ROCK inhibitor reduces Myc-induced apoptosis and mediates immortalization of human keratinocytes

The Myc/Max/Mad network plays a critical role in cell proliferation, differentiation and apoptosis and c-Myc is overexpressed in many cancers, including HPV-positive cervical cancer cell lines. Despite the tolerance of cervical cancer keratinocytes to high Myc expression, we found that the solitary transduction of the Myc gene into primary cervical and foreskin keratinocytes induced rapid cell death. These findings suggested that the anti-apoptotic activity of E7 in cervical cancer cells might be responsible for negating the apoptotic activity of over-expressed Myc. Indeed, our earlier in vitro studies demonstrated that Myc and E7 synergize in the immortalization of keratinocytes. Since we previously postulated that E7 and the ROCK inhibitor, Y-27632, were members of the same functional pathway in cell immortalization, we tested whether Y-27632 would inhibit apoptosis induced by the over-expression of Myc. Our findings indicate that Y-27632 rapidly inhibited Myc-induced membrane blebbing and cellular apoptosis and, more generally, functioned as an inhibitor of extrinsic and intrinsic pathways of cell death. Most important, Y-27632 cooperated with Myc to immortalize keratinocytes efficiently, indicating that apoptosis is a major barrier to Myc-induced immortalization of keratinocytes. The anti-apoptotic activity of Y-27632 correlated with a reduction in p53 serine 15 phosphorylation and the consequent reduction in the expression of downstream target genes p21 and DAPK1, two genes involved in the induction of cell death.

Gait deviations in transverse plane after SCFE in dependence on the femoral offset

Residual deformity of the femoral head after slipped capital femoral epiphysis (SCFE) may be accompanied by a loss of femoral offset and lead to femoro-acetabular impingement (FAI), especially during hip flexion. It is hypothesized that during phases of the gait cycle, when the hip is flexed, the offset-loss is compensated by an increased external rotation. The gait pattern of 36 patients suffering from SCFE, who were treated by pinning-in-situ, were compared to a control group of 40 healthy adults by an instrumented 3D-gait analysis. Total patient group was subdivided into 3 subgroups in dependence on the offset (offset groups (OG)) quantified by the angle α according to Nötzli: OG1: α-angle <55°, OG2: α-angle between 55 and 75°, OG3: α-angle >75°. Comparisons were made at 3 instants: initial foot contact (0% gait cycle (GC)), 40-60% GC and 90-100% GC. Patients showed an increased external hip rotation during all 3 periods of the GC with a tendency of increasing external rotation in association with offset-loss. Only during hip extension (40-60% GC) there was a weak correlation between angle α and hip rotation (r=-0.375, p=0.024). In conclusion, the offset-loss does not lead to a functional relevant impingement during walking which needs compensation strategies like increasing external rotation during periods of hip flexion.

Traumatic Carotid Artery Dissection and Pseudoaneurysm Treated with Endovascular Coils and Stent

Purpose:

To report a case of post-traumatic internal carotid artery dissection and pseudoaneurysm formation at the C-1 level successfully treated by a percutaneous endovascular technique.

Methods and Results:

A 20-year-old female presented 72 hours after a motor vehicle accident with incomplete occulosympathetic paresis (Horner's syndrome), carotidynia, and left-sided weakness. Arteriography confirmed the diagnosis of carotid dissection and an associated 1.5-cm × 2.5-cm pseudoaneurysm at the C-1 level. Neuroradiologists embolized the pseudoaneurysm with Guglielmi detachable coils and controlled the dissection with placement of a Wallstent.

Conclusions:

This report illustrates successful percutaneous endovascular treatment of a carotid dissection and pseudoaneurysm near the base of the skull.

Iliofemoral Venous Thrombosis Caused by Compression of an Internal Iliac Artery Aneurysm: A Minimally Invasive Treatment

Purpose:

To report the success of a minimally invasive treatment for phlegmasia cerulea dolens without gangrene caused by compression from an internal iliac artery aneurysm.

Methods and Results:

An 81-year-old male with a 1-month history of paralysis owing to a hemorrhagic stroke presented with massive edema and skin mottling of the right lower extremity. Imaging confirmed right iliofemoral deep vein thrombosis caused by compression from a 4-cm internal iliac artery aneurysm. With thrombolysis ruled out, a minimally invasive treatment plan was undertaken, featuring percutaneous coil embolization of the aneurysm and surgical venous thrombectomy with proximal arteriovenous fistula creation and iliac vein stent placement. Failure of the coils to embolize the iliac aneurysm prompted the use of an endovascular graft to exclude the aneurysm. The patient's symptoms subsided, and he has a patent right iliofemoral venous system and internal iliac artery at his latest (16-month) follow-up.

Conclusions:

This case demonstrates that minimally invasive endovascular and open techniques can be combined to achieve an optimum outcome in patients at high risk for standard surgical approaches.

