Inhibition of XPO1 (CRM1)-mediated nuclear export of multiple tumor suppressor proteins has been proposed as a novel cancer therapeutic strategy to turn off oncogenic signals and enhance tumor ...suppression. Survivin is a multifunctional protein with oncogenic properties when expressed in the cytoplasm that requires the XPO1-RanGTP complex for its nuclear export. We investigated the antitumor mechanisms of the drug-like selective inhibitors of nuclear export (SINE) XPO1 antagonists KPT-185, KPT-251 KPT-276, and KPT-330 in estrogen receptor-positive and triple-negative breast cancer (TNBC) cell lines and xenograft models of human breast tumors. KPT compounds significantly inhibited breast cancer cell growth and induced tumor cell death, both in vitro and in vivo. These drugs initially promoted survivin accumulation within tumor cell nuclei. However, their major in vitro effect was to decrease survivin cytoplasmic protein levels, correlating with the onset of apoptosis. XPO1 inhibition repressed Survivin transcription by inhibiting CREB-binding protein-mediated STAT3 acetylation, and blocking STAT3 binding to the Survivin promoter. In addition, caspase-3 was activated to cleave survivin, rendering it unavailable to bind X-linked inhibitor of apoptosis protein and block the caspase cascade. Collectively, these data demonstrate that XPO1 inhibition by SINE compounds represses STAT3 transactivation to block the selective oncogenic properties of survivin and supports their clinical use in TNBC.
Perioperative strokes are a major cause of death and disability. There is limited information on which to base decisions for how long to delay elective nonneurologic, noncardiac surgery in patients ...with a history of stroke.
To examine whether an association exists between the time elapsed since an ischemic stroke and the risk of recurrent stroke in older patients undergoing elective nonneurologic, noncardiac surgery.
This cohort study used data from the 100% Medicare Provider Analysis and Review files, including the Master Beneficiary Summary File, between 2011 and 2018 and included elective nonneurologic, noncardiac surgeries in patients 66 years or older. Patients were excluded if they had more than 1 procedure during a 30-day period, were transferred from another hospital or facility, were missing information on race and ethnicity, were admitted in December 2018, or had tracheostomies or gastrostomies. Data were analyzed May 7 to October 23, 2021.
Time interval between a previous hospital admission for acute ischemic stroke and surgery.
Acute ischemic stroke during the index surgical admission or rehospitalization for stroke within 30 days of surgery, 30-day all-cause mortality, composite of stroke and mortality, and discharge to a nursing home or skilled nursing facility. Multivariable logistic regression models were used to estimate adjusted odds ratios (AORs) to quantify the association between outcome and time since ischemic stroke.
The final cohort included 5 841 539 patients who underwent elective nonneurologic, noncardiac surgeries (mean SD age, 74.1 6.1 years; 3 371 329 57.7% women), of which 54 033 (0.9%) had a previous stroke. Patients with a stroke within 30 days before surgery had higher adjusted odds of perioperative stroke (AOR, 8.02; 95% CI, 6.37-10.10; P < .001) compared with patients without a previous stroke. The adjusted odds of stroke were not significantly different at an interval of 61 to 90 days between previous stroke and surgery (AOR, 5.01; 95% CI, 4.00-6.29; P < .001) compared with 181 to 360 days (AOR, 4.76; 95% CI, 4.26-5.32; P < .001). The adjusted odds of 30-day all-cause mortality were higher in patients who underwent surgery within 30 days of a previous stroke (AOR, 2.51; 95% CI, 1.99-3.16; P < .001) compared with those without a history of stroke, and the AOR decreased to 1.49 (95% CI, 1.15-1.92; P < .001) at 61 to 90 days from previous stroke to surgery but did not decline significantly, even after an interval of 360 or more days.
The findings of this cohort study suggest that, among patients undergoing nonneurologic, noncardiac surgery, the risk of stroke and death leveled off when more than 90 days elapsed between a previous stroke and elective surgery. These findings suggest that the recent scientific statement by the American Heart Association to delay elective nonneurologic, noncardiac surgery for at least 6 months after a recent stroke may be too conservative.
