Oncocytic cell tumors are characterized by the accumulation of morphologically abnormal mitochondria in their cells, suggesting a role for abnormal mitochondrial biogenesis in oncocytic cell ...transformation. Little is known about the reason for the dysmorphology of accumulated mitochondria. The proteins regulating the morphology of mitochondria, the "mitochondria-shaping" proteins, can modulate their size and number; however, nothing is known hitherto about a possible involvement of mitochondrial dynamics in oncocytic cell transformation in tumors. Our aim was to assess the status of the mitochondria morphology and its role in oncocytic cell transformation. We therefore evaluated the expression pattern of the main mitochondrial fusion and fission proteins in a series of thyroid cell tumor samples, as well as in thyroid tumor cell lines, with and without oncocytic cell features. The expression of mitochondrial fusion (Opa1, Mfn1 and Mfn2) and fission (Drp1 and Fis1) proteins were evaluated by immunohistochemistry (IHC) in a series of 88 human thyroid tumors. In vitro studies, for comparative purposes and to deepen the study, were performed using TPC1--a papillary thyroid carcinoma derived cell line--and XTC.UC1, an oncocytic follicular thyroid carcinoma-derived cell line. Both IHC and in vitro protein analyses showed an overall increase in the levels of "mitochondrial-shaping" proteins in oncocytic thyroid tumors. Furthermore, overexpression of the pro-fission protein Drp1 was found to be associated with malignant oncocytic thyroid tumors. Interestingly, genetic and pharmacological blockage of Drp1 activity was able to influence thyroid cancer cells' migration/invasion ability, a feature of tumor malignancy. In this study we show that unbalanced mitochondrial dynamics characterize the malignant features of thyroid oncocytic cell tumors, and participate in the acquisition of the migrating phenotype.
Mitochondrial dynamics are known to have an important role in so-called age-related diseases, including cancer. Mitochondria is an organelle involved in many key cellular functions and responds to ...physiologic or stress stimuli by adapting its structure and function. Perhaps the most important structural changes involve mitochondrial dynamics (fission and fusion), which occur in normal cells as well as in cells under dysregulation, such as cancer cells. Dynamin-related protein 1 (DRP1), a member of the dynamin family of guanosine triphosphatases (GTPases), is the key component of mitochondrial fission machinery. Dynamin-related protein 1 is associated with different cell processes such as apoptosis, mitochondrial biogenesis, mitophagy, metabolism, and cell proliferation, differentiation, and transformation. The role of DRP1 in tumorigenesis may seem to be paradoxical, since mitochondrial fission is a key mediator of two very different processes, cellular apoptosis and cell mitosis. Dynamin-related protein 1 has been associated with the development of distinct human cancers, including changes in mitochondrial energetics and cellular metabolism, cell proliferation, and stem cell maintenance, invasion, and promotion of metastases. However, the underlying mechanism for this association is still being explored. Herein, we review the published knowledge on the role of DRP1 in cancer, exploring its interaction with different biological processes in the tumorigenesis context.
Helicobacter pylori is a major cause of gastric carcinoma. To investigate a possible link between bacterial infection and genetic instability of the host genome, we examined the effect of H. pylori ...infection on known cellular repair pathways in vitro and in vivo. Moreover, various types of genetic instabilities in the nuclear and mitochondrial DNA (mtDNA) were examined.
We observed the effects of H. pylori infection on a gastric cell line (AGS), on C57BL/6 mice, and on individuals with chronic gastritis. In AGS cells, the effect of H. pylori infection on base excision repair and mismatch repair (MMR) was analyzed by reverse transcription-PCR, Western blot, and activity assays. In mice, MMR expression was analyzed by reverse transcription-PCR and the CA repeat instabilities were examined by Mutation Detection Enhancement gel electrophoresis. Mutation spectra in AGS cells and chronic gastritis tissue were determined by PCR, single-stranded conformation polymorphism, and sequencing. H. pylori vacA and cagA genotyping was determined by multiplex PCR and reverse hybridization.
Following H. pylori infection, the activity and expression of base excision repair and MMR are down-regulated both in vitro and in vivo. Moreover, H. pylori induces genomic instability in nuclear CA repeats in mice and in mtDNA of AGS cells and chronic gastritis tissue, and this effect in mtDNA is associated with bacterial virulence.
Our results suggest that H. pylori impairs central DNA repair mechanisms, inducing a transient mutator phenotype, rendering gastric epithelial cells vulnerable to the accumulation of genetic instability and thus contributing to gastric carcinogenesis in infected individuals.
