Paula Comune Pennacchi

Targeting the hedgehog transcription factors GLI1 and GLI2 restores sensitivity to vemurafenib-resistant human melanoma cells

BRAF inhibitor (BRAFi) therapy for melanoma patients harboring the V600E mutation is initially highly effective, but almost all patients relapse within a few months. Understanding the molecular mechanisms underpinning BRAFi-based therapy is therefore an important issue. Here we identified a previously unsuspected mechanism of BRAFi resistance driven by elevated Hedgehog (Hh) pathway activation that is observed in a cohort of melanoma patients after vemurafenib treatment. Specifically, we demonstrate that melanoma cell lines, with acquired in vitro-induced vemurafenib resistance, show increased levels of glioma-associated oncogene homolog 1 and 2 (GLI1/GLI2) compared with naïve cells. We also observed these findings in clinical melanoma specimens. Moreover, the increased expression of the transcription factors GLI1/GLI2 was independent of canonical Hh signaling and was instead correlated with the noncanonical Hh pathway, involving TGFβ/SMAD (transforming growth factor-β/Sma- and Mad-related family) signaling. Knockdown of GLI1 and GLI2 restored sensitivity to vemurafenib-resistant cells, an effect associated with both growth arrest and senescence. Treatment of vemurafenib-resistant cells with the GLI1/GLI2 inhibitor Gant61 led to decreased invasion of the melanoma cells in a three-dimensional skin reconstruct model and was associated with a decrease in metalloproteinase (MMP2/MMP9) expression and microphthalmia transcription factor upregulation. Gant61 monotherapy did not alter the drug sensitivity of naïve cells, but could reverse the resistance of melanoma cells chronically treated with vemurafenib. We further noted that alternating dosing schedules of Gant61 and vemurafenib prevented the onset of BRAFi resistance, suggesting that this could be a potential therapeutic strategy for the prevention of therapeutic escape. Our results suggest that targeting the Hh pathway in BRAFi-resistant melanoma may represent a viable therapeutic strategy to restore vemurafenib sensitivity, reducing or even inhibiting the acquired chemoresistance in melanoma patients.

A new reconstructed human epidermis for in vitro skin irritation testing

Different models of reconstructed human epidermis (RHE) are currently validated to assess skin irritation in vitro and ultimately to the animal replacement of the Draize test. The development of a new RHE model is a challenge for many laboratories, representing a potential gain of autonomy and improvement of technological knowledge. The Organization for Economic Co-operation and Development (OECD) encourages the development of new models and, for this purpose, offers a thorough guideline on quality control parameters (OECD TG 439 performance standards). This work aimed to develop an RHE model (i.e. USP-RHE) for in vitro skin irritation assays, following the OECD TG 439. The developed model presents a well-differentiated epidermis similar to the Validated Reference Methods (VRM) and to native human epidermis. Quality parameters, i.e. optical density of negative control, tissue integrity and barrier function, were similar to VRM and in accordance with OECD TG 439. Moreover, the USP-RHE model was shown to have 85,7% of specificity (6/7), 100% of sensitivity (6/6) and 92,3% of accuracy (12/13) when compared to in vivo UN GHS classification. The within-laboratory reproducibility was 92.3% (12/13). Thus, we demonstrated that USP-RHE model attends to all OECD TG 439 performance standards and is ready to be used by private and public laboratories and companies for future validation studies.

DNA Methylation Levels of Melanoma Risk Genes Are Associated with Clinical Characteristics of Melanoma Patients

In melanoma development, oncogenic process is mediated by genetic and epigenetic mutations, and few studies have so far explored the role of DNA methylation either as predisposition factor or biomarker. We tested patient samples for germline CDKN2A methylation status and found no evidence of inactivation by promoter hypermethylation. We have also investigated the association of clinical characteristics of samples with the DNA methylation pattern of twelve genes relevant for melanomagenesis. Five genes (BAP1, MGMT, MITF, PALB2, and POT1) presented statistical association between blood DNA methylation levels and either CDKN2A-mutation status, number of lesions, or Breslow thickness. In tumors, five genes (KIT, MGMT, MITF, TERT, and TNF) exhibited methylation levels significantly different between tumor groups including acral compared to nonacral melanomas and matched primary lesions and metastases. Our data pinpoint that the methylation level of eight melanoma-associated genes could potentially represent markers for this disease both in peripheral blood and in tumor samples.