Survivin is an inhibitor of apoptosis protein that also plays critical roles in regulating the cell cycle and mitosis. Its prominent expression in essentially all human malignancies, and low or ...absent expression in most normal tissues, suggests that it would be an ideal target for cancer-directed therapy. Impeding development of safe and effective survivin antagonists for clinical use is a lack of understanding of the molecular mechanisms by which survivin differentially affects apoptosis and cell division, in normal and malignant cells. We show that the diverse functional roles of survivin can be explained, in part, by its heterodimerization with survivin splice variants in tumor cells. Survivin and survivin-DeltaEx3 interact within the mitochondria where they may inhibit mitochondrial-dependent apoptosis. If the expression of all survivin forms is eliminated by siRNA transfections, cells undergo both apoptosis and defective cell division. Overall, we provide new insights suggesting that targeting specific survivin isoforms, rather than survivin alone, may selectively and effectively destroy tumor cells. These findings are likely to have a significant impact in the design of biologic agents for clinical therapy.
Survivin is an oncogenic protein that is highly expressed in breast cancer and has a dual function that is dependent on its subcellular localization. In the cytosol, survivin blocks programmed cell ...death by inactivating caspase proteins; however, in the nucleus it facilitates cell division by regulating chromosomal movement and cytokinesis. In prior work, we showed that survivin is acetylated by CREB-binding protein (CBP), which restricts its localization to the nuclear compartment and thereby inhibits its anti-apoptotic function. Here, we identify histone deacetylase 6 (HDAC6) as responsible for abrogating CBP-mediated survivin acetylation in the estrogen receptor (ER)-positive breast cancer cell line, MCF-7. HDAC6 directly binds survivin, an interaction that is enhanced by CBP. In quiescent breast cancer cells in culture and in malignant tissue sections from ER+ breast tumors, HDAC6 localizes to a perinuclear region of the cell, undergoing transport to the nucleus following CBP activation where it then deacetylates survivin. Genetically modified mouse embryonic fibroblasts that lack mhdac6 localize survivin predominantly to the nuclear compartment, whereas wild-type mouse embryonic fibroblasts localize survivin to distinct cytoplasmic structures. Together, these data imply that HDAC6 deacetylates survivin to regulate its nuclear export, a feature that may provide a novel target for patients with ER+ breast cancer.
Background: Survivin is an oncogenic protein that is acetylated by CBP, which restricts its location to the nuclear compartment and blocks its anti-apoptotic effect.
Results: HDAC6 deacetylates survivin to promote its nuclear exit in estrogen receptor-positive breast cancer cells.
Conclusion: Cross-talk between estrogen, CBP, and HDAC6 regulate the amount of nuclear acetylated survivin.
Significance: Understanding how estrogen regulates survivin nuclear export may influence breast cancer treatment.
Neuroblastoma is an embryonal tumor of childhood with a heterogenous clinical presentation that reflects differences in activation of complex biological signaling pathways. Protein phosphorylation is ...a key component of cellular signal transduction and plays a critical role in processes that control cancer cell growth and survival. We used shotgun LC/MS to compare phosphorylation between a human MYCN amplified neuroblastoma cell line (NB10), modeling a resistant tumor, and a human neural precursor cell line (NPC), modeling a normal baseline neural crest cell. 2181 unique phosphorylation sites representing 1171 proteins and 2598 phosphopeptides were found. Protein kinases accounted for 6% of the proteome, with a predominance of tyrosine kinases, supporting their prominent role in oncogenic signaling pathways. Highly abundant receptor tyrosine kinase (RTK) phosphopeptides in the NB10 cell line relative to the NPC cell line included RET, insulin-like growth factor 1 receptor/insulin receptor (IGF-1R/IR), and fibroblast growth factor receptor 1 (FGFR1). Multiple phosphorylated peptides from downstream mediators of the PI3K/AKT/mTOR and RAS pathways were also highly abundant in NB10 relative to NPC. Our analysis highlights the importance of RET, IGF-1R/IR and FGFR1 as RTKs in neuroblastoma and suggests a methodology that can be used to identify potential novel biological therapeutic targets. Furthermore, application of this previously unexploited technology in the clinic opens the possibility of providing a new wide-scale molecular signature to assess disease progression and prognosis.
