YB-1 Mediates a Crosstalk between ERα and TGFβ Signaling in Breast Cancer Cells

The multifunctional Y-box binding protein-1 (YB-1) belongs to the highly conserved family of cold shock proteins being involved in transcriptional/translational regulation, DNA repair as well as stress response. Additionally, it is highly expressed in many malignant tissues which seems to correlate with a high proliferation level, drug resistance and a poor prognosis in a variety of tumors including breast cancer.Using quantitative immunohistochemistry we now confirm the previously described negative prognostic impact of YB-1 on survival in a clinical study with tumor samples from 199 breast cancer patients (p=0.0146; median follow up 79 months).Treatment of the estrogen receptor α (ERα) positive human breast cancer cell line MCF-7 with antiestrogens (4-hydroxytamoxifen, faslodex) resulted in a time and dose dependent decrease of YB-1 expression on the RNA- as well as on the protein level. In contrast, antiestrogen treatment of the ERα negative cell line MDA-MB-231 does not have any effect indicating that the antiestrogen effect on YB-1 is mediated by ERα. We have already demonstrated that the action of all antiestrogens is at least partially mediated by transforming growth factor β (TGFβ) (e.g. Breast Cancer Res. Treat. 107: 15-24, 2008). Using TGFβ-responsive reporter gene assays we now show that overexpression of YB-1 in MCF-7 cells enhances the induction of p3TPlux activity by TGFβ suggesting a crosstalk between YB-1 and TGFβ signaling pathways. Moreover, YB-1 also increases the antiestrogen induction of the TGFβ2-mRNA level coming along with a YB-1 regulated enhancement of the antiestrogen effect on cell growth.Very recent findings of our group point towards a ligand-independent influence of ERα on TGFβ signaling (Breast Cancer Res. Treat., in press). Due to the antiestrogen regulation of YB-1 via ERα and its crosstalk with the TGFβ pathway, the potential role of YB-1 as a mediator of the interaction between ERα and TGFβ signaling was analyzed. Performing pull-down assays with recombinant GST-ERα and whole cell lysates of MCF-7 cells confirms a protein-protein interaction between YB-1 and ERα. The physiological relevance of this interaction could be demonstrated, as the TGFβ-induced p3TPlux activity is clearly modulated by both, YB-1 and ERα.In conclusion, we present evidence that YB-1 and TGFβ signaling are functionally linked in MCF-7 cells. Combined with the detection of a physical interaction between YB-1 and ERα, our findings shed new light on a potential role of YB-1 as a part of the mechanism responsible for switching TGFβ from its anti-proliferative role in early tumor stages to tumor promoting effects in late-stage disease, most likely via a YB-1 regulated shift of TGFβ-signaling to pro-invasive pathways. This would also explain why high levels of YB-1 correlate with a poor prognosis in breast cancer patients.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4172.

Identification of claudin-4 as a marker highly overexpressed in both primary and metastatic prostate cancer

In the quest for markers of expression and progression for prostate cancer (PCa), the majority of studies have focussed on molecular data exclusively from primary tumours. Although expression in metastases is inferred, a lack of correlation with secondary tumours potentially limits their applicability diagnostically and therapeutically. Molecular targets were identified by examining expression profiles of prostate cell lines using cDNA microarrays. Those genes identified were verified on PCa cell lines and tumour samples from both primary and secondary tumours using real-time RT–PCR, western blotting and immunohistochemistry. Claudin-4, coding for an integral membrane cell-junction protein, was the most significantly (P<0.00001) upregulated marker in both primary and metastatic tumour specimens compared with benign prostatic hyperplasia at both RNA and protein levels. In primary tumours, claudin-4 was more highly expressed in lower grade (Gleason 6) lesions than in higher grade (Gleason ⩾7) cancers. Expression was prominent throughout metastases from a variety of secondary sites in fresh-frozen and formalin-fixed specimens from both androgen-intact and androgen-suppressed patients. As a result of its prominent expression in both primary and secondary PCas, together with its established role as a receptor for Clostridium perfringens enterotoxin, claudin-4 may be useful as a potential marker and therapeutic target for PCa metastases.

