Molecular Bases of Disease
A rare germline CDKN2A variant (47T>G; p16-L16R) predisposes carriers to pancreatic cancer by reducing cell cycle inhibition
Germline mutations in CDKN2A, encoding the tumor suppressor p16, are responsible for a large proportion of familial melanoma cases and also increase risk of pancreatic cancer. We identified four families through pancreatic cancer probands that were affected by both cancers. These families bore a germline missense variant of CDKN2A (47T>G), encoding a p16-L16R mutant protein associated with high cancer occurrence. Here, we investigated the biological significance of this variant. When transfected into p16-null pancreatic cancer cells, p16-L16R was expressed at lower levels than wild-type (WT) p16.E3 ubiquitin ligase PARK2, an inhibitor of melanoma cell growth, is repressed by the oncogenic ERK1/2-ELK1 transcriptional axis
Malignant melanoma, the most aggressive form of skin cancer, is characterized by high prevalence of BRAF/NRAS mutations and hyperactivation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), mitogen-activated protein kinases (MAPK), leading to uncontrolled melanoma growth. Efficacy of current targeted therapies against mutant BRAF or MEK1/2 have been hindered by existence of innate or development of acquired resistance. Therefore, a better understanding of the mechanisms controlled by MAPK pathway driving melanogenesis will help develop new treatment approaches targeting this oncogenic cascade.The extracellular sulfatase SULF2 promotes liver tumorigenesis by stimulating assembly of a promoter-looping GLI1-STAT3 transcriptional complex
The expression of the extracellular sulfatase SULF2 has been associated with increased hepatocellular carcinoma (HCC) growth and poor patient survival. However, the molecular mechanisms underlying SULF2-associated tumor growth remain unclear. To address this gap, here we developed a transgenic mouse overexpressing Sulf2 in hepatocytes under the control of the transthyretin promoter. In this model, Sulf2 overexpression potentiated diethylnitrosamine-induced HCC. Further analysis indicated that the transcription factor GLI family zinc finger 1 (GLI1) mediates Sulf2 expression during HCC development.Gli Transcription Factors Mediate the Oncogenic Transformation of Prostate Basal Cells Induced by a Kras-Androgen Receptor Axis
Although the differentiation of oncogenically transformed basal progenitor cells is one of the key steps in prostate tumorigenesis, the mechanisms mediating this cellular process are still largely unknown. Here we demonstrate that an expanded p63+ and CK5+ basal/progenitor cell population, induced by the concomitant activation of oncogenic Kras(G12D) and androgen receptor (AR) signaling, underwent cell differentiation in vivo. The differentiation process led to suppression of p63-expressing cells with a decreased number of CK5+ basal cells but an increase of CK8+ luminal tumorigenic cells and revealed a hierarchal lineage pattern consisting of p63+/CK5+ progenitor, CK5+/CK8+ transitional progenitor, and CK8+ differentiated luminal cells.Nuclear Factor of Activated T Cells-dependent Down-regulation of the Transcription Factor Glioma-associated Protein 1 (GLI1) Underlies the Growth Inhibitory Properties of Arachidonic Acid
Numerous reports have demonstrated a tumor inhibitory effect of polyunsaturated fatty acids (PUFAs). However, the molecular mechanisms modulating this phenomenon are in part poorly understood. Here, we provide evidence of a novel antitumoral mechanism of the PUFA arachidonic acid (AA). In vivo and in vitro experiments showed that AA treatment decreased tumor growth and metastasis and increased apoptosis. Molecular analysis of this effect showed significantly reduced expression of a subset of antiapoptotic proteins, including BCL2, BFL1/A1, and 4-1BB, in AA-treated cells.
