scholarly journals Abstract 1990: Aberrant cell surface expression of GRP78 in breast cancer cells marks a stem-like population that has increased metastatic potentialin vivo

2018 ◽  
Author(s):  
Tyson W. Lager ◽  
Henry C. Conner ◽  
Ian H. Guldner ◽  
Michael Z. Wu ◽  
Yuriko Hishida ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Surface ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Aberrant Cell

scholarly journals Subcellular dynamics and functional activity of the cleaved Na+ channel β1 subunit intracellular domain

2021 ◽  
Author(s):  
Alexander S Haworth ◽  
Samantha L Hodges ◽  
Lori L Isom ◽  
Christoph G Baumann ◽  
William J Brackenbury
Keyword(s):  
Breast Cancer ◽  
Plasma Membrane ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Surface Expression ◽  
Proteolytic Processing ◽  
Cell Surface Expression ◽  
Na Channel ◽  
Na Current ◽  
Intracellular Domain

The voltage-gated Na+ channel β1 subunit, encoded by SCN1B, regulates cell surface expression and gating of α subunits, and participates in cell adhesion. β1 is cleaved by α/β and γ-secretases, releasing an extracellular domain and intracellular domain (ICD) respectively. Abnormal SCN1B expression/function is linked to pathologies including epilepsy, cardiac arrhythmia, and cancer. In this study, we sought to determine the effect of secretase cleavage on β1 function in breast cancer cells. Using a series of GFP-tagged β1 constructs, we show that β1-GFP is mainly retained intracellularly, particularly in the endoplasmic reticulum and endolysosomal pathway, and accumulates in the nucleus. Reduction in endosomal β1-GFP levels occurred following γ-secretase inhibition, implicating endosomes, and/or the preceding plasma membrane, as important sites for secretase processing. Using live-cell imaging, we report β1-ICD-GFP accumulation in the nucleus. Furthermore, β1-GFP and β1ICD-GFP both increased Na+ current, whereas β1STOP-GFP, which lacks the ICD, did not, thus highlighting that the β1-ICD was necessary and sufficient to increase Na+ current measured at the plasma membrane. Importantly, although the endogenous Na+ current expressed in MDA-MB-231 cells is TTX-resistant (carried by Nav1.5), the Na+ current increased by β1-GFP or β1ICD-GFP was TTX-sensitive. Taken together, this work suggests that the β1-ICD is a critical regulator of β subunit function. Our data further support the notion that γ-secretase may play a key role in regulating β1 function in breast cancer cells. This work thus highlights proteolytic processing of β1 by secretase cleavage to be a relevant mechanism in diseases associated with abnormal β1 function.

scholarly journals GRP78 regulates CD44v membrane homeostasis and cell spreading in tamoxifen-resistant breast cancer

2019 ◽  
Vol 2 (4) ◽  
pp. e201900377 ◽  
Author(s):  
Chun-Chih Tseng ◽  
Ramunas Stanciauskas ◽  
Pu Zhang ◽  
Dennis Woo ◽  
Kaijin Wu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Surface ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Cancer Metastasis ◽  
Cell Spreading ◽  
Single Particle Tracking ◽  
Cell Surface Expression ◽  
Juxtamembrane Region ◽  
Tamoxifen Resistant

GRP78 conducts protein folding and quality control in the ER and shows elevated expression and cell surface translocation in advanced tumors. However, the underlying mechanisms enabling GRP78 to exert novel signaling functions at cell surface are just emerging. CD44 is a transmembrane protein and an important regulator of cancer metastasis, and isoform switch of CD44 through incorporating additional variable exons to the extracellular juxtamembrane region is frequently observed during cancer progression. Using super-resolution dual-color single-particle tracking, we report that GRP78 interacts with CD44v in plasma membrane nanodomains of breast cancer cells. We further show that targeting cell surface GRP78 by the antibodies can effectively reduce cell surface expression of CD44v and cell spreading of tamoxifen-resistant breast cancer cells. Our results uncover new functions of GRP78 as an interacting partner of CD44v and as a regulator of CD44v membrane homeostasis and cell spreading. This study also provides new insights into anti-CD44 therapy in tamoxifen-resistant breast cancer.

scholarly journals Growth factor–induced shedding of syndecan-1 confers glypican-1 dependence on mitogenic responses of cancer cells

2005 ◽  
Vol 171 (4) ◽  
pp. 729-738 ◽  
Author(s):  
Kan Ding ◽  
Martha Lopez-Burks ◽  
José Antonio Sánchez-Duran ◽  
Murray Korc ◽  
Arthur D. Lander
Keyword(s):  
Breast Cancer ◽  
Growth Factor ◽  
Cell Surface ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Sulfate Proteoglycan ◽  
Matrix Metalloproteinase 7 ◽  
Over Time

The cell surface heparan sulfate proteoglycan (HSPG) glypican-1 is up-regulated by pancreatic and breast cancer cells, and its removal renders such cells insensitive to many growth factors. We sought to explain why the cell surface HSPG syndecan-1, which is also up-regulated by these cells and is a known growth factor coreceptor, does not compensate for glypican-1 loss. We show that the initial responses of these cells to the growth factor FGF2 are not glypican dependent, but they become so over time as FGF2 induces shedding of syndecan-1. Manipulations that retain syndecan-1 on the cell surface make long-term FGF2 responses glypican independent, whereas those that trigger syndecan-1 shedding make initial FGF2 responses glypican dependent. We further show that syndecan-1 shedding is mediated by matrix metalloproteinase-7 (MMP7), which, being anchored to cells by HSPGs, also causes its own release in a complex with syndecan-1 ectodomains. These results support a specific role for shed syndecan-1 or MMP7–syndecan-1 complexes in tumor progression and add to accumulating evidence that syndecans and glypicans have nonequivalent functions in vivo.

