Early cancers of the skin: clinical, histopathological, and molecular characteristics

From actinic keratosis to cutaneous squamous cell carcinoma: the key pathogenesis and treatments

Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer, among which 82% arise from actinic keratosis (AK) characterized by lesions of epidermal keratinocyte dysplasia. It is of great significance to uncover the progression mechanisms from AK to cSCC, which will facilitate the early therapeutic intervention of AK before malignant transformation. Thus, more and more studies are trying to ascertain the potential transformation mechanisms through multi-omics, including genetics, transcriptomics, and epigenetics. In this review, we gave an overview of the specific biomarkers and signaling pathways that may be involved in the pathogenesis from AK to cSCC, pointing out future possible molecular therapies for the early intervention of AK and cSCC. We also discussed current interventions on AK and cSCC, together with future perspectives.

An update on the implications of cyclin D1 in melanomas

Cyclin D1 is a protein encoded by the CCND1 gene, located on 11q13 chromosome, which is a key component of the physiological regulation of the cell cycle. CCND1/cyclin D1 is upregulated in several types of human tumors including melanoma and is currently classified as an oncogene that promotes uncontrolled cell proliferation. Despite the demonstrated importance of CCND1/cyclin D1 as a central oncogene in several types of human tumors, its knowledge in melanoma is still limited. This review examines data published on upregulation of the CCND1 gene and cyclin D1 protein in the melanoma setting, focusing on the pathways and molecular mechanisms involved in the activation of the gene and on the clinical and therapeutic implications.

Management of posterior uveal melanoma: past, present, and future: the 2014 Charles L. Schepens lecture

PURPOSE

To review the management of ciliary body and choroidal melanoma (posterior uveal melanoma [PUM]) over the last century with an emphasis on changing concepts.

DESIGN

Retrospective review.

PARTICIPANTS

Review of personal experience over 40 years and pertinent literature on management of PUM.

METHODS

Diagnosis and therapy for PUM.

MAIN OUTCOME MEASURES

Patient survival.

RESULTS

In the early 1900s, most patients presented with a large symptomatic melanoma that necessitated enucleation, and the systemic prognosis was poor. In the 1970s, controversy erupted regarding the role of enucleation for PUM. Some authorities advocated prompt enucleation, and others proposed that enucleation promoted metastasis, known as the "Zimmerman hypothesis." Others recommended observation, withholding treatment until tumor growth was documented. During the 1970s, there was a trend toward eye-saving procedures, including laser photocoagulation, surgical removal of tumor, and techniques of radiotherapy. Despite local treatment success, systemic prognosis remained guarded with approximately 40% mortality overall. However, there was convincing evidence that smaller tumors offered a significantly better prognosis. Currently, there is a movement toward earlier identification and treatment of small melanomas using clinical factors predictive of malignant potential, in keeping with similar philosophy regarding other cancers. Further understanding of melanoma cytogenetics and molecular pathways have helped to recognize patients at risk for metastasis. At-risk patients are offered systemic therapeutic trials to prevent metastasis. We anticipate that the future management of PUM will focus on detection of clinical and imaging clues for earliest diagnosis, prompt local tumor treatment, and systemic targeted therapies for microscopic metastasis or prevention of metastasis. Personalized evaluation of patient-specific melanoma molecular pathway signature could allow for therapeutic intervention at a site specific to the pathway abnormality that leads to the development of melanoma.

CONCLUSIONS

Management of PUM has made major strides over the past century from the days of enucleation for massive, fatal tumor to early detection of smallest tumors with a more favorable prognosis. Current and future targeted specific tumor pathway interruption using systemic agents could improve survival.

In vivo diagnosis of melanoma and nonmelanoma skin cancer using oblique incidence diffuse reflectance spectrometry

Early detection and treatment of skin cancer can significantly improve patient outcome. However, present standards for diagnosis require biopsy and histopathologic examinations that are relatively invasive, expensive, and difficult for patients with many early-stage lesions. Here, we show an oblique incidence diffuse reflectance spectroscopic (OIDRS) system that can be used for rapid skin cancer detection in vivo. This system was tested under clinical conditions by obtaining spectra from pigmented and nonpigmented skin lesions, including melanomas, differently staged dysplastic nevi, and common nevi that were validated by standard pathohistologic criteria. For diagnosis of pigmented melanoma, the data obtained achieved 90% sensitivity and specificity for a blinded test set. In a second analysis, we showed that this spectroscopy system can also differentiate nonpigmented basal cell or squamous cell carcinomas from noncancerous skin abnormalities, such as actinic keratoses and seborrheic keratoses, achieving 92% sensitivity and specificity. Taken together, our findings establish how OIDRS can be used to more rapidly and easily diagnose skin cancer in an accurate and automated manner in the clinic.

