Increased expression of activating transcription factor 3 is related to the biologic behavior of cutaneous squamous cell carcinomas

Biology and Treatment Advances in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most common skin cancer diagnosed worldwide. CSCC is generally localized and managed with local therapies such as excision and/or radiotherapy. For patients with unresectable or metastatic disease, recent improvements in our understanding of the underlying biology have led to significant advancements in treatment approaches-including the use of immune checkpoint inhibition (ICI)-which have resulted in substantial gains in response and survival compared to traditional cytotoxic approaches. However, there is a lack of understanding of the biology underpinning CSCC in immunocompromised patients, in whom the risk of developing CSCC is hundreds of times higher compared to immunocompetent patients. Furthermore, current ICI approaches are associated with significant risk of graft rejection in organ transplant recipients who make up a significant proportion of immunocompromised patients. Ongoing scientific and clinical research efforts are needed in order to maintain momentum to increase our understanding and refine our therapeutic approaches for patients with CSCC.

The mTOR-inhibitor Sirolimus decreases the cyclosporine-induced expression of the oncogene ATF3 in human keratinocytes

BACKGROUND

Due to their immunosuppressive therapy, organtransplant recipients (OTRs) exhibit a high incidence for the development of cutaneous squamous cell carcinoma (cSCC). Randomized studies of kidney-transplanted patients indicate a significant lower susceptibility for cSCC among patients receiving the mTOR-inhibitor Sirolimus, compared to patients without mTOR-regimen. The exact mechanism, how mTOR inhibition affects keratinocyte carcinogenesis remains unclear.

OBJECTIVE

Our aim was to investigate the impact of Sirolimus on the expression level of the oncogene ATF3, which is involved in the development and progression of cSCC.

METHODS

We incubated human keratinocytes, cSSC cell lines and 3D skin equivalents with Sirolimus, exposed the cells to calcineurin inhibitors (CNI) and UVA-radiation and measured the expression level of ATF3 by real-time PCR and western blot.

RESULTS

We show that Sirolimus downregulates the expression of ATF3 induced by cyclosporine or cyclosporine plus UV-radiation in keratinocytes. In line with this we demonstrate a decrease in ATF3 expression, by incubating 3D skin equivalents with Sirolimus prior to cyclosporine and UV-light. However, Sirolimus has no significant impact on the ATF3 expression levels of cyclosporine stimulated cSCC cell lines.

CONCLUSION

Taken together, our study demonstrates that Sirolimus downregulates the CNI or UV-induced ATF3 expression in human keratinocytes, which could be a potential molecular mechanism how Sirolimus reduces cSCC in OTRs. The lack of ATF3 suppression by Sirolimus in cSCC cell lines fits to observations from clinical studies which demonstrated a clinical benefit from the switch to a mTOR-regimen in patients with low tumor burden in early stage of disease.

Activation of autophagic pathways is related to growth inhibition and senescence in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (SCC) is a very common resectable cancer; however, cutaneous SCC is highly resistant to chemotherapy if metastasis develops. Activating transcription factor 3 (ATF3) has been suggested as a marker of advanced or metastatic cutaneous SCC. Autophagy is one of the most important mechanisms in cancer biology and commonly induced by in vitro serum starvation. To investigate the role of autophagy activation in cutaneous SCC, we activated autophagic pathways by serum starvation in SCC13 and ATF3-overexpressing SCC13 (ATF3-SCC13) cell lines. ATF3-SCC13 cells demonstrated high proliferative capacity and low p53 and autophagy levels in comparison with control SCC13 cells under basal conditions. Intriguingly, autophagic stimulation via serum starvation resulted in growth inhibition and senescence in both cells, while ATF3-SCC13 cells further demonstrated growth inhibition and senescence. Apoptosis was not significantly induced by autophagy activation. Taken together, autophagy activation may be a promising antitumor approach for advanced cutaneous SCC.