Compensatory and long-range changes in picosecond-nanosecond main-chain dynamics upon complex formation: 15N relaxation analysis of the free and bound states of the ubiquitin-like domain of human plexin-B1 and the small GTPase Rac1

The formation of a complex between Rac1 and the cytoplasmic domain of plexin-B1 is one of the first documented cases of a direct interaction between a small guanosine 5'-triphosphatase (GTPase) and a transmembrane receptor. Structural studies have begun to elucidate the role of this interaction for the signal transduction mechanism of plexins. Mapping of the Rac1 GTPase surface that contacts the Rho GTPase binding domain of plexin-B1 by solution NMR spectroscopy confirms the plexin domain as a GTPase effector protein. Regions neighboring the GTPase switch I and II regions are also involved in the interaction and there is considerable interest to examine the changes in protein dynamics that take place upon complex formation. Here we present main-chain nitrogen-15 relaxation measurements for the unbound proteins as well as for the Rho GTPase binding domain and Rac1 proteins in their complexed state. Derived order parameters, S2, show that considerable motions are maintained in the bound state of plexin. In fact, some of the changes in S2 on binding appear compensatory, exhibiting decreased as well as increased dynamics. Fluctuations in Rac1, already a largely rigid protein on the picosecond-nanosecond timescale, are overall diminished, but isomerization dynamics in the switch I and II regions of the GTPase are retained in the complex and appear to be propagated to the bound plexin domain. Remarkably, fluctuations in the GTPase are attenuated at sites, including helices alpha6 (the Rho-specific insert helix), alpha7 and alpha8, that are spatially distant from the interaction region with plexin. This effect of binding on long-range dynamics appears to be communicated by hinge sites and by subtle conformational changes in the protein. Similar to recent studies on other systems, we suggest that dynamical protein features are affected by allosteric mechanisms. Altered protein fluctuations are likely to prime the Rho GTPase-plexin complex for interactions with additional binding partners.

Self-assembled monolayers of aromatic selenolates on noble metal substrates

Self-assembled monolayers (SAMs) formed from bis(biphenyl-4-yl) diselenide (BBPDSe) on Au(111) and Ag(111) substrates have been characterized by high-resolution X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, infrared reflection absorption spectroscopy, water contact angle measurements, and scanning tunneling microscopy (STM). BBPDSe was found to form contamination-free, densely packed, and well-ordered biphenyl selenolate (BPSe) SAMs on both Au and Ag. Spectroscopic data suggest very similar packing density, orientational order, and molecular inclination in BPSe/Au and BPSe/Ag. STM data give a similar intermolecular spacing of 5.3 +/- 0.4 A on both Au and Ag but exhibit differences in the exact arrangement of the BPSe molecules on these two substrates, with the (2 square root[3] x square root[3])R30 degrees and (square root[3] x square root[3])R30 degrees unit cells on Au and Ag, respectively. There is strong evidence for adsorbate-mediated substrate restructuring in the case of Au, whereas no clear statement on this issue can be made in the case of Ag. The film quality of the BPSe SAMs is superior to their thiol analogues, which is presumably related to a better ability of the selenolates to adjust the surface lattice of the substrate to the most favorable 2D arrangement of the adsorbate molecules. This suggests that aromatic selenolates represent an attractive alternative to the respective thiols.

