Targeted therapy in nonmelanoma skin cancers

Targeting the Hippo/YAP/TAZ signalling pathway: Novel opportunities for therapeutic interventions into skin cancers

Skin cancers are by far the most frequently diagnosed human cancers. The closely related transcriptional co-regulator proteins YAP and TAZ (WWTR1) have emerged as important drivers of tumour initiation, progression and metastasis in melanoma and non-melanoma skin cancers. YAP/TAZ serve as an essential signalling hub by integrating signals from multiple upstream pathways. In this review, we summarize the roles of YAP/TAZ in skin physiology and tumorigenesis and discuss recent efforts of therapeutic interventions that target YAP/TAZ in in both preclinical and clinical settings, as well as their prospects for use as skin cancer treatments.

Construction and evaluation of an efficient C-Jun siRNA to downregulate matrix metalloproteinase in human keratinocytes and fibroblasts under UV exposure

Background

C‐Jun and EGFR have not been explored as targets via the mechanism of RNA silencing. Hence, this study designed an efficient C‐Jun‐h‐825 small interfering RNA (siRNA) and investigated its effect on matrix metalloproteinase (MMP) and collagen expression in human keratinocytes exposed to UV radiation.

Methods

Five C‐Jun siRNAs were designed and screened for their ability to downregulate C‐Jun expression in human fibroblasts. These constructs were used to study changes in skin cancer‐related protein expression. HaCaT cells were grouped into 5‐carboxyfluorescien (FAM‐labeled) C‐Jun‐h‐825 siRNA + 2 hr prior irradiation; mock transfected + 2 hr prior irradiation; normal control; irradiation only for 2 hr; and Blank. Twenty‐four hours posttransfection, mRNA and protein levels of MMP‐I, MMP‐III, collagen‐I and collagen‐III were determined using standard RT‐PCR and ELISA kits.

Results

FAM‐labeled C‐Jun siRNA showed 80%–90% transfection efficiency. There was a significant increase in MMP‐I and MMP‐III and decrease in Col‐I and III mRNA levels when the cells were exposed to UV irradiation without siRNA transfection compared to blank (p < .05). This effect was reversed upon transfection with C‐Jun‐h‐825 (p < .01).

Conclusion

Thus, C‐Jun‐h‐825 siRNA might help restore skin collagen by decreasing MMP expression in cells exposed to UVA. Constructs and vectors designed herein have the potential to be translated into a treatment for photoaging induced skin cancer.

The Roles of YAP/TAZ and the Hippo Pathway in Healthy and Diseased Skin

Skin is the largest organ of the human body. Its architecture and physiological functions depend on diverse populations of epidermal cells and dermal fibroblasts. Reciprocal communication between the epidermis and dermis plays a key role in skin development, homeostasis and repair. While several stem cell populations have been identified in the epidermis with distinct locations and functions, there is additional heterogeneity within the mesenchymal cells of the dermis. Here, we discuss the current knowledge of how the Hippo pathway and its downstream effectors Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) contribute to the maintenance, activation and coordination of the epidermal and dermal cell populations during development, homeostasis, wound healing and cancer.

A Retrospective Study of the Diagnostic Accuracy of In Vivo Reflectance Confocal Microscopy for Basal Cell Carcinoma Diagnosis and Subtyping

Current national and European guidelines recommend distinct management approaches for basal cell carcinoma (BCC) based on tumor location, size, and histopathological subtype. In vivo reflectance confocal microscopy (RCM) is a non-invasive skin imaging technique which may change the diagnostic pathway for BCC patients. This study aimed to determine the sensitivity and specificity of RCM for BCC diagnosis, assess the predictive values of several confocal criteria in correctly classifying BCC subtypes, and evaluate the intraobserver reliability of RCM diagnosis for BCC. We conducted a retrospective study in two tertiary care centers in Bucharest, Romania. We included adults with clinically and dermoscopic suspect BCCs who underwent RCM and histopathological examination of excision specimens. For RCM examinations, we used the VivaScope 1500 and histopathology of the surgical excision specimen was the reference standard. Of the 123 cases included in the analysis, BCC was confirmed in 104 and excluded in 19 cases. RCM showed both high sensitivity (97.1%, 95% CI (91.80, 99.40)) and specificity (78.95%, 95% CI (54.43, 93.95)) for detecting BCC. Several RCM criteria were highly predictive for BCC subtypes: cords connected to the epidermis for superficial BCC, big tumor islands, peritumoral collagen bundles and increased vascularization for nodular BCC, and hyporefractile silhouettes for aggressive BCC. Excellent intraobserver agreement (κ = 0.909, p < 0.001) was observed. This data suggests that RCM could be used for preoperative diagnosis and BCC subtype classification in patients with suspected BCCs seen in tertiary care centers.

