scholarly journals Regulation of transferrin-induced endocytosis by wild-type and C282Y-mutant HFE in transfected HeLa cells

2002 ◽  
Vol 282 (5) ◽  
pp. C973-C979 ◽  
Author(s):  
Lukas Schwake ◽  
Andreas W. Henkel ◽  
Hans D. Riedel ◽  
Thorsten Schlenker ◽  
Matthias Both ◽  
...  
Keyword(s):  
Hela Cells ◽  
Single Cells ◽  
Hereditary Hemochromatosis ◽  
Inhibitory Effect ◽  
Membrane Capacitance ◽  
Wild Type ◽  
Time Resolved ◽  
Cell Membrane Capacitance ◽  
Endocytic Vesicles ◽  
In Cells

The hereditary hemochromatosis protein HFE is known to complex with the transferrin receptor; however, its function regarding endocytosis of transferrin is unclear. We performed patch-clamp capacitance measurements in transfected HeLa cells carrying wild-type or C282Y-mutant HFE cDNA under the control of a tetracycline-sensitive promoter. Whole cell experiments in cells with suppressed expression of wild-type HFE revealed a decrease in membrane capacitance, reflecting predominance of endocytosis in the presence of transferrin. Cells overexpressing C282Y-mutant HFE displayed less intense capacitance decreases, whereas no significant decrease was observed in cells overexpressing wild-type HFE. The formation of single endocytic vesicles in cells with suppressed expression of wild-type HFE was greatly increased in the presence of transferrin as revealed by cell-attached recordings. According to their calculated diameters, many of these vesicles corresponded to clathrin-coated vesicles. These results suggest that wild-type HFE negatively modulates the endocytic uptake of transferrin. This inhibitory effect is attenuated in cells expressing C282Y-mutant HFE. Time-resolved measurements of cell membrane capacitance provide a powerful tool to study transferrin-induced endocytosis in single cells.

scholarly journals Ezrin binding domain-deficient NHERF attenuates cAMP-mediated inhibition of Na+/H+ exchange in OK cells

2001 ◽  
Vol 281 (2) ◽  
pp. F374-F380 ◽  
Author(s):  
Edward J. Weinman ◽  
Deborah Steplock ◽  
James B. Wade ◽  
Shirish Shenolikar
Keyword(s):  
Epithelial Cells ◽  
Surface Expression ◽  
Inhibitory Effect ◽  
Cell Surface Expression ◽  
Wild Type ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Proposed Model ◽  
Exchange Activity ◽  
In Cells

Na+/H+ exchanger regulatory factor (NHERF), an essential protein cofactor in cAMP-mediated inhibition of Na+/H+ exchange transporter 3 (NHE3), facilitates the formation of a signal complex of proteins that includes NHE3, NHERF, and ezrin. This model for NHE3 regulation was developed in fibroblasts and its applicability to epithelial cells remains to be established. Opossum kidney (OK) cells were transfected with either empty vector (control), full-length mouse (m) NHERF(1–355), or a truncated mNHERF(1–325) that lacked ezrin binding and had been demonstrated in fibroblasts to bind NHE3 but not mediate its cAMP-associated inhibition. 8-Bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP) at 10−4 M inhibited Na+/H+ exchange activity in control and OK cells expressing wild-type mNHERF(1–355) by >60% but by <10% in cells expressing mNHERF(1–325). NHE3 coimmunoprecipitated with mNHERF(1–325), but cAMP phosphorylation of NHE3 was impaired in cells expressing mNHERF(1–325). The inhibitory effect of hyperosmolality on NHE3 activity and the uptake of 3- O-methyl-d-glucose was the same in all three cell lines. Cell surface expression of NHE3 was not changed by cAMP in any of the cells lines. These data indicate that disruption of the NHERF-ezrin signal complex attenuates the inhibitory effect of cAMP on NHE3 activity in OK cells and provides evidence supporting the proposed model of protein kinase A regulation of NHE3 in epithelial cells.