Molecular discrimination of cutaneous squamous cell carcinoma from actinic keratosis and normal skin

Actinic keratosis is widely believed to be a neoplastic lesion and a precursor to invasive squamous cell carcinoma. However, there has been some debate as to whether actinic keratosis is in fact actually squamous cell carcinoma and should be treated as such. As the clinical management and prognosis of patients is widely held to be different for each of these lesions, our goal was to identify unique gene signatures using DNA microarrays to discriminate among normal skin, actinic keratosis, and squamous cell carcinoma, and examine the molecular pathways of carcinogenesis involved in the progression from normal skin to squamous cell carcinoma. Formalin-fixed and paraffin-embedded blocks of skin: five normal skins (pooled), six actinic keratoses, and six squamous cell carcinomas were retrieved. The RNA was extracted and amplified. The labeled targets were hybridized to the Affymetrix human U133plus2.0 array and the acquisition and initial quantification of array images were performed using the GCOS (Affymetrix). The subsequent data analyses were performed using DNA-Chip Analyzer and Partek Genomic Suite 6.4. Significant differential gene expression (>2 fold change, P<0.05) was seen with 382 differentially expressed genes between squamous cell carcinoma and normal skin, 423 differentially expressed genes between actinic keratosis and normal skin, and 9 differentially expressed genes between actinic keratosis and squamous cell carcinoma. The differentially expressed genes offer the possibility of using DNA microarrays as a molecular diagnostic tool to distinguish between normal skin, actinic keratosis, and squamous cell carcinoma. In addition, the differentially expressed genes and their molecular pathways could be potentially used as prognostic markers or targets for future therapeutic innovations.

Heterogeneous topographic profiles of kinetic and cell cycle regulator microsatellites in atypical (dysplastic) melanocytic nevi

Atypical (dysplastic) melanocytic nevi are clinically heterogeneous malignant melanoma precursors, for which no topographic analysis of cell kinetic, cell cycle regulators and microsatellite profile is available. We selected low-grade atypical melanocytic nevi (92), high-grade atypical melanocytic nevi (41), melanocytic nevi (18 junctional, 25 compound) and malignant melanomas (16 radial growth phase and 27 vertical growth phase). TP53, CDKN2A, CDKN1A, and CDKN1B microsatellite patterns were topographically studied after microdissection; Ki-67, TP53, CDKN2A, CDKN1A, and CDKN1B expressions and DNA fragmentation by in situ end labeling for apoptosis were topographically scored. Results were statistically analyzed. A decreasing junctional-dermal marker expression gradient was observed, directly correlating with atypical melanocytic nevus grading. High-grade atypical melanocytic nevi revealed coexistent TP53-CDKN2A-CDKN1B microsatellite abnormalities, and significantly higher junctional Ki67-TP53 expression (inversely correlated with CDKN1A-CDKN1B expression and in situ end labeling). Malignant melanomas showed coexistent microsatellite abnormalities (CDKN2A-CDKN1B), no topographic gradient, and significantly decreased expression. Melanocytic nevi and low-grade atypical melanocytic nevi revealed sporadic junctional CDKN2A microsatellite abnormalities and no significant topographic kinetic differences. High-grade atypical melanocytic nevi accumulate junctional TP53-CDKN1A-CDKN1B microsatellite abnormalities, being progression TP53-independent and better assessed in the dermis. Melanocytic nevi and low-grade atypical melanocytic nevi show low incidence of microsatellite abnormalities, and kinetic features that make progression unlikely.

Induction of apoptosis by [6]-gingerol associated with the modulation of p53 and involvement of mitochondrial signaling pathway in B[a]P-induced mouse skin tumorigenesis

PURPOSE

To unravel the molecular mechanisms underlying the chemopreventive potential of [6]-gingerol, a pungent ingredient of ginger rhizome (Zingiber officinale Roscoe, Zingiberaceae), against benzo[a]pyrene (B[a]P)-induced mouse skin tumorigenesis.

METHODS

Topical treatment of [6]-gingerol (2.5 muM/animal) was given to the animals 30 min prior and post to B[a]P (5 mug/animal) for 32 weeks. At the end of the study period, the skin tumors/tissues were dissected out and examined histopathologically. Flow cytometry was employed for cell cycle analysis. Further immunohistochemical localization of p53 and regulation of related apoptogenic proteins were determined by Western blotting.

RESULTS

Chemopreventive properties of [6]-gingerol were reflected by delay in onset of tumorigenesis, reduced cumulative number of tumors, and reduction in tumor volume. Cell cycle analysis revealed that the appearance of sub-G1 peak was significantly elevated in [6]-gingerol treated animals with post treatment showing higher efficacy in preventing tumorigenesis induced by B[a]P. Moreover, elevated apoptotic propensity was observed in tumor tissues than the corresponding non-tumor tissues. Western blot analysis also showed the same pattern of chemoprevention with [6]-gingerol treatment increasing the B[a]P suppressed p53 levels, also evident by immunohistochemistry, and Bax while decreasing the expression of Bcl-2 and Survivin. Further, [6]-gingerol treatment resulted in release of Cytochrome c, Caspases activation, increase in apoptotic protease-activating factor-1 (Apaf-1) as mechanism of apoptosis induction.

CONCLUSIONS

On the basis of the results we conclude that [6]-gingerol possesses apoptotic potential in mouse skin tumors as mechanism of chemoprevention hence deserves further investigation.

