Analisi di danno cromosomico spontaneo e indotto (test di sensibilità al mutageno) in soggetti affetti da tiroiditi: il ruolo dell'autoimmunità e della funzionalità tiroidea

Obiettivo. Valutare la presenza di danno cromosomico spontaneo e indotto dal farmaco antitumorale bleomicina (BLM) in culture di linfociti periferici di pazienti con patologie tiroidee autoimmunitarie (AITD) e non autoimmunitarie (NAITD) per mezzo di analisi citogenetiche molecolari. Metodi. Abbiamo studiato 30 pazienti con disordini tiroidei (19 autoimmunitari e 11 non autoimmunitari) e 18 controlli sani. Tutti i pazienti erano stratificati sulla base della funzionalità della ghiandola tiroidea (eu-, ipo- ed ipertiroidei). Come marker dell’alterazione cromosomica spontanea e indotta da BLM abbiamo utilizzato il saggio del micronucleo (MN). Risultati. I pazienti con TD, indipendentemente dalla condizione di autoimmunità, mostravano frequenze spontanee di MN significativamente più alte rispetto al gruppo dei controlli (5,12±0,93 contro 2,96±1,19; p<0,05). In particolare, rispetto al gruppo dei controlli (3,35±1,10), agli eutiroidei (4,64±1,07) ed agli ipertiroidei (2,64±1,50), i pazienti ipotiroidei esibivano livelli basali di MN significativamente più alti (8,34±1,40). Un ulteriore approfondimento statistico ha rilevato che erano gli ipotiroidei autoimmunitari ad avere le frequenze spontanee più elevate. I pazienti con NAITD mostravano frequenze di MN indotte da BLM significativamente più alte (40,17±3,42) rispetto ai pazienti con AITD (31,44±3,09) e ai controlli (28,68±3,24), mentre i valori non differivano significativamente tra AITD e controlli. Conclusioni. I nostri risultati mostrano la presenza di livelli spontanei di micronuclei più alti in linfociti circolanti di ipotiroidei autoimmuni, suggerendo un possibile ruolo dello stress ossidativo nel determinare le anomalie citogenetiche. Il saggio di sensibilità al mutageno ha rilevato livelli di MN indotti da BLM più bassi in pazienti con AITD. É possibile che la condizione alterata dell’autoimmunità inneschi un meccanismo protettivo nei confronti del danno prodotto dalla BLM

Targeting MAPK in Cancer 2.0

Mitogen-activated protein kinase (MAPK) pathways are prominently involved in the onset and progression of cancer [...

PO-099 Targeting the mitogen activated protein kinase ERK5 in human melanoma

Introduction Melanoma is the most aggressive skin cancer with a poor prognosis in advanced stages. Available treatments for melanoma are unsatisfactory, because rapidly lead to an acquired resistance in the majority of cases. Therefore, there is urgent need to identify novel possible targets involved in melanoma growth. ERK5/BMK1 is a member of the Mitogen-Activated Protein Kinases (MAPK) family and regulates cell functions critical for tumour development. Indeed, several studies reported a direct involvement of ERK5 in several types of cancer including prostate and breast cancer and hepatocellular carcinoma. However, no data have been reported about a possible role of ERK5 in melanoma. Material and methods Cell lines and patient-derived primary melanoma cells (wild type B-RAF: SSM2c and M26c; BRAFV600E: A375, SK-Mel-5, SK-Mel-28, 501-Mel, expressing; NRASQ61R: SK-Mel-2; MeWo) have been used for in vitro and in vivo experiments. HEK293T cells were used for protein overexpression. ERK5 inhibition was achieved using ERK5 and MEK5 inhibitors or lentiviral vectors encoding shRNA specific for ERK5. BRAF inhibition was achieved using Vemurafenib, a BRAFV600E inhibitor. Results and discussions In silico data analysis indicated that components of the ERK5 pathway are upregulated in up to 47% melanoma patients. Accordingly, we found that ERK5 is consistently expressed and active in commercial and patients derived melanoma cell lines. On that basis, we investigated the role of ERK5 in melanoma cell growth. In vitro , pharmacological or genetic inhibition of ERK5 decreased the number of viable cells in several melanoma cell lines. Moreover, xenografts performed using LV-shERK5-transduced A375 or SSM2c cells showed a reduced tumour growth when compared to those transduced with control LV-shC. We also found that oncogenic BRAF positively regulates expression, phosphorylation and nuclear localization of exogenous and endogenous ERK5. Accordingly, combined pharmacological inhibition of BRAFV600E and MEK5 is required to decrease nuclear ERK5, that is critical for the regulation of cell proliferation. Furthermore, the combination of MEK5 or ERK5 inhibitors with vemurafenib is more effective than single treatments in reducing 2D colony formation and growth of BRAFV600E melanoma cells and xenografts. Conclusion Our results identify ERK5 as a critical regulator of melanoma growth in vitro and in vivo , and point toward the possibility of targeting ERK5, alone or in combination with BRAF-MEK1/2 inhibitors, for the treatment of melanoma

