Progression of mouse skin carcinogenesis is associated with increased ERα levels and is repressed by a dominant negative form of ERα.

Estrogen receptors (ER), namely ERα and ERβ, are hormone-activated transcription factors with an important role in carcinogenesis. In the present study, we aimed at elucidating the implication of ERα in skin cancer, using chemically-induced mouse skin tumours, as well as cell lines representing distinct stages of mouse skin oncogenesis. First, using immunohistochemical staining we showed that ERα is markedly increased in aggressive mouse skin tumours in vivo as compared to the papilloma tumours, whereas ERβ levels are low and become even lower in the aggressive spindle tumours of carcinogen-treated mice. Then, using the multistage mouse skin carcinogenesis model, we showed that ERα gradually increases during promotion and progression stages of mouse skin carcinogenesis, peaking at the most aggressive stage, whereas ERβ levels only slightly change throughout skin carcinogenesis. Stable transfection of the aggressive, spindle CarB cells with a dominant negative form of ERα (dnERα) resulted in reduced ERα levels and reduced binding to estrogen responsive elements (ERE)-containing sequences. We characterized two highly conserved EREs on the mouse ERα promoter through which dnERα decreased endogenous ERα levels. The dnERα-transfected CarB cells presented altered protein levels of cytoskeletal and cell adhesion molecules, slower growth rate and impaired anchorage-independent growth in vitro, whereas they gave smaller tumours with extended latency period of tumour onset in vivo. Our findings suggest an implication of ERα in the aggressiveness of spindle mouse skin cancer cells, possibly through regulation of genes affecting cell shape and adhesion, and they also provide hints for the effective targeting of spindle cancer cells by dnERα

Radiation Type- and Dose-Specific Transcriptional Responses across Healthy and Diseased Mammalian Tissues

Ionizing radiation (IR) is a genuine genotoxic agent and a major modality in cancer treatment. IR disrupts DNA sequences and exerts mutagenic and/or cytotoxic properties that not only alter critical cellular functions but also impact tissues proximal and distal to the irradiated site. Unveiling the molecular events governing the diverse effects of IR at the cellular and organismal levels is relevant for both radiotherapy and radiation protection. Herein, we address changes in the expression of mammalian genes induced after the exposure of a wide range of tissues to various radiation types with distinct biophysical characteristics. First, we constructed a publicly available database, termed RadBioBase, which will be updated at regular intervals. RadBioBase includes comprehensive transcriptomes of mammalian cells across healthy and diseased tissues that respond to a range of radiation types and doses. Pertinent information was derived from a hybrid analysis based on stringent literature mining and transcriptomic studies. An integrative bioinformatics methodology, including functional enrichment analysis and machine learning techniques, was employed to unveil the characteristic biological pathways related to specific radiation types and their association with various diseases. We found that the effects of high linear energy transfer (LET) radiation on cell transcriptomes significantly differ from those caused by low LET and are consistent with immunomodulation, inflammation, oxidative stress responses and cell death. The transcriptome changes also depend on the dose since low doses up to 0.5 Gy are related with cytokine cascades, while higher doses with ROS metabolism. We additionally identified distinct gene signatures for different types of radiation. Overall, our data suggest that different radiation types and doses can trigger distinct trajectories of cell-intrinsic and cell-extrinsic pathways that hold promise to be manipulated toward improving radiotherapy efficiency and reducing systemic radiotoxicities

