Effects of HIV protease inhibitor ritonavir on Akt-regulated cell proliferation in breast cancer.

PURPOSE: These studies were designed to determine whether ritonavir inhibits breast cancer in vitro and in vivo and, if so, how. EXPERIMENTAL DESIGN: Ritonavir effects on breast cancer cell growth were studied in the estrogen receptor (ER)-positive lines MCF7 and T47D and in the ER-negative lines MDA-MB-436 and MDA-MB-231. Effects of ritonavir on Rb-regulated and Akt-mediated cell proliferation were studied. Ritonavir was tested for inhibition of a mammary carcinoma xenograft. RESULTS: ER-positive estradiol-dependent lines (IC50, 12-24 micromol/L) and ER-negative (IC50, 45 micromol/L) lines exhibit ritonavir sensitivity. Ritonavir depletes ER-alpha levels notably in ER-positive lines. Ritonavir causes G1 arrest, depletes cyclin-dependent kinases 2, 4, and 6 and cyclin D1 but not cyclin E, and depletes phosphorylated Rb and Ser473 Akt. Ritonavir induces apoptosis independent of G1 arrest, inhibiting growth of cells that have passed the G1 checkpoint. Myristoyl-Akt, but not activated K-Ras, rescues ritonavir inhibition. Ritonavir inhibited a MDA-MB-231 xenograft and intratumoral Akt activity at a clinically attainable serum Cmax of 22 +/- 8 micromol/L. Because heat shock protein 90 (Hsp90) substrates are depleted by ritonavir, ritonavir effects on Hsp90 were tested. Ritonavir binds Hsp90 (K(D), 7.8 micromol/L) and partially inhibits its chaperone function. Ritonavir blocks association of Hsp90 with Akt and, with sustained exposure, notably depletes Hsp90. Stably expressed Hsp90alpha short hairpin RNA also depletes Hsp90, inhibiting proliferation and sensitizing breast cancer cells to low ritonavir concentrations. CONCLUSIONS: Ritonavir inhibits breast cancer growth in part by inhibiting Hsp90 substrates, including Akt. Ritonavir may be of interest for breast cancer therapeutics and its efficacy may be increased by sustained exposure or Hsp90 RNA interference.     

Bone formation is not coupled to bone resorption in site-specific manner in adult rats

The trabecular bone of the secondary spongiosa of mature rats shows a coupling of bone formation to resorption. It has been clearly shown that in adult man the coupling of formation and resorption involves a site-specific sequence of events, in which bone resorption is normally followed, at the same site, by bone formation. Whether the coupled processes of bone resorption and formation also occur at the same site in the rat is controversial. To elucidate the spatial relationship between bone formation and resorption in the rat, we compared the percentage of crenated and non-crenated cement lines with the percentage of crenated and non-crenated bone surfaces in the proximal tibia of adult rats aged 16 weeks to 2 years. A similar comparison was also made using bone from adult human iliac crest. We found that the trabecular bones of 16-week-old and 7-month-old rats exhibited a low percentage (7–11%) of crenated cement lines, which is opposite to the proportion (88%) we observed in human trabecular bone. In contrast, the surfaces of rat bone trabeculae showed a similar low proportion of crenated surface to human bone (rat 1.1–1.4% vs. 5% in humans). In older (2 years) rats, in which bones have ceased to grow in length, the percentage of cement lines that were crenated increased to 45%. These results imply that the major proportion of bone formation in the trabecular bone of growing rats occurs on non-resorbed surfaces. Thus, although there is substantial evidence that bone formation is coupled to resorption in the rat, such that increased resorption is associated with increased formation, and suppression of resorption suppresses bone formation, bone formation does not necessarily occur on a previously resorbed site. This suggests that in the rat, the processes are not coupled by local release of cytokines or local cell interactions but by some other signal, such as mechanical stimulation. Since site-specificity appears not to be crucial to the coupling of formation to resorption, the greater site-specificity of coupling in man, and in older rats, may be attributable to a more static skeleton, which engenders a closer spatial correlation between bone formation and the resorption that induced it. © 1993 Wiley-Liss, Inc.     

