Apoptotic Vascular Smooth Muscle Cell Depletion via BCL2 Family of Proteins in Human Ascending Aortic Aneurysm and Dissection

Cataloged from PDF version of article.Aims: This study investigates the expression patterns of BCL2 (B-cell CLL/lymphoma2) family of proteins and the extent of vascular smooth muscle cell (VSMC) apoptosis in thoracic aortic aneurysms (TAA), type-A aortic dissections (TAD), and nondilated ascending aortic samples. Methods: Aortic wall specimens were obtained from patients undergoing surgical repair for TAA (n = 24), TAD (n = 20), and normal aortic tissues from organ donors (n = 6). The expression pattern of BCL2, BCL2L1 (BCL2-like1), BAK1 (BCL2-antagonist/killer1), and BAX (BCL2-associated X protein) proteins was investigated by immunohistochemistry. Furthermore, colocalization of alpha smooth muscle actin (ACTA2) and caspase3 (CASP3) in aortic VSMCs was analyzed by double-immunofluorescence staining. Onset of DNA fragmentation was measured by TUNEL assay. Results: Apoptotic index was significantly increased in both TAD group (31.3 ± 17.2, P < 0.001) and TAA group (21.1 ± 12.7, P = 0.001) relative to control aortas (2.0 ± 1.2). Anti-CASP3 and ACTA2 double-immunostaining confirmed apoptosis in VSMCs in TAA and TAD groups but not in controls. Proapoptotic BAX expression was significantly elevated in VSMCs of TAA patients, compared with that of controls (OR = 20; P = 0.02; 95% CI, 16-250). In contrast, antiapoptotic BCL2L1 expression was higher in controls compared with that of TAA group (OR = 11.2; P = 0.049; 95% CI, 1.0-123.9). Furthermore, BAX/BCL2 ratio was significantly increased in both TAA (1.2 ± 0.7, P < 0.001) and TAD (0.6 ± 0.4, P = 0.05) groups relative to controls (0.2 ± 0.1, P < 0.001). Conclusions: Apoptotic VSMC depletion in human TAA/TAD is associated with disturbance of the balance between proapoptotic and antiapoptotic members of the BCL2 family proteins, which may have a role in the pathogenesis of vascular remodelling in aortic disease. In light of the future studies, targeting apoptotic pathways in TAA and TAD pathogenesis may provide therapeutic benefits to patients by slowing down the progression and even possibly preventing the TAD. © 2012 Blackwell Publishing Ltd

The Ability to Generate Senescent Progeny as a Mechanism Underlying Breast Cancer Cell Heterogeneity

Background Breast cancer is a remarkably heterogeneous disease. Luminal, basal-like, "normal-like", and ERBB2+ subgroups were identified and were shown to have different prognoses. The mechanisms underlying this heterogeneity are poorly understood. In our study, we explored the role of cellular differentiation and senescence as a potential cause of heterogeneity. Methodology/Principal Findings A panel of breast cancer cell lines, isogenic clones, and breast tumors were used. Based on their ability to generate senescent progeny under low-density clonogenic conditions, we classified breast cancer cell lines as senescent cell progenitor (SCP) and immortal cell progenitor (ICP) subtypes. All SCP cell lines expressed estrogen receptor (ER). Loss of ER expression combined with the accumulation of p21Cip1 correlated with senescence in these cell lines. p21Cip1 knockdown, estrogen-mediated ER activation or ectopic ER overexpression protected cells against senescence. In contrast, tamoxifen triggered a robust senescence response. As ER expression has been linked to luminal differentiation, we compared the differentiation status of SCP and ICP cell lines using stem/progenitor, luminal, and myoepithelial markers. The SCP cells produced CD24+ or ER+ luminal-like and ASMA+ myoepithelial-like progeny, in addition to CD44+ stem/progenitor-like cells. In contrast, ICP cell lines acted as differentiation-defective stem/progenitor cells. Some ICP cell lines generated only CD44+/CD24-/ER-/ASMA- progenitor/stem-like cells, and others also produced CD24+/ER- luminal-like, but not ASMA+ myoepithelial-like cells. Furthermore, gene expression profiles clustered SCP cell lines with luminal A and "normal-like" tumors, and ICP cell lines with luminal B and basal-like tumors. The ICP cells displayed higher tumorigenicity in immunodeficient mice. Conclusions/Significance Luminal A and "normal-like" breast cancer cell lines were able to generate luminal-like and myoepithelial-like progeny undergoing senescence arrest. In contrast, luminal B/basal-like cell lines acted as stem/progenitor cells with defective differentiation capacities. Our findings suggest that the malignancy of breast tumors is directly correlated with stem/progenitor phenotypes and poor differentiation potential. © 2010 Mumcuoglu et al