Phase II study of gemcitabine and oxaliplatin in patients with recurrent ovarian cancer: an Australian and New Zealand Gynaecological Oncology Group study

Gemcitabine and oxaliplatin have shown single-agent activity in relapsed ovarian cancer. This combination was used to determine response rates, time-to-event efficacy measures, and toxicity in patients with recurrent ovarian cancer. Patients with prior platinum-based chemotherapy who had measurable lesions and/or elevated CA-125 levels were identified as group A (platinum-refractory/platinum-resistant patients) and group B (platinum-sensitive patients). All patients received gemcitabine 1000 mg/m(2) on days 1 and 8 and oxaliplatin 130 mg/m(2) on day 8 every 21 days for up to eight cycles. Seventy-five patients (21 in group A and 54 in group B), with a median age of 58 years (range, 37-78), were enrolled. A median of six cycles (range, 1-8) was administered. By intent-to-treat analysis, 15 patients with measurable disease achieved partial response for an overall best response rate of 20.0% (9.5% in group A and 24.1% in group B). CA-125 response was observed in 48.4% patients (30.0% in group A and 57.1% in group B). Median time to progressive disease was 7.1 months (95% CI, 5.6-9.0 months) with 5.0 months in group A and 8.3 months in group B. Median overall survival was 17.8 months (95% CI, 12.9-21.3 months) with 9.2 months for group A and 20.0 months for group B. Major grade 3/4 toxicities were neutropenia (61.3%), leukopenia (24.0%), nausea (16.0%), and vomiting (22.7%). We conclude that the combination of oxaliplatin and gemcitabine is active in patients with recurrent ovarian cancer, but the regimen is unsatisfactory for further study due to modest response and relatively high toxicity.

Phase II study of carboplatin followed by sequential gemcitabine and paclitaxel as first-line treatment for advanced ovarian cancer

The aim of this exploratory phase II study was to evaluate sequential chemotherapy with carboplatin followed by gemcitabine-paclitaxel combination in chemonaive patients with advanced ovarian cancer. The primary objective was to evaluate time to progressive disease (TTPD); secondary objectives included the evaluation of 1- and 3-year survival, response rates, and toxicity. Following initial debulking surgery or biopsy, patients with FIGO stage IIC-IV disease received four cycles of carboplatin area under the curve (AUC) 6 (day 1) every 21 days, followed by four cycles of gemcitabine 1000 mg/m(2) (days 1 and 8) and paclitaxel 175 mg/m(2) (day 8) every 21 days. A total of 47 patients enrolled, 44 (93.6%) completed the initial four cycles, and 39 patients (82.9%) completed the planned eight cycles. The median and maximum lengths of follow-up were 31.2 and 43.7 months, respectively. Median TTPD was 13.8 months (95% CI, 11.6-21.0 months), and median survival time was 31.2 months (95% CI, 25.2-39.6 months). Survival at 1 and 3 years was 95.7% and 44.2%, respectively. Of the 43 evaluable patients, most (95.3%) of them achieved a CA-125 marker response based on Gynecologic Cancer Intergroup (GCIG) definition. The partial response rate in the seven patients with measurable disease was 46.4%. Myelosuppression was the major toxicity, with grade 3 and 4 neutropenia observed in 76.6% patients and thrombocytopenia in 12.8% patients. The sequential approach of carboplatin followed by gemcitabine-paclitaxel as first-line treatment for patients with ovarian cancer is feasible and well tolerated, and depending upon the findings from other major trials, it may merit further evaluation.

Phase II trial of weekly docetaxel for patients with relapsed ovarian cancer who have previously received paclitaxel—ANZGOG 02-01

OBJECTIVE

To determine the response rate of weekly docetaxel in women with relapsed epithelial ovarian cancer previously treated with paclitaxel and at least one line of platinum-based chemotherapy.

METHODS

In this multi-center phase II trial, 37 patients with relapsed disease were enrolled and treated with weekly docetaxel at 35 mg/m for 5 out of 6 consecutive weeks. Two patient cohorts were considered, those who progressed or relapsed within 4 months (N=7) or at greater than 4 months (N=30) from the time of completing their last course of paclitaxel.