Cetuximab-radiotherapy combination in the management of locally advanced cutaneous squamous cell carcinoma

INTRODUCTION

We report the outcomes of using a combination of cetuximab with radiation therapy (Cetux-RT) to treat a selected group of patients with locally advanced (unresectable) cutaneous squamous cell carcinoma (LA-cSCC). This study presents two-year efficacy and safety data for 8 patients with LA-cSCC treated within a single institution.

METHODS

Between 2014 and 2017 a total of eight patients (seven males, one female) with LA-cSCC received curative intent treatment with Cetux-RT. All patients received an initial loading dose of cetuximab at 400 mg/m² seven days prior to radiotherapy, followed by weekly treatment with 250 mg/m² , continuing through the end of radiotherapy. Radiation doses were 6600 cGy/30 fr (n = 2), 6300 cGy/30fr (n = 2) and 5500 cGy/22 fr (n = 4).

RESULTS

The median age was 81 years (range, 55-87). The ECOG performance status of all patients was between 0 and 2. With a median duration of follow-up of 25 months (range 10-48 months), five patients remain in a complete response. After a partial response, another patient has relapsed and is receiving palliative chemotherapy, while two patients have died during the period of follow up (one of whom died following progression of disease, the other of an unrelated cause). Treatment in this group of patients was well tolerated, with most toxicities ≤ grade 2, and no toxicities of grade 4/5 reported.

CONCLUSIONS

Cetux-RT was well tolerated and provided durable disease control within this patient sample. Our data support the use of the Cetux-RT regimen for selected patients with inoperable LA-cSCC and adequate performance status.

Construction of a plasmid vector containing epidermal growth factor receptor and C-Jun shRNA

The objective of this study was to construct a plasmid vector for EGFR-hm-1 and C-Junh-825 small interfering RNA (siRNA). EGFR-hm-1 and C-Jun-hm-825 oligonucleotide fragments were synthesized and short hairpin RNA (shRNA) were amplified by PCR. Plasmids were isolated from E. coli TOP10 bacterium by restriction enzyme digestion using pst1 and BamH1 and oligonucleotide fragments were cloned into the pSilencer plasmid containing the U6 promoter. Recombinant clones were generated by transforming JM109 competent cells with plasmid vectors containing shRNA molecules. 58 base-paired EGFR-hm-1 and 59 base-paired C-Jun-hm-825 oligonucleotide fragments were isolated. The fragments were 100% homologous with human sequences available on GenBank. The recombinant pSilencer1.0 vector containing a 58-bp EGFR-hm-1 and 59-bp C-Jun-hm-825 fragment was constructed. These vectors have the potential to be used as treatment to combat skin photoaging under UV exposure.

Molecular signaling cascades involved in nonmelanoma skin carcinogenesis

Nonmelanoma skin cancer (NMSC) is the most common cancer worldwide and the incidence continues to rise, in part due to increasing numbers in high-risk groups such as organ transplant recipients and those taking photosensitizing medications. The most significant risk factor for NMSC is ultraviolet radiation (UVR) from sunlight, specifically UVB, which is the leading cause of DNA damage, photoaging, and malignant transformation in the skin. Activation of apoptosis following UVR exposure allows the elimination of irreversibly damaged cells that may harbor oncogenic mutations. However, UVR also activates signaling cascades that promote the survival of these potentially cancerous cells, resulting in tumor initiation. Thus, the UVR-induced stress response in the skin is multifaceted and requires coordinated activation of numerous pathways controlling DNA damage repair, inflammation, and kinase-mediated signal transduction that lead to either cell survival or cell death. This review focuses on the central signaling mechanisms that respond to UVR and the subsequent cellular changes. Given the prevalence of NMSC and the resulting health care burden, many of these pathways provide promising targets for continued study aimed at both chemoprevention and chemotherapy.