Study of the role of p73 isoforms in lung cancer

The p73 gene possesses an extrinsic P1 promoter and an intrinsic P2 promoter, resulting in synthesis of the full-length TAp73 and the N-terminal-truncated ΔNp73 isoforms, respectively. The ultimate effect of p73 in oncogenesis is thought to depend on the apoptotic TAp73 to the antiapoptotic ΔNp73 isoforms’ ratio. The selective activation of p73 promoters could trigger the expression of either the apoptotic or the antiapoptotic p73 isoforms, thus shifting the ΔN/ΤΑ ratio towards an oncogenic or an oncosuppression direction. Therefore, the epigenetic and transcription factors that differentially activate P1 and P2 promoters are crucial deterninants of the role of p73 in cancer, since they can alter the ΔN/ΤΑ ratio. This study was aimed at identifying novel epigenetic and transcription factors that affect both TAp73 and ΔNp73 isoform synthesis in the context of lung cancer, where both TAp73 and ΔNp73 isoforms have been previously found overexpressed. First, we investigated the DNA methylation status of both promoters as a means of epigenetic transcriptional control of their corresponding isoforms in 102 primary non-small cell lung carcinomas (NSCLCs). We demonstrated that while P1 hypermethylation-associated reduction of TAp73 mRNA levels is rare, the P2 hypomethylation-associated overexpression of ΔNp73 mRNA is a frequent event, particularly among squamous cell carcinomas. P1 promoter remained essentially unmethylated in the majority of lung cancer carcinomas. On the other hand, P2 hypomethylation strongly correlated with the hypomethylation of LINE-1 transposon, a marker of global DNA hypomethylation, indicating that ΔNp73 overexpression may be a passive consequence of global DNA hypomethylation. Since overexpression of TAp73 isoforms could not be attributed to change in the methylation status of P1 promoter, we plausibly hypothesized that it could potentially be caused by deregulated activity of specific transcription factor(s) . In the light of this notion, we then searched for novel transcription factors that could activate P1 promoter and result to TAp73 overexpression in lung cancer. With the use of bioinformatics tools, in vitro binding assays, and chromatin immunoprecipitation analysis, a region extending -233 to -204 bps upstream of the transcription start site of the human p73 P1 promoter, containing conserved Sp1 binding sites, was characterized. Treatment of cells with Sp1 RNAi and Sp1 inhibitor functionally suppresses TAp73 expression, indicating positive regulation of P1 by the Sp1 protein. Notably Sp1 inhibition or silencing also reduces ΔΝp73 protein levels. Therefore, Sp1 directly regulates TAp73 transcription and affects ΔΝp73 levels in lung cancer. TAp73γ was shown to be the only TA isoform overexpressed in several lung cancer cell lines and in 26 non-small cell lung cancers, consistent with Sp1 overexpression, thereby questioning the apoptotic role of this specific p73 isoform in lung cancer.Το γονίδιο p73 διαθέτει έναν εξωτερικό υποκινητή (P1) και έναν εσωτερικό υποκινητή (P2), από τους οποίους συντίθενται οι ισομορφές TAp73 πλήρους μήκους και οι ισομορφές ΔNp73 με περικομμένο αμινοτελικό άκρο, αντίστοιχα. Το τελικό αποτέλεσμα του γονιδίου p73 πιστεύεται ότι εξαρτάται από την αναλογία των αποπτωτικών ισομορφών TAp73 προς τις αντιαποπτωτικές ισομορφές ΔNp73. Η επιλεκτική ενεργοποίηση των υποκινητών του γονιδίου p73 θα μπορούσε να επάγει την έκφραση είτε των αποπτωτικών είτε των αντιαποπτωτικών ισομορφών του p73, μετατοπίζοντας με αυτό τον τρόπο την αναλογία ΔN/ΤΑ προς μια ογκογόνο ή ογκοκατασταλτική κατεύθυνση. Κατά συνέπεια, οι επιγενετικοί και οι μεταγραφικοί παράγοντες οι οποίοι ενεργοποιούν με διαφορικό τρόπο τους υποκινητές P1 και P2 αποτελούν σημαντικούς καθοριστικούς συντελεστές του ρόλου του γονιδίου p73, αφού μπορούν να μεταβάλλουν την αναλογία ΔN/ΤΑ. Ο στόχος της παρούσας μελέτης ήταν η ταυτοποίηση νέων επιγενετικών και μεταγραφικών παραγόντων οι οποίοι επηρεάζουν τη σύνθεση των ισομορφών TAp73 και ΔNp73 στον καρκίνο του πνεύμονα, στον οποίο έχουν βρεθεί υπερεκφρασμένες και οι δύο τάξεις ισομορφών. Αρχικά, διερευνήθηκε η κατάσταση μεθυλίωσης του DNA και των δύο υποκινητών, προκειμένου να καθοριστεί η επιγενετική ρύθμιση της μεταγραφής των αντίστοιχων ισομορφών τους σε 102 πρωτοπαθείς όγκους ασθενών με μη μικροκυτταρικό καρκίνο του πνεύμονα (NSCLC). Καταδείχτηκε ότι η μείωση των επιπέδων mRNA του TAp73 η οποία οφείλεται σε υπερμεθυλίωση του υποκινητή P1 είναι σπάνια, ενώ αντίθετα η υπερέκφραση του mRNA του ΔNp73 η οποία οφείλεται σε υπομεθυλίωση του υποκινητή Ρ2 είναι ένα συχνό συμβάν, ιδιαίτερα μεταξύ ασθενών με καρκίνο του πνεύμονα εκ πλακωδών κυττάρων. Ο υποκινητής P1 παρέμεινε ουσιαστικά μη μεθυλιωμένος στην πλειονότητα των καρκινωμάτων του πνεύμονα. Από την άλλη πλευρά, η υπομεθυλίωση του υποκινητή P2 συσχετίσθηκε έντονα με την υπομεθυλίωση του μεταθετονίου LINE-1, το οποίο αποτελεί δείκτη συνολικής υπομεθυλίωσης του DNA. Το γεγονός αυτό υποδεικνύει ότι η υπερέκφραση του ΔNp73 ενδέχεται να αποτελεί παθητική συνέπεια της συνολικής υπομεθυλίωσης του DNA. Καθώς η υπερέκφραση των ισομορφών TAp73 δεν ήταν δυνατό να αποδοθεί σε μεταβολή της κατάστασης μεθυλίωσης του υποκινητή P1, διατυπώθηκε η εύλογη υπόθεση ότι θα μπορούσε πιθανόν να οφείλεται σε απορρυθμισμένη ενεργότητα ειδικού ή ειδικών μεταγραφικών παραγόντων. ..............................