Prevention of Gynaecological Adhesions using Haemostatic Fleece in a Rabbit Model

This pre-clinical study was performed to investigate the ability of the haemostatic fleece TachoComb® to prevent adhesion formation following uterine surgery. Thirty rabbits were randomized to receive TachoComb® or no intervention following incision to the right uterine horn. After 14 days, the animals were killed and examined for the presence of adhesion. The lengths of any adhesions were measured and the severity was recorded as a score (0, no adhesion; 1, adhesion easy to lyse; 2, adhesion lysed with traction; 3, adhesion separated by sharp dissection). The incidence of adhesions was 100% in the control group compared with 33% in the TachoComb®-treated animals. The mean adhesion score was significantly lower (0.7 versus 2.2) and the mean adhesion length category was significantly shorter (0.4 versus 2.0) with TachoComb® than in the control group. This study indicates that TachoComb® is a well-tolerated and effective means of preventing adhesion following gynaecological surgery.

Abstract 5145: Y-27632 inhibits Myc-induced apoptosis and cooperates with Myc to immortalize human keratinocytes

The high-risk HPV E6 and E7 genes are sufficient to immortalize human foreskin keratinocytes (HFKs) through activation of telomerase and inactivation of the RB/p16 pathway, respectively. Our previous work has shown that Myc (via induction of hTERT) may substitute for E6 and immortalize HFKs when combined with HPV E7. When expressed alone, however, Myc induced p53 expression and apoptosis. In the current study we found that Myc, in combination with the ROCK inhibitor (Y-27632), led immortalization of human foreskin keratinocytes. Our data confirmed that Myc induced apoptosis and blebbing of human keratinocytes when cultured in serum free synthetic medium (KGM) and that Y-27632 rapidly inhibits this process. Thus, our data demonstrate that Myc is capable of independently immortalizing HFKs when apoptosis pathways are blocked.

Citation Format: Aleksandra Dakic, Kyle Divito, Shuang Fang, Nancy Palechor-Ceron, Vera Simic, Sujata Choudhury, Songtao Yu, Cynthia M. Simbulan-Rosenthal, Dean Rosenthal, Richard Schlegel, Xuefeng Liu. Y-27632 inhibits Myc-induced apoptosis and cooperates with Myc to immortalize human keratinocytes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5145. doi:10.1158/1538-7445.AM2015-5145

Abstract 825: Id3: Tumor suppressor of squamous cell carcinoma

Skin cancer, the most common type of cancer with more than 1 million cases diagnosed in the US every year, occurs at least once to about half of Americans 65 years or older. The three main types of skin cancer—Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), and melanoma have mortality rates that are estimated to be 0.1%, 4.3% and 10% respectively in 2011. The Inhibitor of DNA Binding/Differentiation 3 (Id3) protein, a helix-loop-helix (HLH), dominant negative transcription factor, is one of four Id proteins found in mammals (Id1-4). The Id protein family plays a role in many cellular processes, including differentiation, proliferation, apoptosis, and angiogenesis. Previous studies in the Rosenthal lab have shown that Id3 over-expression in immortalized human keratinocytes induces apoptosis in part by activation of a Bax-caspase-9-caspase-3-dependent mitochondrial pathway via upregulation of bax promoter activity. To further elucidate the roles of Id3 in apoptosis, proliferation, and tumorigenesis, our studies focused on effects of induced Id3 expression on tumor growth in vivo.

To investigate the role of Id3 in SCC, a tetracycline (Tet)-regulated expression (T-REx™) system was utilized to induce Id3 expression in A431 cells, a human malignant cervical SCC cell line. Immunoblot and RT-PCR analysis of A431-TRex-Id3 cells verified Id3 expression in the presence of Tet. When Id3 was induced by Tet in these cells in vitro, caspase-3 and -9 were activated. Cells were stably transfected with GFP to monitor tumor growth over thirty days by Maestro® in vivo imaging. Effects of Id3 on tumorigenesis in vivo was examined by subcutaneous injection of these cells onto athymic nude mice, half of which were fed with a doxycycline (Dox; a tetracycline derivative)-containing feed, leading to induced Id3 expression in the tumor, and half with a regular diet. Subcutaneously-injected A431 cells formed significantly (50%) smaller tumors upon Id3 induction. Immunofluorescent staining of tumor sections from Dox-fed mice revealed a 1.5-fold increase in active caspase-3 but no significant change in Ki-67, a proliferation marker. To investigate the mechanism of tumor shrinkage caused by Id3, microarray analysis was performed, and four genes were found to be significantly up- or down-regulated by Id3. Id3 deletion mutants were further created to study the domain(s) responsible for the decrease in tumor size. Mutation analysis showed that Id3 induces Max dimerization protein 3 (MXD3) protein expression through its HLH domain. Other candidate genes remain to be tested. The role of Id3 in SCC cell killing by cisplatin, a commonly used chemotherapeutic drug for SCC, is also currently under investigation. Our results together indicate that Id3 is a potential apoptosis inducer and therefore a therapeutic target in treating SCC.

Citation Format: You-Shin Chen, Cynthia Rosenthal, Dean Rosenthal. Id3: Tumor suppressor of squamous cell carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 825. doi:10.1158/1538-7445.AM2013-825