Superficial temporal artery pseudoaneurysm: diagnosis and preoperative planning with CT angiography

We report the use of CT angiography in the diagnosis and preoperative planning of a superficial temporal artery pseudoaneurysm. A 50-year-old man presented with a pulsatile preauricular mass 4 weeks after undergoing pterional craniotomy for aneurysm repair. CT angiography revealed a 2.5-cm pseudoaneurysm arising from the posterior margin of the right superficial temporal artery at the inferior margin of the craniotomy incision. To our knowledge, this is the first reported case showing the usefulness of CT angiography alone in the diagnosis and characterization of a superficial temporal artery pseudoaneurysm.     

Intraductal hepatocellular carcinoma with normal liver--case report.

Hepatocellular carcinoma commonly invades the portal vein but is rarely seen in the bile duct. When seen, a minor intraductal component usually accompanies a prominent hepatic involvement. We report a case of hepatocellular carcinoma that entirely involved the common bile duct, the hepatic involvement was undiscernible at operation or ultrasonography. The patient had obstructive jaundice both at first presentation and at recurrence. The liver was normal at both explorations. The elevated AFP levels returned to normal after second resection. The diagnosis was confirmed by electron microscopy.     

Morphological changes in breast tissue with menstrual cycle.

Whether the breast tissue undergoes morphologic changes in relation to the menstrual cycle had been a subject of debate. Elegant studies performed in the early 1980s provided conclusive evidence of cyclical changes in the normal breast lobules. These studies were almost entirely based on autopsy material and have not been validated in the clinical setting. In the present study, we examine breast tissues from surgical specimens from 73 premenopausal women and use morphological criteria to characterize the stage of the menstrual cycle. Patients taking oral contraceptives or hormonal therapy were excluded from this study. The following histological parameters were used to assess the menstrual stage: number of cell layers in the acini and presence and degree of vacuolation of the myoepithelial cells, stromal edema, infiltrate, mitosis, and apoptosis. The morphological stage was then correlated with the stage of the cycle, as determined by last menstrual period and the usual menstrual cycle length and in some patients with serum estrogen and progesterone levels. The morphologic stage was concordant with dates in 54 of the 73 patients (74%, P =.001). In 31 of these patients, serum levels of estradiol and progesterone at the time of surgery were available for correlation. Twenty-five (80%) of these were phase concordant by morphology and progesterone levels (P =.01), and 25 (80%), by dates and progesterone levels (P =.007). Women with a high morphologic score were seven times as likely to be in luteal phase as were women with a low score (odds ratio, 7.1; 95% confidence interval). Menstrual phase can be determined by the morphology of the normal lobules present within the surgically excised breast specimens. This will permit retrospective analysis of large archival databases to analyze the effect of timing of surgery in relation to menstrual cycle phase. It will also aid the design of epidemiological studies for breast cancer risk assessment.     

Bronchial artery embolization: monitoring with somatosensory evoked potentials. Work in progress

Surgery remains the treatment of choice for massive and recurrent hemoptysis. In some instances, however, immediate surgical intervention is contraindicated. In these situations, bronchial artery embolization (BAE) has proved to be a successful definitive treatment for non-surgical candidates and a palliative therapy in patients requiring hemodynamic stabilization prior to surgery. The most serious complication of BAE is spinal cord ischemia. This relates directly to the potential anastomotic connections between the bronchial circulation and the anterior spinal artery. Somatosensory evoked potentials (SSEPs) have been used in the past to monitor spinal cord ischemia during procedures that threaten the vascularity of the spinal cord. The authors report two cases in which SSEPs were employed to monitor spinal cord ischemia during bronchial artery embolization.