The CALM-PD trial evaluated the development of motor complications in subjects with early Parkinson disease (PD) randomized to initial treatment with either pramipexole or levodopa. A secondary ...finding of the trial was a higher than anticipated development or worsening of somnolence and edema and development of hallucinations.
To investigate risk factors for somnolence, edema, and hallucinations in patients with early PD initiating dopaminergic therapy.
This was a secondary analysis of data from the CALM-PD trial. Baseline patient characteristics were evaluated for their associations with the development or worsening of somnolence and edema and the development of hallucinations using Cox proportional hazards regression models.
Kaplan-Meier estimates of the 4-year incidence of the development or worsening of somnolence and edema and the development of hallucinations were 35%, 45%, and 17%. Initial pramipexole treatment (hazard ratio HR 2.22, 95% CI 1.41, 3.50, p < 0.001), male gender (HR 1.79, 95% CI 1.09, 2.93, p = 0.02), and >5 systems with a comorbid illness (HR 1.62, 95% CI 1.04, 2.51, p = 0.03) were associated with somnolence. Initial pramipexole treatment (HR 3.18, 95% CI 1.95, 5.18, p < 0.0001), female gender (HR 1.46, 95% CI 0.94, 2.27, p = 0.09), and comorbid cardiac disease (HR 1.59, 95% CI 1.02, 2.47, p = 0.04) were associated with edema. Age > or =65 (HR 2.06, 95% CI 0.98, 4.32, p = 0.06), Mini-Mental State Examination score >28 (HR 0.42, 95% CI 0.19, 0.91, p = 0.03), and >5 systems with a comorbid illness (HR 3.42, 95% CI 1.59, 7.38, p = 0.002) were associated with hallucinations.
Comorbid illnesses are important and overlooked risk factors for the development of somnolence, edema, and hallucinations. When initiating therapy with pramipexole, patients should be counseled about and monitored for somnolence and edema. Slight decrements in cognitive function and older age are associated with an increased risk of hallucinations.
The multiple functions of the oncofetal protein survivin are dependent on its selective expression patterns within immunochemically distinct subcellular pools. The mechanism by which survivin ...localizes to these compartments, however, is only partly understood. Here we show that nuclear accumulation of survivin is promoted by CREB-binding protein (CBP)-dependent acetylation on lysine 129 (129K, Lys-129). We demonstrate a mechanism by which survivin acetylation at this position results in its homodimerization, while deacetylation promotes the formation of survivin monomers that heterodimerize with CRM1 and facilitate its nuclear export. Using proteomic analysis, we identified the oncogenic transcription factor STAT3 as a binding partner of nuclear survivin. We show that acetylated survivin binds to the N-terminal transcriptional activation domain of the STAT3 dimer and represses STAT3 transactivation of target gene promoters. Using multiplex PCR and DNA sequencing, we identified a single-nucleotide polymorphism (A → G) at Lys-129 that exists as a homozygous mutation in a neuroblastoma cell line and corresponds with a defect in survivin nuclear localization. Our results demonstrate that the dynamic equilibrium between survivin acetylation and deacetylation at amino acid 129 determines its interaction with CRM1, its subsequent subcellular localization, and its ability to inhibit STAT3 transactivation, providing a potential route for therapeutic intervention in STAT3-dependent tumors.
