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

Latent-Transforming Growth Factor β-Binding Protein 1/Transforming Growth Factor β1 Complex Drives Antitumoral Effects upon ERK5 Targeting in Melanoma

Melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. Available treatments have improved survival, although long-term benefits still are unsatisfactory. The mitogen-activated protein kinase extracellular signal-regulated kinase 5 (ERK5) promotes melanoma growth, and ERK5 inhibition determines cellular senescence and the senescence-associated secretory phenotype. Here, latent-transforming growth factor β-binding protein 1 (LTBP1) mRNA was found to be up-regulated in A375 and SK-Mel-5 BRAFV600E melanoma cells after ERK5 inhibition. In keeping with a key role of LTBP1 in regulating transforming growth factor β (TGF-β), TGF-β1 protein levels were increased in lysates and conditioned media of ERK5-knockdown (KD) cells, and were reduced upon LTBP1 KD. Both LTBP1 and TGF-β1 proteins were increased in melanoma xenografts in mice treated with the ERK5 inhibitor XMD8-92. Moreover, treatment with conditioned media from ERK5-KD melanoma cells reduced cell proliferation and invasiveness, and TGF-β1-neutralizing antibodies impaired these effects. In silico data sets revealed that higher expression levels of both LTBP1 and TGFB1 mRNA are associated with better overall survival of melanoma patients, and that increased LTBP1 or TGF-β1 expression proved a beneficial role in patients treated with anti-PD1 immunotherapy, making a possible immunosuppressive role of LTBP1/TGF-β1 unlikely upon ERK5 inhibition. This study, therefore, identifies additional desirable effects of ERK5 targeting, providing evidence of an ERK5-dependent tumor-suppressive role of TGF-β in melanoma.

GLI1 Coamplification in Well-Differentiated/Dedifferentiated Liposarcomas: Clinicopathologic and Molecular Analysis of 92 Cases

GLI1(12q13.3) amplification is identified in a subset of mesenchymal neoplasms with a distinct nested round cell/epithelioid phenotype. MDM2 and CDK4 genes are situated along the oncogenic 12q13-15 segment, amplification of which defines well-differentiated liposarcoma (WDLPS)/dedifferentiated liposarcoma (DDLPS). The 12q amplicon can occasionally include GLI1, a gene in close proximity to CDK4. We hereby describe the first cohort of GLI1/MDM2/CDK4 coamplified WD/DDLPS. The departmental database was queried retrospectively for all cases of WD/DDLPS having undergone next-generation (MSK-IMPACT) sequencing with confirmed MDM2, CDK4, and GLI1 coamplification. Clinicopathologic data was obtained from a review of the medical chart and available histologic material. Four hundred eighty-six WD/DDLPS cases underwent DNA sequencing, 92 (19%) of which harbored amplification of the GLI1 locus in addition to that of MDM2 and CDK4. These included primary tumors (n = 60), local recurrences (n = 29), and metastases (n = 3). Primary tumors were most frequently retroperitoneal (47/60, 78%), mediastinal (4/60, 7%), and paratesticular (3/60, 5%). Average age was 63 years, with a male:female ratio of 3:2. The cohort was comprised of DDLPS (86/92 [93%], 6 of which were WDLPS with early dedifferentiation) and WDLPS without any longitudinal evidence of dedifferentiation (6/92, 7%). One-fifth (13/86, 17%) of DDLPS cases showed no evidence of a well-differentiated component in any of the primary, recurrent, or metastatic specimens. Dedifferentiated areas mostly showed high-grade undifferentiated pleomorphic sarcoma-like (26/86,30%) and high-grade myxofibrosarcoma-like (13/86,16%) morphologies. A disproportionately increased incidence of meningothelial whorls with/without osseous metaplasia was observed as the predominant pattern in 16/86 (19%) cases, and GLI1-altered morphology as described was identified in a total of 10/86 (12%) tumors. JUN (1p32.1), also implicated in the pathogenesis of WD/DDLPS, was coamplified with all 3 of MDM2, CDK4, and GLI1 in 7/91 (8%) cases. Additional loci along chromosomal arms 1p and 6q, including TNFAIP3, LATS1, and ESR1, were also amplified in a subset of cases. In this large-scale cohort of GLI1 coamplified WD/DDLPS, we elucidate uniquely recurrent features including meningothelial whorl-like and GLI-altered morphology in dedifferentiated areas. Assessment of tumor location (retroperitoneal or mediastinal), identification of a well-differentiated liposarcoma component, and coamplification of other spatially discrete genomic segments (1p and 6q) might aid in distinction from tumors with true driver GLI1 alterations.

