Pathogenesis Of cSCC Research Articles

MiR-34a-5p suppresses cutaneous squamous cell carcinoma progression by targeting SIRT6

Cutaneous squamous cell carcinoma (cSCC) is a malignant tumor originating from epidermal or appendageal keratinocytes, with a rising incidence in recent years. Understanding the molecular mechanism driving its development is crucial. This study aims to investigate whether miR-34a-5p is involved in the pathogenesis of cSCC by targeting Sirtuin 6 (SIRT6).The expression levels of miR-34a-5p and SIRT6 were determined in 15 cSCC tissue specimens, 15 normal tissue specimens and cultured cells via real-time polymerase chain reaction (RT-qPCR). Pearson’s correlation analysis was conducted to evaluate the relationship between miR-34a-5p and SIRT6 expression levels in cSCC tissues. A431 and SCL-1 cells were transfected with miR-34a-5p mimic, negative control or miR-34a-5p mimic together with recombinant plasmids containing SIRT6 gene. Cell counting kit-8, clone formation assay, wound healing assay, and flow cytometry were employed to assess the effects of these transfections on proliferation, migration, and apoptosis, respectively. The interaction between miR-34a-5p and SIRT6 was characterized using a dual-luciferase reporter assay.MiR-34a-5p expression was down-regulated in cSCC tissues significantly, while the SIRT6 expression was the opposite. A negative correlation was observed between the expression of miR-34a-5p and SIRT6 in cSCC tissues. Furthermore, overexpression of miR-34a-5p led to a significant reduction in the proliferation and migration abilities of A431 and SCL-1 cells, accompanied by an increase in apoptosis levels and a decrease in SIRT6 expression levels. MiR-34a-5p was identified as a direct target of SIRT6. Importantly, overexpression of SIRT6 effectively counteracted the inhibitory effect mediated by miR-34a-5p in cSCC cells.Our findings suggest that miR-34a-5p functions as a tumor suppressor in cSCC cells by targeting SIRT6.

Abstract 279: Iatrogenic immunosuppression emplaces tacrolimus to drive squamous skin cancer progression and influence the microenvironment

Abstract One in thirteen organ transplant recipients (OTRs) develop post-transplant cutaneous squamous cell carcinoma (cSCC), leading to significant morbidity upon disease progression. Although chronic ultraviolet (UV) exposure primarily underlies keratinocyte carcinogenesis, long-term immunosuppression is a critical etiologic risk factor due to reduced systemic surveillance of dysplasia. Calcineurin inhibitors such as tacrolimus are commonly administered to suppress the immune system by blocking T-cell proliferation and preventing donor organ rejection. Contrarily, studies have evinced the off-target effects of immunosuppressives, namely azathioprine and cyclosporine, but not tacrolimus — the most widely used in all immunosuppression. In addition, the preclinical research literature has overlooked the contribution of stromal fibroblasts in the cSCC tumor microenvironment (TME). Hence, we hypothesize that tacrolimus exerts direct carcinogenic effects on keratinocytes and fibroblasts in the skin. We further postulate that tacrolimus enables a tumor-permissive microenvironment by activating dermal fibroblasts to cause aggressive and invasive keratinocyte carcinoma in OTRs. To examine this cellular crosstalk phenomenon, we used human keratinocytes, primary dermal fibroblasts and cSCC cells in mono- and co-cultures to mimic cutaneous and tumor complexities. Next, we assessed the molecular mechanisms utilized by tacrolimus to potentiate tumorigenesis pertinent to cell survival, proliferation and invasion. Herein, we show that tacrolimus promotes cell survival dose-dependently in cSCC cells. We also found that a fibroblast-cSCC spheroid co-culture significantly enhances cell invasion. In a wound-healing migration assay, tacrolimus increased the migratory capacity of normal keratinocytes and cSCC cells. However, cell proliferation remains nebulous due to cyclical dose-response effects in vitro. We then queried whether cell proliferation is affected in vivo using immunodeficient mice, and similar results were observed. We confirmed via immunoblotting that tacrolimus induced elevated expression of proliferation markers at distinct drug concentrations. Altogether, our findings illuminate keratinocyte-stroma interactions and particularly isolate the contributory role of tacrolimus in non-immune mediated cSCC pathogenesis. This knowledge suggests newer immunosuppressives that do not inhibit calcineurin activity may help relieve cutaneous malignancies in transplant recipients. Citation Format: Edwin Kumah, Yash Chhabra, Vania Wang, Agrani Dixit, Ashani Weeraratna, Kristin Bibee. Iatrogenic immunosuppression emplaces tacrolimus to drive squamous skin cancer progression and influence the microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 279.