Preparation and characterization of poly(hydroxyethyl methacrylate-co -poly(ethyleneglycol-methacrylate)/hydroxypropyl-chitosan) hydrogel films: Adhesion of rat mesenchymal stem cells

This study examined the effects of the surface properties of the materials, such as the hydroxyl, methyl and amino groups, on rat bone marrow derived Mesenchymal Stem Cell (MSC) seeding. A series of hydrogels were prepared in film form using 2-hydroxyethyl methacrylate (pHEMA), poly(ethyleneglycol) methacrylate (PEG-MA), and/or hydroxypropyl-chitosan (HPC). The physicochemical properties of these hydrogel films, such as water content, functional groups, contact angle, surface energy and thermal properties were affected by the composition of the materials. The ability of the MSCs to form colonies, as well as their viability on these materials were also analyzed. The water content of the hydrogel films increased with increasing PEG-MA and HPC ratio in the hydrogel. Contact angle measurements of the surface of the hydrogel films demonstrated that all the materials gave rise to a significantly hydrophilic surface compared to pure pHEMA. The blood protein interactions and platelet adhesion were reduced significantly on the surface of the materials upon the incorporation of PEG-MA compared to the control pure pHEMA and vice versa for HPC. The ability of the MSCs to adhere and form colonies on these materials was also analyzed. The results showed that these materials are suitable candidates to isolate and expand MSCs. [Figure not available: see fulltext.] © 2011 The Polymer Society of Korea and Springer Netherlands

Imetelstat (A Telomerase Antagonist) Exerts Off-Target Effects On The Cytoskeleton

Telomerase is a cellular ribonucleoprotein reverse transcriptase that plays a crucial role in telomere maintenance. This enzyme is expressed in approximately 90% of human tumors, but not in the majority of normal somatic cells. Imetelstat sodium (GRN163L), is a 13-mer oligonucleotide N3′→P5′ thio-phosphoramidate lipid conjugate, which represents the latest generation of telomerase inhibitors targeting the template region of the human functional telomerase RNA (hTR) subunit. In preclinical trials, this compound has been found to inhibit telomerase activity in multiple cancer cell lines, as well as in vivo xenograft mouse models. Currently, GRN163L is being investigated in several clinical trials, including a phase II human non-small cell lung cancer clinical trial, in a maintenance setting following standard doublet chemotherapy. In addition to the inhibition of telomerase activity in cancer cell lines, GRN163L causes morphological cell rounding changes, independent of hTR expression or telomere length. This leads to the loss of cell adhesion properties; however, the mechanism underlying this effect is not yet fully understood. In the present study, we observed that GRN163L treatment leads to the loss of adhesion in A549 lung cancer cells, due to decreased E-cadherin expression, leading to the disruption of the cytoskeleton through the alteration of actin, tubulin and intermediate filament organization. Consequently, the less adherent cancer cells initially cease to proliferate and are arrested in the G1 phase of the cell cycle, accompanied by decreased matrix metalloproteinase-2 (MMP-2) expression. These effects of GRN163L are independent of its telomerase catalytic activity and may increase the therapeutic efficacy of GRN163L by decreasing the adhesion, proliferation and metastatic potential of cancer cells in vivo.PubMedWoSScopu