Effects of clotrimazole on the growth, morphological characteristics, and cisplatin sensitivity of human glioblastoma cells in vitro

1999 ◽  
Vol 90 (5) ◽  
pp. 918-927 ◽  
Author(s):  
M. Humayun Khalid ◽  
Shobu Shibata ◽  
Tsuyoshi Hiura
Keyword(s):  
P53 Gene ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Glioblastoma Cells ◽  
Content Type ◽  
Growth Inhibitory ◽  
Wild Type P53 ◽  
Fine Print ◽  
In Cells

Object. Clotrimazole, an antimycotic drug, inhibits proliferation of normal and cancer cells by downregulating the movement of intracellular Ca++ and K+. The authors examined the effect of clotrimazole on the growth and sensitivity to cisplatin of two human glioblastoma cell lines—A172, which has the wild-type p53 gene, and T98G, which has the mutant p53 gene in vitro.Methods. The A172 and T98G glioblastoma cells were exposed to clotrimazole and cell growth was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium chloride colorimetric assay. Clotrimazole produced a dose-dependent inhibition of cell proliferation and caused changes in cellular structure toward a well-differentiated form. The growth inhibitory effect of clotrimazole was reversible. Western immunoblot analysis revealed a marked increase in cellular glial fibrillary acidic protein and wild-type p53 and a decrease in c-myc and c-fos oncoproteins in both cell lines treated with clotrimazole. Flow cytometric analysis revealed that clotrimazole-treated cells accumulated in the G0/G1 phase with a marked decrease in cells in the S phase; when clotrimazole was washed out from the culture medium, cells again started to proliferate, with a marked decrease in cells in the G0/G1 phase and an increase in cells in the S phase. The growth inhibitory effect of clotrimazole could not be overcome by exogenous stimulation with either epidermal growth factor or c-myc peptide. A combined treatment with clotrimazole and cisplatin significantly enhanced cell cytotoxicity compared with treatment using either drug alone. A DNA fragmentation assay showed that both clotrimazole and cisplatin induced apoptosis, which was increased in cells treated by both drugs.Conclusions. The present study indicates that clotrimazole inhibits cell proliferation accompanied by morphological changes toward differentiation of glioblastoma cells and that this drug synergistically enhances the antitumor effect of cisplatin by inducing wild-type p53—mediated apoptosis.

scholarly journals Bcl-xL acts as an inhibitor of IP3R channels, thereby antagonizing Ca2+-driven apoptosis

2021 ◽  
Author(s):  
Nicolas Rosa ◽  
Hristina Ivanova ◽  
Larry E. Wagner ◽  
Justin Kale ◽  
Rita La Rovere ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Cancer Cells ◽  
Hela Cells ◽  
Breast Cancer Cells ◽  
Single Channel ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Current Paradigm

AbstractAnti-apoptotic Bcl-2-family members not only act at mitochondria but also at the endoplasmic reticulum, where they impact Ca2+ dynamics by controlling IP3 receptor (IP3R) function. Current models propose distinct roles for Bcl-2 vs. Bcl-xL, with Bcl-2 inhibiting IP3Rs and preventing pro-apoptotic Ca2+ release and Bcl-xL sensitizing IP3Rs to low [IP3] and promoting pro-survival Ca2+ oscillations. We here demonstrate that Bcl-xL too inhibits IP3R-mediated Ca2+ release by interacting with the same IP3R regions as Bcl-2. Via in silico superposition, we previously found that the residue K87 of Bcl-xL spatially resembled K17 of Bcl-2, a residue critical for Bcl-2’s IP3R-inhibitory properties. Mutagenesis of K87 in Bcl-xL impaired its binding to IP3R and abrogated Bcl-xL’s inhibitory effect on IP3Rs. Single-channel recordings demonstrate that purified Bcl-xL, but not Bcl-xLK87D, suppressed IP3R single-channel openings stimulated by sub-maximal and threshold [IP3]. Moreover, we demonstrate that Bcl-xL-mediated inhibition of IP3Rs contributes to its anti-apoptotic properties against Ca2+-driven apoptosis. Staurosporine (STS) elicits long-lasting Ca2+ elevations in wild-type but not in IP3R-knockout HeLa cells, sensitizing the former to STS treatment. Overexpression of Bcl-xL in wild-type HeLa cells suppressed STS-induced Ca2+ signals and cell death, while Bcl-xLK87D was much less effective in doing so. In the absence of IP3Rs, Bcl-xL and Bcl-xLK87D were equally effective in suppressing STS-induced cell death. Finally, we demonstrate that endogenous Bcl-xL also suppress IP3R activity in MDA-MB-231 breast cancer cells, whereby Bcl-xL knockdown augmented IP3R-mediated Ca2+ release and increased the sensitivity towards STS, without altering the ER Ca2+ content. Hence, this study challenges the current paradigm of divergent functions for Bcl-2 and Bcl-xL in Ca2+-signaling modulation and reveals that, similarly to Bcl-2, Bcl-xL inhibits IP3R-mediated Ca2+ release and IP3R-driven cell death. Our work further underpins that IP3R inhibition is an integral part of Bcl-xL’s anti-apoptotic function.

