Chromatin state and oncogenic competence
Although specific DNA mutations can lead to tumor generation, they are not transforming in all cellular contexts. This may be due to the intrinsic transcriptional program present in the cell of origin. Using zebrafish and human pluripotent stem cell cancer models, Baggiolini
et al
. report that neural crest cells and melanoblasts (precursors to melanocytes) are susceptible to specific mutation of the
BRAF
gene, whereas melanocytes are relatively resistant (see the Perspective by Vredevoogd and Peeper). The competent cells display higher levels of chromatin factors such as the protein ATAD2 compared with the less competent ones. ATAD2 forms a complex with the neural crest transcription factor SOX10 and establishes a chromatin state that makes them permissive to BRAF mutagenesis. These data indicate that developmental chromatin programs are a determinant of how cells respond to DNA mutations. —BAP
Oral cancer is one of the most commonly occurring cancers worldwide, decreasing the patient's survival rate due to tumor recurrence and metastasis. Menadione (Vitamin K3) is known to exhibit cytotoxicity in various cancer cells but the present study focused on its effects on viability, apoptosis, epithelial to mesenchymal transition (EMT), anchorage independent growth and migration of oral cancer cells. The results show that menadione is more cytotoxic to SAS (oral squamous carcinoma) cells but not to non-tumorigenic HEK293 and HaCaT cells. Menadione treatment increased the expression of pro-apoptotic proteins, Bax and p53, with a concurrent decrease in anti-apoptotic proteins, Bcl-2 and p65. Menadione induced the expression of E-cadherin but reduced the expression of EMT markers, vimentin and fibronectin. Menadione also inhibited anchorage independent growth and migration in SAS cells. These findings reveal and confirm that menadione is a potential candidate in oral cancer therapy as it exhibits cytotoxic, antineoplastic and antimigratory effects besides effectively blocking EMT in oral cancer cells.
PROTOCADHERIN 7 (PCDH7), a transmembrane receptor and member of the Cadherin superfamily, is frequently overexpressed in lung adenocarcinoma and is associated with poor clinical outcome. Although PCDH7 was recently shown to promote transformation and facilitate brain metastasis in lung and breast cancers, decreased PCDH7 expression has also been documented in colorectal, gastric, and invasive bladder cancers. These data suggest contextdependent functions for PCDH7 in distinct tumor types. Given that PCDH7 is a potentially targetable molecule on the surface of cancer cells, further investigation of its role in tumorigenesis in vivo is needed to evaluate the therapeutic potential of its inhibition. Here, we report the analysis of novel PCDH7 gain-and loss-of-function mouse models and provide compelling evidence that this cell-surface protein acts as a potent lung cancer driver. Employing a Creinducible transgenic allele, we demonstrated that enforced PCDH7 expression significantly accelerates Kras G12D -driven lung tumorigenesis and potentiates MAPK pathway activa-tion. Furthermore, we performed in vivo somatic genome editing with CRISPR/Cas9 in Kras LSL-G12D ; Tp53 fl/fl (KP) mice to assess the consequences of PCDH7 loss of function. Inactivation of PCDH7 in KP mice significantly reduced lung tumor development, prolonged survival, and diminished phospho-activation of ERK1/2. Together, these findings establish a critical oncogenic function for PCDH7 in vivo and highlight the therapeutic potential of PCDH7 inhibition for lung cancer. Moreover, given recent reports of elevated or reduced PCDH7 in distinct tumor types, the new inducible transgenic model described here provides a robust experimental system for broadly elucidating the effects of PCDH7 overexpression in vivo.
Implications:In this study, we establish a critical oncogenic function for PCDH7 in vivo using novel mouse models and CRISPR/Cas9 genome editing, and we validate the therapeutic potential of PCDH7 inhibition for lung cancer.Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis):
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