Loss of CDKN2A and p14ARF expression occurs frequently in human nonmelanoma skin cancers

The Mutational and Microenvironmental Landscape of Cutaneous Squamous Cell Carcinoma: A Review

Cutaneous squamous cell carcinoma (cSCC) manifests through the complex interactions of UV-induced DNA damage, genetic mutations, and alterations in the tumor microenvironment. A high mutational burden is present in cSCC, as well as both cSCC precursors and normal skin, making driver genes difficult to differentiate. Despite this, several key driver genes have been identified, including TP53, the NOTCH family, CDKN2A, PIK3CA, and EGFR. In addition to mutations, the tumor microenvironment and the manipulation and evasion of the immune system play a critical role in cSCC progression. Novel therapeutic approaches, such as immunotherapy and EGFR inhibitors, have been used to target these dysregulations, and have shown promise in treating advanced cSCC cases, emphasizing the need for targeted interventions considering both genetic and microenvironmental factors for improved patient outcomes.

Has-miR-300-GADD45B promotes melanoma growth via cell cycle

Response to oncogenic factors like UV, GADD45 family in skin participates in scavenging ROS, DNA repair and cell cycle control. Because of this, the previous study of the chronic UVB injury model has found that hsa-miR-300 can conduct intercellular transport by exosomes and target regulation of GADD45B. Whether the hsa-miR-300-GADD45B still regulates tumor development by cell cycle pathway is unclear. Through transcriptomic analysis of primary (n=39) and metastatic (n=102) melanoma, it was confirmed that in metastatic samples, some of the 97 down-regulated genes participate in maintaining skin homeostasis while 42 up-regulated genes were enriched in cancer-related functions. Furthermore, CDKN1A, CDKN2A, CXCR4 and RAD51 in the melanoma pathway, were also differentially expressed between normal skin and melanoma. CDKN1A and CDKN2A were also found to be involved in TP53-dependent cell cycle regulation. In conclusion, it was speculated that CDKN1A, CDKN2A, TP53, GADD45B and hsa-miR-300 may have regulatory relationships. It was demonstrated that there is a bidirectional regulation between hsa-miR-300 and TP53. In addition, miR-300 can regulate CDKN1A by GADD45B/TP53 and promote melanoma growth by accelerating the cell cycle transition from G1/S to G2 phase.

Transethosomal Gel for the Topical Delivery of Celecoxib: Formulation and Estimation of Skin Cancer Progression

The topical delivery of therapeutics is a promising strategy for managing skin conditions. Cyclooxygenase-2 (COX-2) inhibitors showed a possible target for chemoprevention and cancer management. Celecoxib (CXB) is a selective COX-2 inhibitor that impedes cell growth and generates apoptosis in different cell tumors. Herein, an investigation proceeded to explore the usefulness of nano lipid vesicles (transethosomes) (TES) of CXB to permit penetration of considerable quantities of the drug for curing skin cancer. The prepared nanovesicles were distinguished for drug encapsulation efficiency, vesicle size, PDI, surface charge, and morphology. In addition, FT-IR and DSC analyses were also conducted to examine the influence of vesicle components. The optimized formulation was dispersed in various hydrogel bases. Furthermore, in vitro CXB release and ex vivo permeability studies were evaluated. A cytotoxicity study proceeded using A431 and BJ1 cell lines. The expression alteration of the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene and DNA damage and fragmentation using qRT-PCR and comet assays were also investigated. Optimized CXB-TES formulation was spherically shaped and displayed a vesicle size of 75.9 ± 11.4 nm, a surface charge of -44.7 ± 1.52 mV, and an entrapment efficiency of 88.8 ± 7.2%. The formulated TES-based hydrogel displayed a sustained in vitro CXB release pattern for 24 h with an enhanced flux and permeation across rat skin compared with the control (free drug-loaded hydrogel). Interestingly, CXB-TES hydrogel has a lower cytotoxic effect on normal skin cells compared with TES suspension and CXB powder. Moreover, the level of expression of the CDKN2A gene was significantly (p ≤ 0.01, ANOVA/Tukey) decreased in skin tumor cell lines compared with normal skin cell lines, indicating that TES are the suitable carrier for topical delivery of CXB to the cancer cells suppressing their progression. In addition, apoptosis demonstrated by comet and DNA fragmentation assays was evident in skin cancer cells exposed to CXB-loaded TES hydrogel formulation. In conclusion, our results illustrate that CXB-TES-loaded hydrogel could be considered a promising carrier and effective chemotherapeutic agent for the management of skin carcinoma.