Molecular targeted therapies for cutaneous squamous cell carcinoma: recent developments and clinical implications.

Cutaneous Squamous Cell Carcinoma (cSCC) is a common and potentially fatal type of skin cancer that poses a significant threat to public health and has a high prevalence rate. Exposure to ultraviolet radiation on the skin surface increases the risk of cSCC, especially in those with genetic syndromes like xerodermapigmentosum and epidermolysis bullosa. Therefore, understanding the molecular pathogenesis of cSCC is critical for developing personalized treatment approaches that are effective in cSCC. This article provides a comprehensive overview of current knowledge of cSCC pathogenesis, emphasizing dysregulated signaling pathways and the significance of molecular profiling. Several limitations and challenges associated with conventional therapies, however, are identified, stressing the need for novel therapeutic strategies. The article further discusses molecular targets and therapeutic approaches, i.e., epidermal growth factor receptor inhibitors, hedgehog pathway inhibitors, and PI3K/AKT/mTOR pathway inhibitors, as well as emerging molecular targets and therapeutic agents. The manuscript explores resistance mechanisms to molecularly targeted therapies and proposes methods to overcome them, including combination strategies, rational design, and optimization. The clinical implications and patient outcomes of molecular-targeted treatments are assessed, including response rates and survival outcomes. The management of adverse events and toxicities in molecular-targeted therapies is crucial and requires careful monitoring and control. The paper further discusses future directions for therapeutic advancement and research in this area, as well as the difficulties and constraints associated with conventional therapies.

P21 Tyrosine and serine STAT3 phosphorylation drives cutaneous squamous cell carcinoma in recessive dystrophic epidermolysis bullosa as demonstrated using a 3D in vitro model

Abstract The early onset of aggressive cutaneous squamous cell carcinoma (cSCC) and its rapid progression in recessive dystrophic epidermolysis bullosa (RDEB) leads to nearly 100% mortality rates in these patients. Elevated levels of phospho-STAT3 on tyrosine residue (STAT3Tyr705) have been intensively demonstrated in RDEB-derived cSCC cells, demonstrating that the constitutive activation and dysregulation of the Janus kinase (JAK)/STAT pathway plays a role in RDEB cSCC pathogenesis. We efficiently applied ruxolitinib (JAK1/2 inhibitor that blocks phosphorylation on STAT3Tyr705) to a RDEB–cSCC xenograph mouse model, reducing the size of small tumours but found that it was insufficient to reduce bigger tumours completely. Recently, phosphorylation at serine-727 (STAT3Ser727) has been shown to be relevant in the evolution of some cancers, but it has not yet been studied in RDEB cSCC. We hypothesized that phosphorylation at serine-727 of the STAT3 pathway might play a role in RDEB cSCC tumour development and progression, and could not be inhibited by ruxolitinib. To validate our hypothesis, we studied two RDEB cSCC human patient samples with different degrees of dedifferentiation (normal RDEB skin, edge of the tumour and centre of the RDEB cSCC). We demonstrated that STAT3Tyr705 was preferentially upregulated in the normal RDEB skin followed by the tumour edge skin, presenting less phosphorylation on the tumour. When we analysed STAT3 phosphorylation on STAT3Ser727, we could see that it presented the opposite phosphorylation pattern, being more phosphorylated in the tumour and less in normal RDEB skin. Furthermore, we validated the STAT3Ser727residue pattern across other cSCC cell lines and found that serine phosphorylation is present in other SCCs, demonstrating its crucial role in tumour development. To further investigate and analyse cancer progression in more detail, an easy and robust RDEB cSCC model is instrumental. Therefore, we generated RDEB cSCC spheroids in vitro, which has four key advantages over the previous models developed: (i) it is easy to generate; (ii) small amounts of cells are required; (iii) it is suitable for drug testing; and (iv) it can be used to recapitulate different stages of tumour development. We have been able to control their size and use them for drug testing, observing a 20% size decrease after 6 days of ruxolitinib treatment. Taken together, this three-dimensional RDEB cSCC in vitro model, along with analysis of human samples, will allow us to better understand RDEB cSCC progression at different stages, allowing us to investigate new treatments for RDEB cSCC.

