title: Olfactomedin III expression contributes to anoikis-resistance in clonal variants of a human lung squamous carcinoma cell line.
abstract: Three clonal subpopulations of DLKP, a poorly differentiated squamous lung carcinoma cell line, display striking differences in ability to survive in suspension (anoikis resistance). DLKP-SQ is anoikis resistant (7.5% anoikis at 24 h). In contrast, DLKP-M and DLKP-I are sensitive to anoikis (49.2% and 42.6% respectively). DLKP-I shows increased apoptosis consistently over all time points tested while DLKP-M appear to slow down metabolically and perhaps delays onset of anoikis by undergoing autophagy. Expression microarray analysis identified pronounced differential expression of Olfactomedin 3 (OLFM3) between the clones. High expression of OLFM3 was confirmed at the RNA level by qRT-PCR in DLKP-SQ and at the protein level by Western blotting (within the cell and secreted). Little or no OLFM3 was detected in the other two clones (DLKP-M and DLKP-I). Following siRNA knockdown of OLFM3 in DLKP-SQ, anoikis was increased 2.8-fold to 21% which was intermediate between the anoikis levels in DLKP-SQ and DLKP-M or DLKP-I. This knockdown correlated with increased apoptosis in suspension but not in attached culture conditions. Addition of recombinant OLFM3 reduced anoikis in DLKP-I. This is the first instance of OLFM3 being linked with anoikis resistance in a human cancer cell line.
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland. Joanne.keenan@dcu.ie
authors.forename: Joanne
authors.initials: J
authors.lastname: Keenan
authors.forename: Helena
authors.initials: H
authors.lastname: Joyce
authors.forename: Sinead
authors.initials: S
authors.lastname: Aherne
authors.forename: Shirley
authors.initials: S
authors.lastname: O'Dea
authors.forename: Padraig
authors.initials: P
authors.lastname: Doolan
authors.forename: Vincent
authors.initials: V
authors.lastname: Lynch
authors.forename: Martin
authors.initials: M
authors.lastname: Clynes
mesh_terms: D023102:Anoikis; D001343:Autophagy; D002294:Carcinoma, Squamous Cell; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002470:Cell Survival; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C466064:OLFM3 protein, human; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C505407:CASP3 protein, human; D053148:Caspase 3