Bladder cancer (BC) ranks as the sixth most prevalent cancer in the world, with a steady rise in its incidence and prevalence, and is accompanied by a high morbidity and mortality. BC is a complex ...disease with several molecular and pathological pathways, thus reflecting different behaviors depending on the clinical staging of the tumor and molecular type. Diagnosis and monitoring of BC is mainly performed by invasive tests, namely periodic cystoscopies; this procedure, although a reliable method, is highly uncomfortable for the patient and it is not exempt of comorbidities. Currently, there is no formal indication for the use of molecular biomarkers in clinical practice, even though there are several tests available. There is an imperative need for a clinical non-invasive testing for early detection, disease monitoring, and treatment response in BC. In this review, we aim to assess and compare different tests based on molecular biomarkers and evaluate their potential role as new molecules for bladder cancer diagnosis, follow-up, and treatment response monitoring.
Reactivation of telomerase has been implicated in human tumorigenesis, but the underlying mechanisms remain poorly understood. Here we report the presence of recurrent somatic mutations in the TERT ...promoter in cancers of the central nervous system (43%), bladder (59%), thyroid (follicular cell-derived, 10%) and skin (melanoma, 29%). In thyroid cancers, the presence of TERT promoter mutations (when occurring together with BRAF mutations) is significantly associated with higher TERT mRNA expression, and in glioblastoma we find a trend for increased telomerase expression in cases harbouring TERT promoter mutations. Both in thyroid cancers and glioblastoma, TERT promoter mutations are significantly associated with older age of the patients. Our results show that TERT promoter mutations are relatively frequent in specific types of human cancers, where they lead to enhanced expression of telomerase.
Intestinal stem cells (ISCs) fuel the lifelong self‐renewal of the intestinal tract and are paramount for epithelial repair. In this context, the Wnt pathway component LGR5 is the most consensual ISC ...marker to date. Still, the effort to better understand ISC identity and regulation remains a challenge. We have generated a Mex3a knockout mouse model and show that this RNA‐binding protein is crucial for the maintenance of the Lgr5+ ISC pool, as its absence disrupts epithelial turnover during postnatal development and stereotypical organoid maturation ex vivo. Transcriptomic profiling of intestinal crypts reveals that Mex3a deletion induces the peroxisome proliferator‐activated receptor (PPAR) pathway, along with a decrease in Wnt signalling and loss of the Lgr5+ stem cell signature. Furthermore, we identify PPARγ activity as a molecular intermediate of MEX3A‐mediated regulation. We also show that high PPARγ signalling impairs Lgr5+ ISC function, thus uncovering a new layer of post‐transcriptional regulation that critically contributes to intestinal homeostasis.
Synopsis
The RNA‐binding protein MEX3A is expressed at the base of intestinal crypts and is critical for the maintenance of Lgr5+ ISCs during postnatal development. MEX3A regulates the PPARγ pathway, thereby modulating ISC identity and tissue homeostasis.
Mex3a−/− mice exhibit growth retardation, postnatal mortality, and a severe impairment of intestinal crypt development.
Crypts of Mex3a knockout mice exhibit loss of Lgr5+ intestinal stem cells and disruption of epithelial turnover.
Mex3a deletion leads to the aberrant activation of the PPARγ signalling pathway in intestinal crypts.
High PPARγ signalling impairs Lgr5+ stem cell function in intestinal organoids.
The RNA‐binding protein MEX3A is expressed at the base of intestinal crypts and is critical for the maintenance of Lgr5+ ISCs during postnatal development. MEX3A regulates the PPARγ pathway, thereby modulating ISC identity and tissue homeostasis.
Telomerase reverse transcriptase gene promoter (
) mutations are recognized as one of the most frequent genetic events in bladder cancer (BC). No studies have focused on the relevance of TERTp ...mutations in the specific group of tumors treated with Bacillus Calmette-Guérin (BCG) intravesical therapy. Methods - 125 non muscle invasive BC treated with BCG therapy (BCG-NMIBC) were screened for
mutations,
rs2853669 single nucleotide polymorphism, and Fibroblast Growth Factor Receptor 3 (
) hotspot mutations. Results -
mutations were found in 56.0% of BCG-NMIBC and were not associated with tumor stage or grade.
mutations were found in 44.9% of the cases and were not associated with tumor stage or grade nor with
mutations. The
rs2853669 single nucleotide polymorphism was associated with tumors of higher grade. The specific c.1-146G>A
mutation was an independent predictor of nonrecurrence after BCG therapy (hazard ratio-0.382; 95% confidence interval-0.150-0.971,
= 0.048). Conclusions -
mutations are frequent in BCG-NMIBC and -146G>A appears to be an independent predictive marker of response to BCG treatment with an impact in recurrence-free survival.