The Hedgehog-GLI Pathway Regulates MEK5-ERK5 Expression and Activation in Melanoma Cells

Malignant melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. We recently showed that the extracellular signal-regulated kinase 5 (ERK5), encoded by the MAPK7 gene, plays a pivotal role in melanoma by regulating cell functions necessary for tumour development, such as proliferation. Hedgehog-GLI signalling is constitutively active in melanoma and is required for proliferation. However, no data are available in literature about a possible interplay between Hedgehog-GLI and ERK5 pathways. Here, we show that hyperactivation of the Hedgehog-GLI pathway by genetic inhibition of the negative regulator Patched 1 increases the amount of ERK5 mRNA and protein. Chromatin immunoprecipitation showed that GLI1, the major downstream effector of Hedgehog-GLI signalling, binds to a functional non-canonical GLI consensus sequence at the MAPK7 promoter. Furthermore, we found that ERK5 is required for Hedgehog-GLI-dependent melanoma cell proliferation, and that the combination of GLI and ERK5 inhibitors is more effective than single treatments in reducing cell viability and colony formation ability in melanoma cells. Together, these findings led to the identification of a novel Hedgehog-GLI-ERK5 axis that regulates melanoma cell growth, and shed light on new functions of ERK5, paving the way for new therapeutic options in melanoma and other neoplasms with active Hedgehog-GLI and ERK5 pathways

The metabolically-modulated stem cell niche: a dynamic scenario regulating cancer cell phenotype and resistance to therapy.

This Perspective addresses the interactions of cancer stem cells (CSC) with environment which result in the modulation of CSC metabolism, and thereby of CSC phenotype and resistance to therapy. We considered first as a model disease chronic myeloid leukemia (CML), which is triggered by a well-identified oncogenetic protein (BCR/Abl) and brilliantly treated with tyrosine kinase inhibitors (TKi). However, TKi are extremely effective in inducing remission of disease, but unable, in most cases, to prevent relapse. We demonstrated that the interference with cell metabolism (oxygen/glucose shortage) enriches cells exhibiting the leukemia stem cell (LSC) phenotype and, at the same time, suppresses BCR/Abl protein expression. These LSC are therefore refractory to the TKi Imatinib-mesylate, pointing to cell metabolism as an important factor controlling the onset of TKi-resistant minimal residual disease (MRD) of CML and the related relapse. Studies of solid neoplasias brought another player into the control of MRD, low tissue pH, which often parallels cancer growth and progression. Thus, a 3-party scenario emerged for the regulation of CSC/LSC maintenance, MRD induction and disease relapse: the “hypoxic” versus the “ischemic” vs. the “acidic” environment. As these environments are unlikely constrained within rigid borders, we named this model the “metabolically-modulated stem cell niche.

Inhibition of ERK5 elicits cellular senescence in melanoma via the cyclin-dependent kinase inhibitor p21

2021 The Authors.Melanoma is the deadliest skin cancer with a very poor prognosis in advanced stages. Although targeted and immune therapies have improved survival, not all patients benefit from these treatments. The mitogen-activated protein kinase ERK5 supports the growth of melanoma cells in vitro and in vivo. However, ERK5 inhibition results in cell-cycle arrest rather than appreciable apoptosis. To clarify the role of ERK5 in melanoma growth, we performed transcriptomic analyses following ERK5 knockdown in melanoma cells expressing BRAFV600E and found that cellular senescence was among the most affected processes. In melanoma cells expressing either wild-type or mutant (V600E) BRAF, both genetic and pharmacologic inhibition of ERK5 elicited cellular senescence, as observed by a marked increase in senescence-associated β-galactosidase activity and p21 expression. In addition, depletion of ERK5 from melanoma cells resulted in increased levels of CXCL1, CXCL8, and CCL20, proteins typically involved in the senescence-associated secretory phenotype. Knockdown of p21 suppressed the induction of cellular senescence by ERK5 blockade, pointing to p21 as a key mediator of this process. In vivo, ERK5 knockdown or inhibition with XMD8–92 in melanoma xenografts promoted cellular senescence. Based on these results, small-molecule compounds targeting ERK5 constitute a rational series of prosenescence drugs that may be exploited for melanoma treatment.The work in E. Rovida’s lab was supported by grants from Associazione Italiana per la Ricerca sul Cancro (AIRC, IG-15282 and IG-21349), by Ente Fondazione Cassa di Risparmio di Firenze (ECRF), and Universita degli Studi di Firenze (Fondo di Ateneo ex-60%). A. Tubita was supported by a “Carlo Zanotti” Fondazione Italiana per la Ricerca sul Cancro (FIRC)-AIRC fellowship (ID-23847)

