hep3B), 66.0%(MCF-7), 71.0%(AGS)와 74.3%(A549)의 가장 높은 억제활성을 나타내었다. 반면에 인간 정상 신장세포에서는 3~36%의 세포독성을 나타내었다. In vivo에서 잔대 추출물의 항암효과를 시험하기 위하여 Balb/c 마우스에 sarcoma-180 종양세포로 고형암을 유발시켰다. 그 결과 잔대 에틸아세테이트 층의 최고농도 50 ㎎/㎏에서 37.2%의 고형암 성장 억제효과를 나타내었고, 이는 모든 처리군 중 가장 높은 억제율이었다.

Caffeoylquinic acids from leaves of Etlingera species (Zingiberaceae)

Abstract 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid (chlorogenic acid), and 5-O-caffeoylquinic acid methyl ester, as elucidated by 1H and 13C NMR, were isolated from leaves of Etlingera elatior. This is the first report of caffeoylquinic acids (CQA) including chlorogenic acid (CGA) in Zingiberaceae. Leaves of Etlingera species were rich in total phenols and CQA, and non-cytotoxic to normal human liver and African green monkey kidney cells. Content of CQA of E. elatior, Etlingera fulgens, and Etlingera rubrostriata leaves was significantly higher than leaves of Ipomoea batatas, and comparable to flowers of Lonicera japonica. CGA found only in leaves of E. elatior and E. fulgens was significantly higher in content than flowers of L. japonica, the commercial source.

Periostin induces proliferation of human autosomal dominant polycystic kidney cells through αV-integrin receptor

Progressive renal enlargement due to the growth of innumerable fluid-filled cysts is a central pathophysiological feature of autosomal dominant polycystic kidney disease (ADPKD). These epithelial neoplasms enlarge slowly and damage noncystic parenchyma by mechanisms that have not been clearly defined. In a microarray analysis of cultured human ADPKD cyst epithelial cells, periostin mRNA was overexpressed 15-fold compared with normal human kidney (NHK) cells. Periostin, initially identified in osteoblasts, is not expressed in normal adult kidneys but is expressed transiently during renal development. We found periostin in cyst-lining cells in situ in the extracellular matrix adjacent to the cysts and within cyst fluid. ADPKD cells secreted periostin across luminal and basolateral plasma membranes. Periostin increased proliferation of cyst epithelial cells 27.9 +/- 3.1% (P < 0.001) above baseline and augmented in vitro cyst growth but did not affect proliferation of normal renal cells. Expression of alphaV-integrin, a periostin receptor, was ninefold higher in ADPKD cells compared with NHK cells, and antibodies that block alphaV-integrin inhibited periostin-induced cell proliferation. We conclude that periostin is a novel autocrine mitogen secreted by mural epithelial cells with the potential to accelerate cyst growth and promote interstitial remodeling in ADPKD.

해양심층수염 및 다시마분말을 첨가한 개량식 된장의 항돌연변이원성 및 암세포성장억제에 미치는 영향

Dept. of Biotechnology and Engineering, Kangwon National University, Chuncheon 200-701, KoreaAbstractThis study was performed to determine the antimutagenic and anticytotoxic effects of soybean paste (doenjang) added deep sea water salt and see tangle in Salmonella Typhimurium TA98, TA100 and human cancer cell lines. In the Ames test, methanol extract of doenjang did not exhibit any mutagenicity but showed substantial inhibitory effects against mutation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 4-nitroquinoline-1-oxide (4NQO). The methanol extracts of doenjang (200 μg/plate) added deep sea salt and see tangle (doenjang C) showed approximately 89.1% and 70% inhibitory effect on the mutagenesis induced by MNNG and 4NQO against TA100 strain, whereas 84.4% inhibitions were observed on the mutagenesis in-duced by 4NQO against TA98 strain. The cytotoxic effects of doenjang methanol extracts against the cell lines with human cervical adenocarcinoma (HeLa), human hepatocellular carcinoma (Hep3B), human gastric carcinoma (AGS), human lung carcinoma (A549) and human breast adenocarcinoma (MCF-7) were inhibited with the increase of the extract concentration. The treatment of 1.0 mg/mL doenjang C of methanol extracts showed strong cytotoxicities of 71%, 74.4%, 66.2%, 77.3%, and 71.2% against HeLa, Hep3B, AGS, A549, and MCF-7, respectively. In contrast 1 mg/mL treatment of doenjang C methanol extracts had only 10～40% cyto-toxicity on normal human embryonal kidney cell (293). Doenjang methanol extract inhibited significantly the tumor growth in mice injected sarcoma-180 cells. Especially, doenjang C methanol extract showed an inhibition of tumor cell activity of 33% by the administration of 25 mg/kg methanol extracts.Key words: deep sea water, Ames test, antimutagenic effect, cytotoxicity

Calcium channel inhibition accelerates polycystic kidney disease progression in the Cy/+ rat

