title: Increased plasticity of the stiffness of melanoma cells correlates with their acquisition of metastatic properties.
abstract: The stiffness of tumor cells varies during cancer progression. In particular, metastatic carcinoma cells analyzed by Atomic Force Microscopy (AFM) appear softer than non-invasive and normal cells. Here we examined by AFM how the stiffness of melanoma cells varies during progression from non-invasive Radial Growth Phase (RGP) to invasive Vertical Growth Phase (VGP) and to metastatic tumors. We show that transformation of melanocytes to RGP and to VGP cells is characterized by decreased cell stiffness. However, further progression to metastatic melanoma is accompanied by increased cell stiffness and the acquisition of higher plasticity by tumor cells, which is manifested by their ability to greatly augment or reduce their stiffness in response to diverse adhesion conditions. We conclude that increased plasticity, rather than decreased stiffness as suggested for other tumor types, is a marker of melanoma malignancy. These findings advise caution about the potential use of AFM for melanoma diagnosis.
  
  
  BACKGROUND
  This study investigates the changes to cellular stiffness in metastatic melanoma cells examined via atomic force microscopy. The results demonstrate that increased plasticity is a marker of melanoma malignancy, as opposed to decreased stiffness.
authors.affiliation: Swiss Centre for Electronics and Microtechnology, CSEM SA, Nanotechnology and Life Sciences, Neuchâtel, Switzerland.
authors.forename: Gilles
authors.initials: G
authors.lastname: Weder
authors.affiliation: Department of Oncology, CHUV, University of Lausanne, Epalinges, Switzerland.
authors.forename: Mariëlle C
authors.initials: MC
authors.lastname: Hendriks-Balk
authors.affiliation: Swiss Centre for Electronics and Microtechnology, CSEM SA, Nanotechnology and Life Sciences, Neuchâtel, Switzerland.
authors.forename: Rita
authors.initials: R
authors.lastname: Smajda
authors.affiliation: Ludwig Institute for Cancer Research, Lausanne Cancer Center, University of Lausanne, Epalinges, Switzerland.
authors.forename: Donata
authors.initials: D
authors.lastname: Rimoldi
authors.affiliation: Swiss Centre for Electronics and Microtechnology, CSEM SA, Nanotechnology and Life Sciences, Neuchâtel, Switzerland.
authors.forename: Martha
authors.initials: M
authors.lastname: Liley
authors.affiliation: Swiss Centre for Electronics and Microtechnology, CSEM SA, Nanotechnology and Life Sciences, Neuchâtel, Switzerland.
authors.forename: Harry
authors.initials: H
authors.lastname: Heinzelmann
authors.affiliation: Swiss Centre for Electronics and Microtechnology, CSEM SA, Nanotechnology and Life Sciences, Neuchâtel, Switzerland.
authors.forename: André
authors.initials: A
authors.lastname: Meister
authors.affiliation: Department of "Formation et Recherche", CHUV, University of Lausanne, Epalinges, Switzerland. Electronic address: Agnese.Mariotti@unil.ch.
authors.forename: Agnese
authors.initials: A
authors.lastname: Mariotti
mesh_terms: D045744:Cell Line, Tumor; D018450:Disease Progression; D006801:Humans; D008544:Melanocytes / Q000473:pathology*; D008545:Melanoma / Q000175:diagnosis / Q000473:pathology*; D018625:Microscopy, Atomic Force; D009362:Neoplasm Metastasis / Q000175:diagnosis / Q000473:pathology; D012878:Skin Neoplasms / Q000175:diagnosis / Q000473:pathology*
keywords: Atomic force microscope; Cell stiffness; Malignant progression; Melanoma