P53 in skin cancer: From a master player to a privileged target for prevention and therapy

The increasing incidence of skin cancer (SC) is a global health concern. The commonly reported side effects and resistance mechanisms have imposed the pursuit for new therapeutic alternatives. Moreover, additional preventive strategies should be adopted to strengthen prevention and reduce the rising number of newly SC cases. This review provides relevant insights on the role of p53 tumour suppressor protein in melanoma and non-melanoma skin carcinogenesis, also highlighting the therapeutic potential of p53-targeting drugs against SC. In fact, several evidences are provided demonstrating the encouraging outcomes achieved with p53-activating drugs, alone and in combination with currently available therapies in SC. Another pertinent perspective falls on targeting p53 mutations, as molecular signatures in premature phases of photocarcinogenesis, in future SC preventive approaches. Overall, this review affords a critical and timely discussion of relevant issues related to SC prevention and therapy. Importantly, it paves the way to future studies that may boost the clinical translation of p53-activating agents, making them new effective alternatives in precision medicine of SC therapy and prevention.

Whole genome and whole transcriptome genomic profiling of a metastatic eccrine porocarcinoma

Eccrine porocarcinomas (EPs) are rare malignant tumours of the intraepidermic sweat gland duct and most often arise from benign eccrine poromas. Some recurrent somatic genomic events have been identified in these malignancies, but very little is known about the complexity of their molecular pathophysiology. We describe the whole genome and whole transcriptome genomic profiling of a metastatic EP in a 66-year-old male patient with a previous history of localized porocarcinoma of the scalp. Whole genome and whole transcriptome genomic profiling was performed on the metastatic EP. Whole genome sequencing was performed on blood-derived DNA in order to allow a comparison between germline and somatic events. We found somatic copy losses of several tumour suppressor genes including APC, PTEN and CDKN2A, CDKN2B and CDKN1A. We identified a somatic hemizygous CDKN2A pathogenic splice site variant. De novo transcriptome assembly revealed abnormal splicing of CDKN2A p14ARF and p16INK4a. Elevated expression of oncogenes EGFR and NOTCH1 was noted and no somatic mutations were found in these genes. Wnt pathway somatic alterations were also observed. In conclusion, our results suggest that the molecular pathophysiology of malignant EP features high complexity and subtle interactions of multiple key genes. Cell cycle dysregulation and CDKN2A loss of function was found to be a new potential driver in EP tumourigenesis. Moreover, the combination of somatic copy number variants and abnormal gene expression perhaps partly related to epigenetic mechanisms, all likely contribute to the development of this rare malignancy in our patient.

Methylation profiling identifies two subclasses of squamous cell carcinoma related to distinct cells of origin

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer and usually progresses from a UV-induced precancerous lesion termed actinic keratosis (AK). Despite various efforts to characterize these lesions molecularly, the etiology of AK and its progression to cSCC remain partially understood. Here, we use Infinium MethylationEPIC BeadChips to interrogate the DNA methylation status in healthy, AK and cSCC epidermis samples. Importantly, we show that AK methylation patterns already display classical features of cancer methylomes and are highly similar to cSCC profiles. Further analysis identifies typical features of stem cell methylomes, such as reduced DNA methylation age, non-CpG methylation, and stem cell-related keratin and enhancer methylation patterns. Interestingly, this signature is detected only in half of the samples, while the other half shows patterns more closely related to healthy epidermis. These findings suggest the existence of two subclasses of AK and cSCC emerging from distinct keratinocyte differentiation stages.

Loss of INK4a/Arf gene enhances ultraviolet radiation-induced cutaneous tumor development

The CDKN2A locus encodes for tumor suppressor genes p16^INK4a and p14^Arf which are frequently inactivated in human skin tumors. The purpose of this study was to determine the relationship between loss of INK4a/Arf activity and inflammation in the development of ultraviolet (UV) radiation-induced skin tumors. Panels of INK4a/Arf^-/- mice and wild-type (WT) mice were treated with a single dose of UVB (200 mJ/cm² ). For long-term studies, these mice were irradiated with UVB (200 mJ/cm² ) three times weekly for 30 weeks. At the end of the experiment, tissues were harvested from mice and assayed for inflammatory biomarkers and cytokines. A single dose of UVB resulted in a significant increase in reactive oxygen species (ROS) and 8-dihydroxyguanosine (8-oxo-dG) lesions in INK4a/Arf^-/- mice compared to WT mice. When subjected to chronic UVB, we found that 100% of INK4a/Arf^-/- mice had tumors, whereas there were no tumors in WT controls after 24 weeks of UVB exposure. The increase in tumor development correlated with a significant increase in nuclear factor (NF)-κB, cyclooxygenase-2 (COX-2), prostaglandin E₂ (PGE₂ ) and its receptors both in UVB-exposed skin and in the tumors. A significant increase was seen in inflammatory cytokines in skin samples of INK4a/Arf^-/- mice following treatment with chronic UVB radiation. Furthermore, significantly more CD11b⁺ Gr1⁺ myeloid cells were present in UVB-exposed INK4a/Arf^-/- mice compared to WT mice. Our data indicate that by targeting UVB-induced inflammation, it may be possible to prevent UVB-induced skin tumors in individuals that carry CDKN2A mutation.

