Biology subjects

Gerami, P.

Publications and source records attributed to Gerami, P..

4 recordsLinked to original sources

bioRxiv2024

Genetic evolution of keratinocytes to cutaneous squamous cell carcinoma

We performed multi-omic profiling of epidermal keratinocytes, precancerous actinic keratoses, and squamous cell carcinomas to understand the molecular transitions during skin carcinogenesis. Single-cell mutational analyses of normal skin cells showed that most keratinocytes have remarkably low mutation burdens, despite decades of sun exposure, however keratinocytes with TP53 or NOTCH1 mutations had substantially higher mutation burdens. These observations suggest that wild-type keratinocytes (i.e. without pathogenic mutations) are able to withstand high dosages of cumulative UV radiation, but certain pathogenic mutations break these adaptive mechanisms, priming keratinocytes for transformation by increasing their mutation rate. Mutational profiling of squamous cell carcinomas adjacent to actinic keratoses revealed TERT promoter and CDKN2A mutations emerging in actinic keratoses, whereas additional mutations inactivating ARID2 and activating the MAPK-pathway delineated the transition to squamous cell carcinomas. Surprisingly, actinic keratoses were often not related to their neighboring squamous cell carcinoma, indicating that collisions of unrelated neoplasms are common in the skin. Spatial variation in gene expression patterns was common in both tumor and immune cells, with high expression of checkpoint molecules at the invasive front of tumors. In conclusion, this study catalogues the key events during the evolution of cutaneous squamous cell carcinoma.

genomics↗

bioRxiv2024

Molecular effects of indoor tanning

BackgroundTanning bed users have a significantly increased risk of melanoma, but it remains unclear how indoor tanning drives melanomagenesis. Tanning bed radiation is often thought of as a substitute for natural UV radiation despite differences in the maximum doses, UV content, body sites exposed, and patterns of melanoma that arise. MethodsTo better understand the epidemiologic trends and etiology of melanoma associated with tanning bed use, we described the patterns of melanoma in patients with quantifiable tanning bed usage and performed exome sequencing of 182 melanocytes from normal skin of a subset of these patients. ResultsTanning bed users were more likely than non-users to have melanoma on body sites with low cumulative levels of sun damage and were more likely to have multiple melanomas. The melanocytes in normal appearing skin from tanning bed users had higher mutation burdens, a higher proportion of melanocytes with pathogenic mutations, and distinct mutational signatures. These differences were most prominent over body sites that experience comparatively less exposure to natural sunlight. ConclusionsWe conclude that tanning bed radiation induces melanoma by increasing the mutation burden of melanocytes and by mutagenizing a broader field of melanocytes than are typically exposed to natural sunlight. The unique signatures of mutations in skin cells of tanning users may be attributable to the distinct spectra of radiation emitted from solariums.

genomics↗

bioRxiv2022

Keratinocyte desmosomal cadherin Desmoglein 1 as a mediator and target of paracrine signaling in the melanoma niche

Melanoma is an aggressive cancer typically arising from transformation of melanocytes residing in the basal layer of the epidermis, where they are in direct contact with surrounding keratinocytes. The role of keratinocytes in shaping the melanoma tumor microenvironment remains understudied. We previously showed that temporary loss of the keratinocyte-specific cadherin, Desmoglein 1 (Dsg1) controls paracrine signaling between normal melanocytes and keratinocytes to stimulate the protective tanning response. Here, we provide evidence that melanoma cells hijack this intercellular communication by secreting factors that keep Dsg1 expression low in surrounding keratinocytes, which in turn generate their own paracrine signals that enhance melanoma spread through CXCL1/CXCR2 signaling. Evidence suggests a model whereby paracrine signaling from melanoma cells increases levels of the transcriptional repressor Snai2 (Slug), and consequently decreases the Dsg1 transcriptional activator Grhl1 (Grainyhead like 1), a known promoter of epidermal differentiation and barrier function. Together, these data support the idea that paracrine crosstalk between melanoma cells and keratinocytes resulting in chronic keratinocyte Dsg1 reduction contributes to melanoma cell movement associated with tumor progression.

cancer biology↗

bioRxiv2018

Keratinocyte desmoglein 1 regulates the epidermal microenvironment and tanning response

Coordinated responses to environmental stimuli within the keratinocyte:melanocyte niche are poorly understood. Desmoglein 1 (Dsg1), a keratinocyte-specific desmosomal cell-cell adhesion protein with emerging signaling roles, is reduced by ultraviolet light radiation. Loss-of-function Dsg1 mutations elevate keratinocyte cytokines in Severe dermatitis, multiple Allergies, and Metabolic wasting (SAM) syndrome. We asked whether Dsg1 regulates keratinocyte:melanocyte paracrine communication to induce the tanning response. Dsg1-silenced keratinocytes increased Pro-opiomelanocortin mRNA and cytokine secretion. Melanocytes treated with conditioned media from Dsg1-silenced keratinocytes exhibited increased Mitf and Trp1 mRNA, melanin secretion, and dendrite length. Inhibiting the melanocyte pigment-associated melanocortin 1 receptor reduced pigment secretion in response to Dsg1-deficient conditioned media. Melanocytes incorporated into Dsg1-deficient human skin equivalents relocalized suprabasally, reminiscent of early melanoma pagetoid behavior. Dsg1 decreased in keratinocytes surrounding dysplastic nevi and early melanoma, but not benign nevi. We posit Dsg1 controls keratinocyte:melanocyte communication through paracrine signaling, which goes awry upon Dsg1 loss in melanoma development.

cell biology↗