The Novel Plasminogen Receptor, Plg-RKT, and Breast Cancer Progression

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 853-853 ◽  
Author(s):  
Lindsey A Miles ◽  
Nagyung Baik ◽  
Stan Krajewski ◽  
Robert J Parmer ◽  
Barbara M Mueller
Keyword(s):  
Breast Cancer ◽  
Cell Surface ◽  
Cancer Cells ◽  
Human Breast Cancer ◽  
Breast Cancer Cells ◽  
Ductal Carcinoma ◽  
Lung Metastases ◽  
Treated Group ◽  
Human Breast ◽  
Plasminogen Activation System

Abstract Abstract 853 The ability of tumor cells to bind plasminogen is highly correlated with their invasive and metastatic potential. Here we evaluate cell surface plasminogen binding in human breast cancer. In a xenograft model for aggressive, triple-negative human breast cancer, tumor cells harvested from orthotopic mammary fat pad (mfp) tumors of the invasive human breast cancer line, MDA-MB-231, exhibit dramatic increases in tumor growth and lung and lymph node metastases, compared to parental cells. The breast cancer cells isolated from the mfp have been designated as 231mfp cells. Although the levels of most secreted proteins are similar, the plasminogen activators, urokinase-type plasminogen activator (uPA) and tissue type plasminogen activator (tPA) are highly upregulated in 231mfp cells, compared with MDA-MB-231 parental cells, suggesting a role for the plasminogen activation system in the differences in growth and metastasis between these two cell lines (Jessani et al., Proc Natl Acad Sci USA 101:13756, 2004). Further evaluation of the plasminogen activation system in this model revealed that plasminogen bound to both 231mfp and MDA-MB-231 cells and plasminogen binding was specifically inhibited by the lysine analog, ε-aminocaproic acid (EACA). 231mfp cells exhibited a 3-fold greater capacity for plasminogen compared to MDA-MB-231 cells: Quantitative FACS analysis yielded a Bmax of 3.8 ± 0.5 × 105 plasminogen binding sites with a Kd of 1.2 μM for the 231 mfp cells and a Bmax of 1.2 ± 0.3 × 105 binding sites with a Kd of 1.5 μM for the parental cells. We recently discovered a novel cell surface receptor for plasminogen, Plg-RKT (Andronicos et al., Blood 115:1319, 2010). Plg-RKT enhances enzymatic activation of plasminogen to plasmin and localizes and spatially orients plasmin on the cell surface. We compared cell-surface expression of Plg-RKT on 231mfp and MDA-MB-231 cells using a specific monoclonal antibody raised against the C-terminus of human Plg-RKT, termed mAb7H1. In FACS analysis with mAB7H1, expression of Plg-RKT was markedly (5-fold) higher on 231mfp cells, compared to the parental cells. These data were confirmed in Western blotting. To further determine expression of Plg-RKT in breast cancer, human tissues were stained with anti-Plg-RKT antibodies. We found very high expression of Plg-RKT in human invasive ductal carcinoma and ductal carcinoma in situ and minimal expression in normal breast ducts and lobules in control subjects. We considered whether Plg-RKT expressed on breast cancer cells can a therapeutic target and we tested the ability of anti-Plg-RKT mAb7H1 to inhibit lung metastasis of 231mfp cells in immune deficient mice. Mice were injected into the tail vein with cells either mixed with mAb7H1 or with buffer control. The antibody-treated group received a second dose of mAb7H1 24 hr later. Four weeks after tumor cell injection, mice were sacrificed and tumor foci on the lungs were compared between the two groups. Anti-Plg-RKT mAb7H1 markedly reduced the number of 231mfp lung metastases per mouse: mean number of lung foci in the mAb7H1 treated group was 109 (± 47.8) and in the vehicle-treated control group 270.4 (± 61.7), probability of no difference between the groups by t-test P<0.05. The size distribution of the individual foci was not different between the groups. These data demonstrate that anti-Plg-RKT mAb7H1 has activity in the mouse model of metastatic breast cancer and suggest that it interferes with an early step in the establishment of lung metastases. In summary, the highly metastatic 231mfp breast cancer cells have increased plasminogen binding capacity and increased expression of the plasminogen receptor, Plg-RKT, compared to parental MDA-MB-231 cells. Plg-RKT was highly expressed in human breast cancer tissue but not in normal mammary glands. Furthermore, anti-Plg-RKT mAb inhibited establishment of lung metastases in a model of human breast cancer. Therefore, the presence of Plg-RKT on breast cancer cells may represent a new control point in the establishment of breast cancer metastases. Disclosures: No relevant conflicts of interest to declare.

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