Cross-species identification of genomic drivers of squamous cell carcinoma development across preneoplastic intermediates

Cutaneous squamous cell carcinoma (cuSCC) comprises 15-20% of all skin cancers, accounting for over 700,000 cases in USA annually. Most cuSCC arise in association with a distinct precancerous lesion, the actinic keratosis (AK). To identify potential targets for molecularly targeted chemoprevention, here we perform integrated cross-species genomic analysis of cuSCC development through the preneoplastic AK stage using matched human samples and a solar ultraviolet radiation-driven Hairless mouse model. We identify the major transcriptional drivers of this progression sequence, showing that the key genomic changes in cuSCC development occur in the normal skin to AK transition. Our data validate the use of this ultraviolet radiation-driven mouse cuSCC model for cross-species analysis and demonstrate that cuSCC bears deep molecular similarities to multiple carcinogen-driven SCCs from diverse sites, suggesting that cuSCC may serve as an effective, accessible model for multiple SCC types and that common treatment and prevention strategies may be feasible.

Expression of G1/S-cyclins and cyclin-dependent kinase inhibitors in actinic keratosis and squamous cell carcinoma

BACKGROUND

Actinic keratosis (AK) and Bowen's disease (squamous cell carcinoma in situ, SCCIS) are pre-invasive stages in the development of squamous cell carcinoma (SCC).

METHODS

Immunohistochemical study of cyclin D1, cyclin E, p16(INK4a) and p21(Cip1) (/Waf1) in AK (53 cases), SCCIS (16 cases) and SCC (40 cases), in relation to the type of the lesion and SCC prognostic parameters (grade, diameter and thickness).

RESULTS

Diffuse cyclin D1 distribution was more frequent in SCCIS and SCC than in AK (p = 0.03) and similar pattern was observed for p16(INK4a) . For cyclin E, central distribution dominated in SCC compared with the AK (p = 0.001) and SCCIS (p = 0.03). p21(Cip1) (/Waf1) displayed suprabasal distribution more frequently in AK than in SCCIS (p = 0.001) and SCC (p = 0.0004). Semiquantitative assessment showed more positive cells in AK (p = 0.04) and SCCIS (p = 0.04) than in SCC for cyclin E. SCC with diameter over 20 mm and those thicker than 6 mm revealed higher labeling index with p16(INK4a) and p21(Cip1) (/Waf1) , respectively.

CONCLUSIONS

Our results suggest different alterations for p16(INK4a) and p21(Cip1) (/Waf1) in AK, SCCIS and SCC. Immunostaining distribution showed closer correlation with the type of the lesion, whereas percentage of positive cells displayed better association with the SCC prognostic parameters.

Non-melanoma Skin Cancer in Canada Chapter 1: Introduction to the Guidelines

BACKGROUND

Non-melanoma skin cancer (NMSC), including basal and squamous cell carcinoma, represents the most common malignancy.

OBJECTIVE

The aim of this document is to provide guidance to Canadian health care practitioners on NMSC management.

METHODS

After conducting a literature review, the group developed recommendations for prevention, management, and treatment of basal cell carcinomas, squamous cell carcinomas, and actinic keratoses. These tumour types are considered separately in the accompanying articles. The Grading of Recommendations Assessment, Development and Evaluation system was used to assign strength to each recommendation.

RESULTS

This introduction describes the scope and structure of the guidelines and the methods used to develop them. The epidemiology of NMSC is reviewed, as are the pathophysiologic changes occurring with damage to the skin, which lead to the formation of actinic keratoses and invasive squamous or basal cell carcinomas.

CONCLUSIONS

This introduction describes the need for primary prevention and offers an overview of treatment options that are discussed in later chapters of the guidelines.

Squamous cell carcinoma in a psoriasis patient after multiple courses of phototherapy

The authors present a clinical case study of squamous cell carcinoma in a psoriasis patient after 24 courses of phototherapy (22 courses of PUVA therapy and two courses of mid-wavelength ultraviolet therapy (311 nm)). The malignant neoplasm developed against the background of signs of a chronic photodamage of the skin: lentigo, actinic elastosis, diffuse hyperpigmentation, spotty skin pigmentation.