RESULTS

Patients in both cohorts received a median of 2 cycles of treatment (range; 1-4). In evaluable patients, the combined overall response rate, using both CA125 and RECIST response criteria was 18.9% (7/37; 95% CI; 10-34%). The combined overall progression-free survival was 3.1 months (95% CI; 2.5-3.8), and the combined overall survival was 12.3 months (95% CI; 8.2-16.4). Treatment was generally well tolerated with the only grade 4 toxicity being skin toxicity (3%). The most common grade 3 toxicities were fatigue (14%) and watery eyes (8%) with grade 3 neutropenia observed in only 5% of patients.

CONCLUSION

Weekly docetaxel is well tolerated and has activity in patients with relapsed ovarian cancer previously treated with platinum and paclitaxel.

A second paradigm for gene activation in bacteria

Control of gene expression is key to development and adaptation. Using purified transcription components from bacteria, we employ structural and functional studies in an integrative manner to elaborate a detailed description of an obligatory step, the accessing of the DNA template, in gene expression. Our work focuses on a specialized molecular machinery that utilizes ATP hydrolysis to initiate DNA opening and permits a description of how the events triggered by ATP hydrolysis within a transcriptional activator can lead to DNA opening and transcription. The bacterial EBPs (enhancer binding proteins) that belong to the AAA(+) (ATPases associated with various cellular activities) protein family remodel the RNAP (RNA polymerase) holoenzyme containing the sigma(54) factor and convert the initial, transcriptionally silent promoter complex into a transcriptionally proficient open complex using transactions that reflect the use of ATP hydrolysis to establish different functional states of the EBP. A molecular switch within the model EBP we study [called PspF (phage shock protein F)] is evident, and functions to control the exposure of a solvent-accessible flexible loop that engages directly with the initial RNAP promoter complex. The sigma(54) factor then controls the conformational changes in the RNAP required to form the open promoter complex.

Self-assembled monolayers of semifluorinated alkaneselenolates on noble metal substrates

Self-assembled monolayers (SAMs) formed from semifluorinated dialkyldiselenol (CF(3)(CF(2))(5)(CH(2))(2)Se-)(2) (F6H2SeSeH2F6) on polycrystalline Au(111) and Ag(111) were characterized by high-resolution X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, near edge X-ray absorption fine structure spectroscopy, scanning tunneling microscopy, and contact angle measurements. The Se-Se linkage of F6H2SeSeH2F6 was found to be cleaved upon the adsorption, followed by the formation of selenolate-metal bond. The resulting F6H2Se SAMs are well-ordered, densely packed, and contamination-free. The packing density of these films is governed by the bulky fluorocarbon part, which exhibits the expected helical conformation. A noncommensurate hexagonal arrangement of the F6H2Se molecules with an average nearest-neighbor spacing of about 5.8 +/- 0.2 A, close to the van der Waals diameter the fluorocarbon chain, was observed on Au(111). The orientation of the fluorocarbon chains in the F6H2Se SAMs does not depend on the substrate-the average tilt angle of these moieties was estimated to be about 21-22 degrees on both Au and Ag.

Cisplatin and gemcitabine induction chemotherapy followed by concurrent chemoradiotherapy or surgery for locally advanced non-small cell lung cancer

BACKGROUND

We report a study of induction chemotherapy followed by concurrent chemoradiotherapy for stage IIIA/IIIB non-small cell lung cancer.

METHODS

Patients received two cycles of induction chemotherapy with cisplatin 100 mg/m(2) on day 1 and gemcitabine 1000 mg/m(2) on days 1, 8, and 15 of a 28-day cycle. If the disease was resectable [corrected] surgery was followed with two further cycles. If unresectable, patients received cisplatin 100 mg/m(2) day 1, 29 with 5-fluorouracil 1000 mg/m(2) per 24 h continuous infusion for 96 h on days 2-5 and days 30-33 of the radiotherapy administration. Radiation therapy consisted of 63 Gy, 35 fractions, 7 weeks.