scholarly journals Bcl-xL Acts as an Inhibitor of IP3R Channels, Thereby Antagonizing Ca2+-Driven Apoptosis

2021 ◽  
Author(s):  
Nicolas Rosa ◽  
Hristina Ivanova ◽  
Larry Wagner II ◽  
Justin Kale ◽  
Rita La Rovere ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Cancer Cells ◽  
Hela Cells ◽  
Breast Cancer Cells ◽  
Single Channel ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Current Paradigm

Abstract Anti-apoptotic Bcl-2-family members not only act at mitochondria but also at the endoplasmic reticulum, where they impact Ca2+ dynamics by controlling IP3 receptor (IP3R) function. Current models propose distinct roles for Bcl-2 vs Bcl-xL, with Bcl-2 inhibiting IP3Rs and preventing pro-apoptotic Ca2+ release and Bcl-xL sensitizing IP3Rs to low [IP3] and promoting pro-survival Ca2+ oscillations. We here demonstrate that Bcl-xL too inhibits IP3R-mediated Ca2+ release by interacting with the same IP3R regions as Bcl-2. Via in silico superposition, we previously found that the residue K87 of Bcl-xL spatially resembled K17 of Bcl-2, a residue critical for Bcl-2’s IP3R-inhibitory properties. Mutagenesis of K87 in Bcl-xL impaired its binding to IP3R and abrogated Bcl-xL’s inhibitory effect on IP3Rs. Single-channel recordings demonstrate that purified Bcl-xL, but not Bcl-xLK87D, suppressed IP3R single-channel openings stimulated by sub-maximal and threshold [IP3]. Moreover, we demonstrate that Bcl-xL-mediated inhibition of IP3Rs contributes to its anti-apoptotic properties against Ca2+-driven apoptosis. Staurosporine (STS) elicits long-lasting Ca2+ elevations in wild-type but not in IP3R-knockout HeLa cells, sensitizing the former to STS treatment. Overexpression of Bcl-xL in wild-type HeLa cells suppressed STS-induced Ca2+ signals and cell death, while Bcl-xLK87D was much less effective in doing so. In the absence of IP3Rs, Bcl-xL and Bcl-xLK87D were equally effective in suppressing STS-induced cell death. Finally, we demonstrate that endogenous Bcl-xL also suppress IP3R activity in MDA-MB-231 breast cancer cells, whereby Bcl-xL knockdown augmented IP3R-mediated Ca2+ release and increased the sensitivity towards STS, without altering the ER Ca2+ content. Hence, this study challenges the current paradigm of divergent functions for Bcl-2 and Bcl-xL in Ca2+-signaling modulation and reveals that, similarly to Bcl-2, Bcl-xL inhibits IP3R-mediated Ca2+ release and IP3R-driven cell death. Our work further underpins that IP3R inhibition is an integral part of Bcl-xL’s anti-apoptotic function.

scholarly journals PRIMA-1met Induces Autophagy in Colorectal Cancer Cells With Different p53 Status

2020 ◽  
Author(s):  
Xiao-lan Li ◽  
Jianbiao Zhou ◽  
Chen-jing Xia ◽  
Zhong-kai Lu ◽  
Zhi-rong Chen
Keyword(s):  
Colorectal Cancer ◽  
Cell Lines ◽  
Inhibitory Effect ◽  
Cell Counting ◽  
Signaling Cascade ◽  
Mutant P53 ◽  
Wild Type ◽  
P53 Status ◽  
Wild Type P53 ◽  
In Cells

