A novel, small molecule inhibitor of Hsc70/Hsp70 potentiates Hsp90 inhibitor induced apoptosis in HCT116 colon carcinoma cells

PURPOSE

The anti-apoptotic function of the 70 kDa family of heat shock proteins and their role in cancer is well documented. Dual targeting of Hsc70 and Hsp70 with siRNA induces proteasome-dependent degradation of Hsp90 client proteins and extensive tumor specific apoptosis as well as the potentiation of tumor cell apoptosis following pharmacological Hsp90 inhibition.

METHODS

We have previously described the discovery and synthesis of novel adenosine-derived inhibitors of the 70 kDa family of heat shock proteins; the first inhibitors described to target the ATPase binding domain. The in vitro activity of VER-155008 was evaluated in HCT116, HT29, BT474 and MDA-MB-468 carcinoma cell lines. Cell proliferation, cell apoptosis and caspase 3/7 activity was determined for VER-155008 in the absence or presence of small molecule Hsp90 inhibitors.

RESULTS

VER-155008 inhibited the proliferation of human breast and colon cancer cell lines with GI(50)s in the range 5.3-14.4 microM, and induced Hsp90 client protein degradation in both HCT116 and BT474 cells. As a single agent, VER-155008 induced caspase-3/7 dependent apoptosis in BT474 cells and non-caspase dependent cell death in HCT116 cells. VER-155008 potentiated the apoptotic potential of a small molecule Hsp90 inhibitor in HCT116 but not HT29 or MDA-MB-468 cells. In vivo, VER-155008 demonstrated rapid metabolism and clearance, along with tumor levels below the predicted pharmacologically active level.

CONCLUSION

These data suggest that small molecule inhibitors of Hsc70/Hsp70 phenotypically mimic the cellular mode of action of a small molecule Hsp90 inhibitor and can potentiate the apoptotic potential of a small molecule Hsp90 inhibitor in certain cell lines. The factors determining whether or not cells apoptose in response to Hsp90 inhibition or the combination of Hsp90 plus Hsc70/Hsp70 inhibition remain to be determined.

Combining hit identification strategies: fragment-based and in silico approaches to orally active 2-aminothieno[2,3-d]pyrimidine inhibitors of the Hsp90 molecular chaperone

Inhibitors of the Hsp90 molecular chaperone are showing considerable promise as potential molecular therapeutic agents for the treatment of cancer. Here we describe novel 2-aminothieno[2,3-d]pyrimidine ATP competitive Hsp90 inhibitors, which were designed by combining structural elements of distinct low affinity hits generated from fragment-based and in silico screening exercises in concert with structural information from X-ray protein crystallography. Examples from this series have high affinity (IC50 = 50-100 nM) for Hsp90 as measured in a fluorescence polarization (FP) competitive binding assay and are active in human cancer cell lines where they inhibit cell proliferation and exhibit a characteristic profile of depletion of oncogenic proteins and concomitant elevation of Hsp72. Several examples (34a, 34d and 34i) caused tumor growth regression at well tolerated doses when administered orally in a human BT474 human breast cancer xenograft model.

Antagonists of the human A(2A) adenosine receptor. 4. Design, synthesis, and preclinical evaluation of 7-aryltriazolo[4,5-d]pyrimidines

Antagonism of the human A(2A) receptor has been implicated as a point of therapeutic intervention in the alleviation of the symptoms associated with Parkinson's disease. This is thought to occur, at least in part, by increasing the sensitivity of the dopaminergic neurons to the residual, depleted levels of striatal dopamine. We herein describe a novel series of functionalized triazolo[4,5-d]pyrimidine derivatives that display functional antagonism of the A(2A) receptor. Optimization of these compounds has resulted in improvements in potency, selectivity, and the pharmacokinetic properties of key derivatives. These efforts have led to the discovery of 60 (V2006/BIIB014), which demonstrates strong oral activity in commonly used models of Parkinson's disease. Furthermore, this derivative has shown excellent preclinical pharmacokinetics and has successfully completed phase I clinical studies. This compound is presently undergoing further clinical evaluation in collaboration with Biogen Idec.

