Anna Parenti

The Hippo Transducer TAZ Confers Cancer Stem Cell-Related Traits on Breast Cancer Cells

Cancer stem cells (CSCs) are proposed to drive tumor initiation and progression. Yet, our understanding of the cellular and molecular mechanisms that underlie CSC properties is limited. Here we show that the activity of TAZ, a transducer of the Hippo pathway, is required to sustain self-renewal and tumor-initiation capacities in breast CSCs. TAZ protein levels and activity are elevated in prospective CSCs and in poorly differentiated human tumors and have prognostic value. Gain of TAZ endows self-renewal capacity to non-CSCs. In epithelial cells, TAZ forms a complex with the cell-polarity determinant Scribble, and loss of Scribble--or induction of the epithelial-mesenchymal transition (EMT)--disrupts the inhibitory association of TAZ with the core Hippo kinases MST and LATS. This study links the CSC concept to the Hippo pathway in breast cancer and reveals a mechanistic basis of the control of Hippo kinases by cell polarity.

A Mutant-p53/Smad Complex Opposes p63 to Empower TGFβ-Induced Metastasis

TGFbeta ligands act as tumor suppressors in early stage tumors but are paradoxically diverted into potent prometastatic factors in advanced cancers. The molecular nature of this switch remains enigmatic. Here, we show that TGFbeta-dependent cell migration, invasion and metastasis are empowered by mutant-p53 and opposed by p63. Mechanistically, TGFbeta acts in concert with oncogenic Ras and mutant-p53 to induce the assembly of a mutant-p53/p63 protein complex in which Smads serve as essential platforms. Within this ternary complex, p63 functions are antagonized. Downstream of p63, we identified two candidate metastasis suppressor genes associated with metastasis risk in a large cohort of breast cancer patients. Thus, two common oncogenic lesions, mutant-p53 and Ras, selected in early neoplasms to promote growth and survival, also prefigure a cellular set-up with particular metastasis proclivity by TGFbeta-dependent inhibition of p63 function.

A MicroRNA Targeting Dicer for Metastasis Control

Although specific microRNAs (miRNAs) can be upregulated in cancer, global miRNA downregulation is a common trait of human malignancies. The mechanisms of this phenomenon and the advantages it affords remain poorly understood. Here we identify a microRNA family, miR-103/107, that attenuates miRNA biosynthesis by targeting Dicer, a key component of the miRNA processing machinery. In human breast cancer, high levels of miR-103/107 are associated with metastasis and poor outcome. Functionally, miR-103/107 confer migratory capacities in vitro and empower metastatic dissemination of otherwise nonaggressive cells in vivo. Inhibition of miR-103/107 opposes migration and metastasis of malignant cells. At the cellular level, a key event fostered by miR-103/107 is induction of epithelial-to-mesenchymal transition (EMT), attained by downregulating miR-200 levels. These findings suggest a new pathway by which Dicer inhibition drifts epithelial cancer toward a less-differentiated, mesenchymal fate to foster metastasis.

SHARP1 suppresses breast cancer metastasis by promoting degradation of hypoxia-inducible factors.

The molecular determinants of malignant cell behaviours in breast cancer remain only partially understood. Here we show that SHARP1 (also known as BHLHE41 or DEC2) is a crucial regulator of the invasive and metastatic phenotype in triple-negative breast cancer (TNBC), one of the most aggressive types of breast cancer. SHARP1 is regulated by the p63 metastasis suppressor and inhibits TNBC aggressiveness through inhibition of hypoxia-inducible factor 1α (HIF-1α) and HIF-2α (HIFs). SHARP1 opposes HIF-dependent TNBC cell migration in vitro, and invasive or metastatic behaviours in vivo. SHARP1 is required, and sufficient, to limit expression of HIF-target genes. In primary TNBC, endogenous SHARP1 levels are inversely correlated with those of HIF targets. Mechanistically, SHARP1 binds to HIFs and promotes HIF proteasomal degradation by serving as the HIF-presenting factor to the proteasome. This process is independent of pVHL (von Hippel–Lindau tumour suppressor), hypoxia and the ubiquitination machinery. SHARP1 therefore determines the intrinsic instability of HIF proteins to act in parallel to, and cooperate with, oxygen levels. This work sheds light on the mechanisms and pathways by which TNBC acquires invasiveness and metastatic propensity.

