Abstract 761: The relationship between ANGPTL4 and epidermal malignant transformation
Authors: Yawson Nat Ato , Diedrich Jonathan D. , Liby Karen T. , Veenstra Jesse , Bernard Jamie Jenna 
Published: March 2024

Abstract
High body mass index (BMI) is a risk factor for several types of cancers. Although epidemiology suggests obesity is negatively associated with non-melanoma skin cancer (NMSC), bariatric surgery has been shown to reduce the risk, suggesting a possible role of adipose tissue in the initiation and promotion of skin cancer. To gain mechanistic insight into how adipose tissue drives cutaneous carcinogenesis, we cultured non-tumorigenic mouse keratinocytes (JB6 P+ cells) with or without factors released from murine visceral adipose tissue (mFTF) and performed RNA-Sequencing. Published work demonstrated mFTF induces anchorage-independent cell growth, a surrogate marker for malignant transformation. Transcriptomic analysis demonstrated a significant induction of Angptl4 mRNA in JB6 P+ cells cultured with mFTF for 3 and 8 hours compared to the vehicle-treated cells. ANGPTL4 is an endogenous inhibitor of lipoprotein lipase that modulates free fatty acid delivery to adipose tissue and oxidative tissues such as muscle and liver. The C-terminal protein demonstrates tumor-associated activities such as angiogenesis, metastasis, protection against anoikis, and enhancement of cell survival. Therefore, we hypothesized that the induction of this gene promotes malignant transformation. RNA-seq data was validated in multiple cell models, including primary keratinocytes with human adipose tissue. Immunohistochemistry was used to assess ANGPTL4 expression in 37 actinic keratosis (pre-malignant) and cutaneous squamous cell carcinoma (cSCC) from patients with different BMIs (18.6 - 49.5). Notably, ANGPTL4 was only observed in the suprabasal epidermal layers in normal skin. For samples containing both lesional and perilesional skin, there was an increase in ANGPTL4 expression in the lesional epidermis relative to the normal perilesional skin. Furthermore, ANGPTL4 expression increased from transition to actinic keratosis to cSCC in situ, suggesting that ANGTL4 is induced during malignant transformation as observed in our pre-clinical models. Interestingly, once cSCC developed an invasive component, ANGTPL4 expression was lost in the invasive keratinocytes but persisted in the in situ component. There was no association between ANGPTL4 expression and BMI in lesional tissue. These data suggest that targeting ANTPLT4 may be a novel therapy for the prevention of skin cancer and that ANGPTL4-high patients or cancer patients with obesity may be a critical demographic for potential risk assessment or therapeutic intervention. Future studies will determine the impact of knocking out ANGTPL4 in our models of malignant transformation.
Citation Format: Nat Ato Yawson, Jonathan D. Diedrich, Karen T. Liby, Jesse Veenstra, Jamie Jenna Bernard. The relationship between ANGPTL4 and epidermal malignant transformation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 761.