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Biomedical subjects

Z E Winters

Publications and source records attributed to Z E Winters.

9 recordsLinked to original sources
PubMed2006

Insulin-like growth factor binding protein 3 has opposing actions on malignant and nonmalignant breast epithelial cells that are each reversible and dependent upon cholesterol-stabilized integrin receptor complexes.

IGF-binding protein (IGFBP)-3 is generally considered to have actions that counterbalance those of IGFs and is therefore being developed as a cancer treatment. In breast tumors, however, high levels are associated with aggressive tumors and poor prognosis. Consistent with this we have demonstrated that although IGFBP-3 and a non-IGF-binding fragment (serine phosphorylation domain peptide) reduced attachment and enhanced apoptosis of Hs578T breast cancer cells cultured on collagen or laminin, it promoted their attachment and survival on fibronectin, which is abundant in the matrix of aggressive tumors. We have now examined the factors that determine whether IGFBP-3 has positive or negative actions on breast epithelial cells. IGFBP-3 also promoted survival of Hs578T cells in the presence of an antibody to the beta1-integrin subunit or when cholesterol-stabilized complexes were disrupted. These actions were blocked by IGF-I or a MAPK inhibitor. Serine phosphorylation domain peptide had similar actions on MCF-7 cells that were again reversed on fibronectin or with disruption of cholesterol-stabilized complexes and blocked by the beta1-integrin antibody. In contrast, IGFBP-3 promoted growth and survival for nonmalignant MCF-10A cells, but these effects were again reversed on fibronectin and blocked by the beta1 antibody or a MAPK inhibitor or by disruption of cholesterol-stabilized complexes. On Hs578T cells, IGFBP-3 bound to caveolin-1 and beta1-integrins, enhancing their aggregation, the recruitment of focal adhesion kinase, and the activation of MAPK. In summary, with three breast epithelial cell lines, IGFBP-3 had positive or negative effects on growth and survival dependent upon the status of cholesterol-stabilized integrin receptor complexes.

Apoptosis↗
PubMed2006

Randomized clinical trial of the effect of quilting latissimus dorsi flap donor site on seroma formation.

BACKGROUND: Latissimus dorsi (LD) flap breast reconstruction is associated with a high incidence of donor site seromas, despite the use of surgical drains. The aim of this study was to evaluate the use of donor site quilting sutures, as well as drains, on the incidence, volume and frequency of seroma aspiration. METHODS: The trial randomized 108 women undergoing LD breast reconstruction to quilting procedures (54) or control group (52) for intention-to-treat analysis; two were excluded. Outcome measures were the incidence and volume of postoperative seroma. Secondary outcome measures included postoperative back pain, analgesic consumption, shoulder movement and duration of hospital stay. RESULTS: Quilting significantly reduced the overall incidence of seroma from 46 of 48 (96 per cent) to 43 of 52 (83 per cent) (P = 0.036), including the 38 women who had extended LD flap (with or without implants). There were further significant reductions in seroma volume (P = 0.004), frequency of aspiration (P = 0.001) and overall seroma volumes, including surgical drainage and symptomatic seromas (P = 0.013). Subset analyses for LD-implant (60 women) and extended LD (with or without implant) showed similar significance. Quilting did not affect back pain or compromise shoulder mobility. CONCLUSION: Quilting significantly reduced overall seroma volumes after LD breast reconstruction including extended LD, and is recommended in combination with surgical drains.

Adult↗
PubMed2005

Activated Akt expression in breast cancer: correlation with p53, Hdm2 and patient outcome.

Activation of protein kinase-B/Akt (pAkt) is mediated by oestrogen and involves HER-2 in vitro, to phosphorylate Hdm2 and influence p53 cytoplasmic localisation and degradation. Expression of all active Akt isoforms (pAkt) were examined, together with p53/Hdm2 subcellular expression in invasive ductal breast cancers (IDCs), to evaluate whether in vitro findings were related to clinical data and determine the effect on outcome. Immunohistochemical expression of serine 473 specific phosphorylated Akt (pAkt) isoforms (Akt-1,2,3) was evaluated in 97 patients, together with subcellular expression of p53/Hdm2. The results show that pAkt was evaluable in 95 patients with cytoplasmic expression in 81% and more likely to be associated with larger tumours (P=0.007), with no correlation with HER-2 expression. pAkt correlated with increasing levels of cytoplasmic p53 (P=0.025) and was associated with a reduced disease-free survival (P=0.04; univariate). In conclusion, pAkt has implications in breast cancer growth through mechanisms inactivating p53 with an association with immunohistochemical p53 expression, which is preferentially cytoplasmic. Despite in vitro associations, pAkt appears to be a variable marker of HER-2 expression.

