ΔNp63 is a transcription factor playing a fundamental role in the regulation of development and homeostasis of stratified epithelial tissues as well as in sustaining the pathogenesis of several epithelial tumors, such as basal breast carcinoma and squamous cell carcinoma. Triple negative breast cancers (TNBC) represent the most aggressive and clinically relevant breast carcinomas. On the basis of specific molecular signature, the majority of TNBC can be classified as basal-like breast carcinoma. In first part of my PhD program, we report data showing that in basal-like breast carcinoma cells ΔNp63 is capable of sustaining the production of the hyaluronic acid (HA), one of the major components of the extracellular matrix (ECM). We found that ΔNp63 regulates the expression of HA-related genes, such as the HA synthase HAS3, the hyaluronidase HYAL-1 and CD44, the major HA cell membrane receptor. By controlling this pathway, ΔNp63 contributes to maintain the self-renewal of breast cancer stem cells. Importantly, high HAS3 expression is a negative prognostic factor of TNBC patients. Our data suggest that in basal-type breast carcinoma, ΔNp63 might favour a HA-rich microenviroment, which can sustain tumor proliferation and stemness. ΔNp63 ability to enhance the self-renewal ability of cancer cells might be a direct consequence of its physiological function in normal stratified epithelia, such as the epidermis, where it maintenances the proliferative state of keratinocytes in the basal layer. Long noncoding RNAs (lncRNAs) represent an important class of RNA involved in various physiological processes such as cellular differentiation. The functional link between p63 transcriptional activity and lncRNAs has not been explored. In second part of my PhD program, we aimed to identify and characterize lncRNAs potentially regulated by ΔNp63 in human primary keratinocytes. By exploiting different molecular, biochemical and bioinformatics approaches we identified the Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and the nuclear enriched abundant transcript 1 (NEAT1) as ΔNp63-regulated lncRNA. We showed that ΔNp63 directly binds to the promotor region of NEAT1 and MALAT1, repressing their expression by recruiting the histone deacetylates HDAC1/2. Furthermore, we found that NEAT1 and MALAT1 expression is upregulated during keratinocytes differentiation, both in vitro and in vivo. Further studies are necessary to understand the physiological relevance of the ΔNp63-dependent regulation of NEAT1 and MALAT1 during epidermal differentiation.
ΔNp63 è un fattore trascrizionale che riveste un ruolo fondamentale nella regolazione dello sviluppo e dell’omeostasi dei tessuti epiteliali stratificati e nello sviluppo della patogenesi di molti tumori epiteliali, così come cancro alla mammella di tipo basale e cancro delle cellule squamose. Tumore alla mammella triplo negativo (TNBC) rappresenta uno dei più aggressivi e clinicamente rilevanti di tumore alla mammella. La maggior parte di TNBC può essere classificato come cancro alla mammella di tipo basale in base alle caratteristiche molecolare. Nella prima parte del mio programma di PhD, i dati che mostriamo suggeriscono che nelle cellule del cancro della mammella di tipo basale, ΔNp63 è capace di sostenere la produzione di acido ialuronico (HA), uno dei maggiori componenti della matrice extracellulare (ECM). Infatti, ΔNp63 regola l’espressione dei geni relativi al metabolismo e al pathway di HA, così come HAS3 sintasi di HA, HYAL1 ialuronidasi e CD44, il maggiore recettore di membrana per HA. In questo modo, ΔNp63 permette alle cellule staminali del cancro della mammella mantengono la loro capacità di autorigenerarsi. Inoltre, l’elevata espressione di HAS3 è un fattore prognostico negativo dei pazienti TNBC. I nostri dati suggeriscono che nel cancro della mammella di tipo basale, ΔNp63 può favorire un microambiente ricco di HA il quale può sostenere la proliferazione e la staminalità del tumore. La capacità di ΔNp63 di sostenere il potenziale staminale delle cellule del cancro può essere una diretta conseguenza della sua funzione nei tessuti normali epiteliali stratificati, come l’epidermide in cui mantiene lo stato proliferativo dei cheratinociti nello strato basale. In più, i long noncoding RNAs (lncRNAs) rappresentano un importante classe di RNA non codificati coinvolti in vari processi fisiologici come il differenziamento cellulare. Fino ad ora non è stato trovato un collegamento tra l’attività trascrizionale di p63 e l’espressione di lncRNAs. Noi abbiamo usato un microarray per comparare l’espressione dei lncRNAs in cheratinociti silenziati per p63 rispetto al controllo e abbiamo identificato Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), la cui espressione aumenta in cellule silenziate per p63. Il locus genomico di MALAT1 è adiacente al locus di un altro lncRNA, NEAT1, un lncRNA essenziale per la formazione dei nucleari paraspeckles. Nella seconda parte del mio programma di PhD, abbiamo studiato la regolazione di NEAT1 and MALAT1 e mostriamo il legame diretto di p63 al promotore di essi, reprimendo la loro espressione mediante HDAC1/2. Inoltre, abbiamo osservato un aumento dell’espressione di NEAT1 and MALAT1 durante il differenziamento dei cheratinociti. Questi dati potranno contribuire per identificare il potenziale ruolo di NEAT1 and MALAT1 nel differenziamento epidermico.
Role of p63 in physiological and pathological conditions
FIERRO, CLAUDIA
2019
Abstract
ΔNp63 is a transcription factor playing a fundamental role in the regulation of development and homeostasis of stratified epithelial tissues as well as in sustaining the pathogenesis of several epithelial tumors, such as basal breast carcinoma and squamous cell carcinoma. Triple negative breast cancers (TNBC) represent the most aggressive and clinically relevant breast carcinomas. On the basis of specific molecular signature, the majority of TNBC can be classified as basal-like breast carcinoma. In first part of my PhD program, we report data showing that in basal-like breast carcinoma cells ΔNp63 is capable of sustaining the production of the hyaluronic acid (HA), one of the major components of the extracellular matrix (ECM). We found that ΔNp63 regulates the expression of HA-related genes, such as the HA synthase HAS3, the hyaluronidase HYAL-1 and CD44, the major HA cell membrane receptor. By controlling this pathway, ΔNp63 contributes to maintain the self-renewal of breast cancer stem cells. Importantly, high HAS3 expression is a negative prognostic factor of TNBC patients. Our data suggest that in basal-type breast carcinoma, ΔNp63 might favour a HA-rich microenviroment, which can sustain tumor proliferation and stemness. ΔNp63 ability to enhance the self-renewal ability of cancer cells might be a direct consequence of its physiological function in normal stratified epithelia, such as the epidermis, where it maintenances the proliferative state of keratinocytes in the basal layer. Long noncoding RNAs (lncRNAs) represent an important class of RNA involved in various physiological processes such as cellular differentiation. The functional link between p63 transcriptional activity and lncRNAs has not been explored. In second part of my PhD program, we aimed to identify and characterize lncRNAs potentially regulated by ΔNp63 in human primary keratinocytes. By exploiting different molecular, biochemical and bioinformatics approaches we identified the Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and the nuclear enriched abundant transcript 1 (NEAT1) as ΔNp63-regulated lncRNA. We showed that ΔNp63 directly binds to the promotor region of NEAT1 and MALAT1, repressing their expression by recruiting the histone deacetylates HDAC1/2. Furthermore, we found that NEAT1 and MALAT1 expression is upregulated during keratinocytes differentiation, both in vitro and in vivo. Further studies are necessary to understand the physiological relevance of the ΔNp63-dependent regulation of NEAT1 and MALAT1 during epidermal differentiation.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/210142
URN:NBN:IT:UNIROMA2-210142