scholarly journals Loss of SIM2s inhibits RAD51 binding and leads to unresolved replication stress

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Scott J. Pearson ◽  
Jessica Elswood ◽  
Rola Barhoumi ◽  
Brittini Ming-Whitfield ◽  
Monique Rijnkels ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Replication Fork ◽  
Replication Stress ◽  
Genotoxic Stress ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Genomic Integrity

Abstract Background Mutations in genes associated with homologous recombination (HR) increase an individual’s risk of developing triple-negative breast cancer (TNBC). Although known for their role in repairing dsDNA breaks, HR repair elements also stabilize and restart stalled replication forks. Essential to these functions are RAD51 and its paralogs, each of which has a unique role in preventing replication fork collapse and restart. However, progress toward understanding the regulation of these factors has been slow. With such a pivotal role in the maintenance of genomic integrity, furthering our understanding of this pathway through the discovery of new factors involved in HR is important. Recently, we showed that singleminded-2s (SIM2s) is stabilized in response to dsDNA breaks and is required for effective HR. Methods Initial analysis of the effect loss of SIM2s has on replication stress resolution was conducted using DNA combing assays in established breast cancer cell lines. Further analysis was conducted via immunostaining to determine the effect loss of SIM2s has on factor recruitment. In vivo confirmation was achieved through the use of a mammary epithelial cell conditional knockout mouse model before SIM2s’ role in RAD51 recruitment was determined by immunoblotting. Results Here, we show loss of SIM2s decreases replication fork stability, leading to fork collapse in response to genotoxic stress. Furthermore, loss of SIM2s results in aberrant separation of sister chromatids during mitosis, which has been previously shown to result in chromosomal fragmentation and aneuploidy. Interestingly, loss of SIM2s was shown to result in failure of RAD51 to localize to sites of replication stress in both breast cancer cell lines and primary mammary epithelial cells. Finally, we observed SIM2 is stabilized in response to genotoxic stress and interacts with RAD51, which is necessary for RAD51-DNA binding. Conclusions Together, these results show a role for SIM2s in the resolution of replication stress and further characterize the necessity of SIM2s for effective RAD51 loading in response to DNA damage or stress, ultimately promoting genomic integrity and thus preventing the accumulation of cancer-promoting mutations.

scholarly journals Profiling Flavonoid Cytotoxicity in Human Breast Cancer Cell Lines: Determination of Structure-Function Relationships

2012 ◽  
Vol 7 (10) ◽  
pp. 1934578X1200701 ◽  
Author(s):  
Sina Yadegarynia ◽  
Anh Pham ◽  
Alex Ng ◽  
Duong Nguyen ◽  
Tetiana Lialiutska ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Mammary Epithelial Cells ◽  
Cancer Cell Lines ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Mitochondrial Outer Membrane ◽  
Outer Membrane Permeability

Flavonoids have been shown to be cytotoxic to cancer cells. However, the mechanism of cytotoxicity has not been clearly defined. It has previously been reported that HER2/ERBB2, the estrogen receptor, progesterone receptor, and p53 were required for flavonoid induced cytotoxicity in breast cancer cell lines. We have used a panel of breast cancer cell lines, known to contain as well as be deficient in these signaling pathways, to screen fourteen different flavonoids. Comparing the cytotoxicity for all flavonoids allows us to determine if a structure-functional relationship exists between cytotoxicity and flavonoid, and if a particular signaling pathway is required for cytotoxicity. We show that several flavonoids are cytotoxic to all cell lines including primary mammary epithelial cells tested. The cytotoxic flavonoids are also able to inhibit Mitochondrial Outer Membrane Permeability while at the same time stimulate ATP levels whereas the non-cytotoxic flavonoids are not able to do this. We also show that both cytotoxic and non-cytotoxic flavonoids can transverse the cell membrane to enter MDA-MB-231 cells at different levels. Finally, all flavonoids regardless of their cytotoxicity were able to induce some form of cell cycle arrest. We conclude that for flavonoids to be strongly cytotoxic, they must possess the 2,3-double bond in the C-ring and we believe the cytotoxicity occurs through mitochondrial poisoning in both cancer and normal cells.

scholarly journals Profiling Flavonoid Cytotoxicity in Human Breast Cancer Cell Lines: Determination of Structure-Function Relationships

2014 ◽  
Vol 9 (5) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Sina Yadegarynia ◽  
Anh Pham ◽  
Alex Ng ◽  
Duong Nguyen ◽  
Tetiana Lialiutska ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Mammary Epithelial Cells ◽  
Cancer Cell Lines ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Mitochondrial Outer Membrane ◽  
Outer Membrane Permeability

Flavonoids have been shown to be cytotoxic to cancer cells. However, the mechanism of cytotoxicity has not been clearly defined. It has previously been reported that HER2/ERBB2, the estrogen receptor, progesterone receptor, and p53 were required for flavonoid induced cytotoxicity in breast cancer cell lines. We have used a panel of breast cancer cell lines, known to contain as well as be deficient in these signaling pathways, to screen fourteen different flavonoids. Comparing the cytotoxicity for all flavonoids allows us to determine if a structure-functional relationship exists between cytotoxicity and flavonoid, and if a particular signaling pathway is required for cytotoxicity. We show that several flavonoids are cytotoxic to all cell lines including primary mammary epithelial cells tested. The cytotoxic flavonoids are also able to inhibit Mitochondrial Outer Membrane Permeability while at the same time stimulate ATP levels whereas the non-cytotoxic flavonoids are not able to do this. We also show that both cytotoxic and non-cytotoxic flavonoids can transverse the cell membrane to enter MDA-MB-231 cells at different levels. Finally, all flavonoids regardless of their cytotoxicity were able to induce some form of cell cycle arrest. We conclude that for flavonoids to be strongly cytotoxic, they must possess the 2,3-double bond in the C-ring and we believe the cytotoxicity occurs through mitochondrial poisoning in both cancer and normal cells.