The biology and the genetics of Hürthle cell tumors are reviewed starting from the characterization and differential diagnosis of the numerous benign and malignant, neoplastic and nonneoplastic ...lesions of the thyroid in which Hürthle cell transformation is frequently observed. The clinicopathologic and molecular evidence obtained from the comparative study of the aforementioned conditions indicate that Hürthle cell appearance represents a phenotype that is superimposed on the genotypic and conventional histopathologic features of the tumors. Hürthle cell tumors differ from their non-Hürthle counterparts regarding the prevalence of large deletions of mitochondrial DNA (mtDNA), mutations of mtDNA genes coding for oxidative phosphorylation (OXPHOS) proteins (namely mutations of complex I subunit genes) and mutations of nuclear genes coding also for mitochondrial OXPHOS proteins. Such mitochondrial alterations lead to energy production defects in Hürthle cell tumors; the increased proliferation of mitochondria may reflect a compensatory mechanism for such defects and is associated with the overexpression of factors involved in mitochondrial biogenesis. The mitochondrial abnormalities are also thought to play a major role in the predisposition for necrosis instead of apoptosis which seems to be blocked in most Hürthle cell tumors. Finally, the results obtained in experimental models using cybrid cell lines and the data obtained from histopathologic and molecular studies of familial Hürthle cell tumors are used, together with the aforementioned genetic and epigenetic alterations, to progress in the understanding of the mechanisms through which mitochondrial abnormalities may be involved in the different steps of thyroid carcinogenesis, from tumor initiation to metastization.
In a family with Familial Non-Medullary Thyroid Carcinoma (FNMTC), our investigation using Whole-Exome Sequencing (WES) uncovered a novel germline
mutation
. USP42 is known for regulating p53, cell ...cycle arrest, and apoptosis, and for being reported as overexpressed in breast and gastric cancer patients. Recently, a
missense mutation was described in FNMTC, suggesting a potential involvement in thyroid cancer. Aiming to explore the
mutation as an underlying cause of FNMTC, our team validated the mutation in blood and tissue samples from the family. Using immunohistochemistry, the expression of USP42, Caspase-3, and p53 was assessed. The
gene was silenced in human thyroid Nthy-Ori 3-1 cells using siRNAs. Subsequently, expression, viability, and morphological assays were conducted. p53, Cyclin D1, p21, and p27 proteins were evaluated by Western blot. USP42 protein was confirmed in all family members and was found to be overexpressed in tumor samples, along with an increased expression of p53 and cleaved Caspase-3. siRNA-mediated
downregulation in Nthy-Ori 3-1 cells resulted in reduced cell viability, morphological changes, and modifications in cell cycle-related proteins. Our results suggest a pivotal role of
mutation in thyroid cell biology, and this finding indicates that USP42 may serve as a new putative target in FNMTC.
STAT3 negatively regulates thyroid tumorigenesis Couto, Joana Pinto; Daly, Laura; Almeida, Ana ...
Proceedings of the National Academy of Sciences - PNAS,
08/2012, Volume:
109, Issue:
35
Journal Article
Peer reviewed
Open access
Although tyrosine-phosphorylated or activated STAT3 (pY-STAT3) is a well-described mediator of tumorigenesis, its role in thyroid cancer has not been investigated. We observed that 63 of 110 (57%) ...human primary papillary thyroid carcinoma (PTC) cases expressed nuclear pY-STAT3 in tumor cells, preferentially in association with the tumor stroma. An inverse relationship between pY-STAT3 expression with tumor size and the presence of distant metastases was observed. Using human thyroid cancer-derived cell lines harboring rearranged during transfection (RET)/PTC, v-RAF murine sarcoma viral oncogene homolog B (BRAF), or rat sarcoma virus oncogene (RAS) alterations, we determined that IL-6/gp130/JAK signaling is responsible for STAT3 activation. STAT3 knockdown by shRNA in representative thyroid cancer cell lines that express high levels of pY-STAT3 had no effect on in vitro growth. However, xenografted short hairpin STAT3 cells generated larger tumors than control cells. Similarly, STAT3 deficiency in a murine model of BRAF V600E-induced PTC led to thyroid tumors that were more proliferative and larger than those tumors expressing STAT3wt. Genome expression analysis revealed that STAT3 knockdown resulted in the down-regulation of multiple transcripts, including the tumor suppressor insulin-like growth factor binding protein 7. Furthermore, STAT3 knockdown led to an increase in glucose consumption, lactate production, and expression of Hypoxia-inducible factor 1 (HIF1α) target genes, suggesting that STAT3 is a negative regulator of aerobic glycolysis. Our studies show that, in the context of thyroid cancer, STAT3 is paradoxically a negative regulator of tumor growth. These findings suggest that targeting STAT3 in these cancers could enhance tumor size and highlight the complexities of the role of STAT3 in tumorigenesis.
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