FUNDC2, a mitochondrial outer membrane protein, mediates triple-negative breast cancer progression via the AKT/GSK3β/GLI1 pathway

Triple-negative breast cancer (TNBC) lacks effective therapeutic targets and has a poor prognosis, easy recurrence and metastasis. It is urgent and important to explore TNBC treatment targets. Through mass spectrometry combined with qRT-PCR validation in luminal A cells and TNBC cells, high-content screening and clinical sample analysis, FUNDC2 was discovered as a novel target. The function of the outer mitochondrial membrane protein FUNDC2 in breast cancer is still unclear. In this study, we find that FUNDC2 expression in TNBC tissues is significantly higher than that in luminal subtype breast cancer tissues. FUNDC2 silencing in TNBC cells significantly reduces cell proliferation, migration and invasion. As demonstrated in vivo using subcutaneous tumor xenografts in mice, FUNDC2 suppression significantly inhibits tumor growth. The underlying mechanism might be mediated by inactivating its downstream signal AKT/GSK3β and GLI1, a key factor of the Hedgehog signaling pathway. Therefore, FUNDC2 may promote TNBC progression and provide a therapeutic target for treating TNBC.

Etiopathogenic role of ERK5 signaling in sarcoma: prognostic and therapeutic implications

Sarcomas constitute a heterogeneous group of rare and difficult-to-treat tumors that can affect people of all ages, representing one of the most common forms of cancer in childhood and adolescence. Little is known about the molecular entities involved in sarcomagenesis. Therefore, the identification of processes that lead to the development of the disease may uncover novel therapeutic opportunities. Here, we show that the MEK5/ERK5 signaling pathway plays a critical role in the pathogenesis of sarcomas. By developing a mouse model engineered to express a constitutively active form of MEK5, we demonstrate that the exclusive activation of the MEK5/ERK5 pathway can promote sarcomagenesis. Histopathological analyses identified these tumors as undifferentiated pleomorphic sarcomas. Bioinformatic studies revealed that sarcomas are the tumors in which ERK5 is most frequently amplified and overexpressed. Moreover, analysis of the impact of ERK5 protein expression on overall survival in patients diagnosed with different sarcoma types in our local hospital showed a 5-fold decrease in median survival in patients with elevated ERK5 expression compared with those with low expression. Pharmacological and genetic studies revealed that targeting the MEK5/ERK5 pathway drastically affects the proliferation of human sarcoma cells and tumor growth. Interestingly, sarcoma cells with knockout of ERK5 or MEK5 were unable to form tumors when engrafted into mice. Taken together, our results reveal a role of the MEK5/ERK5 pathway in sarcomagenesis and open a new scenario to be considered in the treatment of patients with sarcoma in which the ERK5 pathway is pathophysiologically involved.

The ERK5/NF-κB signaling pathway targets endometrial cancer proliferation and survival

Endometrial cancer (EC) is the most common type of gynecologic cancer in women of developed countries. Despite surgery combined with chemo-/radiotherapy regimens, overall survival of patients with high-risk EC tumors is poor, indicating a need for novel therapies. The MEK5-ERK5 pathway is activated in response to growth factors and to different stressors, including oxidative stress and cytokines. Previous evidence supports a role for the MEK5-ERK5 pathway in the pathology of several cancers. We investigated the role of ERK5 in EC. In silico analysis of the PanCancer Atlas dataset showed alterations in components of the MEK5-ERK5 pathway in 48% of EC patients. Here, we show that ERK5 inhibition or silencing decreased EGF-induced EC cell proliferation, and that genetic deletion of MEK5 resulted in EC impaired proliferation and reduced tumor growth capacity in nude mice. Pharmacologic inhibition or ERK5 silencing impaired NF-kB pathway in EC cells and xenografts. Furthermore, we found a positive correlation between ERK5 and p65/RELA protein levels in human EC tumor samples. Mechanistically, genetic or pharmacologic impairment of ERK5 resulted in downregulation of NEMO/IKKγ expression, leading to impaired p65/RELA activity and to apoptosis in EC cells and xenografts, which was rescued by NEMO/IKKγ overexpression. Notably, ERK5 inhibition, MEK5 deletion or NF-kB inhibition sensitized EC cells to standard EC chemotherapy (paclitaxel/carboplatin) toxicity, whereas ERK5 inhibition synergized with paclitaxel to reduce tumor xenograft growth in mice. Together, our results suggest that the ERK5-NEMO-NF-κB pathway mediates EC cell proliferation and survival. We propose the ERK5/NF-κB axis as new target for EC treatment.

Apprising Diagnostic and Prognostic Biomarkers in Cutaneous Melanoma—Persistent Updating

The incidence of melanoma, a very aggressive skin cancer, has increased over the past few decades. Although there are well-established clinical, dermoscopic and histopathological criteria, the diagnosis is often performed late, which has important implications on the patient’s clinical outcome. Unfortunately, melanoma is one of the most challenging tumors to diagnose because it is a heterogeneous neoplasm at the clinical, histopathological, and molecular level. The use of reliable biomarkers for the diagnosis and monitoring of disease progression is becoming a standard of care in modern medicine. In this review, we discuss the latest studies, which highlight findings from the genomics, epitranscriptomics, proteomics and metabolomics areas, pointing out different genes, molecules and cells as potential diagnostic and prognostic biomarkers in cutaneous melanoma.