CPC08 Cutaneous squamous cell carcinoma and MYH9-associated elastin aggregation (MALTA) syndrome

Abstract MYH9-associated elastin aggregation (MALTA) syndrome is a rare, inherited, irregular elastin aggregation and sweat duct proliferation syndrome caused by pathogenic variants in MYH9. MALTA syndrome was proposed in 2019, unifying Nicolau Balus and Rombo syndromes as phenotypes arising from pathogenic variants in the same gene, but it has not been associated with cutaneous squamous cell carcinoma (cSCC) [Fewings E, Ziemer M, Hörtnagel K et al. Malta (MYH9 associated elastin aggregation) syndrome: germline variants in MYH9 cause rare sweat duct proliferations and irregular elastin aggregations. J Invest Dermatol 2019; 139:2238–41]. Here, we report the clinical features of a family with a novel MYH9 c.1952A>C p.(Lys651Thr) pathogenic variant, providing evidence that cSCC may be an associated feature of MALTA syndrome. A 57-year-old woman presented with a longstanding skin lesion overlying her left infraorbital ridge, which had been present for 13 years. Lesion biopsy revealed a highly infiltrative tumour within the dermis that was composed of keratocysts with small islands of basaloid cells; immunostaining was positive for CK5/6, CK7, CK19, p63 and BerEP4. These histological features were consistent with a microcystic adnexal carcinoma (MAC)-like ductal proliferation, recognized in MALTA. In addition, she had previously developed one cSCC on her left shoulder and two basal cell carcinomas and had cutaneous milia. Her sister had a history of MAC-like ductal proliferation and cSCC, and her brother had two keratoacanthoma-like cSCCs. The copresentation of MAC-like ductal proliferations and early-onset cSCC in this family prompted targeted genetic testing of MYH9. This identified a heterozygous pathogenic variant in a highly conserved region of MYH9 [c.1952A>C p.(Lys651Thr)] that segregated with the phenotype in all three affected members. MYH9 has previously been identified as an important gene in the pathogenesis of cSCC in a genetic screen in transgenic mice, and our family adds novel clinical data, underscoring its importance in cSCC development (Schramek D, Sendoel A, Segal JP et al. Direct in vivo RNAi screen unveils myosin IIa as a tumor suppressor of squamous cell carcinomas. Science 2014; 343:309–13). Based on the recurrent presentation of early-onset cSCC in three members of this family, we propose the inclusion of cSCC in MALTA syndrome. This has implications for skin cancer surveillance of MYH9 pathogenic variant carriers, and the need to consider MALTA syndrome in patients presenting with multiple early-onset cSCC.

010 Enhanced outcome prediction in cutaneous squamous cell carcinoma using deep-learning and computational histopathology (cSCCnet)

Abstract Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer and leads to a significant disease burden. Although metastases occur in < 5% of patients, effective treatments are limited and 5-year survival is poor, with mortality rates equivalent to those of melanoma in some regions of the world. Despite recent advances in understanding the molecular pathogenesis of cSCC, patient risk stratification is limited and based on clinicopathological staging, with few validated prognostic biomarkers available to guide management [de Jong E, Lammerts MUPA, Genders RE, Bowes Bavinck JN. Update of advanced cutaneous squamous cell carcinoma. J Eur Acad Dermatol Venereol 2022; 36(Suppl. 1):6–10]. In this study, we aimed to use artificial intelligence technology to develop a deep learning model using digitized whole-slide images of cSCC to quantify the risk of metastasis. Routine haematoxylin and eosin-stained slides of 256 primary cSCCs from immunocompetent patients at four collaborating centres were scanned. The area of interest encompassing tumour and peritumoral stroma was annotated, and 512 × 512 pixel tiles were generated from each slide. High-quality tiles (containing sufficient tumour content) were pooled together, with patient-level labels inherited by tiles. We trained multiple models using an 80:10:10 split for training, validation and testing, and the model achieving the highest tile- and slide-level validation accuracy was identified (ResNet50). The final model, namely, cSCCnet, achieved 88% sensitivity, 73% specificity, 64% positive predictive value and 92% negative predictive values on the independent test set. Blinded review of the top predictive tiles by three histopathologists suggested that the predictive features identified by cSCCnet were distinct from histopathological features commonly used by clinicians to estimate metastatic risk. We have demonstrated that it is possible to train a deep learning model using digital pathology to predict the risk of metastasis. cSCCnet surpassed the published performance of currently used staging systems, as well as commercially available gene panel testing (de Jong et al.; Wysong A, Newman JG, Covington KR et al. Validation of a 40-gene expression profile test to predict metastatic risk in localized high-risk cutaneous squamous cell carcinoma. J Am Acad Dermatol 2021; 84:361–9). The morphological features and patterns identified by cSCCnet are different from established histopathological high-risk criteria, indicating that this technology can enhance current practice. Although further validation in a prospective cohort is pending, this is an important step toward creating a risk stratification tool that can be incorporated into routine pathology workflows, significantly improving patient outcomes for this common cancer.