The expression of miR-30a* and miR-30e* is associated with a dualistic model for grading ovarian papillary serious carcinoma

Histological grade has already been recognized as a very important prognostic factor for ovarian papillary serous carcinoma (OPSC). On the basis of pathogenetic mechanisms, recent findings suggest a dualistic model of OPSC consisting of types I (low-grade) and II (high-grade) cancers. High-grade OPSC is responsible for most ovarian cancer deaths. The goal of our investigation was to identify the differences in key miRNAs and possible regulators through miRNA microarray chip analysis, as well as functional target prediction and clinical outcome between the low and high-grade OPSC patients. The pathogenic basis in differentiation of ovarian cancer subtypes was studied to provide insight into diagnosis and therapy for high-grade cases. Through microarray analysis, we found that miR-30a* and miR-30e* were the top 2 significantly different miRNAs between type I and type II OPSC patients, and both were remarkably downregulated in the latter type. ATF3 and MYC were indicated as potential co-targets of miR-30a* and miR-30e*, and showed a significant upregulation in type II patients. As ATF3 and MYC are often associated with aggressive behavior and poor differentiation, especially in human cancers, these results are in good agreement with our findings and point toward a regulating differentiation function of the miR-30a* and miR-30e* genes. Further analysis using leave‑one-out cross predictions and Kaplan-Meier survival analysis strongly suggested that miR-30a* and miR-30e* can be used as biomarkers to tailor histological grade before starting the regimen, and they showed important roles in ovarian cancer differentiation resulting in poorer prognosis. In general, miR-30a* and miR-30e* coupled with expression data that reveal pathogenic regulation to predict histological differentiation, may operate to direct the formation of early detection and therapeutic approaches to individual OPSC patients, especially differentiation therapy to high-grade cases.

miRNA expression pattern associated with prognosis in elderly patients with advanced OPSC and OCC

The long-term survival for elderly patients with advanced ovarian papillary serous carcinoma (OPSC) does not exceed 30%, and the incidence and prognosis rise continuously after menopause. The aim of this study was to identify the differences in key miRNAs and their potential regulators through miRNA microarray analysis, functional target prediction, and clinical outcome between the elderly patients with advanced OPSC and ovarian clear cell carcinoma (OCC) who all suffered poor prognosis, to identify the pathogenetic basis, and to improve the understanding of the molecular basis of advanced OPCS in elderly patients. Through microarray analysis, we found 52 unique miRNAs with significant fold‑change in expression levels, of which 9 were upregulated, whereas 43 were downregulated in OCC patients compared to elderly OPSC patients with advanced stage. Among these prediction miRNAs, miR-30a, miR-30e and miR-505 were found to have some common cancer-related targets. Lower expression of these three miRNAs of advanced OPSC in elderly patients, all associated with significantly poorer survival rate, strongly suggesting that they could be critical oncogenes and take important roles in OPSC etiology in elderly patients with advantaged stage. Functional analyses support the above hypothesis. Their targets, ATF3, STMN1 and MYC suggest that OPSC also has aggressive biological behavior when presented with advanced stage, and support the epidemiology results that incidence and mortality of advanced OPSC increases continuously. miR-30a, miR-30e and miR-505 may be important pathogenetic factors for OPSC in elderly patients with advanced stage. Age could be regarded as a continuous covariate in this process. This may improve the understanding of molecular underpinnings of advanced OPSC in elderly patients, and provide improved diagnostic, prognostic and therapeutic approaches.

The utility of ATF3 in distinguishing cutaneous squamous cell carcinoma among other cutaneous epithelial neoplasms

The histopathologic distinction between benign and malignant cutaneous keratinocytic proliferations can pose a difficult diagnostic challenge - often with important clinical implications. Activating transcription factor 3 (ATF3) has emerged as a potential biomarker which may aid in the segregation of these lesions, and we hypothesize that ATF3 expression may be a specific marker of cutaneous squamous cell carcinoma (SCC). Using immunohistochemistry, we characterized ATF3 expression in a series of 126 cutaneous epithelial proliferations, including SCC (n = 27), basal cell carcinomas (BCC, n = 59), seborrheic keratoses with atypia (SK, n = 16), hyperplastic actinic keratoses (AK, n = 12) and prurigo nodularis cases (PN, n = 12). We showed strong, nuclear and/or nucleolar expression of ATF3 in a statistically significant number of cases of SCC compared to BCC, SK and PN. We conclude that ATF3 expression is a surrogate of malignancy (or pre-malignancy) in keratinocytic epithelial proliferations and thus helps distinguish SCC from other cutaneous epithelial neoplasms.

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.