MMP-9/RECK Imbalance: A Mechanism Associated with High-Grade Cervical Lesions and Genital Infection by Human Papillomavirus and Chlamydia trachomatis

Background: Matrix metalloproteinases (MMP) are important enzymes in the tumor microenvironment associated with progression of cervical intraepithelial neoplasia (CIN) toward squamous cell carcinoma (SCC) of the cervix. However, the role of MMPs in the inflammatory process associated with Chlamydia trachomatis infection concomitant with the carcinogenic process driven by HPV has not yet been addressed. In the present study, we analyzed the state of the MMP-9–RECK axis in cervical carcinogenesis. Methods: The levels of MMP-9 and RECK expression were analyzed by immunocytochemistry in liquid-based cytology samples from 136 women with high-grade cervical lesions (CIN2/CIN3) and cervical SCC diagnosed by LLETZ, and in 196 women without cervical neoplasia or CIN1. Real-time qPCR was performed to analyze expression of MMP-9 and RECK in 15 cervical samples. The presence of HPV-DNA and other genital pathogens was evaluated by PCR. Results: We found a higher expression of MMP-9 [OR, 4.2; 95% confidence interval (CI), 2.2–7.8] and lower expression of RECK (OR, 0.4; 95% CI, 0.2–0.7) in women with CIN2/CIN3/SCC when compared with women from the control group (no neoplasia/CIN1). A statistically significant association was also found between MMP-9/RECK imbalance and infection by alpha-9 HPV and C. trachomatis. The prevalence of C. trachomatis infection was significantly higher in women with high-grade cervical disease (OR, 3.7; 95% CI, 1.3–11.3). Conclusions: MMP-9/RECK imbalance in cervical smears is significantly associated with high-grade cervical diseases and infection by alpha-9 HPV and C. trachomatis. Impact: MMP-9/RECK imbalance during cervical inflammation induced by C. trachomatis might play a role in HPV-mediated cervical carcinogenesis. Cancer Epidemiol Biomarkers Prev; 24(10); 1539–47. ©2015 AACR.

Inhibition of proliferation and invasion in 2D and 3D models by 2-methoxyestradiol in human melanoma cells

Graphical abstract Figure. No Caption available. ABSTRACT Despite the recent advances in the clinical management of melanoma, there remains a need for new pharmacological approaches to treat this cancer. 2‐methoxyestradiol (2ME) is a metabolite of estrogen that has shown anti‐tumor effects in many cancer types. In this study we show that 2ME treatment leads to growth inhibition in melanoma cells, an effect associated with entry into senescence, decreased pRb and Cyclin B1 expression, increased p21/Cip1 expression and G2/M cell cycle arrest. 2ME treatment also inhibits melanoma cell growth in colony formation assay, including cell lines with acquired resistance to BRAF and BRAF + MEK inhibitors. We further show that 2ME is effective against melanoma with different BRAF and NRAS mutational status. Moreover, 2ME induced the retraction of cytoplasmic projections in a 3D spheroid model and significantly decreased cell proliferation in a 3D skin reconstruct model. Together our studies bring new insights into the mechanism of action of 2ME allowing melanoma targeted therapy to be further refined. Continued progress in this area is expected to lead to improved anti‐cancer treatments and the development of new and more effective clinical analogues.

LINE-1 hypomethylation and mutational status in cutaneous melanomas.

Epigenetic dysregulation is an important emerging hallmark of cutaneous melanoma development. The global loss of DNA methylation in gene-poor regions and transposable DNA elements of cancer cells contributes to increased genomic instability. Long interspersed element-1 (LINE-1) sequences are the most abundant repetitive sequence of the genome and can be evaluated as a surrogate marker of the global level of DNA methylation. In this work, LINE-1 methylation levels were evaluated in cutaneous melanomas and normal melanocyte primary cell cultures to investigate their possible association with both distinct clinicopathological characteristics and tumor mutational profile. A set of driver mutations frequently identified in cutaneous melanoma was assessed by sequencing (actionable mutations in BRAF, NRAS, and KIT genes, and mutations affecting the TERT promoter) or multiplex ligation-dependent probe amplification (MLPA) (CDKN2A deletions). Pyrosequencing was performed to investigate the methylation level of LINE-1 and CDKN2A promoter sequences. The qualitative analysis showed a trend toward an association between LINE-1 hypomethylation and CDKN2A inactivation (p=0.05). In a quantitative approach, primary tumors, mainly the thicker ones (>4 mm), exhibited a trend toward LINE-1 hypomethylation when compared with control melanocytes. To date, this is the first study reporting in cutaneous melanomas a possible link between the dysregulation of LINE-1 methylation and the presence of driver mutations.