Lycorine transfersomes modified with cell-penetrating peptides for topical treatment of cutaneous squamous cell carcinoma

BackgroundTopical anticancer drugs offer a potential therapeutic modality with high compliance for treating cutaneous squamous cell carcinoma (cSCC). However, the existing topical treatments for cSCC are associated with limited penetrating ability to achieve the desired outcome. Therefore, there remains an urgent requirement to develop drugs with efficient anticancer activity suitable for treating cSCC and to overcome the skin physiological barrier to improve the efficiency of drug delivery to the tumor.ResultsWe introduced lycorine (LR) into the topical treatment for cSCC and developed a cell-penetrating peptide (CPP)-modified cationic transfersome gel loaded with lycorine-oleic acid ionic complex (LR-OA) (LR@DTFs-CPP Gel) and investigated its topical therapeutic effects on cSCC. The anti-cSCC effects of LR and skin penetration of LR-OA transfersomes were confirmed. Simultaneously, cationic lipids and modification of R5H3 peptide of the transfersomes further enhanced the permeability of the skin and tumor as well as the effective delivery of LR to tumor cells.ConclusionsTopical treatment of cSCC-xenografted nude mice with LR@DTFs-CPP Gel showed effective anticancer properties with high safety. This novel formulation provides novel insights into the treatment and pathogenesis of cSCC.

Abstract 4448: Chemokine (C-X-C motif) ligand 17 promotes cutaneous squamous cell carcinoma via modulating tumor-immune evasion

Abstract Cutaneous squamous cell carcinoma (cSCC) is a keratinocyte-derived invasive and metastatic tumor of the skin. It is the second-most commonly diagnosed form of skin cancer, striking 200,000 Americans annually. Further, organ transplant patients are at significantly increased risk of cSCC compared to the general population. Excision of cSCC of the head and neck area results in significant facial disfigurement. An increased understanding of the mechanisms involved in the pathogenesis of cSCC could identify means to prevent, inhibit, and reverse this process. Chemokine (C-X-C motif) ligand 17 (CXCL17) is the latest chemokine family member, and an increased CXCL17 protein expression was observed in both mouse and human cSCC cell lines. Further, deletion of CXCL17 was associated with significant inhibition of tumor cell-intrinsic properties such as proliferation, migration, and motility. CXCL17 is identified as a potent chemoattractant for macrophages, dendritic cells and myeloid-derived suppressive cells. Accordingly, utilizing a syngeneic, tumor-cell xenograft cSCC mouse model, we evaluated the effect of CXCL17 deletion on cSCC tumor-immune evasion and elucidated the underlying mechanism. Deletion of CXCL17 was associated with a significant reduction in tumor volume compared to the wild-type counterparts. Further, CXCL17 deleted cSCC tumor cell xenografts exhibited a significant increase in CD8+, cytotoxic T cells in the tumor microenvironment, suggesting an important role of CXCL17 in mediating tumor-immune evasion. Interestingly, treatment with CXCL17 induced macrophage M2 polarization and promoted macrophage efferocytosis via modulating efferocytotic machinery proteins such as MERTK, TIM4, GAS6 and AXL. Our studies have established substantial evidence for the role of CXCL17 in modulating tumor-cell extrinsic properties to affect the progression of cSCC. Citation Format: Alok R. Khandelwal, Rema Anisha Kandula, Emily Daniel, Md Maksudul Alam, Henry Craighead, Tara Moore-Medlin, Cherie-Ann O. Nathan. Chemokine (C-X-C motif) ligand 17 promotes cutaneous squamous cell carcinoma via modulating tumor-immune evasion. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4448.

Proteasome Subunit Alpha Type-7 Expression Suppresses Cutaneous Squamous Cell Carcinoma Progression by Inhibiting Cancer-associated Cytokines.