Lipidomic analysis of phospholipids from human mammary epithelial and breast cancer cell lines

2012 ◽  
Vol 228 (2) ◽  
pp. 457-468 ◽  
Author(s):  
M. Luísa Dória ◽  
Cândida Z. Cotrim ◽  
Cláudia Simões ◽  
Bárbara Macedo ◽  
Pedro Domingues ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Cancer Cell Lines ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Lipidomic Analysis ◽  
Human Mammary Epithelial

scholarly journals Oncogenic PIK3CA mutations increase dependency on the mRNA cap methyltransferase, RNMT, in breast cancer cells

Open Biology ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 190052 ◽  
Author(s):  
Sianadh Dunn ◽  
Olivia Lombardi ◽  
Radoslaw Lukoszek ◽  
Victoria H. Cowling
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Mammary Epithelial Cells ◽  
Cancer Therapeutics ◽  
Cancer Cell Lines ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Pik3ca Mutations

Basic mechanisms in gene expression are currently being investigated as targets in cancer therapeutics. One such fundamental process is the addition of the cap to pre-mRNA, which recruits mediators of mRNA processing and translation initiation. Maturation of the cap involves mRNA cap guanosine N-7 methylation, catalysed by RNMT (RNA guanine-7 methyltransferase). In a panel of breast cancer cell lines, we investigated whether all are equivalently dependent on RNMT for proliferation. When cellular RNMT activity was experimentally reduced by 50%, the proliferation rate of non-transformed mammary epithelial cells was unchanged, whereas a subset of breast cancer cell lines exhibited reduced proliferation and increased apoptosis. Most of the cell lines which exhibited enhanced dependency on RNMT harboured oncogenic mutations in PIK3CA, which encodes the p110α subunit of PI3Kα. Conversely, all cell lines insensitive to RNMT depletion expressed wild-type PIK3CA. Expression of oncogenic PIK3CA mutants, which increase PI3K p110α activity, was sufficient to increase dependency on RNMT. Conversely, inhibition of PI3Kα reversed dependency on RNMT, suggesting that PI3Kα signalling is required. Collectively, these findings provide evidence to support RNMT as a therapeutic target in breast cancer and suggest that therapies targeting RNMT would be most valuable in a PIK3CA mutant background.

scholarly journals Genotoxic stress leads to centrosome amplification in breast cancer cell lines that have an inactive G1/S cell cycle checkpoint

Oncogene ◽  
2004 ◽  
Vol 23 (23) ◽  
pp. 4068-4075 ◽  
Author(s):  
Antonino B D'Assoro ◽  
Robert Busby ◽  
Kelly Suino ◽  
Emmanuella Delva ◽  
Gustavo J Almodovar-Mercado ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Genotoxic Stress ◽  
Centrosome Amplification ◽  
Cell Cycle Checkpoint ◽  
Breast Cancer Cell Lines ◽  
Cycle Checkpoint

scholarly journals Evaluation of the antiproliferative effects of the HASPIN inhibitor CHR-6494 in breast cancer cell lines

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249912
Author(s):  
Hisayo Nishida-Fukuda ◽  
Keizo Tokuhiro ◽  
Yukio Ando ◽  
Hiroaki Matsushita ◽  
Morimasa Wada ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Mammary Epithelial Cells ◽  
Cancer Cell Lines ◽  
Mammary Epithelial ◽  
Breast Cancer Cell Lines ◽  
Antiproliferative Effects

HASPIN is a serine/threonine kinase that regulates mitosis by phosphorylating histone H3 at threonine 3. The expression levels of HASPIN in various cancers are associated with tumor malignancy and poor survival, suggesting that HASPIN inhibition may suppress cancer growth. As HASPIN mRNA levels are elevated in human breast cancer tissues compared with adjacent normal tissues, we examined the growth-suppressive effects of CHR-6494, a potent HASPIN inhibitor, in breast cancer cell lines in vitro and in vivo. We found that HASPIN was expressed in breast cancer cells of all molecular subtypes, as well as in immortalized mammary epithelial cells. HASPIN expression levels appeared to be correlated with the cell growth rate but not the molecular subtype of breast cancer. CHR-6494 exhibited potent antiproliferative effects against breast cancer cell lines and immortalized mammary epithelial cells in vitro, but failed to inhibit the growth of MDA-MB-231 xenografted tumors under conditions that have significant effects in a colorectal cancer model. These results imply that CHR-6494 does have antiproliferative effects in some situations, and further drug screening efforts are anticipated to identify more potent and selective HASPIN inhibition for use as an anticancer agent in breast cancer patients.

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