Abstract Background: PRIMA-1met (APR246), a methylated form of PRIMA-1 (p53-reactivation and induction of massive apoptosis-1, APR-017), targets mutant p53 for restoring its wild-type structure and function. We previously demonstrated that PRIMA-1met was efficient in suppressing the growth of colorectal cancer (CRC) cells in a p53-independent manner, and distinctly induced apoptosis mediated by up-regulation of Noxa in p53-mutant cell lines. Here we aimed to the effect of PRIMA-1met on autophagy in different CRC cell lines, to further investigate mechanisms underlying the inhibitory effect in cells with different p53 status.Methods: 3 CRC cell lines with wild-type p53, 5 lines with mutant p53 and 1 line without p53 were obtained for this study. Using western blotting, acridine orange staining, and transmission electron microscopy detection, we assessed autophagy flux in different cells treated with PRIMA-1met, and detected expression of mTOR/AMPK-ULK1-Vps34 autophagic signaling cascade. We also evaluated cell proliferation of cells with PRIMA-1met treatment by cell counting Kit-8 proliferation assay, compared to combination of PRIAM-1met and 3-Methyladenine. Furthermore, we knocked down Noxa gene by siRNA in different CRC cells, to assess LC3 conversion after administration of PRIMA-1met. Values were expressed as mean + standard error of the mean. Comparison between groups of data was made using one-way analysis of variance.Results: In this study, we showed that PRIMA-1met induced autophagy in CRC cells independent on p53 status. PRIMA-1met not only promoted autophagic vesicles (AVs) formation and AV-lysosome fusion, but also increased lysosomal degradation. Mechanistically, activation of mTOR/AMPK-ULK1-Vps34 autophagic signaling cascade was important for PRIMA-1met-induced autophagy. Furthermore, autophagy played a crucial role in the inhibitory effect of PRIMA-1met only in cells harboring wild-type p53, which was closely related to the increased Noxa.Conclusions: Our results indicated that PRIMA-1met induced autophagy in CRC cells regardless of p53 status via activating mTOR/AMPK-ULK1-Vps34 signaling cascade. However, induced autophagy was relevant to the cytotoxicity of PRIMA-1met in cells carrying wild-type p53, along with up-regulation of Noxa. Implying that, PRIMA-1met-based therapy could be an effective strategy for CRC.Trail registration: Not applicable.

Transferrin-induced endocytosis in stably transfected HeLa cells expressing wild-type and C282Y-mutant HFE measured by patch-clamp capacitance techniques

2001 ◽  
Vol 120 (5) ◽  
pp. A564-A565
Author(s):  
L SCHWAKE ◽  
A HENKEL ◽  
H RIEDEL ◽  
B HADASCHIK ◽  
T SCHLENKER ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Hela Cells ◽  
Wild Type

scholarly journals The GNAQ T96S Mutation Affects Cell Signaling and Enhances the Oncogenic Properties of Hepatocellular Carcinoma

2021 ◽  
Vol 22 (6) ◽  
pp. 3284
Author(s):  
Eugene Choi ◽  
Sung Jean Park ◽  
Gunhee Lee ◽  
Seung Kew Yoon ◽  
Minho Lee ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Expression Vector ◽  
Signal Transduction Pathway ◽  
Inhibitory Effect ◽  
The Cancer Genome Atlas ◽  
Treatment Modalities ◽  
Protein Signaling ◽  
Wild Type ◽  
Anchorage Independent Growth ◽  
Mapk Pathways