Cutaneous squamous cell carcinoma (cSCC) is a common non-melanoma skin cancer, and its incidence is increasing. Proteasome subunit alpha type-7 (PSMA7) has been found to be aberrantly expressed in several cancers. However, whether it functions as a tumor suppressor or oncogene in the pathogenesis of cancers, particularly cSCC, remains controversial. Here, we aimed to investigate the functions of PSMA7 in cSCC pathogenesis. Clinicopathological characteristics were evaluated in 131 patients with cSCC using tissue sections. The expression of PSMA7, nucleotide-binding oligomerization domain-containing protein 1 (NOD1), and mitochondrial antiviral signaling protein (MAVS) was determined in cSCC tissue sections using immunohistochemical staining. The effect of PSMA7 expression on the biological behavior of cSCC cells was investigated in vitro. High immunoreactivity of PSMA7 (high-PSMA7) was detected in 53 (40.5%) patients with cSCC and was significantly associated with histologic grade (p=0.008) and favorable recurrence-free survival (p=0.018). The expression of PSMA7 and NOD1 (p=0.026) and MAVS (p=0.032) was negatively correlated in cSCC tissues. Contrary to the results of the cohort study, cell viability and invasiveness significantly decreased after PSMA7 down-regulation in cSCC cells in vitro. mRNA expression of tumor necrosis factor-alpha, interleukin-1 alpha (IL-1α), IL-6, and IL-8 were significantly increased after PSMA7 down-regulation in cSCC cells (all p=0.002). PSMA7-mediated degradation of NOD1 and MAVS as well as the subsequent reduction of the cancer-associated cytokine network may be a crucial mechanism of the antitumoral function of PSMA7 in patients with cSCC.

Modelling cutaneous squamous cell carcinoma for laboratory research.

Cutaneous squamous cell carcinoma (cSCC) leads to significant morbidity for patients with progression and metastases. However, the molecular underpinnings of these tumors are still poorly understood. Dissecting human cSCC pathogenesis amplifies the exigence for preclinical models that mimic invasion and nodal spread. This review discusses the currently available models, including two- and three-dimensional tissue cultures, syngeneic and transgenic mice, and cell line-derived and patient-derived xenografts. We further highlight studies that have utilized the different models, considering how they recapitulate specific hallmarks of cSCC. Finally, we discuss the advantages, limitations and future research directions.

Exploring Potential Biomarkers, Ferroptosis Mechanisms, and Therapeutic Targets Associated with Cutaneous Squamous Cell Carcinoma via Integrated Transcriptomic Analysis.

Background Cutaneous squamous cell carcinoma (cSCC) is the leading cause of death in patients with nonmelanoma skin cancers (NMSC). However, the unclear pathogenesis of cSCC limits the application of molecular targeted therapy. Methods Three microarray datasets (GSE2503, GSE45164, and GSE66359) were downloaded from the Gene Expression Omnibus (GEO). After identifying the differentially expressed genes (DEGs) in tumor and nontumor tissues, five kinds of analyses, namely, functional annotation, protein-protein interaction (PPI) network, hub gene selection, TF-miRNA-mRNA regulatory network analysis, and ferroptosis mechanism, were performed. Results A total of 146 DEGs were identified with significant differences, including 113 upregulated genes and 33 downregulated genes. The enriched functions and pathways of the DEGs included microtubule-based movement, ATP binding, cell cycle, P53 signaling pathway, oocyte meiosis, and PLK1 signaling events. Nine hub genes were identified (CDK1, AURKA, RRM2, CENPE, CCNB1, KIAA0101, ZWINT, TOP2A, and ASPM). Finally, RRM2, AURKA, and SAT1 were identified as significant ferroptosis-related genes in cSCC. The differential expression of these genes has been verified in two other independent datasets. Conclusions By integrated bioinformatic analysis, the hub genes identified in this study elucidated the molecular mechanism of the pathogenesis and progression of cSCC and are expected to become future biomarkers or therapeutic targets.

Combined Kdm6a and Trp53 Deficiency Drives the Development of Squamous Cell Skin Cancer in Mice

Cutaneous squamous cell carcinoma (cSCC) has among the highest mutation burdens of all cancers, reflecting its pathogenic association with the mutagenic effects of UV light exposure. Although mutations in cancer-relevant genes such as TP53 and NOTCH1 are common in cSCC, they are also tolerated in normal skin and suggest that other events are required for transformation; it is not yet clear whether epigenetic regulators cooperate in the pathogenesis of cSCC. KDM6A encodes a histone H3K27me2/me3 demethylase that is frequently mutated in cSCC and other cancers. Previous sequencing studies indicate that roughly 7% of cSCC samples harbor KDM6A mutations, including frequent truncating mutations, suggesting a role for this gene as a tumor suppressor in cSCC. Mice with epidermal deficiency of both Kdm6a and Trp53 exhibited 100% penetrant, spontaneous cSCC development within a year, and exome sequencing of resulting tumors reveals recurrent mutations in Ncstn and Vcan. Four of 16 tumors exhibited deletions in large portions of chromosome 1 involving Ncstn, whereas another 25% of tumors harbored deletions in chromosome 19 involving Pten, implicating the loss of other tumor suppressors as cooperating events for combined KDM6A- and TRP53-dependent tumorigenesis. This study suggests that KDM6A acts as an important tumor suppressor for cSCC pathogenesis.