ERK5 Is a Major Determinant of Chemical Sarcomagenesis: Implications in Human Pathology

Simple Summary

Sarcoma is a heterogeneous group of tumors poorly studied with few therapeutic opportunities. Interestingly, the role of MAPKs still remains unclear in sarcomatous pathology. Here, we describe for the first time the critical role of ERK5 in the biology of soft tissue sarcoma by using in vitro and in vivo approaches in a murine experimental model of chemical sarcomagenesis. Indeed, our observations were extrapolated to a short series of human leiomyosarcoma and rhabdomyosarcomas. Furthermore, transcriptome analysis allows us to demonstrate the critical role of KLF2 in the biological effects of ERK5. Therefore, the data presented here open new windows in the diagnosis and therapy of soft tissue sarcomas.

Abstract

Sarcomas are a heterogeneous group of tumors in which the role of ERK5 is poorly studied. To clarify the role of this MAPK in sarcomatous pathology, we used a murine 3-methyl-cholanthrene (3MC)-induced sarcoma model. Our data show that 3MC induces pleomorphic sarcomas with muscle differentiation, showing an increased expression of ERK5. Indeed, this upregulation was also observed in human sarcomas of muscular origin, such as leiomyosarcoma or rhabdomyosarcoma. Moreover, in cell lines derived from these 3MC-induced tumors, abrogation of Mapk7 expression by using specific shRNAs decreased in vitro growth and colony-forming capacity and led to a marked loss of tumor growth in vivo. In fact, transcriptomic profiling in ERK5 abrogated cell lines by RNAseq showed a deregulated gene expression pattern for key biological processes such as angiogenesis, migration, motility, etc., correlating with a better prognostic in human pathology. Finally, among the various differentially expressed genes, Klf2 is a key mediator of the biological effects of ERK5 as indicated by its specific interference, demonstrating that the ERK5–KLF2 axis is an important determinant of sarcoma biology that should be further studied in human pathology.

Targeting MAPK in Cancer 2.0

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

The Effects of Hedgehog Signaling Pathway on the Proliferation and Apoptosis of Melanoma Cells

Background

Studies have found that the abnormality of the Hedgehog signaling pathway is related to the occurrence and development of a variety of tumors, but the effect of this signaling pathway on melanoma cells is still unclear.

Methods

This study aimed to discuss the effect of Hedgehog signaling pathway on the proliferation and apoptosis of human malignant melanoma A375 cells and explore its possible mechanism in the proliferation and apoptosis of melanoma cells. Different concentrations of Hedgehog signaling pathway inhibitor cyclopamine (5, 10, 20 and 40 μM) were used to treat human melanoma A375 cells for 24, 48, and 72 h, and set a blank control group (0 μM). Trypan blue cell counting method was used to detect cell viability. MTT method was used to detect the inhibition rate of cell proliferation. Transwell was used to detect cell invasion, and flow cytometry was used to detect cell apoptosis.

Results

Through the trypan blue cell counting method and MTT experiment, it was found that the Hedgehog signaling pathway inhibitor cyclopamine has an inhibitory effect on the proliferation and viability of melanoma A375 cells (P < 0.05), and the proliferation inhibitory effect is enhanced with prolonged action time in a dose- and time-dependent manner. Transwell experiment showed that compared with the blank control group, the invasion and migration ability of the treated melanoma A375 cells are significantly reduced, and the difference is statistically significant (P < 0.05). Cell apoptosis experiment showed that compared with the blank control group, the apoptosis rate of A375 cells is significantly higher after treated by 40 μM cyclopamine for 24 h, and the difference is statistically significant (P < 0.05). Gli1 and Bcl-2 protein are highly expressed in melanoma A375 cells, and their expressions show a downward trend (P < 0.05) after being treated by cyclopamine.

Conclusion

Cyclopamine inhibits cell proliferation and induces cell apoptosis by downregulating Gli1. Hedgehog signaling pathway can be used as a new target for the treatment of malignant melanoma, and multiple measures can be used to inhibit the signaling pathway to achieve a therapeutic effect.

Clinical Significance and Regulation of ERK5 Expression and Function in Cancer

Extracellular signal-regulated kinase 5 (ERK5) is a unique kinase among MAPKs family members, given its large structure characterized by the presence of a unique C-terminal domain. Despite increasing data demonstrating the relevance of the ERK5 pathway in the growth, survival, and differentiation of normal cells, ERK5 has recently attracted the attention of several research groups given its relevance in inflammatory disorders and cancer. Accumulating evidence reported its role in tumor initiation and progression. In this review, we explore the gene expression profile of ERK5 among cancers correlated with its clinical impact, as well as the prognostic value of ERK5 and pERK5 expression levels in tumors. We also summarize the importance of ERK5 in the maintenance of a cancer stem-like phenotype and explore the major known contributions of ERK5 in the tumor-associated microenvironment. Moreover, although several questions are still open concerning ERK5 molecular regulation, different ERK5 isoforms derived from the alternative splicing process are also described, highlighting the potential clinical relevance of targeting ERK5 pathways.