Changes in intra-ocular pressure during general anaesthesia. A comparison of spontaneous breathing through a laryngeal mask with positive pressure ventilation through a tracheal tube

Changes in-intra-ocular pressure during spontaneous ventilation with a laryngeal mask were compared with controlled ventilation using a tracheal tube in 40 patients undergoing intra-ocular surgery under general anaesthesia. Intra-ocular pressure was measured before induction, after establishing the airway, at the end of the operation and after removal of the airway device. Anaesthesia was induced with propofol and maintained with enflurane and nitrous oxide in oxygen. Mean end-tidal carbon dioxide tension was significantly higher during spontaneous ventilation than during controlled ventilation 5 min after establishing the airway (5.7 versus 4.5) and at the end of surgery (6.1 versus 4.2) (p < 0.001). Despite this, intra-ocular pressures were lower than baseline and similar in the two groups throughout anaesthesia. At the end of surgery, intra-ocular pressure (mmHg) was 11.2 and 8.6 during spontaneous or controlled ventilation respectively. One min after removal of the device, mean intra-ocular pressure (mmHg) in the tracheal tube group (16.0) was slightly higher than baseline (15.3) and was significantly higher than the laryngeal mask group (10.9) (p < 0.01). Spontaneous ventilation with a laryngeal mask is an acceptable alternative to controlled ventilation with tracheal intubation in elective intra-ocular surgery.

The polyurethane nasotracheal tube

An uncuffed nasotracheal tube for use in minor maxillofacial surgery has been developed using polyurethane. The suitability of this tube as an alternative to the existing soft red rubber and harder polyvinyl chloride materials has been assessed at four centres during anaesthesia for routine oral surgery. The tube was found to be satisfactory.

Blood glucose concentrations in children undergoing outpatient dental anaesthesia

Fifty-six children, aged between 2 and 16 yr, undergoing dental extractions under general anaesthesia had their plasma glucose concentrations estimated before surgery. The mean concentration was 3.80 mmol litre-1. The lowest value was 2.2 mmol litre-1 in spite of starvation for 16.5 h. It is possible that outpatients are less susceptible to hypoglycaemia.

Early days of anaesthesia in sheffield

An account is given of the early days of anaesthesia in Sheffield with reference to articles published in local newspapers.

Recovery comparison between enflurane and halothane techniques. A study of outpatients undergoing cytoscopy

A comparison of recovery from either halothane or enflurane with nitrous oxide and oxygen after induction with Althesin by outpatients in a cystoscopy clinic is presented. The recovery rate was scored by the recovery room nurses, who were ignorant of which agent had been used. Recovery after enflurane was quicker than after halothane.

Underlying immunopathology as a cause of adverse responses to two intravenous anaesthetic agents

A patient who had shown some evidence of immunological sensitivity underwent several operations under general anaesthesia for otitis media without ill effect. On his second exposure to Althesin, however, he suffered a severe reaction. Facial angioneurotic oedema was accompanied by peripheral vasodilatation and sweating, and C3 conversion was observed in his plasma. Subsequent anaesthetics produced no reactions until four years later, when thiopentone and suxamethonium were given. This reaction was much milder, but C3 conversion again occurred. Although the clinical signs indicated an anaphylactoid reaction, the laboratory findings suggested that this patient had an underlying immunopathological condition involving complement activation, which could be triggered by any intravenous agent that activated complement. The judgment that a reaction to a particular drug is anaphylactic cannot be made on the basis of clinical signs alone. Simple laboratory analysis will show whether the reaction is due to an underlying immunopathological condition that may be triggered by any of several drugs.

Cardio-respiratory effects of nitrous oxide:oxygen:halothane anaesthesia administered to dental outpatients in the upright position

The cardio-respiratory responses of fifty-three healthy dental patients receiving 30% oxygen with nitrous oxide and halothane whilst seated upright are reported. A high degree of sympathetic autonomic activity was noted with considerable lability of the blood pressure and pulse rate. Hypoxaemia caused by respiratory obstruction, unrecognised by the anaesthetist, occurred in approximately 20% of patients at the time of insertion of the prop or pack and during removal of teeth.

Immune-mediated reactions to althesin (alphaxalone)

Measurements of complement conversion and white cell variations were made on sequential blood samples obtained from a single volunteer following repeated administration of Althesin. The results suggest a mechanism by which a clinically significant hypersensitivity reaction to the drug might be mediated. Studies of patients receiving routine anaesthesia revealed a very high incidence of subclinical "hypersensitivity" reaction, some of which appear to be immune-mediated. These reactions occurred irrespective of whether the patients were induced with Althesin, methohexitone or propanidid.