Targeting HSF1 disrupts HSP90 chaperone function in chronic lymphocytic leukemia

CLL is a disease characterized by chromosomal deletions, acquired copy number changes and aneuploidy. Recent studies have shown that overexpression of Heat Shock Factor (HSF) 1 in aneuploid tumor cells can overcome deficiencies in heat shock protein (HSP) 90-mediated protein folding and restore protein homeostasis. Interestingly, several independent studies have demonstrated that HSF1 expression and activity also affects the chaperoning of HSP90 kinase clients, although the mechanism underlying this observation is unclear. Here, we determined how HSF1 regulates HSP90 function using CLL as a model system. We report that HSF1 is overexpressed in CLL and treatment with triptolide (a small molecule inhibitor of HSF1) induces apoptosis in cultured and primary CLL B-cells. We demonstrate that knockdown of HSF1 or its inhibition with triptolide results in the reduced association of HSP90 with its kinase co-chaperone cell division cycle 37 (CDC37), leading to the partial depletion of HSP90 client kinases, Bruton''s Tyrosine Kinase (BTK), c-RAF and cyclin-dependent kinase 4 (CDK4). Treatment with triptolide or HSF1 knockdown disrupts the cytosolic complex between HSF1, p97, HSP90 and the HSP90 deacetylase- Histone deacetylase 6 (HDAC6). Consequently, HSF1 inhibition results in HSP90 acetylation and abrogation of its chaperone function. Finally, tail vein injection of Mec-1 cells into Rag2−/−IL2Rγc−/− mice followed by treatment with minnelide (a pro-drug of triptolide), reduced leukemia, increased survival and attenuated HSP90-dependent survival signaling in vivo. In conclusion, our study provides a strong rationale to target HSF1 and test the activity of minnelide against human CLL.     

Primary aldosteronism: diagnosis, localization, and treatment.

New diagnostic techniques have enhanced the detection of primary aldosteronism. However, the response of blood pressure after operation in unilateral and bilateral adrenal disease is different. We have compared four localizing techniques--adrenal venography, adrenal isotopic scanning, a modified adrenal venous sampling for steroid measurements, and the anomalous postural decrease in plasma aldosterone concentration--in 51 patients with primary aldosteronism, all of whom had undergone operative confirmation. Adrenalectomy resulted in normal blood pressure in 59%, improvement in 25%, and no change in 16%. Correct localization of the lesion was obtained in 47% by the adrenal isotopic scan, in 66% by adrenal venography, and in 91% by the modified adrenal venous hormone technique despite four false-positives. Of the 26 patients with an anomalous postural decrease in plasma aldosterone, 88% had a unilateral lesion.     

Viability of M. leprae under normal and adverse atmospheric conditions

Harvested bacilli from fresh lepromas were subjected to drying at room temperature for varying periods, were exposed to direct sun-rays, UVR, and were then injected into the foot pads of thymectomised irradiated mice for checking the viability. The organisms could survive UVR for 30 minutes, direct sunlight for 2 hours and room temperature for 7 days. Details are presented.     

Clonidine suppression test--an evaluation of its diagnostic significance in hypertensive patients

The Clonidine Suppression Test (CST) was performed in 8 patients with Labile hypertension (Group I), 8 patients with mild and moderate Essential hypertension (Group IIa), 8 patients with severe Essential hypertension (Group IIb) and 6 patients with pheochromocytoma (Group III). The mean plasma catecholamine (CA) levels as estimated by a Spectrofluorimetric method were significantly reduced 3-4 hours after administration of clonidine (5 micrograms/kg) by mouth in Group I, IIa & IIb patients. Plasma norepinephrine levels fell from 1.82 +/- SEM 0.35 ng/ml to 1.03 +/- 0.11 ng/ml (p less than 0.05) in Group I, 1.64 +/- 0.36 ng/ml to 0.88 +/- 0.12 ng/ml (p less than 0.025) in Group IIa, 1.23 +/- 0.16 ng/ml to 0.86 +/- 0.12 ng/ml (p less than 0.005) in Group IIb patients. Plasma epinephrine levels fell from 0.35 +/- 0.06 ng/ml to 0.16 +/- 0.03 ng/ml (p less than 0.05) in Group I, 0.34 +/- 0.04 ng/ml to 0.22 +/- 0.03 ng/ml (p less than 0.01) in Group IIa, 0.33 +/- 0.06 ng/ml to 0.18 +/- 0.03 ng/ml (p less than 0.025) in Group IIb patients. The blood pressure and heart rate showed a similar response. By contrast, in patients with pheochromocytoma, the mean plasma CA levels did not show any significant fall, and even rose during the CST, but, when repeated post-operatively, showed normal suppression. No serious side effects were noticed. We conclude that the CST is a safe and reliable test for the diagnosis of pheochromocytoma.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acute effect of captopril on aldosterone secretory responses to endogenous or exogenous adrenocorticotropin

The aldosterone secretory response to Captopril (12.5 mg, orally) was studied in five normal men. Endogenous ACTH and epinephrine secretion was stimulated by the induction of hypoglycemia. Normally this stimulus increases plasma cortisol, GH, aldosterone, and PRA. Administration of captopril resulted in a blunted plasma aldosterone response to hypoglycemia, but no concomitant blunting of the plasma cortisol response. The responses of other hormones, with the exception of PRA, were not affected. When exogenous ACTH was administered to the same men with and without captopril, the plasma aldosterone response was again blunted by captopril, while the plasma cortisol response was unaffected. We conclude that angiotensin II may be required for ACTH to stimulate aldosterone secretion. Alternatively, the possibility that captopril may selectively inhibit aldosterone secretion at the adrenal cellular level cannot be excluded.