RESULTS

Of 48 patients, 40% had a partial response to induction chemotherapy. Four of eleven patients with stage IIIA tumours had resectable disease. The remaining seven patients plus 37 with stage IIIB disease had chemoradiotherapy. Response at the completion of all therapy was 62% (IIIA 73%, IIIB 59%). For all patients the median survival was 15.3 months: 1 year and 3 years, 58% and 25%, respectively. Those with IIIB disease responding to induction chemotherapy had significantly superior survival to those that did not respond (37 months vs 11 months; P = 0.005). This remained significant from a landmark at 8 weeks after the start of treatment (P = 0.01).

CONCLUSION

These results are equivalent to other studies using induction chemotherapy prior to concurrent chemoradiotherapy. Response to induction chemotherapy may have major prognostic significance.

Drug-age alerting for outpatient geriatric prescriptions: a joint study using interoperable drug standards

For more than a decade, the Beers criteria have identified specific medications that should generally be avoided in the geriatric population. Studies that have shown high prevalence rates of these potentially inappropriate medications have used disparate methodologies to identify these medications and hence are difficult to replicate and generalize. In an effort to improve prescribing behavior, we are building a drug-age alerting system utilizing standard drug coding systems for use in our Electronic Health Record (EHR) systems.

Decision support for management of febrile children ages 2 months to 5 years in tropical developing countries

Developing countries rarely have enough physicians to follow the traditional diagnostic process found in wealthier nations. Initial diagnoses often must be made by non-physician personnel. In order to enhance the quality of these diagnoses, we have built an expert decision-support system for triaging childhood fever cases for malaria, measles, and acute respiratory infections. The user is guided through a series of questions that produces clinical care guidelines tailored to the patient's condition.

Nucleotide-dependent interactions between a fork junction-RNA polymerase complex and an AAA+ transcriptional activator protein

Enhancer-dependent transcriptional activators that act upon the sigma54 bacterial RNA polymerase holoenzyme belong to the extensive AAA+ superfamily of mechanochemical ATPases. Formation and collapse of the transition state for ATP hydrolysis engenders direct interactions between AAA+ activators and the sigma54 factor, required for RNA polymerase isomerization. A DNA fork junction structure present within closed complexes serves as a nucleation point for the DNA melting seen in open promoter complexes and restricts spontaneous activator-independent RNA polymerase isomerization. We now provide physical evidence showing that the ADP.AlF(x) bound form of the AAA+ domain of the transcriptional activator protein PspF changes interactions between sigma54-RNA polymerase and a DNA fork junction structure present in the closed promoter complex. The results suggest that one functional state of the nucleotide-bound activator serves to alter DNA binding by sigma54 and sigma54-RNA polymerase and appears to drive events that precede DNA opening. Clear evidence for a DNA-interacting activity in the AAA+ domain of PspF was obtained, suggesting that PspF may make a direct contact to the DNA component of a basal promoter complex to promote changes in sigma54-RNA polymerase-DNA interactions that favour open complex formation. We also provide evidence for two distinct closed promoter complexes with differing stabilities.

Mechanochemical ATPases and transcriptional activation

Transcriptional activator proteins that act upon the sigma54-containing form of the bacterial RNA polymerase belong to the extensive AAA+ superfamily of ATPases, members of which are found in all three kingdoms of life and function in diverse cellular processes, often via chaperone-like activities. Formation and collapse of the transition state of ATP for hydrolysis appears to engender the interaction of the activator proteins with sigma54 and leads to the protein structural transitions needed for RNA polymerase to isomerize and engage with the DNA template strand. The common oligomeric structures of AAA+ proteins and the creation of the active site for ATP hydrolysis between protomers suggest that the critical changes in protomer structure required for productive interactions with sigma54-holoenzyme occur as a consequence of sensing the state of the gamma-phosphate of ATP. Depending upon the form of nucleotide bound, different functional states of the activator are created that have distinct substrate and chaperone-like binding activities. In particular, interprotomer ATP interactions rely upon the use of an arginine finger, a situation reminiscent of GTPase-activating proteins.