Crosstalk among p53 family members in cutaneous carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with a frequency increasing worldwide. The risk of developing cSCC has been strongly associated with chronic sun exposure, especially in light skin people. The aim of this viewpoint is to discuss the contribution of the tumor suppressor p53 and its homologues p63 and p73 in the formation and progression of cSCC. Mutations in the p53 gene are early and frequent events in skin carcinogenesis mainly as a consequence of UV light exposure, often followed by loss of function of the second allele. Although rarely mutated in cancer, p63 and p73 play key roles in human cancers, with their truncated isoforms lacking the N-terminal transactivating domain (∆N) being often upregulated as compared to normal tissues. ∆Np63 is abundantly expressed in cSCC, and it is likely to favour tumor initiation and progression. The function of p73 in cSCC is more enigmatic and awaits further studies. Interestingly, an intimate interplay exists between both p53 and p63, and the Notch signalling pathway, often inactivated in cSCC. Here, we summarize our current knowledge about the biological activities of p53 family members in cSCC and propose that integration of their signalling with Notch is key to cSCC formation and progression.

Molecular pathology of skin neoplasms of the head and neck

CONTEXT

Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region.

OBJECTIVE

To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations.

DATA SOURCES

Literature review.

CONCLUSIONS

Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.

Immunohistochemical staining for p16 is a useful adjunctive test in the diagnosis of Bowen's disease

AIMS

The aim of this study was to document the pattern of immunohistochemical staining seen with p16 (INK4a) in actinic keratosis, Bowen's disease and seborrhoeic keratosis.

METHODS

We gathered 20 examples each of actinic keratosis, Bowen's disease and seborrheic keratosis. The cases were stained for p16 using standard immunohistochemical techniques, and the staining patterns were categorised into one of five different patterns.

RESULTS

All cases of Bowen's disease as defined in our practice showed strong positive staining in all abnormal cells, and 95% of these cases showed a distinctive pattern of sparing in a layer of palisaded basal cells. None of the actinic keratoses or seborrheic keratoses, as defined by our morphological criteria, showed this distinctive pattern.

CONCLUSIONS

Bowen's disease, as we define the term, shows a distinctive, repeatable pattern of staining with p16, characterised by moderate to strong staining of all abnormal cells with sparing of a layer of basal cells. This pattern is not seen in actinic keratoses or in seborrheic keratoses. Thus immunohistochemistry for p16 is a useful adjunctive test in the differential diagnosis of these lesions.

Squamous cell carcinoma of the skin: Emerging need for novel biomarkers

The incidence of non-melanoma skin cancers (NMSC) is rising worldwide resulting in demand for clinically useful prognostic biomarkers for these malignant tumors, especially for invasive and metastatic cutaneous squamous cell carcinoma (cSCC). Important risk factors for the development and progression of cSCC include ultraviolet radiation, chronic skin ulcers and immunosuppression. Due to the role of cumulative long-term sun exposure, cSCC is usually a disease of the elderly, but the incidence is also growing in younger individuals due to increased recreational exposure to sunlight. Although clinical diagnosis of cSCC is usually easy and treatment with surgical excision curable, it is responsible for the majority of NMSC related deaths. Clinicians treating skin cancer patients are aware that certain cSCCs grow rapidly and metastasize, but the underlying molecular mechanisms responsible for the aggressive progression of a subpopulation of cSCCs remain incompletely understood. Recently, new molecular markers for progression of cSCC have been identified.

Genome-wide characterization of pancreatic adenocarcinoma patients using next generation sequencing

Pancreatic adenocarcinoma (PAC) is among the most lethal malignancies. While research has implicated multiple genes in disease pathogenesis, identification of therapeutic leads has been difficult and the majority of currently available therapies provide only marginal benefit. To address this issue, our goal was to genomically characterize individual PAC patients to understand the range of aberrations that are occurring in each tumor. Because our understanding of PAC tumorigenesis is limited, evaluation of separate cases may reveal aberrations, that are less common but may provide relevant information on the disease, or that may represent viable therapeutic targets for the patient. We used next generation sequencing to assess global somatic events across 3 PAC patients to characterize each patient and to identify potential targets. This study is the first to report whole genome sequencing (WGS) findings in paired tumor/normal samples collected from 3 separate PAC patients. We generated on average 132 billion mappable bases across all patients using WGS, and identified 142 somatic coding events including point mutations, insertion/deletions, and chromosomal copy number variants. We did not identify any significant somatic translocation events. We also performed RNA sequencing on 2 of these patients' tumors for which tumor RNA was available to evaluate expression changes that may be associated with somatic events, and generated over 100 million mapped reads for each patient. We further performed pathway analysis of all sequencing data to identify processes that may be the most heavily impacted from somatic and expression alterations. As expected, the KRAS signaling pathway was the most heavily impacted pathway (P<0.05), along with tumor-stroma interactions and tumor suppressive pathways. While sequencing of more patients is needed, the high resolution genomic and transcriptomic information we have acquired here provides valuable information on the molecular composition of PAC and helps to establish a foundation for improved therapeutic selection.

