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Lymph node invasion by tumor cells is an important process in the progression of melanoma and is a poor prognostic factor for patients with this cancer. Before they are able to spread to regional lymph nodes, though, melanoma cells must first adhere to lymphatic endothelium and transmigrate into the lymphatic vasculature. In order to study melanoma cell adhesion to lymphatic endothelial cells and the factors that regulate this process, we have developed an in vitro flow cytometry-based assay to measure melanoma cell attachment to lymphatic endothelial cells. This assay will be a useful tool for investigating the interactions that take place between melanoma cells and lymphatic endothelial cells during the adhesion process.

Recent advances in the treatment of metastatic melanoma have emerged only from advances in our understanding of melanoma development and progression at the cellular and molecular levels. Despite the impact that such advances have made on the clinical management of this cancer over the last decade, additional insights into factors that promote melanoma progression and therapeutic resistance are needed to combat this disease. CRISPR-Cas9 gene editing technology is a powerful tool for studying gene function in a timely and cost-effective manner, enabling the manipulation of specific DNA sequences via a targeted approach. Herein, we describe a protocol for generating functional gene knockouts in melanoma cell lines by CRISPR-Cas9 gene editing, and we present an example application of this protocol for the successful knockout of the Foxc2 transcription factor-encoding gene in the B16-F1 murine melanoma cell line.

Although T lymphocytes have long been appreciated for their role in the immunosurveillance of cancer, it has been the realization that cancer cells may ultimately escape a response from tumor-reactive T cells that has ignited efforts to enhance the efficacy of anti-tumor immune responses. Recent advances in our understanding of T cell immunobiology have been particularly instrumental in informing therapeutic strategies to overcome mechanisms of tumor immune escape, and immune checkpoint blockade has emerged as one of the most promising therapeutic options for patients in the history of cancer treatment. Designed to interfere with inhibitory pathways that naturally constrain T cell reactivity, immune checkpoint blockade releases inherent limits on the activation and maintenance of T cell effector function. In the context of cancer, where negative T cell regulatory pathways are often overactive, immune checkpoint blockade has proven to be an effective strategy for enhancing the effector activity and clinical impact of anti-tumor T cells. Checkpoint inhibitors targeting CTLA-4, PD-1, and PD-L1 have yielded unprecedented and durable responses in a significant percentage of cancer patients in recent years, leading to U.S. FDA approval of six checkpoint inhibitors for numerous cancer indications since 2011. In this review, we highlight the clinical success of these FDA-approved immune checkpoint inhibitors and discuss current challenges and future strategies that must be considered going forward to maximize the efficacy of immune checkpoint blockade therapy for cancer.

Background/aim The FOXC2 transcription factor promotes the progression of several cancer types, but has not been investigated in the context of melanoma cells. To study FOXC2's influence on melanoma progression, we generated a FOXC2-deficient murine melanoma cell line and evaluated The Cancer Genome Atlas (TCGA) patient datasets. Materials and methods We compared tumor growth kinetics and RNA-seq/qRT-PCR gene expression profiles from wild-type versus FOXC2-deficient murine melanomas. We also performed Kaplan-Meier survival analysis of TCGA data to assess the influence of FOXC2 gene expression on melanoma patients' response to chemotherapy and immunotherapy. Results FOXC2 promotes melanoma progression and regulates the expression of genes associated with multiple oncogenic pathways, including the oxidative stress response, xenobiotic metabolism, and interferon responsiveness. FOXC2 expression in melanoma correlates negatively with patient response to chemotherapy and immunotherapy. Conclusion FOXC2 drives a tumor-promoting gene expression program in melanoma and is a prognostic indicator of patient response to multiple cancer therapies.

It is increasingly recognized that Alzheimer’s disease (AD) exists before dementia is present and that shifts in amyloid beta occur long before clinical symptoms can be detected. Early detection of these molecular changes is a key aspect for the success of interventions aimed at slowing down rates of cognitive decline. Recent evidence indicates that of the two established methods for measuring amyloid, a decrease in cerebrospinal fluid (CSF) amyloid β1−42 (Aβ1−42) may be an earlier indicator of Alzheimer’s disease risk than measures of amyloid obtained from Positron Emission Tomography (PET). However, CSF collection is highly invasive and expensive. In contrast, blood collection is routinely performed, minimally invasive and cheap. In this work, we develop a blood-based signature that can provide a cheap and minimally invasive estimation of an individual’s CSF amyloid status using a machine learning approach. We show that a Random Forest model derived from plasma analytes can accurately predict subjects as having abnormal (low) CSF Aβ1−42 levels indicative of AD risk (0.84 AUC, 0.78 sensitivity, and 0.73 specificity). Refinement of the modeling indicates that only APOEε4 carrier status and four plasma analytes (CGA, Aβ1−42, Eotaxin 3, APOE) are required to achieve a high level of accuracy. Furthermore, we show across an independent validation cohort that individuals with predicted abnormal CSF Aβ1−42 levels transitioned to an AD diagnosis over 120 months significantly faster than those with predicted normal CSF Aβ1−42 levels and that the resulting model also validates reasonably across PET Aβ1−42 status (0.78 AUC). This is the first study to show that a machine learning approach, using plasma protein levels, age and APOEε4 carrier status, is able to predict CSF Aβ1−42 status, the earliest risk indicator for AD, with high accuracy.

The FOXC2 transcription factor has emerged as a tumor-promoting oncogene in many cancer types. We have recently investigated the impact of Foxc2 gene disruption and FOXC2 overexpression in melanoma on tumor cell adhesion to extracellular matrix (ECM) proteins and lymphatic endothelial cells. We show that melanoma-associated FOXC2 is a critical regulator of tumor cell adhesion to the ECM proteins fibrinogen and fibronectin as well as to lymphatic endothelial cells. These effects on tumor cell adhesion correlate with FOXC2-mediated regulation of the integrins ITGA5 and ITGA9. As changes in cellular adhesion frequently accompany tumor cell transformation and progression, our data suggest that FOXC2 and genes regulated by this transcription factor may play key roles in promoting melanoma invasion and metastasis. Citation Format: Coleman E. Johnson, Corey J. Williams, Kristian M. Hargadon. FOXC2-associated regulation of melanoma cell adhesion to the extracellular matrix and lymphatic endothelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2617.

Melanocytic lesions with lichenoid regression may mimic a benign lichenoid keratosis (BLK) histologically. A total of 336 BLKs were reviewed and deeper sections obtained to determine the frequency of this phenomenon. Two cases (0.6%) showed at least 1 melanocytic nest or junctional multinucleated melanocyte (starburst melanocyte) on deeper sections confirmed by MART-1 immunostaining. Both of these cases demonstrated solar elastosis, and 1 case had an effaced rete ridge pattern. Not included in the histological study are 5 additional cases in which the initial slide showed only lichenoid dermatitis, but deeper sections obtained before to the initial sign-out revealed a melanocytic proliferation. These 5 cases would have been signed out as "consistent with BLK" if deeper sections had not been obtained. Fluorescent in situ hybridization (FISH) was performed on 3 cases; in each case, the melanocytes demonstrated a loss of chromosome 9p21 DNA copy number. The finding of nests of genetically altered melanocytes on severely sun-damaged skin strongly suggests that these cases represent lichenoid regression of melanoma in situ. Pathologists should approach a diagnosis of BLK cautiously in the setting of severely sun-damaged skin.