NUPR1 interacts with p53, transcriptionally regulates p21 and rescues breast epithelial cells from doxorubicin-induced genotoxic stress

Nuclear protein 1 (NUPR1/com1/p8) has been shown to interact with transcriptional regulators such as p300, PTIP, estrogen receptor-β, and SMAD. NUPR1 also has been implicated in the regulation of cell cycle and apoptosis. An increase in NUPR1 expression has been seen with serum starvation and in response to compounds such as cycloheximide, ceramide, and staurosporine. There are several overtly conflicting reports about the exact role of NUPR1 in tumor biology. This work investigates the nature of the relationship between NUPR1 and the cdk-inhibitor p21 (Waf1/Cip1) expression. We show that the expression of resident and doxorubicin-induced p21 paralleled that of endogenous NUPR1 levels. NUPR1 formed a complex with p53 and p300 and bound the p21 promoter and transcriptionally upregulated p21 expression. Moreover, NUPR1 allowed cells to progress through cell cycle in presence of doxorubicin. Since NUPR1 upregulated p21, concomitant with phosphorylation of Rb and upregulation of the anti-apoptotic protein, Bcl-xL we propose that NUPR1 expression imparts a cell growth and survival advantage. Importantly, we also report that NUPR1 conferred resistance to two chemotherapeutic drugs, Taxol and doxorubicin

ALDH1A1 Maintains Ovarian Cancer Stem Cell-Like Properties by Altered Regulation of Cell Cycle Checkpoint and DNA Repair Network Signaling

<div><p>Objective</p><p>Aldehyde dehydrogenase (ALDH) expressing cells have been characterized as possessing stem cell-like properties. We evaluated ALDH+ ovarian cancer stem cell-like properties and their role in platinum resistance.</p><p>Methods</p><p>Isogenic ovarian cancer cell lines for platinum sensitivity (A2780) and platinum resistant (A2780/CP70) as well as ascites from ovarian cancer patients were analyzed for ALDH+ by flow cytometry to determine its association to platinum resistance, recurrence and survival. A stable shRNA knockdown model for ALDH1A1 was utilized to determine its effect on cancer stem cell-like properties, cell cycle checkpoints, and DNA repair mediators.</p><p>Results</p><p>ALDH status directly correlated to platinum resistance in primary ovarian cancer samples obtained from ascites. Patients with ALDH^HIGH displayed significantly lower progression free survival than the patients with ALDH^LOW cells (9 vs. 3 months, respectively p<0.01). ALDH1A1-knockdown significantly attenuated clonogenic potential, PARP-1 protein levels, and reversed inherent platinum resistance. ALDH1A1-knockdown resulted in dramatic decrease of KLF4 and p21 protein levels thereby leading to S and G2 phase accumulation of cells. Increases in S and G2 cells demonstrated increased expression of replication stress associated Fanconi Anemia DNA repair proteins (FANCD2, FANCJ) and replication checkpoint (pS317 Chk1) were affected. ALDH1A1-knockdown induced DNA damage, evidenced by robust induction of γ-H2AX and BAX mediated apoptosis, with significant increases in BRCA1 expression, suggesting ALDH1A1-dependent regulation of cell cycle checkpoints and DNA repair networks in ovarian cancer stem-like cells.</p><p>Conclusion</p><p>This data suggests that ovarian cancer cells expressing ALDH1A1 may maintain platinum resistance by altered regulation of cell cycle checkpoint and DNA repair network signaling.</p></div

ALDH1A1 down regulation differentially affects on cancer stem cell properties.

<p>Lentiviral vectors expressing ALDH1A1 specific shRNAs or nontargeting shRNAs were transfected into A2780/CP70 cells and its effect on stem-like cell properties were evaluated for invasive potential using Matrigel invasion chambers (A), quantitative data as represented (B), clonogenic potential using soft agar colony formation (C, and carboplatin dependent growth inhibition by CellTiter-Glo Luminescent Cell Viability Assay (D). Statistical significance was evaluated using student’s <i>t-test.</i></p

ALDH1A1 status correlates with progression free survival in ovarian cancer patients.

<p>Ascites from 15 consecutive patients with primary advanced stage III/IV ovarian cancer and 2 from benign (Miegs syndrome) was obtained and analyzed for percentage of ALDH+ cells through ALDEFLUOR assay. The histogram in inset shows the percent of ALDH+ cells in benign and malignant ascites (A). The clinicopathologic information from the ovarian cancer patients were correlated with the percent of ALDH+ cells in their ascites and evaluated progression free survival with ALDH^HIGH (>15% ALDH) to ALDH^LOW (<15% ALDH) patients (3 vs. 9 months, respectively; <i>p</i><0.01) (B).</p