Genome-wide characterization of pancreatic adenocarcinoma patients using next generation sequencing

Pancreatic adenocarcinoma (PAC) is among the most lethal malignancies. While research has implicated multiple genes in disease pathogenesis, identification of therapeutic leads has been difficult and the majority of currently available therapies provide only marginal benefit. To address this issue, our goal was to genomically characterize individual PAC patients to understand the range of aberrations that are occurring in each tumor. Because our understanding of PAC tumorigenesis is limited, evaluation of separate cases may reveal aberrations, that are less common but may provide relevant information on the disease, or that may represent viable therapeutic targets for the patient. We used next generation sequencing to assess global somatic events across 3 PAC patients to characterize each patient and to identify potential targets. This study is the first to report whole genome sequencing (WGS) findings in paired tumor/normal samples collected from 3 separate PAC patients. We generated on average 132 billion mappable bases across all patients using WGS, and identified 142 somatic coding events including point mutations, insertion/deletions, and chromosomal copy number variants. We did not identify any significant somatic translocation events. We also performed RNA sequencing on 2 of these patients' tumors for which tumor RNA was available to evaluate expression changes that may be associated with somatic events, and generated over 100 million mapped reads for each patient. We further performed pathway analysis of all sequencing data to identify processes that may be the most heavily impacted from somatic and expression alterations. As expected, the KRAS signaling pathway was the most heavily impacted pathway (P<0.05), along with tumor-stroma interactions and tumor suppressive pathways. While sequencing of more patients is needed, the high resolution genomic and transcriptomic information we have acquired here provides valuable information on the molecular composition of PAC and helps to establish a foundation for improved therapeutic selection.

From keratinocyte to cancer: the pathogenesis and modeling of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with over 250,000 new cases annually in the US and is second in incidence only to basal cell carcinoma. cSCC typically manifests as a spectrum of progressively advanced malignancies, ranging from a precursor actinic keratosis (AK) to squamous cell carcinoma (SCC) in situ (SCCIS), invasive cSCC, and finally metastatic SCC. In this Review we discuss clinical and molecular parameters used to define this range of cutaneous neoplasia and integrate these with the multiple experimental approaches used to study this disease. Insights gained from modeling cSCCs have suggested innovative therapeutic targets for treating these lesions.

RAS mutations are associated with the development of cutaneous squamous cell tumors in patients treated with RAF inhibitors

PURPOSE

RAF inhibitors are effective against melanomas with BRAF V600E mutations but may induce keratoacanthomas (KAs) and cutaneous squamous cell carcinomas (cSCCs). The potential of these agents to promote secondary malignancies is concerning. We analyzed cSCC and KA lesions for genetic mutations in an attempt to identify an underlying mechanism for their formation.

METHODS

Four international centers contributed 237 KA or cSCC tumor samples from patients receiving an RAF inhibitor (either vemurafenib or sorafenib; n = 19) or immunosuppression therapy (n = 53) or tumors that developed spontaneously (n = 165). Each sample was profiled for 396 known somatic mutations across 33 cancer-related genes by using a mass spectrometric-based genotyping platform.

RESULTS

Mutations were detected in 16% of tumors (38 of 237), with five tumors harboring two mutations. Mutations in TP53, CDKN2A, HRAS, KRAS, and PIK3CA were previously described in squamous cell tumors. Mutations in MYC, FGFR3, and VHL were identified for the first time. A higher frequency of activating RAS mutations was found in tumors from patients treated with an RAF inhibitor versus populations treated with a non-RAF inhibitor (21.1% v 3.2%; P < .01), although overall mutation rates between treatment groups were similar (RAF inhibitor, 21.1%; immunosuppression, 18.9%; and spontaneous, 17.6%; P = not significant). Tumor histology (KA v cSCC), tumor site (head and neck v other), patient age (≤ 70 v > 70 years), and sex had no significant impact on mutation rate or type.

CONCLUSION

Squamous cell tumors from patients treated with an RAF inhibitor have a distinct mutational profile that supports a mechanism of therapy-induced tumorigenesis in RAS-primed cells. Conceivably, cotargeting of MEK together with RAF may reduce or prevent formation of these tumors.

Expression of TWEAK in normal human skin, dermatitis and epidermal neoplasms: association with proliferation and differentiation of keratinocytes

BACKGROUND

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) has been implicated in the pathogenesis of various inflammatory pathologies and cancer. We aimed to investigate its expression in normal human skin, inflammatory skin diseases and epidermal neoplasms.