P53 OVEREXPRESSION IN THE MULTISTEP PROCESS OF ESOPHAGEAL CARCINOGENESIS

The timing of p53 mutation in the multistep process of esophageal carcinogenesis is still under debate. We tested p53 expression in 16 samples of low-grade and 29 samples of high-grade esophageal dysplasia (ED) coexisting with esophageal squamous cancer (ESC) in 31 patients who underwent total esophagectomy. In normal mucosa, a positive immunoreaction was detected in 10 of 31 cases, always restricted to the lower half of the epithelial thickness. We detected p53-positive nuckei in 11 of 16, 23 of 29. and 23 of 31 samples of low-grade ED, high-grade ED, and ESC, respectively. Cases exhibiting positive staining in dysplastic samples also demonstrated positive immunoreaction in the carcinomatous tissue. Immunoreactivity in cancer cells was never found in the absence of positive dysplastic nuclei. A significantly higher score of immunoreactive nuclei was detected in high-grade versus low-grade and in low-grade compared with normal mucosa. These data suggest that p53 mutation may represent an early event in esophageal oncogenesis.

Mitochondrial DNA D-loop in pancreatic cancer: somatic mutations are epiphenomena while the germline 16519 T variant worsens metabolism and outcome.

We ascertained the frequency of mitochondrial DNA (mtDNA) D-loop region somatic mutations in pancreatic cancer (PC) and verified whether polymorphisms were linked to diagnosis, prognosis, and PC-associated diabetes mellitus (DM) in 99 PC cases, 42 chronic pancreatitis (CP) cases, 18 pancreatobiliary tract tumors, and 87 healthy control subjects (CSs). Tissue samples were obtained from 19 patients with PC and 5 with CP. The D-loop region was sequenced from all tissue samples and from blood DNA of the same patients and 12 CSs. D-loop somatic mutations were found in 3 PC tissue samples (16%). Four single nucleotide polymorphisms (SNPs; T152C, T16189C, T16519C, A73G), more frequently found in PC than in CS, were analyzed by denaturing high-performance liquid chromatography-restriction fragment length polymorphism using blood DNA as the starting template in all cases. The T allele of 16519 SNP correlated with DM. The survival of patients with PC correlated with tumor stage and grade and with DM at diagnosis. When survival analysis was performed considering only patients with locally advanced disease, the T allele of mtDNA 16519 SNP correlated with shorter life expectancy. mtDNA D-loop somatic mutations, rarely found in PC, cannot be considered causative events for this tumor type and probably are epiphenomena; the mtDNA D-loop 16519 variant, which worsens PC prognosis, seems to be a predisposing genetic factor for DM.

The role of botulinum toxin injection and upper esophageal sphincter myotomy in treating oropharyngeal dysphagia.

The aims of this study were to assess the efficacy and safety of botulinum toxin (BoTox) injection in the cricopharyngeus muscle (CP) and CP myotomy in patients with oropharyngeal dysphagia (OPD) and to identify factors predicting the outcome of these treatments. The study involved patients with persistent OPD despite 2–6 months of rehabilitation, who all underwent clinical evaluation, esophageal manometry, upper gastrointestinal endoscopy, and videofluoroscopy (VFS). Patients received 5–10 BoTox units injections in the CP, identified by electromyography. Surgical myotomy of the upper esophageal sphincter was performed when dysphagia persisted after two BoTox injections. After treatment, patients were reevaluated with clinical interviews and VFS. The study population included 21 patients (15 mean and 6 women; median age, 68 years), classified into three groups, based on the etiology of their OPD: eight (38%) had central nervous system abnormalities, five (24%) had peripheral nerve disease, and eight (38%) were classified as idiopathic. The median time since the onset of dysphagia was 18 months. Thirteen of 21 patients (62%) needed supplemental/total gastrostomy feeding, and 5 of 21 (24%) had tracheostomy. One patient died, on posttreatment day 7, due to massive aspiration. No other BoTox-related complications were observed. After BoTox injection, dysphagia improved in 9 of 21 (43%) patients. Severely altered VFS findings and CP incoordination or low activity predicted BoTox failure at multivariate analysis. Dysphagia improved in 8 of 11 (72.7%) patients who failed to respond to BoTox and underwent myotomy. A mild impairment of VFS findings and a higher pressure of pharyngeal contractions best predicted response to BoTox with or without myotomy. BoTox injection can be used as the first therapeutic option in patients with OPD: it is safe and simple and relieves dysphagia in 43% of cases. If BoTox fails, CP myotomy can be offered to patients with preserved oral and tongue activity at VFS and an intact bolus propulsion ability on manometry.