In polycystic kidney disease, abnormal epithelial cell proliferation is the main factor leading to cyst formation and kidney enlargement. Cyclic AMP (cAMP) is mitogenic in cystic but antimitogenic in normal human kidney cells, which is due to reduced steady-state intracellular calcium levels in cystic compared to the normal cells. Inhibition of intracellular calcium entry with channel blockers, such as verapamil, induced cAMP-dependent cell proliferation in normal renal cells. To determine if calcium channel blockers have a similar effect on cell proliferation in vivo, Cy/+ rats, a model of dominant polycystic kidney disease, were treated with verapamil. Kidney weight and cyst index were elevated in verapamil-treated Cy/+ rats. This was associated with increased cell proliferation and apoptosis, elevated expression, and phosphorylation of B-Raf with stimulation of the mitogen-activated protein kinase MEK/ERK (mitogen-activated protein kinase kinase/extracellular-regulated kinase) pathway. Verapamil had no effect on kidney morphology or B-Raf stimulation in wild-type rats. We conclude that treatment of Cy/+ rats with calcium channel blockers increases activity of the B-Raf/MEK/ERK pathway accelerating cyst growth in the presence of endogenous cAMP, thus exacerbating renal cystic disease.

Ouabain stimulates proliferation of epithelial cells from kidneys of patients with autosomal dominant polycystic kidney disease via the Na,K‐ATPase and MEK‐ERK pathway.

The hormone ouabain, through its receptor the Na,K-ATPase, stimulates proliferation of certain cell types. The objective of the present work was to determine the effect and intracellular signaling of ouabain in epithelial cells from kidneys of patients with autosomal dominant polycystic kidney disease (ADPKD cells). Ouabain, in nanomolar concentrations, such as those circulating in blood, induced growth in ADPKD cells, increasing the rate of proliferation and mitosis in the cells. In contrast, ouabain did not significantly affect growth of normal human kidney cells (NHK cells). In ADPKD cells, ouabain also stimulated phosphorylation of the extracellular regulated kinase ERK. AG1478, an inhibitor of the epidermal growth factor receptor (EGFR) and PP2, an inhibitor of Src kinase blocked the effects of ouabain in the cystic cells. U0126, an inhibitor of the mitogen activated protein kinase MEK caused a similar effect. Ouabain stimulated phosphorylation of ERK occurred only when the hormone was applied to the basolateral surface of the cells, where the Na,K-ATPase is localized. Interestingly, dose response curves for inhibition of Na,K-ATPase activity by ouabain showed that approximately 20% of the Na,K-ATPase of ADPKD cells exhibits an abnormally increased affinity for ouabain. Altogether, these results suggest that ouabain is able to bind to the Na,K-ATPase of ADPKD cells with high affinity to activate the MEK-ERK pathway to stimulate proliferation of the cells. This presents ouabain as a factor with a positive effect in the pathophysiology of autosomal dominant polycystic kidney disease. [Supported by NIH grant HD043044-01 and a grant from the PKD Foundation].

Synthetic chalcones, flavanones, and flavones as antitumoral agents: Biological evaluation and structure–activity relationships

A series of synthetic chalcones, flavanones, and flavones has been synthesized and evaluated for antitumor activity against the human kidney carcinoma cells TK-10, human mammary adenocarcinoma cells MCF-7 (estrogen receptor-positive), and human colon adenocarcinoma cells HT-29. The most active series is the chalcone ones with the best results against TK-10 and HT-29 cells. Fourteen out of 53 analyzed compounds resulted very active against at least two of the studied tumoral cells. Alkaline single cell gel electrophoresis, comet assay, was performed as a study of the chromosomal aberrations promoted by the compounds on normal cells. Four active and two inactive chalcones were studied in the comet assay against normal human kidney cells (HK-2). A structure–activity relationship analysis of these compounds was performed and for 4- and 3,4-disubstituted derivatives a quantitative correlation was obtained in the case of anti-HT-29 activity.

Ouabain Binds with High Affinity to the Na,K-ATPase in Human Polycystic Kidney Cells and Induces Extracellular Signal–Regulated Kinase Activation and Cell Proliferation

In autosomal dominant polycystic kidney disease (ADPKD), cyst formation and enlargement require proliferation of mural renal epithelial cells and the transepithelial secretion of fluid into the cyst cavity. Na,K-ATPase is essential for solute and water transport in ADPKD cells, and ouabain blocks fluid secretion in these cells. By binding to the Na,K-ATPase, ouabain also induces proliferation in some cell types. Surprisingly, it was found that nanomolar concentrations of ouabain, similar to those circulating in blood, induced ADPKD cell proliferation but had no statistically significant effect on normal human kidney (NHK) cells. Ouabain, acting from the basolateral side of the cells, also caused an increase in the level of phosphorylated extracellular signal-regulated kinases (ERK). Mitogen-activated protein kinase kinase (MEK) inhibitor U0126 blocked ouabain-induced ERK activation and cell proliferation, suggesting that ouabain effect is mediated through the MEK-ERK pathway. In contrast to NHK cells, the dose-response curve for ouabain inhibition of Na,K-ATPase activity indicated that approximately 20% of the enzyme in ADPKD cells exhibits a higher affinity for ouabain. The increased ouabain affinity of ADPKD cells was not due to differences in Na,K-ATPase isoform expression because these cells, like NHK cells, possess only the alpha1 and beta1 subunits. The gamma variants of the Na,K-ATPase also are expressed in the cells but are elevated in ADPKD cells. Currently, the basis for the differences in ouabain sensitivity of NHK and ADPKD cells is unknown. It is concluded that ouabain stimulates proliferation in ADPKD cells by binding to the Na,K-ATPase with high affinity and via activation of the MEK-ERK pathway.