5-Methylcytosine content of DNA in blood, synovial mononuclear cells and synovial tissue from patients affected by autoimmune rheumatic diseases

The percentage of 5-methylcytosine (m⁵Cyt) has been determined in peripheral blood, synovial mononuclear cells and synovial tissue from patients affected by various rheumatic autoimmune diseases. The determination was performed by reversed-phase high-performance liquid chromatography. Fifteen controls were compared to twenty-one patients affected by rheumatoid arthritis and to nine patients affected by systemic lupus erythematosus. The mean percentage of m⁵Cyt in normal individuals was significantly higher than in the rheumatoid arthritis and systemic lupus erythematosus patients. In addition, patients with active disease showed lower values than patients in remission. This finding is in agreement with the hypothesis that DNA hypomethylation may play a role in the pathogenesis of the autoimmune diseases, resulting in altered oncogen expression. Therapy with cyclosporin A led to a decrease in the percentage of m⁵Cyt in three rheumatoid arthritis patients, but a rebound was observed when the cyclosporin A was suspended. The percentage of m⁵Cyt in the DNA of synovial tissue from four rheumatoid arthritis patients and five patients with osteoarthritis was similar; this observation confirms that, in addition to disease-specific and disease activity-specific variations, the percentage of m⁵Cyt may also show tissue-specific variations.     

DNA Damage and Repair Biomarkers in Cervical Cancer Patients Treated with Neoadjuvant Chemotherapy: An Exploratory Analysis

Cervical cancer cells commonly harbour a defective G₁/S checkpoint owing to the interaction of viral oncoproteins with p53 and retinoblastoma protein. The activation of the G₂/M checkpoint may thus become essential for protecting cancer cells from genotoxic insults, such as chemotherapy. In 52 cervical cancer patients treated with neoadjuvant chemotherapy, we investigated whether the levels of phosphorylated Wee1 (pWee1), a key G₂/M checkpoint kinase, and γ-H2AX, a marker of DNA double-strand breaks, discriminated between patients with a pathological complete response (pCR) and those with residual disease. We also tested the association between pWee1 and phosphorylated Chk1 (pChk1), a kinase acting upstream Wee1 in the G₂/M checkpoint pathway. pWee1, γ-H2AX and pChk1 were retrospectively assessed in diagnostic biopsies by immunohistochemistry. The degrees of pWee1 and pChk1 expression were defined using three different classification methods, i.e., staining intensity, Allred score, and a multiplicative score. γ-H2AX was analyzed both as continuous and categorical variable. Irrespective of the classification used, elevated levels of pWee1 and γ-H2AX were significantly associated with a lower rate of pCR. In univariate and multivariate analyses, pWee1 and γ-H2AX were both associated with reduced pCR. Internal validation conducted through a re-sampling without replacement procedure confirmed the robustness of the multivariate model. Finally, we found a significant association between pWee1 and pChk1. The message conveyed by the present analysis is that biomarkers of DNA damage and repair may predict the efficacy of neoadjuvant chemotherapy in cervical cancer. Further studies are warranted to prospectively validate these encouraging findings.     

Basilar membrane responses to two-tone and broadband stimuli.

The responses to sound of mammalian cochlear neurons exhibit many nonlinearities, some of which (such as two-tone rate suppression and intermodulation distortion) are highly frequency specific, being strongly tuned to the characteristic frequency (CF) of the neuron. With the goal of establishing the cochlear origin of these auditory-nerve nonlinearities, mechanical responses to clicks and to pairs of tones were studied in relatively healthy chinchilla cochleae at a basal site of the basilar membrane with CF of 8-10 kHz. Responses were also obtained in cochleae in which hair cell receptor potentials were reduced by systemic furosemide injection. Vibrations were recorded using either the M?ssbauer technique or laser Doppler-shift velocimetry. Responses to tone pairs contained intermodulation distortion products whose magnitudes as a function of stimulus frequency and intensity were comparable to those of distortion products in cochlear afferent responses. Responses to CF tones could be selectively suppressed by tones with frequency either higher or lower than CF; in most respects, mechanical two-tone suppression resembled rate suppression in cochlear afferents. Responses to clicks displayed a CF-specific compressive nonlinearity, similar to that present in responses to single tones, which could be profoundly and selectively reduced by furosemide. The present findings firmly support the hypothesis that all CF-specific nonlinearities present in the auditory nerve originate in analogous phenomena of basilar membrane vibration. However, because of their lability, it is almost certain that the mechanical nonlinearities themselves originate in outer hair cells.     