STAT3 and STAT5 Targeting for Simultaneous Management of Melanoma and Autoimmune Diseases

Melanoma is a skin cancer which can become metastatic, drug-refractory, and lethal if managed late or inappropriately. An increasing number of melanoma patients exhibits autoimmune diseases, either as pre-existing conditions or as sequelae of immune-based anti-melanoma therapies, which complicate patient management and raise the need for more personalized treatments. STAT3 and/or STAT5 cascades are commonly activated during melanoma progression and mediate the metastatic effects of key oncogenic factors. Deactivation of these cascades enhances antitumor-immune responses, is efficient against metastatic melanoma in the preclinical setting and emerges as a promising targeting strategy, especially for patients resistant to immunotherapies. In the light of the recent realization that cancer and autoimmune diseases share common mechanisms of immune dysregulation, we suggest that the systemic delivery of STAT3 or STAT5 inhibitors could simultaneously target both, melanoma and associated autoimmune diseases, thereby decreasing the overall disease burden and improving quality of life of this patient subpopulation. Herein, we review the recent advances of STAT3 and STAT5 targeting in melanoma, explore which autoimmune diseases are causatively linked to STAT3 and/or STAT5 signaling, and propose that these patients may particularly benefit from treatment with STAT3/STAT5 inhibitors

The Role of Human Endogenous Retroviruses in Cancer Immunotherapy of the Post-COVID-19 World

At the outbreak of the COVID-19 global crisis, diverse scientific groups suggested that this unprecedented emergency could act as a ‘blessing in disguise’ [...

Functions, divergence and clinical value of TAp73 isoforms in cancer.

The p73 gene encodes the tumour suppressive full-length TAp73 and N-terminal-truncated DNp73 isoforms that act as dominant negative inhibitors of TAp73. The overall effect of p73 in oncogenesis is thought to depend on the TAp73 to DNp73 isoforms' ratio. TAp73 isoforms include a number of C-terminal variants as a result of alternative splicing in 3'-end. TAp73 isoforms protect cells from oncogenic alterations in a multifaceted way since they are implicated in the suppression of all demonstrated hallmarks and enabling characteristics of cancer. Their best established role is in apoptosis, a process which seems to be differently affected by each TAp73 C-terminal variant. Based on previous findings and our thorough bioinformatics analysis, we highlight that TAp73 variants are functionally non-equivalent, since they present major differences in their transactivation efficiencies, protein interactions, response to DNA damage and apoptotic effects that are attributable to the primary structure of their C terminus. In this review, we summarise these differences and we unveil the link between crucial C-terminal motifs/residues and the oncosuppressive potential of TAp73 isoforms, emphasising on the importance of considering C terminus during the development of p73-based anticancer biologics

Drug Repurposing at the Interface of Melanoma Immunotherapy and Autoimmune Disease

Cancer cells have a remarkable ability to evade recognition and destruction by the immune system. At the same time, cancer has been associated with chronic inflammation, while certain autoimmune diseases predispose to the development of neoplasia. Although cancer immunotherapy has revolutionized antitumor treatment, immune-related toxicities and adverse events detract from the clinical utility of even the most advanced drugs, especially in patients with both, metastatic cancer and pre-existing autoimmune diseases. Here, the combination of multi-omics, data-driven computational approaches with the application of network concepts enables in-depth analyses of the dynamic links between cancer, autoimmune diseases, and drugs. In this review, we focus on molecular and epigenetic metastasis-related processes within cancer cells and the immune microenvironment. With melanoma as a model, we uncover vulnerabilities for drug development to control cancer progression and immune responses. Thereby, drug repurposing allows taking advantage of existing safety profiles and established pharmacokinetic properties of approved agents. These procedures promise faster access and optimal management for cancer treatment. Together, these approaches provide new disease-based and data-driven opportunities for the prediction and application of targeted and clinically used drugs at the interface of immune-mediated diseases and cancer towards next-generation immunotherapies