SOCS3 inhibits the pathological effects of IL-22 in non-melanoma skin tumor-derived keratinocytes

Basal cell carcinomas (BCC) and squamous-cell carcinomas (SCC) are common malignancies in humans, caused by neoplastic transformation of keratinocytes of the basal or suprabasal layers of epidermis, respectively. Tumor-infiltrating lymphocytes (TILs) are frequently found in BCC and SCC, and functionally promote epithelial carcinogenesis. TILs secreting IL-22, in particular, participate to BCC and SCC growth by inducing keratinocyte proliferation and migration, as well as the expression of inflammatory, anti-apoptotic and pro-angiogenic genes.In this study, we identified SOCS3 as a valid candidate to be manipulated for suppressing tumorigenic functions in BCC and SCC. We found that SOCS3 and SOCS1 expression was reduced in vivo, in tumor lesions of BCC and SCC, as compared to other skin inflammatory conditions such as psoriasis, despite the high number of IL-22-secreting TILs. Moreover, IL-22 was not able to induce in vitro the transcriptional expression of SOCS3 in BCC-or SCC-derived keratinocytes, contrarily to healthy cells. Aimed at rescuing SOCS3 activity in these tumor contexts, a SOCS3-derived peptide, named KIR-ESS, was synthesized, and its ability in suppressing IL-22-induced responses was evaluated in healthy and transformed keratinocytes. We found that KIR-ESS peptide efficiently suppressed the IL-22 molecular signaling in keratinocytes, by acting on STAT3 and Erk1/2 cascade, as well as on the expression of STAT3-dependent downstream genes. Interestingly, after treatment with peptide, both healthy and transformed keratinocytes could no longer aberrantly proliferate and migrate in response to IL-22. Finally, treatment of athymic nude mice bearing SCC xenografts with KIR-ESS peptide concomitantly reduced tumor growth and activated STAT3 levels. As a whole, these data provides the rationale for the use in BCC and SCC skin tumors of SOCS3 mimetics, being able to inhibit the deleterious effects of IL-22 in these contexts.

A specific photoimmunotheranostics agent to detect and eliminate skin cancer cells expressing EGFR

PURPOSE

The term "theranostics" represents a new paradigm in medicine especially for cancer treatment. This term was coined by Funkhouser in 2002 and defines a reagent that combines therapeutic and diagnostic properties. It is widely believed that theranostics agents will have considerable impact on healthcare before, during, and after disease by improving cancer prognosis and management simultaneously. Current theranostics approaches still rely on passive tumor targeting strategies, which have scattergun effects and tend to damage both neoplastic and non-neoplastic cells.

METHODS

Here we describe a simple, controlled, and efficient method to generate homogeneous photoimmunotheranostics reagents. This method combines molecular optical imaging, photodynamic therapy, and immunotherapy using SNAP-tag technology. SNAP-tag is a derivative of the O(6)-alkylguanine-DNA alkyltransferase (AGT) which has the ability to efficiently conjugate to O(6)-benzylguanine (BG) molecules under physiological conditions depending on its folding pattern.

RESULTS

The theranostics agent was able to specifically recognize various epidermal growth factor receptor (EGFR)-expressing skin cancer cell lines using flow cytometry analysis and confocal microscopy and eliminate them at EC50's of 32-55 nM.

CONCLUSIONS

These experiments provide a framework for using SNAP-tag technology to generate homogeneous photoimmunotheranostics reagents with unified pharmacokinetic and therapeutic profiles. Furthermore, the reagent generated in this work could be used to simultaneously monitor and suppress the growth of skin squamous carcinoma and melanoma cells expressing EGFR.

Retinoic acid receptors: from molecular mechanisms to cancer therapy

Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.