METHODS

Immunohistochemistry for TWEAK was performed in samples of healthy skin, plaque psoriasis, lichen planus, prurigo nodularis, discoid lupus erythematosus, lichen sclerosus, seborrheic keratosis, common warts, actinic keratosis, Bowen's disease, keratoacanthoma and basal and squamous cell carcinoma. Double immunofluorescence was used to investigate co-localization of TWEAK with cytokeratin-10 and proliferating cell nuclear antigen (PCNA).

RESULTS

TWEAK was robustly expressed in the epidermis of healthy skin and decreased in inflammatory conditions, both in the context of epidermal hyperplasia and atrophy. Decreased TWEAK immunoreactivity was regularly observed in common warts, actinic keratosis and Bowen's disease, particularly in areas of marked proliferation as evidenced by PCNA-positive nuclei. In squamous cell carcinoma, expression of TWEAK ranged from strong to completely absent, and it mostly corresponded with the expression of cytokeratin-10. TWEAK was absent in keratoacanthoma and basal cell carcinoma.

CONCLUSIONS

TWEAK is a constitutively expressed epidermal protein whose downregulation might be an early indicator of disturbed differentiation or pathologic proliferation of keratinocytes that accompany inflammatory and neoplastic skin diseases.

Double cancer of plantar malignant melanoma and vulvar extramammary Paget's disease

A 75-year-old woman presented with a 2-year history of a pigmented nodular lesion on her left sole and a 9-year history of a red infiltrative plaque on the vulva. The plantar lesion was a 15-mm ulcerated nodule located at the center of a 25-mm atypical pigmentation region; the nodule was clinically suspected to be a malignant melanoma. Histopathological analysis of the vulvar lesion biopsy sample indicated extramammary Paget's disease (EMPD). There was no evidence of metastasis in the computed tomography (CT) and (18)F-fluorodeoxyglucose positron emission tomography scans. We simultaneously performed a wide excision of both lesions and a left inguinal sentinel lymph node biopsy. Melanoma cells were identified in the sentinel lymph nodes, and left radical lymph node dissection was performed after a course of neoadjuvant chemotherapy. All the lymph nodes that were resected during the second operation tested negative for melanomas, and the plantar lesion was diagnosed as a stage IIIB malignant melanoma (pT4b, Na2, M0). Thereafter, we administrated four courses of chemotherapy, and 8 months after the operation, there was no evidence of recurrence or metastatic lesions. We present a case report of double cancer: a plantar malignant melanoma and vulvar EMPD, and also discuss the possible genetic mutations responsible for these two tumors.

p14ARF promoter region methylation as a marker for gliomas diagnosis

Methylation in the promoter region is one of the mechanisms through which tumor suppressors are inactivated, resulting in tumorigenesis and/or tumor progression. Herein, we studied the methylation status in the promoter region of the p14ARF tumor suppressor gene in 33 brain tissues isolated from glioma patients (astrocytomas) and compared to 12 brain tissues isolated from autopsy donors using methylation-specific polymerase chain reaction (MSP). The correlation between the expression of P14 and P53 was investigated using immunohistochemistry (IHC). The average percentage of methylation in the promoter region of p14ARF gene in brain samples from glioma patients is 39.4%, while 0 from autopsy donors. No difference in the methylation level between low-grade and high-grade gliomas was detected. The methylation status has no correlation with the prognosis in glioma patients. A significant correlation between the expression of mutant form of TP53 and the grade of the glioma was established. Furthermore, there was a negative correlation between methylation of the p14ARF promoter and the expression of the mutant form of TP53. Therefore, our data suggest that methylation in the promoter region of the p14ARF gene may be used as a biomarker for the diagnosis of gliomas.

Comparison of the inhibitory effects of three transcriptional variants of CDKN2A in human lung cancer cell line A549

Background

The tumor suppressor gene CDKN2A generates at least three different transcriptional variants, each of which is thought to encode a tumor suppressor. However, the inhibitory activities of these variants have not yet been compared in the same cells. Protein therapy is known to have several advantages over gene therapy. Thus, investigation of the exogenous protein molecule of the most effective suppressor may yield meaningful information regarding protein-based cancer therapy.

Methods

The inhibitory effects of p16INK4a, p14ARF and p12 were studied in the human lung cancer cell line A549 which lacks the CDKN2A locus. The eukaryotic expression plasmids of the three transcriptional variants were constructed and stably transfected into the cells. RNA and protein expression by the plasmids was confirmed using RT-PCR and fluorescence immunocytochemistry, respectively. Cell growth inhibition and cell-cycle redistribution after transfection were investigated based on growth curve and flow cytometry analyses. An exogenous His-tag fusion p16INK4a protein was obtained and purified by affinity chromatography. Cell growth inhibition and cell cycle arrest induced by the expression of p16INK4a protein were measured in A549 cells transduced with the exogenous protein.

