ΔNp63-mediated regulation of hyaluronic acid metabolism and signaling supports HNSCC tumorigenesis.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and several molecular pathways that underlie the molecular tumorigenesis of HNSCC have been identified. Among them, amplification or overexpression of ΔNp63 isoforms is observed in the majority of HNSCCs. Here, we unveiled a ΔNp63-dependent transcriptional program able to regulate the metabolism and the signaling of hyaluronic acid (HA), the major component of the extracellular matrix (ECM). We found that ∆Np63 is capable of sustaining the production of HA levels in cell culture and in vivo by regulating the expression of the HA synthase HAS3 and two hyaluronidase genes, HYAL-1 and HYAL-3. In addition, ∆Np63 directly regulates the expression of CD44, the major HA cell membrane receptor. By controlling this transcriptional program, ∆Np63 sustains the epithelial growth factor receptor (EGF-R) activation and the expression of ABCC1 multidrug transporter gene, thus contributing to tumor cell proliferation and chemoresistance. Importantly, p63 expression is positively correlated with CD44, HAS3, and ABCC1 expression in squamous cell carcinoma datasets and p63-HA pathway is a negative prognostic factor of HNSCC patient survival. Altogether, our data shed light on a ∆Np63-dependent pathway functionally important to the regulation of HNSCC progression.

ΔNp63 regulates the expression of hyaluronic acid-related genes in breast cancer cells.

Triple negative breast cancers (TNBC) represent the most aggressive and clinically relevant breast carcinomas. On the basis of specific molecular signature, the majority of TNBC can be classified as basal-like breast carcinoma. Here, we report data showing that in basal-like breast carcinoma cells ΔNp63 is capable of sustaining the production of the hyaluronic acid (HA), one of the major component of the extracellular matrix (ECM). At molecular level, we found that ΔNp63 regulates the expression of HA-related genes, such as the HA synthase HAS3, the hyaluronidase HYAL-1 and CD44, the major HA cell membrane receptor. By controlling this pathway, ∆Np63 contributes to maintain the self-renewal of breast cancer stem cells. Importantly, high HAS3 expression is a negative prognostic factor of TNBC patients. Our data suggest that in basal-type breast carcinoma ∆Np63 might favor a HA-rich microenviroment, which can sustain tumor proliferation and stemness.

Mathematical models of cancer metabolism.

Metabolism is essential for life, and its alteration is implicated in multiple human diseases. The transformation from a normal to a cancerous cell requires metabolic changes to fuel the high metabolic demands of cancer cells, including but not limited to cell proliferation and cell migration. In recent years, there have been a number of new discoveries connecting known aberrations in oncogenic and tumour suppressor pathways with metabolic alterations required to sustain cell proliferation and migration. However, an understanding of the selective advantage of these metabolic alterations is still lacking. Here, we review the literature on mathematical models of metabolism, with an emphasis on their contribution to the identification of the selective advantage of metabolic phenotypes that seem otherwise wasteful or accidental. We will show how the molecular hallmarks of cancer can be related to cell proliferation and tissue remodelling, the two major physiological requirements for the development of a multicellular structure. We will cover different areas such as genome-wide gene expression analysis, flux balance models, kinetic models, reaction diffusion models and models of the tumour microenvironment. We will also highlight current challenges and how their resolution will help to achieve a better understanding of cancer metabolism and the metabolic vulnerabilities of cancers.

p63 regulates glutaminase 2 expression.

The transcription factor p63 is critical for many biological processes, including development and maintenance of epidermal tissues and tumorigenesis. Here, we report that the TAp63 isoforms regulate cell metabolism through the induction of the mitochondrial glutaminase 2 (GLS2) gene both in primary cells and tumor cell lines. By ChIP analysis and luciferase assay, we confirmed that TAp63 binds directly to the p53/p63 consensus DNA binding sequence within the GLS2 promoter region. Given the critical role of p63 in epidermal differentiation, we have investigated the regulation of GLS2 expression during this process. GLS2 and TAp63 expression increases during the in vitro differentiation of primary human keratinocytes, and depletion of GLS2 inhibits skin differentiation both at molecular and cellular levels. We found that GLS2 and TAp63 expression are concomitantly induced in cancer cells exposed to oxidative stresses. siRNA-mediated depletion of GLS2 sensitizes cells to ROS-induced apoptosis, suggesting that the TAp63/GLS2 axis can be functionally important as a cellular antioxidant pathway in the absence of p53. Accordingly, we found that GLS2 is upregulated in colon adenocarcinoma. Altogether, our findings demonstrate that GLS2 is a bona fide TAp63 target gene, and that the TAp63-dependent regulation of GLS2 is important for both physiological and pathological processes.