Adult↗
PubMed2004

p14ARF expression in invasive breast cancers and ductal carcinoma in situ--relationships to p53 and Hdm2.

INTRODUCTION: p14ARF stabilises nuclear p53, with a variable expression of p14ARF mRNA in breast cancers. In vitro, nuclear p14ARF binds Hdm2 to block Hdm2-dependent nucleocytoplasmic shuttling of p53, which is required before cytoplasmic degradation of p53. p14ARF is negatively regulated by p53 and through p53-independent pathways. No studies have yet examined levels of p14ARF protein expression in breast cancer and their relationship to Hdm2/p53 immunoreactivity or subcellular localisation. Previously, immunohistochemical expression of cytoplasmic p14ARF, p53 and Hdm2 has been described. HER-2 (c-erbB2/neu) predicts prognosis and interacts with the p14ARF/Hdm2 pathway to inactivate p14ARF and to influence Hdm2 activity and localisation. This study examined p14ARF and p53/Hdm2 expression and subcellular localisation by using immunohistochemistry in a series of invasive ductal breast cancers (IDCs) with concomitant ductal carcinoma in situ (DCIS), to evaluate whether findings in vitro were related to clinicopathological parameters such as HER-2 and their effect on patient outcome. METHODS: The 4C6 anti-p14ARF monoclonal antibody and Dako Envision Plus system were used to evaluate p14ARF expression in 103 patients; p53/Hdm2 staining was performed. RESULTS: p14ARF was evaluable in 96 patients, with nuclear p14ARF expression (modified Quick-score > or = 3) in 79% (n = 76) of IDCs and in associated DCIS in 74 patients. Cytoplasmic p14ARF was detectable in 23 breast cancers. Nuclear and cytoplasmic p14ARF showed no correlation with p53 subcellular immunoreactivity. Increasing levels of cytoplasmic p14ARF were associated with nuclear and cytoplasmic Hdm2 expression (P < 0.001). Subcellular ARF expression was not associated with clinicopathological parameters, and although not an independent prognosticator, these preliminary findings suggest that cytoplasmic p14ARF might be associated with a better overall survival (P = 0.09; log rank). The association between HER-2 positivity and nuclear p14ARF (P = 0.038), as well as nuclear Hdm2 (P = 0.019), reflects the in vitro findings of HER-2 interaction with the ARF/Hdm2 pathway. Cytoplasmic p53 and Hdm2 expression might have biological implications, through an association of cytoplasmic p53 with increased tumour proliferation (P = 0.005), and an improved overall survival (P = 0.002, log rank) in cytoplasmic Hdm2-expressing tumours, that independently predict favourable overall survival (P = 0.02) and disease-free survival (P = 0.03). CONCLUSIONS: Nuclear p14ARF expression is similar in IDCs and DCIS and is associated with Hdm2 immunoreactivity. Nuclear p14ARF and Hdm2 might be regulated by HER-2. Clearly, our findings in vivo suggest a complexity of p14ARF/Hdm2 and p53 pathways in which consideration of cytoplasmic p14ARF and Hdm2 might have tumorigenic implications.

Adult↗
PubMed2004

Prolactin acts as a potent survival factor for human breast cancer cell lines.

