Analysis of sequence data to identify potential risk variants for oral clefts in multiplex families
MOLECULAR GENETICS & GENOMIC MEDICINE
Authors: Holzinger, Emily R.; Li, Qing; Parker, Margaret M.; Hetmanski, Jacqueline B.; Marazita, Mary L.; Mangold, Elisabeth; Ludwig, Kerstin U.; Taub, Margaret A.; Begum, Ferdouse; Murray, Jeffrey C.; Albacha-Hejazi, Hasan; Alqosayer, Khalid; Al-Souki, Giath; Hejazi, Abdullatiff Albasha; Scott, Alan F.; Beaty, Terri H.; Bailey-Wilson, Joan E.
Abstract
BackgroundNonsyndromic oral clefts are craniofacial malformations, which include cleft lip with or without cleft palate. The etiology for oral clefts is complex with both genetic and environmental factors contributing to risk. Previous genome-wide association (GWAS) studies have identified multiple loci with small effects; however, many causal variants remain elusive. MethodsIn this study, we address this by specifically looking for rare, potentially damaging variants in family-based data. We analyzed both whole exome sequence (WES) data and whole genome sequence (WGS) data in multiplex cleft families to identify variants shared by affected individuals. ResultsHere we present the results from these analyses. Our most interesting finding was from a single Syrian family, which showed enrichment of nonsynonymous and potentially damaging rare variants in two genes: CASP9 and FAT4. ConclusionNeither of these candidate genes has previously been associated with oral clefts and, if confirmed as contributing to disease risk, may indicate novel biological pathways in the genetic etiology for oral clefts.
PTK6 Potentiates Gemcitabine-Induced Apoptosis by Prolonging S-phase and Enhancing DNA Damage in Pancreatic Cancer
MOLECULAR CANCER RESEARCH
Authors: Ono, Hiroaki; Basson, Marc D.; Ito, Hiromichi
Abstract
Protein Tyrosine Kinase 6 (PTK6) is a non-receptor-type tyrosine kinase known to be expressed in various cancers, including pancreatic cancer. The role of PTK6 in cancer chemoresistance remains unclear. Therefore, it was hypothesized that PTK6 mechanistically regulates gemcitabine resistance in pancreatic cancer. Gemcitabine treatment stimulated endogenous PTK6 overexpression in MIAPaCa2 and Panc1 cells. PTK6 gene silencing increased cell survival after gemcitabine treatment and decreased apoptosis, whereas PTK6 overexpression decreased cell survival and increased apoptosis. Selection for gemcitabine resistance revealed substantially lower PTK6 expression in the gemcitabine-resistant subclones compared with the parental lines, while restoring PTK6 rescued gemcitabine sensitivity. Gemcitabine induced phosphorylation of H2AX (gamma-H2AX) and ataxia-telangiectasia mutated kinase (pATM), specific markers for DNA double-strand breaks. Both gemcitabine-induced phosphorylation of H2AX and ATM were reduced by PTK6 knockdown and increased by PTK6 overexpression. PTK6 overexpression also increased the S-phase fraction 48 hours after gemcitabine treatment. Although gemcitabine activated both caspase-8 (CASP8) and caspase-9 (CASP9), the effect of PTK6 on gemcitabine-induced apoptosis required CASP8 but not CASP9. In mouse xenografts, PTK6 overexpression in subcutaneous tumors attenuated tumor growth after gemcitabine treatment. In conclusion, PTK6 prolongs S-phase and increases the ability of gemcitabine to cause DNA damage in vitro and in vivo.