Expression of P27, Ki67 and P53 in squamous cell carcinoma, actinic keratosis and Bowen disease

This study aims at evaluating the expression of P27, Ki67 and P53 in Squamous Cell Carcinoma (SCC), Actinic Keratosis (AK) and Bowen Disease (BD) specimens. In an analytic-descriptive setting, skin biopsy specimens of 45 patients were evaluated in three 15-case groups including BD, AK and SCC specimens. Fifteen normal skin biopsy specimens were obtained and used as the control group. Immunohistochemical staining was performed in all the specimens and the expression rates and patterns of Ki67, P27 and P53 were determined. The results were compared between the four groups. Ki67 was expressed in 0.8, 23.7, 12.3 and 19.3% of the cells in the normal skin, AK, BD and SCC groups, respectively. No significant difference was seen between the three pathological conditions regarding the expression rate of Ki67. P27 was positive in 23.4, 26.2, 25.9 and 4.5% of specimens in the normal skin, AK, BD and SCC groups, respectively. This rate was significantly the lowest in the SCC group. P53 expression was detected in 26.6, 41.8 and 54.6% of the assessed cells in the AK, BD and SCC groups, respectively. There was no expression of P53 in the normal skin specimens. This rate was significantly the highest again in the SCC group. Based on these results, the quantitative and qualitative (pattern of distribution) evaluation of the expressions of Ki67, P27 and P53 may be helpful in differentiating malignant and premalignant epidermal lesions, particularly in unsatisfactory or fragmented specimens.

Molecular biology of basal and squamous cell carcinomas

Basal cell carcinomas and Squamous cell carcinomas are the two most common human cancers. The incidence of these two types of cancer is estimated to double within 20 years. Identification of the key molecular events is critical in helping us design novel strategies to treat and to prevent these cancers. For example, identification of hedgehog signaling activation has opened up many opportunities for targeted therapy and prevention of basal cell carcinomas. Significant progress has also been made in our understanding of squamous cell carcinomas of the skin. In this chapter, we will focus on major recent developments in our understanding of basal cell carcinomas and squamous cell carcinomas at the molecular levels and their clinical implications.

Collagen XVII/BP180 protein expression in squamous cell carcinoma of the skin detected with novel monoclonal antibodies in archived tissues using tissue microarrays and digital microscopy

Collagen XVII/BP180, a hemidesmosomal adhesion protein, is lost during normal keratinocyte maturation; however, it may be reexpressed upon malignant transformation. In this work, highly sensitive monoclonal antibodies 6D1 and 9G2 were produced, characterized, and used for the detection of collagen XVII in a tissue microarray series of archived samples of nonmelanocytic epithelial neoplasias, including 5 verruca vulgaris, 14 seborrheic keratosis, 38 actinic keratosis, 38 basal cell carcinoma (BCC), 15 basosquamous carcinoma, 58 squamous cell carcinoma (SCC), and 9 normal skin. Digital microscopy and a new tissue microarray software linking image and patient data allowed easy and validated evaluation and quality archiving of stained samples. In normal skin and benign epidermal lesions, collagen XVII protein was restricted to basal keratinocytes. However, possibly as a sign of undifferentiated/transformed state, it was widely expressed in SCC showing elevated levels around invasive tumor fronts with some staining in tumor adjacent stroma, endothelium, and histiocytes. Collagen XVII immunostaining of atypical keratinocytes in most actinic/solar keratosis supports the view of their malignancy and common origin with SCC. Squamous component of basosquamous carcinoma showed moderate reaction, whereas islets of BCC were mainly negative reflecting the diverse genotype and phenotype, and pathogenesis of SCC and BCC. These results suggest that collagen XVII neoexpression may be associated with early atypia/malignant transformation of keratinocytes. Further investigations are under way to analyze the potential of these antibodies for tracing progression and metastatic potential of skin tumors.

Kinetic model of progression of cutaneous melanoma population

A kinetic model for progression of a population of cutaneous melanomas through categories defined by the range of Breslow thickness, with melanomas in situ (MIS) in category 0, and melanomas with Breslow thickness > or =2 mm in category 3, is described. The model assumes that all melanomas start out in category 0; this category is further subdivided into indolent and progressing melanomas. Steady-state solutions for the distributions of excised melanomas were found. Depending on the proportion of indolent MIS, these solutions predict very different distributions of excised melanomas and melanoma mortality, when either frequency of examinations by physicians or sensitivity to melanoma is changed. Although it is not currently possible to differentiate between indolent and progressing MIS either clinically or histologically, solutions of this kinetic model can be used to determine the proportion of such indolent lesions in a population-based study. The steady-state solutions of the kinetic model can be used to analyze melanoma progression in any stable patient population, in which the total number of melanomas detected per year is either stable or varies slowly. As an example, melanoma progression is analyzed using the American Cancer Society estimates of melanoma incidence and mortality. For a fixed incidence rate, melanoma mortality and melanoma treatment cost in the USA could be significantly reduced by increasing the biopsy sensitivity of physicians to in-situ and thin-invasive melanomas.