Novel allelic mutations in murine Serca2 induce differential development of squamous cell tumors

Patients with Darier disease have an increased risk of keratinocyte carcinoma: a Swedish registry-based nationwide cohort study

BACKGROUND

Darier disease is a genodermatosis which manifests as hyperkeratotic papules and superficial erosions mainly in seborrheic skin areas. This retrospective registry-based cohort study aimed to estimate the association between Darier disease and skin cancer.

RESULTS

Patients diagnosed with Darier disease were identified from the patient registry of Sahlgrenska University Hospital (Gothenburg, Sweden) in 2016-2020. The local cohort included 13 patients. Verification of Darier disease diagnosis in the National Patient Registry showed positive predictive value of more than 90%. National Patient Registry was searched for Darier disease in 2001-2020, Swedish Cancer Registry for cancers and Prescribed Drug Register for medications. The national cohort included 770 patients and tenfold matched control cohort. Patients with Darier disease had an increased relative risk of keratinocyte carcinoma (basal cell carcinoma and cutaneous squamous cell carcinoma combined) (hazard ratio [HR], 1.6, 95% confidence interval [CI], 1.0-2.5, P = 0.036). The risk increase was significant for basal cell carcinoma (HR, 1.8, 95% CI, 1.1-2.9, P = 0.012), whereas there was a trend for cutaneous squamous cell carcinoma, (HR, 1.9, 95% CI, 0.9-4.1, P = 0.086) and cutaneous melanoma (HR, 2.4, 95% CI, 0.9-6.2, P = 0.083). Standardized incidence ratio for keratinocyte cancers was 2.9 (95% CI, 2.4-3.3. The results were consistent in two subgroup analyses adjusting for use of retinoid and/or immunosuppressive drugs.

CONCLUSION

Patients with Darier disease have an increased risk of skin cancer, particularly keratinocyte carcinoma. This risk was consistent even when known risk modifiers for keratinocyte carcinoma were excluded in sensitivity analyses. The results support previously proposed molecular links between Darier disease and skin cancer, but further investigations are needed. Additional studies are also required to develop clinical management recommendations for Darier disease. In the meantime, dermatologists should be aware of the cancer risk in these patients and remain vigilant, as detecting cancer can be challenging in hyperkeratotic and/or eroded skin.

Targeting SERCA2 in organotypic epidermis reveals MEK inhibition as a therapeutic strategy for Darier disease

Mutation of the ATP2A2 gene encoding sarco-endoplasmic reticulum calcium ATPase 2 (SERCA2) was linked to Darier disease more than 2 decades ago; however, there remain no targeted therapies for this disorder causing recurrent skin blistering and infections. Since Atp2a2-knockout mice do not phenocopy its pathology, we established a human tissue model of Darier disease to elucidate its pathogenesis and identify potential therapies. Leveraging CRISPR/Cas9, we generated human keratinocytes lacking SERCA2, which replicated features of Darier disease, including weakened intercellular adhesion and defective differentiation in organotypic epidermis. To identify pathogenic drivers downstream of SERCA2 depletion, we performed RNA sequencing and proteomics analysis. SERCA2-deficient keratinocytes lacked desmosomal and cytoskeletal proteins required for epidermal integrity and exhibited excess MAPK signaling, which modulates keratinocyte adhesion and differentiation. Immunostaining patient biopsies substantiated these findings, with lesions showing keratin deficiency, cadherin mislocalization, and ERK hyperphosphorylation. Dampening ERK activity with MEK inhibitors rescued adhesive protein expression and restored keratinocyte sheet integrity despite SERCA2 depletion or chemical inhibition. In sum, coupling multiomic analysis with human organotypic epidermis as a preclinical model, we found that SERCA2 haploinsufficiency disrupts critical adhesive components in keratinocytes via ERK signaling and identified MEK inhibition as a treatment strategy for Darier disease.

Targeting SERCA2 in organotypic epidermis reveals MEK inhibition as a therapeutic strategy for Darier disease

Mutation of the ATP2A2 gene encoding sarco-endoplasmic reticulum calcium ATPase 2 (SERCA2) was linked to Darier disease more than two decades ago; however, there remain no targeted therapies for this disorder causing recurrent skin blistering and infections. Since Atp2a2 knockout mice do not phenocopy its pathology, we established a human tissue model of Darier disease to elucidate its pathogenesis and identify potential therapies. Leveraging CRISPR/Cas9, we generated human keratinocytes lacking SERCA2, which replicated features of Darier disease, including weakened intercellular adhesion and defective differentiation in organotypic epidermis. To identify pathogenic drivers downstream of SERCA2 depletion, we performed RNA sequencing and proteomic analysis. SERCA2-deficient keratinocytes lacked desmosomal and cytoskeletal proteins required for epidermal integrity and exhibited excess MAP kinase signaling, which modulates keratinocyte adhesion and differentiation. Immunostaining patient biopsies substantiated these findings with lesions showing keratin deficiency, cadherin mis-localization, and ERK hyper-phosphorylation. Dampening ERK activity with MEK inhibitors rescued adhesive protein expression and restored keratinocyte sheet integrity despite SERCA2 depletion or chemical inhibition. In sum, coupling multi-omic analysis with human organotypic epidermis as a pre-clinical model, we found that SERCA2 haploinsufficiency disrupts critical adhesive components in keratinocytes via ERK signaling and identified MEK inhibition as a treatment strategy for Darier disease.

Targeting oncogenic Notch signaling with SERCA inhibitors

P-type ATPase inhibitors are among the most successful and widely prescribed therapeutics in modern pharmacology. Clinical transition has been safely achieved for H+/K+ ATPase inhibitors such as omeprazole and Na+/K+-ATPase inhibitors like digoxin. However, this is more challenging for Ca2+-ATPase modulators due to the physiological role of Ca2+ in cardiac dynamics. Over the past two decades, sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) modulators have been studied as potential chemotherapy agents because of their Ca2+-mediated pan-cancer lethal effects. Instead, recent evidence suggests that SERCA inhibition suppresses oncogenic Notch1 signaling emerging as an alternative to γ-secretase modulators that showed limited clinical activity due to severe side effects. In this review, we focus on how SERCA inhibitors alter Notch1 signaling and show that Notch on-target-mediated antileukemia properties of these molecules can be achieved without causing overt Ca2+ cellular overload.