Human breast cancer is the leading cause of cancer death in women from Western societies, and a large study of the epidemiology demonstrated strong associations between human prolactin and risk of breast cancer. Using established models of apoptosis of human breast cancer cell lines, we assessed the role of prolactin in breast cancer cell growth and survival. We showed that prolactin had no effect on the metabolic activity or total cell number of any cell lines. We confirmed endogenous prolactin production by these cells and that the levels varied. In the presence of a prolactin-neutralising antibody, each of the cell lines responded with the induction of apoptosis as opposed to growth inhibition. The sensitivity of the cell lines to the physiological inducer of apoptosis, C2-ceramide, appeared relative to the levels of endogenous prolactin that they contained. We then showed that exogenously added prolactin acted as a potent survival factor against apoptosis in all the cell lines examined. In addition, we demonstrated that a prolactin-neutralising antibody in combination with C2-ceramide caused an anticipated, additive increase in cell death. This study demonstrated that prolactin protects human breast cancer cell lines against apoptosis and this may have important implications for cancer treatment.

Apoptosis↗
PubMed2002

P53 pathways involving G2 checkpoint regulators and the role of their subcellular localisation.

DNA damage activates checkpoint pathways to produce a G1 or G2 cell cycle arrest and DNA repair. G2 checkpoint integrity prevents inappropriate mitosis of unrepaired DNA. Cell cycle progression is determined by cyclin-dependent kinase (CDK) enzymes in association with specific cyclin proteins, with Cdc2/cyclin B regulating mitosis. The tumour suppressor p53 re-enforces G2 arrest through the CDK inhibitor, p21(WAF1/CIPI). Functional regulation of G2 checkpoint proteins occurs through levels of protein expression, phosphorylation and subcellular localisation

Apoptosis↗
PubMed2001

Subcellular localisation of cyclin B, Cdc2 and p21(WAF1/CIP1) in breast cancer. association with prognosis.

The heterodimeric cyclin B/Cdc2 protein kinase governs entry into mitosis, and can be negatively regulated through p53-mediated transcriptional induction of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1). Ectopic expression of p21(WAF1/CIP1) in cultured cells has been shown previously to influence the subcellular distribution of the cyclin-dependent kinases (CDKs) including Cdc2. In this study, we have examined the subcellular localisation of Cdc2, cyclin B and p21(WAF1/CIP1) by immunohistochemistry in a well characterised series of primary breast cancers. Surprisingly, p21(WAF1/CIP1) was predominantly cytoplasmic in many of the tumours, where it was associated with high p53 levels; cytoplasmic p21(WAF1/CIP1) and high cyclin B levels were also significant predictors of poor prognosis. We conclude that breast tumorigenesis may be characterised by abnormalities in pathways determining not only levels of expression of key regulatory molecules, but also their subcellular localisation. Investigation of the subcellular distribution of cell cycle regulatory proteins, particularly p21(WAF1/CIP1), could provide valuable prognostic markers in breast cancer.

Adult↗
PubMed1998

p53 regulates Cdc2 independently of inhibitory phosphorylation to reinforce radiation-induced G2 arrest in human cells.

We have investigated the influence of p53 on radiation-induced G2 cell cycle arrest using human H1299 cells expressing temperature-sensitive p53. Gamma-irradiated cells lacking p53 arrested transiently in G2 with Cdc2 extensively phosphorylated at the inhibitory sites Thr14 and Tyr15, and with both Cdc2 and cyclin B1 restricted to the cytoplasm. Activation of p53 by temperature shift resulted in a more protracted G2 arrest that could not be overridden by checkpoint-abrogating drugs. Surprisingly, this enhancement of G2 arrest was associated with a marked lack of inhibitory phosphorylation of Cdc2 and with the nuclear localization of both Cdc2 and cyclin B1. While transient expression of an A14F15 mutant form of Cdc2 that is not subject to inhibitory phosphorylation induced mitotic catastrophe in cells lacking p53, the p53-expressing cells were relatively refractory to this effect. Enforced expression of p21WAF1/CJP1 was sufficient to confer nuclear localization on Cdc2 in the p53 null cells, though immunodepletion experiments demonstrated that only a small proportion of Cdc2 was stably associated with p21WAF1/CJP1 in the p53-expressing cells. We conclude that a p53-dependent pathway can operate after exposure of human cells to ionising radiation to promote G2 arrest accompanied by nuclear translocation rather than inhibitory phosphorylation of Cdc2.

Biological Transport↗