Skin corrosion test: a comparison between reconstructed human epidermis and full thickness skin models

Graphical abstract Figure. No caption available. ABSTRACT Currently, there is a strong global trend towards the development of in vitro models to replace the use of animals in safety evaluation tests. Reconstructed Human Epidermis (RHE) models have been employed as an alternative method to animal testing of skin corrosion and irritation potential of chemical compounds. However, the consequences of an absence of the dermal compartment in these models should be considered since the cross‐talk between fibroblasts and keratinocytes is fundamental for promoting proper epidermal stratification, homeostasis, inflammatory response and wound healing. In this study, we compare in‐house developed models of Reconstructed Human Epidermis (i.e. USP‐RHE) and full thickness skin (i.e. USP‐FTS) regarding their response when submitted to skin corrosion assays, based on Guideline 431 (OECD). The results show that both models correctly classified the four substances tested (2‐phenylethyl bromide, benzylacetone, lactic acid, octanoic acid) as corrosive or non‐corrosive. Furthermore, we have demonstrated higher cell viability of the USP‐FTS model compared to the USP‐RHE model, a sign of its improved barrier function, following the exposure to the substances test on the corrosion assay. This emphasizes the importance of employing in vitro models that are more physiologically relevant and that better mimic the in vivo situation for the toxicological screening of substances.

Abstract 4669: Targeting hedgehog transcription factors GLI1 and GLI2 restores sensitivity to vemurafenib-resistant human melanoma cells

Melanoma represents the deadliest of all skin cancers being responsible for more than 75% of skin cancer-related deaths. Although the results with BRAF inhibitors have been very promising, practically all of the patients treated thus far have developed resistance to these drugs. The Hedgehog (Hh) signaling pathway has been implicated in a variety of malignancies, including melanoma. However, there are no reports on the activation of this pathway in the setting of vemurafenib-resistance. Herein, we first identified that melanoma cell lines, with acquired in vitro-induced vemurafenib resistance, showed increased levels of Hh pathway component genes glioma-associated oncogene homolog 1 and 2 (GLI1/GLI2) compared to naive cells. We also observed these findings in melanoma samples from patients. Moreover, the increased expression of the transcription factors GLI1/GLI2 was independent of canonical Hh signaling and was instead correlated with non-canonical Hh signaling, involving TGFβ/SMAD signaling. Knockdown of GLI1 and GLI2 restored the vemurafenib-resistant cells to sensitivity, an effect associated with both growth arrest and senescence. Treatment of vemurafenib-resistant cells with the GLI1/GLI2 inhibitor Gant61 led to decreased invasion of the melanoma cells in a 3D skin reconstruct model and was associated with a decrease in metalloproteinase (MMP2/MMP9) expression and microphtalmia transcription factor (MITF) upregulation. Our findings also demonstrated that GLI1/GLI2 modulation could be a useful strategy to prevent drug resistance. Alternating pre-treatment with vemurafenib and Gant61 significantly reduced IC50 of subsequent vemurafenib treatment in naive melanoma cells, demonstrating a promising approach for the control of vemurafenib-resistance in patients with unresectable melanoma. The modulation of vemurafenib chemosensitivity was triggered by GLI1/GLI2 repression during the acquisition of resistance, which did not occur in the treatment protocols with only vemurafenib continuously or in alternate days. The alternating treatment regimen with vemurafenib and Gant61 was able to suppress GLI expression, delaying or decreasing vemurafenib resistance. Taken together, our data demonstrated an unprecedented mechanism of vemurafenib resistance by GLI1/GLI2 upregulation, shedding light on the development of Hh pathway inhibitors as a promising strategy for melanoma treatment. Citation Format: Fernanda Faiao-Flores, Debora Kristina Magalhaes Alves-Fernandes, Paula Comune Pennacchi, Silvana Sandri, Anna Luiza Silva Almeida Vicente, Cristovam Scapulatempo-Neto, Vinicius de Lima Vazquez, Rui Manuel Reis, Keiran S. Smalley, Silvya Stuchi Maria-Engler. Targeting hedgehog transcription factors GLI1 and GLI2 restores sensitivity to vemurafenib-resistant human melanoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4669.