Hepatocellular carcinoma (HCC), the most common malignant tumor in the liver, grows and metastasizes rapidly. Despite advances in treatment modalities, the five-year survival rate of HCC remains less than 30%. We sought genetic mutations that may affect the oncogenic properties of HCC, using The Cancer Genome Atlas (TCGA) data analysis. We found that the GNAQ T96S mutation (threonine 96 to serine alteration of the Gαq protein) was present in 12 out of 373 HCC patients (3.2%). To examine the effect of the GNAQ T96S mutation on HCC, we transfected the SK-Hep-1 cell line with the wild-type or the mutant GNAQ T96S expression vector. Transfection with the wild-type GNAQ expression vector enhanced anchorage-independent growth, migration, and the MAPK pathways in the SK-Hep-1 cells compared to control vector transfection. Moreover, cell proliferation, anchorage-independent growth, migration, and the MAPK pathways were further enhanced in the SK-Hep-1 cells transfected with the GNAQ T96S expression vector compared to the wild-type GNAQ-transfected cells. In silico structural analysis shows that the substitution of the GNAQ amino acid threonine 96 with a serine may destabilize the interaction between the regulator of G protein signaling (RGS) protein and GNAQ. This may reduce the inhibitory effect of RGS on GNAQ signaling, enhancing the GNAQ signaling pathway. Single nucleotide polymorphism (SNP) genotyping analysis for Korean HCC patients shows that the GNAQ T96S mutation was found in only one of the 456 patients (0.22%). Our data suggest that the GNAQ T96S hotspot mutation may play an oncogenic role in HCC by potentiating the GNAQ signal transduction pathway.

Annona muricata silver nanoparticles exhibit strong anticancer activities against cervical and prostate adenocarcinomas through regulation of CASP9 and the CXCL1/CXCR2 genes axis

Tumor Biology ◽  
2021 ◽  
Vol 43 (1) ◽  
pp. 37-55
Author(s):  
Yahaya Gavamukulya ◽  
Esther N. Maina ◽  
Hany A. El-Shemy ◽  
Amos M. Meroka ◽  
Geoffrey K. Kangogo ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Anticancer Drugs ◽  
Hela Cells ◽  
Selectivity Index ◽  
Annona Muricata ◽  
Anticancer Activities ◽  
Apoptosis Pathway ◽  
Migration Assay ◽  
Intrinsic Apoptosis Pathway ◽  
In Cells

BACKGROUND: Green synthesized nanoparticles have been earmarked for use in nanomedicine including for the development of better anticancer drugs. OBJECTIVE: The aim of this study was to undertake biochemical evaluation of anticancer activities of green synthesized silver nanoparticles (AgNPs) from ethanolic extracts of fruits (AgNPs-F) and leaves (AgNPs-L) of Annona muricata. METHODS: Previously synthesized silver nanoparticles were used for the study. The effects of the AgNPs and 5-Fluorouracil were studied on PC3, HeLa and PNT1A cells. The resazurin, migration and colonogenic assays as well as qRT-PCR were employed. RESULTS: The AgNPs-F displayed significant antiproliferative effects against HeLa cells with an IC50 of 38.58μg/ml and PC3 cells with an IC50 of 48.17μg/ml but selectively spared normal PNT1A cells (selectivity index of 7.8), in comparison with first line drug 5FU and AgNPs-L whose selectivity index were 3.56 and 2.26 respectively. The migration assay revealed potential inhibition of the metastatic activity of the cells by the AgNPs-F while the colonogenic assay indicated the permanent effect of the AgNPs-F on the cancer cells yet being reversible on the normal cells in contrast with 5FU and AgNPs-L. CASP9 was significantly over expressed in all HeLa cells treated with the AgNPs-F (1.53-fold), AgNPs-L (1.52-fold) and 5FU (4.30-fold). CXCL1 was under expressed in HeLa cells treated with AgNPs-F (0.69-fold) and AgNPs-L (0.58-fold) and over expressed in cells treated with 5FU (4.95-fold), but the difference was not statistically significant. CXCR2 was significantly over expressed in HeLa cells treated with 5FU (8.66-fold) and AgNPs-F (1.12-fold) but under expressed in cells treated with AgNPs-L (0.76-fold). CONCLUSIONS: Here we show that biosynthesized AgNPs especially AgNPs-F can be used in the development of novel and better anticancer drugs. The mechanism of action of the AgNPs involves activation of the intrinsic apoptosis pathway through upregulation of CASP9 and concerted down regulation of the CXCL1/ CXCR2 gene axis.

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