Survivin in esophageal cancer: An accurate prognostic marker for squamous cell carcinoma but not adenocarcinoma

We quantified the expression of survivin, both as mRNA in real‐time PCR and protein in immunohistochemistry, in tumor samples of 112 patients with esophageal cancer (56 squamous cell carcinomas and 56 adenocarcinomas). Overall survival of squamous cell carcinoma patients with high survivin mRNA levels was significantly less than that of patients with low survivin mRNA levels (p = 0.0033). Distribution pattern of survivin (nuclear vs. cytoplasmic or mixed) was not correlated to survival, while the extent of immunostaining was significantly correlated to survivin mRNA values (p = 0.016) and had prognostic relevance in univariate analysis (p = 0.0012). Coxs proportional‐hazard regression model showed that tumor survivin expression in esophageal squamous cell carcinoma was the most important prognostic factor, independent of tumor stage and other histopathological factors, both as mRNA relative value (p = 0.0259) and protein immunostaining (p = 0.0147). In esophageal adenocarcinoma, survivin expression and pattern of distribution had no prognostic relevance. Thus, quantifying survivin expression provides a prognostic marker only for esophageal squamous tumors.

Histotopographic study of the fibroadipose connective cheek system.

The purpose of this study was to investigate the morphology of the superficial musculoaponeurotic system (SMAS). Eight embalmed cadavers were analyzed: one side of the face was macroscopically dissected; on the other side, full-thickness samples of the parotid, zygomatic, nasolabial fold and buccal regions were taken. In all specimens, a laminar connective tissue layer (SMAS) bounding two different fibroadipose connective layers was identified. The superficial fibroadipose layer presented vertically oriented fibrous septa, connecting the dermis with the superficial aspect of the SMAS. In the deep fibroadipose connective layer, the fibrous septa were obliquely oriented, connecting the deep aspect of the SMAS to the parotid-masseteric fascia. This basic arrangement shows progressive thinning of the SMAS from the preauricular district to the nasolabial fold (p < 0.05). In the parotid region, the mean thicknesses of the superficial and deep fibroadipose connective tissues were 1.63 and 0.8 mm, respectively, whereas in the region of the nasolabial fold the superficial layer is not recognizable and the mean thickness of the deep fibroadipose connective layer was 2.9 mm. The connective subcutaneous tissue of the face forms a three-dimensional network connecting the SMAS to the dermis and deep muscles. These connective laminae connect adipose lobules of various sizes within the superficial and deep fibroadipose tissues, creating a three-dimensional network which modulates transmission of muscle contractions to the skin. Changes in the quantitative and qualitative characteristics of the fibroadipose connective system, reducing its viscoelastic properties, may contribute to ptosis of facial soft tissues during aging.

The Ankle Retinacula: Morphological Evidence of the Proprioceptive Role of the Fascial System

Study Design: Research report. Objectives: To evaluate the anatomical characteristics of the ankle retinacula and their relationship with the fasciae and muscles in healthy subjects and in patients with ankle sprain outcomes. Background: The role of the retinacula in proprioception has begun to emerge, but without clear anatomical bases or descriptions of their possible damage in patients with ankle sprain outcomes. Methods: Dissection, histological and immunohistochemical analysis of 27 legs. An in vivo radiological study by MRI was also performed on 7 healthy volunteers, 17 patients with outcomes of ankle sprain, and 3 amputated legs. Results: The retinacula are thickenings of the deep fascia presenting bone or muscular connections. They are formed of 2–3 layers of parallel collagen fibre bundles, densely packaged with a little loose connective tissue, without elastic fibres but many nervous fibres and corpuscles. By MRI, the retinacula appeared as low-signal-intensity bands with a mean thickness of 1 mm. In patients with outcomes of ankle sprain, MR findings were abnormal retinacula thickness, signal intensity, and full-thickness gap. Discussion: The retinacula are not static structures for joint stabilisation, like the ligaments, but a specialisation of the fascia for local spatial proprioception of the movements of foot and ankle. Their anatomical variations and accessory bundles may be viewed as morphological evidence of the integrative role of the fascial system in peripheral control of articular motility.