Chronic sun exposure-related fusion oncogenes EGFR-PPARGC1A in cutaneous squamous cell carcinoma

Increased Risk of Local Recurrence in Cutaneous Squamous Cell Carcinoma Arising in Sun-Exposed Skin: A Retrospective Cohort Study

BACKGROUND

The incidence of cutaneous squamous cell carcinoma (cSCC) is increasing over the years. Risk factors for local recurrence and metastasis have been widely studied in highly sun-exposed areas of the body but less data exist about less sun-exposed ones. The main objective of this study is to compare the risk of local recurrence and metastases in patients with cSCC in highly sun-exposed areas compared to cSCC in less sun-exposed areas.

MATERIAL AND METHODS

A retrospective observational study was carried out, including 558 patients with histopathologically confirmed cSCC at the Reina Sofía University Hospital (HURS), Córdoba, during the period from 1 January 2017 to 31 December 2020. Demographic, clinical and anatomopathological data were collected.

RESULTS

Local recurrence occurs more often in highly sun-exposed areas (15.8%) compared to less sun-exposed ones (7.4%) (p < 0.05). However, no differences in the rate of metastases in both groups were found. The presence of affected surgical margins and tumor thickness were identified as independent risk factors for cSCC in low sun-exposure areas.

CONCLUSIONS

cSCC located in anatomical areas of high sun exposure presented a greater risk of developing local recurrence in our population, which could suggest that these tumors have worse prognosis than those that lie in areas that do not receive chronic sun exposure.

Biphenotypic Sinonasal Sarcoma with a Novel PAX7::PPARGC1 Fusion: Expanding the Spectrum of Gene Fusions Beyond the PAX3 Gene

Biphenotypic sinonasal sarcoma (BSNS) is a rare low-grade malignancy occurring in the sinonasal tract that is characterized by dual neural and myogenic differentiation. Rearrangements involving the PAX3 gene, usually with MAML3, are a hallmark of this tumor type and their identification are useful for diagnosis. Rarely, a MAML3 rearrangement without associated PAX3 rearrangement has been described. Other gene fusions have not been previously reported. Herein, we report a 22 year-old woman with a BSNS harboring a novel gene fusion involving the PAX7 gene (specifically PAX7::PPARGC1A), which is a paralogue of PAX3. The histologic features of the tumor were typical with two exceptions: a lack of entrapment of surface respiratory mucosa and no hemangiopericytoma-like vasculature. Immunophenotypically, the tumor was notably negative for smooth muscle actin, which is usually positive in BSNS. However, the classic S100 protein-positive, SOX10-negative staining pattern was present. In addition, the tumor was positive for desmin and MyoD1 but negative for myogenin, a pattern that is common among BSNS with variant fusions. Awareness of the possibility of PAX7 gene fusions in BSNS is important as it may aid in the diagnosis of PAX3 fusion negative tumors.

Glycoprotein M6A upregulation detected by transcriptome analysis controls the proliferation of keloidal fibroblasts

Hypertrophic scars and keloids are fibroproliferative disorders caused by abnormal wound healing. Their exact cause has not been found, but abnormalities during the wound healing process including inflammatory, immune, genetic, and other factors are thought to predispose an individual to excessive scarring. In the present study, we performed transcriptome analysis of established keloid cell lines (KEL FIB), focusing on gene expression analysis and fusion gene detection for the first time. For gene expression analysis, fragments per kilobase per million map read values were calculated, which were validated by real-time PCR and immunohistochemistry. Fusion genes were predicted by transcriptome sequence, and validated by Sanger sequence and G-banding. As a result, GPM6A was shown in the expression analysis to be upregulated in KEL FIB compared with normal fibroblasts. The GPM6A upregulation in KEL FIB was confirmed by real-time PCR, and GPM6A messenger ribonucleic acid expression was consistently significantly elevated in the tissues of hypertrophic scar and keloid compared to normal skin. Immunohistochemistry also revealed that the number of fibroblast-like spindle-shaped cells positive for GPM6A was significantly increased in keloidal tissues. GPM6A inhibition by small interfering ribonucleic acid significantly reduced the number of KEL FIB. On the other hand, although we hypothesized that fusion genes are involved in the pathogenesis of keloids, the transcriptome analysis could not prove the presence of fusion genes in KEL FIB. Taken together, GPM6A upregulation may have an inducible effect on cell proliferation in keloidal fibroblasts. GPM6A can be a novel therapeutic target in hypertrophic scars and keloids. The inflammatory nature may be more prominent in the pathogenesis of keloids, rather than being skin tumors, as proposed by Ogawa et al. Future studies using several cell lines will be required.