Abstract 5425: Quantitative determination of fibroblast growth factor receptor inhibitor-AZD4547 using HPLC analysis in a mouse model of ultraviolet B (UVB)-induced skin carcinogenesis

Abstract Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer affecting more than two million Americans annually. Cumulative sun exposure plays a leading role in the pathogenesis of cSCC. In our previous studies, topical application of Fibroblast growth factor receptor (FGFR) inhibitor AZD4547 was associated with a significant reduction in Ultraviolet B-induced (UVB)-induced acute skin changes such as epidermal hyperplasia and hyperproliferation. Further, chronic, topical application of AZD4547 was associated with significant inhibition in UVB-induced tumor incidence and multiplicity. Unfortunately, oral administration of FGFR inhibitors in clinical trials for solid tumors is associated with notable side effects such as hyperphosphatemia, diarrhea, decreased appetite, fatigue, and liver dysfunction. Therefore, our objective was to investigate whether topical administration of AZD4547 could potentially circumvent systemic absorption, leading to a low toxicity profile. Accordingly, mice were topically administered AZD4547 (400ug/200ul acetone) followed by exposure to UVB three times a week for two weeks. Blood was collected at the end of the study. AZD4547 was extracted using methanol extraction and concentrated using a Savant SpeedVac system. Samples were reconstituted in 25% acetone/75% water solution and analyzed using Reverse-phase HPLC (Shimadzu) with a Zorbax Eclipse C18 3.5-µm 4.6x100mm analytical column operated at ambient temperature and gradient elution using trifluoroacetic acid (TFA) (Mobile A) and 0.1% TFA in Acetonitrile. Data from HPLC analysis demonstrated non-appreciable absorption of AZD4547 (blood levels only from 108-358nM) suggesting that the topical application of AZD4547 was not systemically absorbed and the effect of treatment was restricted to the local skin tissue. Based on the efficacy and low systemic absorption profile, AZD4547 could potentially be utilized as a topical agent to both prevent and treat UVB-induced cSCC. Citation Format: Rema Anisha Kandula, Katherine Claire Babin, Brian Latimer, Kenneth Mc Martin, Lauren Linquest, Tara Moore-Medlin, Megha A. Thakur, Alok R. Khandelwal, John DiGiovanni, Cherie-Ann O. Nathan. Quantitative determination of fibroblast growth factor receptor inhibitor-AZD4547 using HPLC analysis in a mouse model of ultraviolet B (UVB)-induced skin carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5425.

Implication of COPB2 Expression on Cutaneous Squamous Cell Carcinoma Pathogenesis.

Simple SummaryThe present study aimed to evaluate the effect of COPB2 expression on cutaneous squamous cell carcinoma (cSCC) pathogenesis. cSCC, a common category of skin cancer, is marked by a reasonably favorable prognosis. However, there has been a steady rise in the annual incidence of cases; in particular, a subset of cases showed aggressive progression. However, the underlying molecular mechanism of cSCC pathogenesis is largely unknown. In the present study, we found that COPB2 may act as a potential oncogene and modulator of the tumor immune microenvironment in cSCC pathogenesis. Therefore, COPB2 can serve as a novel predictive prognostic biomarker and immunotherapeutic target in cSCC patients.The underlying molecular mechanisms of cutaneous squamous cell carcinoma (cSCC) pathogenesis are largely unknown. In the present study, we aimed to evaluate the effect of coatomer protein complex subunit beta 2 (COPB2) expression on cSCC pathogenesis. Clinicopathological significance of COPB2 in cSCC was investigated by analyzing the Gene Expression Omnibus (GEO) database and through a retrospective cohort study of 95 cSCC patients. The effect of COPB2 expression on the biological behavior of cSCC cells was investigated both in vitro and in vivo. We found that COPB2 expression was significantly higher in cSCC samples than in normal skin samples. In our cohort, a considerable association was found between COPB2 expression and indicators of tumor immune microenvironment (TIME), such as histocompatibility complex class (MHC) I, and MHC II, CD4+/ CD8+ tumor-infiltrating lymphocytes. Additionally, COPB2 expression had an independent impact on worsened recurrence-free survival in our cohort. Furthermore, decreased proliferation, invasion, tumorigenic activities, and increased apoptosis were observed after COPB2 knockdown in cSCC cells. COPB2 may act as a potential oncogene and candidate modulator of the TIME in cSCC. Therefore, it can serve as a novel predictive prognostic biomarker and candidate immunotherapeutic target in cSCC patients.