Results

While all three variants suppressed cell growth, p16INK4a had the strongest effect. Marked G1-phase accumulation and S-phase inhibition were induced by p16INK4a and p14ARF but not by p12. Exogenous p16INK4a protein was successfully expressed and purified and transduction of the fusion protein into A549 cells inhibited cell growth by G1→S arrest.

Conclusions

Among the three transcript variants, p16INK4a has a greater inhibitory effect than p14ARF and p12; exogenous p16INK4a protein should be further investigated for use in cancer therapy as a protein agent.

CDKN2A-CDKN2B deletion defines an aggressive subset of cutaneous T-cell lymphoma

Inactivation of the CDKN2A-CDKN2B locus has been reported in the most frequent subtypes of cutaneous T-cell lymphomas (CTCLs), mycosis fungoides, Sézary syndrome (SS) and CD30+ cutaneous anaplastic large cell lymphoma. To investigate whether genetic or epigenetic inactivation of CDKN2A-CDKN2B is more specifically observed in certain CTCL subtypes with clinical impact, we used array-comparative genomic hybridization, quantitative PCR, interphase fluorescent in situ hybridization and methylation analyses of p14(ARF) p16(INK4A) and p15(INK4B) promoters. We studied 67 samples from 58 patients with either transformed mycosis fungoides (n=24), SS (n=16) or CD30+ cutaneous anaplastic large cell lymphoma (n=18). We observed combined CDKN2A-CDKN2B deletion in both transformed mycosis fungoides (n=17, 71%) and SS patients (n=7, 44%), but, surprisingly, in only one CD30+ cutaneous anaplastic large cell lymphoma case. Interphase fluorescent in situ hybridization showed 9p21 loss in 17 out of 19 cases, with 9p21 deletion indicating either hemizygous (n=4) or homozygous (n=2) deletion, with mixed patterns in most patients (n=11). The limited size of 9p21 deletion was found to account for false-negative detection by either BAC arrays (n=9) or fluorescent in situ hybridization (n=2), especially in patients with Sézary syndrome (n=6). Methylation was found to be restricted to the p15(INK4B) gene promoter in patients with or without 9p21 deletion and did not correlate with prognosis. In contrast, CDKN2A-CDKN2B genetic loss was strongly associated with a shorter survival in CTCL patients (P=0.002) and more specifically at 24 months in transformed mycosis fungoides and SS patients (P=0.02). As immunohistochemistry for p16(INK4A) protein was not found to be informative, the genetic status of the CDKN2A-CDKN2B locus would be relevant in assessing patients with epidermotropic CTCLs in order to identify those cases where the disease was more aggressive.

Non-melanoma skin cancer

The rising incidence and morbidity of non-melanoma skin cancers has generated great interest in unravelling of their pathogenesis and in the search for new non-invasive treatments. Whereas the role of cumulative sun exposure in pathogenesis of squamous-cell carcinoma seems clear, the relation between sun-exposure patterns and subtypes of basal-cell carcinoma remains undetermined. Several complex genotypic, phenotypic, and environmental factors contribute to pathogenesis of non-melanoma skin cancers. Unlike basal-cell carcinoma, squamous-cell carcinomas can arise from precursor lesions. Diagnosis of non-melanoma skin cancer is made clinically and confirmed by histological testing. Prognosis depends on lesion and host characteristics, which also dictate choice of treatment. Prevention strategies aim at reduction of sun exposure, but are of unproven benefit, especially for basal-cell carcinoma. Surgical excision with predetermined margins is the mainstay of treatment for squamous-cell carcinoma and for most basal-cell carcinomas. Of the new non-invasive treatments, only photodynamic therapy and topical imiquimod have become established treatments for specific subtypes of basal-cell carcinoma, and the search for more effective and tissue-salvaging therapies continues.

A genetic variant of Aurora kinase A promotes genomic instability leading to highly malignant skin tumors

Aurora kinase A (Aurora-A) belongs to a highly conserved family of mitotis-regulating serine/threonine kinases implicated in epithelial cancers. Initially we examined Aurora-A expression levels at different stages of human skin cancer. Nuclear Aurora-A was detected in benign lesions and became more diffused but broadly expressed in well and poorly differentiated squamous cell carcinomas (SCC), indicating that Aurora-A deregulation may contribute to SCC development. To mimic the overexpression of Aurora-A observed in human skin cancers, we established a gene-switch mouse model in which the human variant of Aurora-A (Phe31Ile) was expressed in the epidermis upon topical application of the inducer RU486 (Aurora-AGS). Overexpression of Aurora-A alone or in combination with the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA), did not result in SCC formation in Aurora-AGS mice. Moreover, Aurora-A overexpression in naive keratinocytes resulted in spindle defects in vitro and marked cell death in vivo, suggesting that the failure of Aurora-A to initiate tumorigenesis was due to induction of catastrophic cell death. However, Aurora-A overexpression combined with exposure to TPA and the mutagen 7,12-dimethylbenz(a)anthracene accelerated SCC development with greater metastatic activity than control mice, indicating that Aurora-A cannot initiate skin carcinogenesis but rather promotes the malignant conversion of skin papillomas. Further characterization of SCCs revealed centrosome amplification and genomic alterations by array CGH analysis, indicating that Aurora-A overexpression induces a high level of genomic instability that favors the development of aggressive and metastatic tumors. Our findings strongly implicate Aurora-A overexpression in the malignant progression of skin tumors and suggest that Aurora-A may be an important therapeutic target.