Targeting receptor tyrosine kinase signaling: Avenues in the management of cutaneous squamous cell carcinoma

Non-melanoma skin cancer (NMSC) is the most frequently diagnosed cancer worldwide. Among the various types of NMSCs, cutaneous squamous cell carcinoma (cSCC) exhibits more aggressive phenotype and is also the second-most prevalent type. Receptor tyrosine kinases (RTK) triggers key signaling events that play critical roles in the development of various cancers including cSCC. Unsurprisingly, for this reason, this family of proteins has become the cynosure of anti-cancer drug discovery pipelines and is also being considered as attractive targets against cSCC. Though inhibition of RTKs in cSCC has yielded favourable results, there is still scope for bettering the therapeutic outcome. In this review, we discuss the relevance of RTK signaling in the progression of cutaneous squamous cell carcinoma, and observations from clinical trials that used RTK inhibitors against cSCC. Backed by results from preclinical studies, including those from our lab, we also give insights into the scope of using some natural products as effective suppressors of RTK signaling and skin carcinogenesis.

Elevated Alpha 1(I) to Alpha 2(I) Collagen Ratio in Dermal Fibroblasts Possibly Contributes to Fibrosis in Systemic Sclerosis

Systemic sclerosis (SSc) is characterized by excessive collagen deposition in the skin and internal organs. Activated fibroblasts are the key effector cells for the overproduction of type I collagen, which comprises the α1(I) and α2(I) chains encoded by COL1A1 and COL1A2, respectively. In this study, we examined the expression patterns of α1(I) and α2(I) collagen in SSc fibroblasts, as well as their co-regulation with each other. The relative expression ratio of COL1A1 to COL1A2 in SSc fibroblasts was significantly higher than that in control fibroblasts. The same result was observed for type I collagen protein levels, indicating that α2(I) collagen is more elevated than α2(I) collagen. Inhibition or overexpression of α1(I) collagen in control fibroblasts affected the α2(I) collagen levels, suggesting that α1(I) collagen might act as an upstream regulator of α2(I) collagen. The local injection of COL1A1 small interfering RNA in a bleomycin-induced SSc mouse model was found to attenuate skin fibrosis. Overall, our data indicate that α2(I) collagen is a potent regulator of type I collagen in SSc; further investigations of the overall regulatory mechanisms of type I collagen may help understand the aberrant collagen metabolism in SSc.

Investigating Cutaneous Squamous Cell Carcinoma in vitro and in vivo: Novel 3D Tools and Animal Models

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin reconstructs and organoids. Although 3D models demonstrate high potential to enhance the overall knowledge in cancer research, they lack systemic components which may be solved only by using animal models. Zebrafish is emerging as an alternative xenotransplant model in cancer research, offering a high-throughput approach for drug screening and real-time in vivo imaging to study cell invasion. Moreover, several categories of mouse models were developed for pre-clinical purpose, including xeno- and syngeneic transplantation models, autochthonous models of chemically or UV-induced skin squamous carcinogenesis, and genetically engineered mouse models (GEMMs) of cSCC. These models have been instrumental in examining the molecular mechanisms of cSCC and drug response in an in vivo setting. The present review proposes an overview of in vitro, particularly 3D, and in vivo models and their application in cutaneous SCC research.

Oh, the Mutations You'll Acquire! A Systematic Overview of Cutaneous Squamous Cell Carcinoma

Nearly two million cases of cutaneous squamous cell carcinoma (cSCC) are diagnosed every year in the United States alone. cSCC is notable for both its prevalence and its propensity for invasion and metastasis. For many patients, surgery is curative. However, patients experiencing immunosuppression or recurrent, advanced, and metastatic disease still face limited therapeutic options and significant mortality. cSCC forms after decades of sun exposure and possesses the highest known mutation rate of all cancers. This mutational burden complicates efforts to identify the primary factors driving cSCC initiation and progression, which in turn hinders the development of targeted therapeutics. In this review, we summarize the mutations and alterations that have been observed in patients’ cSCC tumors, affecting signaling pathways, transcriptional regulators, and the microenvironment. We also highlight novel therapeutic opportunities in development and clinical trials.

Fusion genes in gynecologic tumors: the occurrence, molecular mechanism and prospect for therapy

Gene fusions are thought to be driver mutations in multiple cancers and are an important factor for poor patient prognosis. Most of them appear in specific cancers, thus satisfactory strategies can be developed for the precise treatment of these types of cancer. Currently, there are few targeted drugs to treat gynecologic tumors, and patients with gynecologic cancer often have a poor prognosis because of tumor progression or recurrence. With the application of massively parallel sequencing, a large number of fusion genes have been discovered in gynecologic tumors, and some fusions have been confirmed to be involved in the biological process of tumor progression. To this end, the present article reviews the current research status of all confirmed fusion genes in gynecologic tumors, including their rearrangement mechanism and frequency in ovarian cancer, endometrial cancer, endometrial stromal sarcoma, and other types of uterine tumors. We also describe the mechanisms by which fusion genes are generated and their oncogenic mechanism. Finally, we discuss the prospect of fusion genes as therapeutic targets in gynecologic tumors.

Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma represents 20% of all skin cancers, resulting in 1 million cases in the United States each year. The lifetime risk of developing squamous cell carcinoma continues to increase annually and will likely continue to increase because of the aging population. Most cutaneous squamous cell carcinoma are treated locally, with a subset leading to recurrence, metastasis, and death. This review of cutaneous squamous cell carcinoma covers incidence, recurrence rates, mortality rates, risk factors, staging systems, treatment, prevention, and monitoring.

Epidermal Growth Factor Receptor's Function in Cutaneous Squamous Cell Carcinoma and Its Role as a Therapeutic Target in the Age of Immunotherapies

OPINION STATEMENT

Recent studies have evidenced the potential of combining anti-EGFR therapies with anti-PD-1/PD-L1 checkpoint therapies. Both anti-EGFR and anti-PD-1/PD-L1 have been separately tested in the treatment of cutaneous SCC (cSCC). Here, we review recent data on EGFR in the context of cancer progression, as a prognostic and as a therapeutic target in cSCC. Anti-EGFR/checkpoint immunotherapy and other combination therapy approaches are discussed. With the advent of immunotherapy, EGFR is still a valid cSCC target.

PPAR-γ signalling as a key mediator of human hair follicle physiology and pathology

Peroxisome proliferator-activated receptors (PPARs) are abundantly expressed in human skin, with PPAR-γ being the most intensively investigated isoform. In various ex vivo and in vivo models, PPAR-γ-mediated signalling has recently surfaced as an essential element of hair follicle (HF) development, growth and stem cell biology. Moreover, the availability of novel, topically applicable PPAR-γ modulators with a favourable toxicological profile has extended the range of potential applications in clinical dermatology. In this review, we synthesize where this field currently stands and sketch promising future research avenues, focussing on the role of PPAR-γ-mediated signalling in the biology and pathology of human scalp HFs, with special emphasis on scarring alopecias such as lichen planopilaris and frontal fibrosing alopecia as model human epithelial stem cell diseases. In particular, we discuss whether and how pharmacological modulation of PPAR-γ signalling may be employed for the management of hair growth disorders, for example, in scarring alopecia (by reducing HF inflammation as well as by promoting the survival and suppressing pathological epithelial-mesenchymal transition of keratin 15 + epithelial stem cells in the bulge) and in hirsutism/hypertrichosis (by promoting catagen development). Moreover, we explore the potential role of PPAR-γ in androgenetic alopecia, HF energy metabolism and HF ageing, and consider clinical perspectives that emanate from the limited data available on this so far. As this field of translational human hair research is still in its infancy, many open questions exist, for which we briefly delineate selected experimental approaches that promise to generate instructive answers in the near future.

High-Risk Human Papillomavirus E6/E7 mRNA Is Rarely Detected in Nonanogenital Cutaneous Squamous Cell Carcinoma: An RNA In Situ Hybridization-Based Tissue Microarray Study

High-risk human papillomavirus (HR-HPV) is known to play an oncogenic role in squamous cell carcinoma (SCC) at certain anatomical sites, namely the uterine cervix, oropharynx, and anogenital skin. However, the association between HR-HPV and nonanogenital cutaneous SCC (CSCC) remains controversial. In this study, we addressed this controversy by performing HR-HPV E6/E7 mRNA in situ hybridization (ISH) on 243 CSCC samples. A cocktail of E6/E7 mRNA ISH probes, recognizing 18 HR-HPV genotypes, was applied to a tissue microarray of paraffin-embedded sections of 154 invasive and 89 in situ CSCC specimens. The anatomical sites of CSCC included the head and neck (n = 100), extremities (n = 100), trunk (n = 25), and anogenitalia (n = 18). We also investigated the correlation between the p16 expression and HR-HPV status by immunohistochemistry. The results of HR-HPV E6/E7 mRNA ISH showed that 5.8% (14/243) of all CSCC samples were positive for HR-HPV, including 66.7% (12/18) of the anogenital and only 0.9% (2/225) of the nonanogenital CSCC samples (P < 0.01). For the detection of diffuse p16 expression by immunohistochemistry, the sensitivity was 100% (14/14 HR-HPV-positive CSCC samples), and the specificity was 72.1% (165/229 HR-HPV-negative specimens). Thus, HR-HPV E6/E7 mRNA was rarely detected in nonanogenital CSCC, making it unlikely that the virus contributes to the pathogenesis of this malignancy. In addition, p16 immunoreactivity has a limited value as a surrogate marker for transcriptionally active HR-HPV in nonanogenital CSCC.