Squamous Cell Carcinoma in Patients with Inherited Epidermolysis Bullosa: Review of Current Literature.

Epidermolysis bullosa (EB) is a group of rare congenital diseases caused by mutations in structural proteins of the dermal/epidermal junction that are characterized by extreme epithelial fragility, which determines the formation of bullae and erosions either spontaneously or after local mechanical traumas. In EB patients, skin fragility leads to many possible complications and comorbidities. One of the most feared complications is the development of cutaneous squamous cell carcinomas (SCCs) that particularly in the dystrophic recessive EB subtype can be extremely aggressive and often metastatic. SCCs in EB patients generally arise more often in the extremities, where chronic blisters and scars are generally located. SCCs represent a big therapeutic challenge in the EB population. No standard of care exists for the treatment of SCC in these patients, and therapy is based on small case studies. Moreover, the pathogenesis of cSCC in EB patients is still unclear. Many theories have been indeed postulated in order to explain why cSCC behaves so much more aggressively in EB patients compared to the general population. cSCC in EB seems to be the result of many complex interactions among cancer cells, skin microenvironment, susceptibility to DNA mutations and host immune response. In this review, we analyze the different pathogenetic mechanisms of cSCC in EB patients, as well as new therapies for this condition.

Increased Expression of Flightless I in Cutaneous Squamous Cell Carcinoma Affects Wnt/β-Catenin Signaling Pathway.

Cutaneous squamous cell carcinoma (cSCC) accounts for 25% of cutaneous malignancies diagnosed in Caucasian populations. Surgical removal in combination with radiation and chemotherapy are effective treatments for cSCC. Nevertheless, the aggressive metastatic forms of cSCC still have a relatively poor patient outcome. Studies have linked actin cytoskeletal dynamics and the Wnt/β-catenin signaling pathway as important modulators of cSCC pathogenesis. Previous studies have also shown that the actin-remodeling protein Flightless (Flii) is a negative regulator of cSCC. The aim of this study was to investigate if the functional effects of Flii on cSCC involve the Wnt/β-catenin signaling pathway. Flii knockdown was performed using siRNA in a human late stage aggressive metastatic cSCC cell line (MET-1) alongside analysis of Flii genetic murine models of 3-methylcholanthrene induced cSCC. Flii was increased in a MET-1 cSCC cell line and reducing Flii expression led to fewer PCNA positive cells and a concomitant reduction in cellular proliferation and symmetrical division. Knockdown of Flii led to decreased β-catenin and a decrease in the expression of the downstream effector of β-catenin signaling protein SOX9. 3-Methylcholanthrene (MCA)-induced cSCC in Flii overexpressing mice showed increased markers of cancer metastasis including talin and keratin-14 and a significant increase in SOX9 alongside a reduction in Flii associated protein (Flap-1). Taken together, this study demonstrates a role for Flii in regulating proteins involved in cSCC proliferation and tumor progression and suggests a potential role for Flii in aggressive metastatic cSCC.

Epigenetic regulatory mechanisms of histone acetylation in the treatment of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy; as such, novel systemic therapies are important for the treatment of locally advanced or metastatic disease. Histone deacetylase (HDAC) inhibitors have been increasingly studied in recent years as epigenome-targeted therapy for cSCC. HDACs inhibitors reduce tumorigenesis by blocking HDAC activity and creating a more relaxed chromatin structure, thus inducing gene expression by inhibiting deacetylation of transcription factors. In vitro experiments and in vivo mice studies have shown that HDAC inhibition halts cSCC pathogenesis. Ginsenoside 20(R)-Rg3 has been successfully employed to inhibit HDAC3 and thereby inhibit cSCC epithelial mesenchymal transition. Similarly, vorinostat has been found to blunt growth of human xenograft epidermoid cSCCs in highly immunosuppressed mice. Additionally, trichostatin A induces irreversible growth arrest in SCC cells, and MS-275 significantly reduces cSCC tumor burden in mice. These recent studies indicate that HDAC inhibitors represent a promising emerging therapy for cSCC.