In vitro translation of archaeal natural mRNAs at high temperature

Abstract Efficient in vitro translation of archaeal natural mRNAs at high (75°C) temperature has been achieved by employing either crude cell lysates or purified ribosomes and soluble proteins of the extreme thermophile Sulfolobus solfataricus . The features of the system are described.     

The secretion and maturation of prosaposin and procathepsin D are blocked in embryonic neural progenitor cells

The notion that prosaposin (Prosap) is likely involved in brain development and regeneration led us to explore its expression in stem/progenitor neural cells and its fate after cell differentiation. The expression of procathepsin-cathepsin D (proCath-Cath D), an endoprotease that plays an important role in the processing and sorting of Prosap, has been concomitantly examined. Our data evidenced that in embryonic human neural progenitor cells (eHNPCs) intact and high molecular weight intermediate forms of Prosap and intermediate forms of Cath D accumulated inside the cells, while the formation of saposins and mature Cath D was impaired. Furthermore, neither Prosap nor proCath D were secreted from eHNPCs. The block of the processing and secretion shared by Prosap and proCath D was overcome during the course of differentiation of eHNPCs into a mixed population of astrocytes and neuronal cells. Upon differentiation, large amounts of Prosap and proCath D were secreted from the cells, while saposins and mature Cath D were produced inside the cells. The dramatic accumulation of Prosap (an antiapoptotic factor) and reduction of mature Cath D (a proapoptotic factor) in the undifferentiated eHNPCs most likely play a role in the molecular mechanisms regulating the resistance to apoptotic signals of these cells and might represent a critically important issue in HNPCs biology.     

The miR-15a-miR-16-1 cluster controls prostate cancer by targeting multiple oncogenic activities

MicroRNAs (miRNAs) are noncoding small RNAs that repress protein translation by targeting specific messenger RNAs. miR-15a and miR-16-1 act as putative tumor suppressors by targeting the oncogene BCL2. These miRNAs form a cluster at the chromosomal region 13q14, which is frequently deleted in cancer. Here, we report that the miR-15a and miR-16-1 cluster targets CCND1 (encoding cyclin D1) and WNT3A, which promotes several tumorigenic features such as survival, proliferation and invasion. In cancer cells of advanced prostate tumors, the miR-15a and miR-16 level is significantly decreased, whereas the expression of BCL2, CCND1 and WNT3A is inversely upregulated. Delivery of antagomirs specific for miR-15a and miR-16 to normal mouse prostate results in marked hyperplasia, and knockdown of miR-15a and miR-16 promotes survival, proliferation and invasiveness of untransformed prostate cells, which become tumorigenic in immunodeficient NOD-SCID mice. Conversely, reconstitution of miR-15a and miR-16-1 expression results in growth arrest, apoptosis and marked regression of prostate tumor xenografts. Altogether, we propose that miR-15a and miR-16 act as tumor suppressor genes in prostate cancer through the control of cell survival, proliferation and invasion. These findings have therapeutic implications and may be exploited for future treatment of prostate cancer.     

The meso-angioblast: a multipotent,self-renewing cell that originates from the dorsal aorta and differentiates into most mesodermal tissues

We have previously reported the origin of a class of skeletal myogenic cells from explants of dorsal aorta. This finding disagrees with the known origin of all skeletal muscle from somites and has therefore led us to investigate the in vivo origin of these cells and, moreover, whether their fate is restricted to skeletal muscle, as observed in vitro under the experimental conditions used. To address these issues, we grafted quail or mouse embryonic aorta into host chick embryos. Donor cells, initially incorporated into the host vessels, were later integrated into mesodermal tissues, including blood, cartilage, bone, smooth, skeletal and cardiac muscle. When expanded on a feeder layer of embryonic fibroblasts, the clonal progeny of a single cell from the mouse dorsal aorta acquired unlimited lifespan, expressed hemo-angioblastic markers (CD34, Flk1 and Kit) at both early and late passages, and maintained multipotency in culture or when transplanted into a chick embryo. We conclude that these newly identified vessel-associated stem cells, the meso-angioblasts, participate in postembryonic development of the mesoderm, and we speculate that postnatal mesodermal stem cells may be derived from a vascular developmental origin.