Andrew Craig Schofield

The clinical and complete pathological response of a primary breast cancer to chemotherapy has been shown to be an important prognostic for survival. However, the majority of patients do not experience a complete pathological response to primary chemotherapy and the significance of lesser degrees of histological response is uncertain and the prognostic significance is unknown. The purpose of this study was to evaluate a new histological grading system to assess response of breast cancers to primary chemotherapy and to determine if such a system has prognostic value.A consecutive series of 176 patients with large (> or =4cm) and locally advanced breast cancers were treated with multimodality therapy comprising primary chemotherapy, surgery, radiotherapy and tamoxifen. All underwent assessment of the primary breast tumour before and after completion of chemotherapy. Residual tumour was excised after completion of chemotherapy (mastectomy or wide local excision with axillary surgery). The removed tissue was assessed and response to chemotherapy graded using a five-point histological grading system based with the fundamental feature being a reduction in tumour cellularity; comparison being made with a pre-treatment core biopsy. All patients were followed up for 5 years or more. Pathological responses were compared to 5 year overall survival and disease-free survival using log rank tests. The overall 5-year survival for all patients was 71%, and 5 year disease free interval was 60%. There was a significant correlation between pathological response using this new grading system and both overall survival (P=0.02) and disease-free interval (P=0.04). In a multivariate analysis of known prognostic factors, the Miller/Payne grading system was an independent predictor of overall patient survival. This grading system, which assesses the histological response to primary chemotherapy, can predict overall survival and disease-free interval in patients with large and locally advanced breast cancers treated with such therapy. The relationship of degree of histological response to overall and disease-free survival has been shown in univariate and multivariate analyses and could potentially have an important role in the clinical management of patients with locally advanced breast cancer undergoing primary chemotherapy.

Plants can survive a limiting nitrogen (N) supply by developing a set of N limitation adaptive responses. However, the Arabidopsis nla (nitrogen limitation adaptation) mutant fails to produce such responses, and cannot adapt to N limitation. In this study, the nla mutant was utilized to understand further the effect of NLA on Arabidopsis adaptation to N limitation. Grown with limiting N, the nla mutant could not accumulate anthocyanins and instead produced an N limitation-induced early senescence phenotype. In contrast, when supplied with limiting N and limiting phosphorus (Pi), the nla mutants accumulated abundant anthocyanins and did not show the N limitation-induced early senescence phenotype. These results support the hypothesis that Arabidopsis has a specific pathway to control N limitation-induced anthocyanin synthesis, and the nla mutation disrupts this pathway. However, the nla mutation does not affect the Pi limitation-induced anthocyanin synthesis pathway. Therefore, Pi limitation induced the nla mutant to accumulate anthocyanins under N limitation and allowed this mutant to adapt to N limitation. Under N limitation, the nla mutant had a significantly down-regulated expression of many genes functioning in anthocyanin synthesis, and an enhanced expression of genes involved in lignin production. Correspondingly, the nla mutant grown with limiting N showed a significantly lower production of anthocyanins (particularly cyanidins) and an increase in lignin contents compared with wild-type plants. These data suggest that NLA controls Arabidopsis adaptability to N limitation by channelling the phenylpropanoid metabolic flux to the induced anthocyanin synthesis, which is important for Arabidopsis to adapt to N limitation.

The RING-type E3 ligase, Keep on Going (KEG), is required for early seedling establishment in Arabidopsis thaliana. Post-germination, KEG negatively regulates abscisic acid (ABA) signalling by targeting Abscisic Acid Insensitive 5 (ABI5) for ubiquitination and subsequent degradation. Previous reports suggest that the role of KEG during early seedling development is not limited to regulation of ABI5 abundance. Using a yeast two-hybrid screen, this study identified Calcineurin B-like Interacting Protein Kinase (CIPK) 26 as a KEG-interacting protein. In vitro pull-down and in planta bimolecular fluorescence complementation assays confirmed the interactions between CIPK26 and KEG. In planta experiments demonstrated that CIPK26 was ubiquitinated and degraded via the 26S proteasome. It was also found that turnover of CIPK26 was increased when KEG protein levels were elevated, suggesting that the RING-type E3 ligase is involved in targeting CIPK26 for degradation. CIPK26 was found to interact with the ABA signalling components ABI1, ABI2, and ABI5. In addition, CIPK26 was capable of phosphorylating ABI5 in vitro. Consistent with a role in ABA signalling, overexpression of CIPK26 increased the sensitivity of germinating seeds to the inhibitory effects of ABA. The data presented in this report suggest that KEG mediates the proteasomal degradation of CIPK26 and that CIPK26 is part of the ABA signalling network.