Survivin is a putative oncogene that is aberrantly expressed in cancer cells. It has been hypothesized to play a central role in cancer progression and resistance to therapy in diverse tumor types. ...Although some of the transcriptional processes regulating its expression have been established, the diversity of genes that may be controlling the levels of its expression in both normal cells as well as in cancer cells has not been fully explored. The most common genetically mutated pathways in human malignancies are the p53 tumor suppressor pathway and the RB/E2F pathway. Both of these pathways, when intact, provide essential checkpoints in the maintenance of normal cell growth and protect the cell from DNA damage. Using non-transformed embryonic fibroblasts, we provide evidence of a molecular link between the regulation of survivin transcription and the RB/E2F family of proteins. We demonstrate that both pRB and p130 can interact with the survivin promoter and can repress survivin transcription. We also show that the E2F activators (E2F1, E2F2, and E2F3) can bind to the survivin promoter and induce survivin transcription. Genetically modified cells that harbor deletions in various members of the RB/E2F family confirm our data from the wild-type cells. Our findings implicate several members of the RB/E2F pathway in an intricate mechanism of survivin gene regulation that, when genetically altered during the process of tumorigenesis, may function within cancer cells to aberrantly alter survivin levels and enhance tumor progression.
CRM1 (Chromosomal Maintenance 1, also known as Exportin 1) is the major mammalian export protein that facilitates the transport of large macromolecules including RNA and protein across the nuclear ...membrane to the cytoplasm. The gene encoding CRM1 was originally identified in yeast as required to maintain higher order chromosome structure. In mammalian cells, CRM1 was found to bind several nuclear pore proteins hence its role in nuclear-cytosolic transport was discovered. In addition to nuclear-cytosolic transport, CRM1 also plays a role in centrosome duplication and spindle assembly, especially in response to DNA damage. The crystal structure of CRM1 suggests a complex protein that binds the Ran protein bound to GTP, allowing for a conformational change that facilitates binding to different cargo proteins through a nuclear export signal (NES). Included in the cadre of cargo are multiple tumor suppressor and oncoproteins as p53, BRCA1, Survivin, NPM, and APC, which function in the nucleus to regulate transcription or aid in chromosomal assembly and movement. An imbalance in the cytosolic level of these proteins has been observed in cancer cells, resulting in either inactivation (tumor suppressor) or an excess of anti-apoptotic activity (oncoprotein). Thus, the concept of inhibiting CRM1 has been explored as a potential therapeutic intervention. Indeed, inhibition of CRM1 by a variety of small molecules that interfere with cargo-NES binding results in cancer cell death. Whether all of these proteins together are responsible for this phenotype or whether specific proteins are required for this effect is unclear at this time.
We postulated that changes in cardiac high-energy phosphate metabolism may underlie the myocardial dysfunction caused by hypobaric hypoxia. Healthy volunteers (n=14) were studied immediately before, ...and within 4 d of return from, a 17-d trek to Mt. Everest Base Camp (5300 m). ³¹P magnetic resonance (MR) spectroscopy was used to measure cardiac phosphocreatine (PCr)/ATP, and MR imaging and echocardiography were used to assess cardiac volumes, mass, and function. Immediately after returning from Mt. Everest, total body weight had fallen by 3% (P<0.05), but left ventricular mass, adjusted for changes in body surface area, had disproportionately decreased by 11% (P<0.05). Alterations in diastolic function were also observed, with a reduction in peak left ventricular filling rates and mitral inflow E/A, by 17% (P<0.05) and 24% (P<0.01), respectively, with no change in hydration status. Compared with pretrek, cardiac PCr/ATP ratio had decreased by 18% (P<0.01). Whether the abnormalities were even greater at altitude is unknown, but all had returned to pretrek levels after 6 mo. The alterations in cardiac morphology, function, and energetics are similar to findings in patients with chronic hypoxia. Thus, a decrease in cardiac PCr/ATP may be a universal response to periods of sustained low oxygen availability, underlying hypoxia-induced cardiac dysfunction in healthy human heart and in patients with cardiopulmonary diseases.--Holloway, C. J., Montgomery, H. U., Murray, A. J., Cochlin, L. E., Codreanu, I. Hopwood, N., Johnson, A. W., Rider, O. J., Levett, D. Z. H., Tyler, D. J., Francis, J. M., Neubauer, S., Grocott, M. P. W., Clarke, K., for the Caudwell Xtreme Everest Research Group. Cardiac response to hypobaric hypoxia: persistent changes in cardiac mass, function, and energy metabolism after a trek to Mt. Everest Base Camp.
PDF