255 PVT1 is overexpressed and acts as an oncogenic long non-coding RNA in cutaneous squamous cell carcinoma

Cutaneous SCC (cSCC) represents the most frequently occurring cancer with metastatic potential accounting for 20% of all skin cancer-related deaths. The incidence of cSCC has been increasing alarmingly especially in Nordic countries. Long noncoding RNAs (lncRNAs) are transcripts that are longer than 200 nt, lack the potential to encode functional proteins and play important roles in gene regulation. In this study, we aimed to investigate the role of lncRNAs in the pathogenesis of cSCC. To identify potential clinically relevant lncRNAs in cSCC, we performed RNA sequencing in human cSCCs.

Seven key hub genes identified by gene co-expression network in cutaneous squamous cell carcinoma

BackgroundCutaneous squamous cell carcinoma (cSCC) often follows actinic keratosis (AK) and is the second most common skin cancer worldwide. To reduce metastasis risk, it is important to diagnose and treat cSCC early. This study aimed to identify hub genes associated with cSCC and AK.MethodsThis study used three datasets GSE45216, GSE98774, and GSE108008. We combined samples from the GSE45216 and GSE98774 datasets into the new dataset GSE45216–98774. We applied a weighted gene co-expression network analysis (WGCNA) to investigate key modules and hub genes associated with cSCC and AK. We considered the hub genes found in both the GSE45216–98774 and GSE108008 datasets as validated hub genes. We tested whether the expression of hub genes could predict patient survival outcomes in other cancers using TCGA pan-cancer data.ResultsWe identified modules most relevant to cSCC and AK. Additionally, we identified and validated seven hub genes of cSCC: GATM, ARHGEF26, PTHLH, MMP1, POU2F3, MMP10 and GATA3. We did not find validated hub genes for AK. Each hub gene was significantly associated with the survival of various cancer types. Only GATA3 was significantly associated with melanoma survival.ConclusionsWe applied WGCNA to find seven hub genes that play important roles in cSCC tumorigenesis. These results provide new insights that help explain the pathogenesis of cSCC. These hub genes may become biomarkers or therapeutic targets for accurate diagnosis and treatment of cSCC in the future.

Serum matrix metalloproteinase-13 as a diagnostic biomarker for cutaneous squamous cell carcinoma

BackgroundA significant proportion of newly diagnosed patients with cutaneous squamous cell carcinoma (cSCC) have metastasis and eventually die of the disease, necessitating the exploration of novel biomarkers for early detection of cSCC aggressiveness, risk assessment and monitoring. Matrix metalloproteinase-13 (MMP-13) has been implicated in cSCC pathogenesis. Serum MMP-13 levels have been shown to predict survival in patients with esophageal SCC, but their diagnostic value for cSCC has not been explored.MethodsWe conducted a case-control study to examine serum MMP-13 as a biomarker for cSCC. Patients with cSCC undergoing surgical resection and health controls undergoing plastic surgery were recruited. ELISA for measurement of serum MMP-13 and immunohistochemistry for detection of tissue MMP-13 were performed, and the results were compared between the case and the control group, and among different patient groups. ROC curve analysis was performed to determine the diagnostic value of serum MMP-13 levels.ResultsThe ratio of male to female, and the age between the case (n = 77) and the control group (n = 50) were not significantly different. Patients had significantly higher serum MMP-13 levels than healthy controls. Subjects with stage 3 cSCC had markedly higher serum MMP-13 levels than those with stage 1 and stage 2 cSCC. Patients with invasive cSCC had remarkably higher serum MMP-13 than those with cSCC in situ. Post-surgery serum MMP-13 measurement was done in 12 patients, and a significant MMP-13 decrease was observed after removal of cSCC. Tumor tissues had a remarkably higher level of MMP-13 than control tissues. Serum MMP-13 predicted the presence of invasive cSCC with an AUC of 0.87 (95% CI [0.78 to 0.95]) for sensitivity and specificity of 81.7 and 82.4%, respectively for a cut-off value of 290 pg/mL. Serum MMP-13 predicted lymph node involvement with an AUC of 0.94 (95% CI [0.88 to 0.99]) for sensitivity and specificity of 93.8 and 88.5%, respectively for a cut-off value of 430 pg/mL.ConclusionSerum MMP-13 might serve as a valuable biomarker for early detection of cSCC invasiveness and monitoring of cSCC progression.