Hepatocyte-specific deletion of HIF2&#945; prevents NASH-related liver carcinogenesis by decreasing cancer cell proliferation

Background & aims: Hypoxia and hypoxia-inducible factors (HIFs) are involved in chronic liver disease progression. We previously showed that hepatocyte HIF-2\u3b1 activation contributed significantly to nonalcoholic fatty liver disease progression in experimental animals and human patients. In this study, using an appropriate genetic murine model, we mechanistically investigated the involvement of hepatocyte HIF-2\u3b1 in experimental nonalcoholic steatohepatitis (NASH)-related carcinogenesis. Methods: The role of HIF-2\u3b1 was investigated by morphologic, cellular, and molecular biology approaches in the following: (1) mice carrying hepatocyte-specific deletion of HIF-2\u3b1 (HIF-2\u3b1-/- mice) undergoing a NASH-related protocol of hepatocarcinogenesis; (2) HepG2 cells stably transfected to overexpress HIF-2\u3b1; and (3) liver specimens from NASH patients with hepatocellular carcinoma. Results: Mice carrying hepatocyte-specific deletion of HIF-2\u3b1 (hHIF-2\u3b1-/-) showed a significant decrease in the volume and number of liver tumors compared with wild-type littermates. These effects did not involve HIF-1\u3b1 changes and were associated with a decrease of cell proliferation markers proliferating cell nuclear antigen and Ki67. In both human and rodent nonalcoholic fatty liver disease-related tumors, HIF-2\u3b1 levels were strictly associated with hepatocyte production of SerpinB3, a mediator previously shown to stimulate liver cancer cell proliferation through the Hippo/Yes-associated protein (YAP)/c-Myc pathway. Consistently, we observed positive correlations between the transcripts of HIF-2\u3b1, YAP, and c-Myc in individual hepatocellular carcinoma tumor masses, while HIF-2\u3b1 deletion down-modulated c-Myc and YAP expression without affecting extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, and AKT-dependent signaling. In\ua0vitro data confirmed that HIF-2\u3b1 overexpression induced HepG2 cell proliferation through YAP-mediated mechanisms. Conclusions: These results indicate that the activation of HIF-2\u3b1 in hepatocytes has a critical role in liver carcinogenesis during NASH progression, suggesting that HIF-2\u3b1-blocking agents may serve as novel putative therapeutic tools

ERK5 is activated by oncogenic BRAF and promotes melanoma growth

Malignant melanoma is among the most aggressive cancers and its incidence is increasing worldwide. Targeted therapies and immunotherapy have improved the survival of patients with metastatic melanoma in the last few years; however, available treatments are still unsatisfactory. While the role of the BRAF-MEK1/2-ERK1/2 pathway in melanoma is well established, the involvement of mitogen-activated protein kinases MEK5-ERK5 remains poorly explored. Here we investigated the function of ERK5 signaling in melanoma. We show that ERK5 is consistently expressed in human melanoma tissues and is active in melanoma cells. Genetic silencing and pharmacological inhibition of ERK5 pathway drastically reduce the growth of melanoma cells and xenografts harboring wild-type (wt) or mutated BRAF (V600E). We also found that oncogenic BRAF positively regulates expression, phosphorylation, and nuclear localization of ERK5. Importantly, ERK5 kinase and transcriptional transactivator activities are enhanced by BRAF. Nevertheless, combined pharmacological inhibition of BRAFV600E and MEK5 is required to decrease nuclear ERK5, that is critical for the regulation of cell proliferation. Accordingly, combination of MEK5 or ERK5 inhibitors with BRAFV600E inhibitor vemurafenib is more effective than single treatments in reducing colony formation and growth of BRAFV600E melanoma cells and xenografts. Overall, these data support a key role of the ERK5 pathway for melanoma growth in vitro and in vivo and suggest that targeting ERK5, alone or in combination with BRAF-MEK1/2 inhibitors, might represent a novel approach for melanoma treatment