Recent advances on skin-resident stem/progenitor cell functions in skin regeneration, aging and cancers and novel anti-aging and cancer therapies

Recent advances in skin-resident adult stem/progenitor cell research have revealed that these immature and regenerative cells with a high longevity provide critical functions in maintaining skin homeostasis and repair after severe injuries along the lifespan of individuals. The establishment of the functional properties of distinct adult stem/progenitor cells found in skin epidermis and hair follicles and extrinsic signals from their niches, which are deregulated during their aging and malignant transformation, has significantly improved our understanding on the etiopathogenesis of diverse human skin disorders and cancers. Particularly, enhanced ultraviolet radiation exposure, inflammation and oxidative stress and telomere attrition during chronological aging may induce severe DNA damages and genomic instability in the skin-resident stem/progenitor cells and their progenies. These molecular events may result in the alterations in key signalling components controlling their self-renewal and/or regenerative capacities as well as the activation of tumour suppressor gene products that trigger their growth arrest and senescence or apoptotic death. The progressive decline in the regenerative functions and/or number of skin-resident adult stem/progenitor cells may cause diverse skin diseases with advancing age. Moreover, the photoaging, telomerase re-activation and occurrence of different oncogenic events in skin-resident adult stem/progenitor cells may also culminate in their malignant transformation into cancer stem/progenitor cells and skin cancer initiation and progression. Therefore, the anti-inflammatory and anti-oxidant treatments and stem cell-replacement and gene therapies as well as the molecular targeting of their malignant counterpart, skin cancer-initiating cells offer great promise to treat diverse skin disorders and cancers.

Recent insights into the molecular mechanisms involved in aging and the malignant transformation of adult stem/progenitor cells and their therapeutic implications

Recent advancements in tissue-resident adult stem/progenitor cell research have revealed that enhanced telomere attrition, oxidative stress, ultraviolet radiation exposure and oncogenic events leading to severe DNA damages and genomic instability may occur in these immature and regenerative cells during chronological aging. Particularly, the alterations in key signaling components controlling their self-renewal capacity and an up-regulation of tumor suppressor gene products such as p16(INK4A), p19(ARF), ataxia-telangiectasia mutated (ATM) kinase, p53 and/or the forkhead box O (FOXOs) family of transcription factors may result in their dysfunctions, growth arrest and senescence or apoptotic death during the aging process. These molecular events may culminate in a progressive decline in the regenerative functions and the number of tissue-resident adult stem/progenitor cells, and age-related disease development. Conversely, the telomerase re-activation and accumulation of numerous genetic and/or epigenetic alterations in adult stem/progenitor cells with advancing age may result in their immortalization and malignant transformation into highly leukemic or tumorigenic cancer-initiating cells and cancer initiation. Therefore, the cell-replacement and gene therapies and molecular targeting of aged and dysfunctional adult stem/progenitor cells including their malignant counterpart, cancer-initiating cells, hold great promise for treating and even curing diverse devastating human diseases. These diseases include premature aging diseases, hematopoietic, cardiovascular, musculoskeletal, pulmonary, ocular, urogenital, neurodegenerative and skin disorders and aggressive and recurrent cancers.

A case of acute radiation syndrome from the dermatological aspect

Accidental whole-body overexposure of radiation occurs very rarely. Radiation exposure causes DNA breaks in the cells and shows various clinical features, which are time dependent, dose dependent and tissue dependent. Neutron rays are more destructive than gamma rays but their actual effect on humans have been under-reported. We observed the time-dependent and the dose-dependent dermatological changes in a patient who was severely irradiated by neutron and gamma rays, with the aim of clarifying the clinicopathological features of severely irradiated skin. The detection of DNA breaks in keratinocytes was performed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling technique. The degenerative changes of the skin and the re-epithelialization varied in a time dependent and dose dependent manner. DNA breaks were significantly higher in irradiated keratinocytes. Neutron rays caused depth-dependent degeneration of the skin. Evaluation of DNA breaks in the skin cells might be a clue to estimate local dosimetry.