PDAC cells self-organise into non-spherical microtumours anchored to the micro/nanoplate. PCI-55 cells were cultured overnight on a micro-patterned plate containing circular microislands of 30 µm in diameter, with roughness (micro/nanoplate) or without roughness (conventional microplate). (a) Schematic overview. A total of 3 × 106 PDAC cells were cultured in 10% FBS DMEM overnight (i). PDAC cells self-organise and anchor to the micro/nanoplate (ii). Anchorage-dependent PDAC microtumours show morphological polarity and motility (iii, iv). Arrows indicate presumed direction of movement. Time-lapse images of PCI-55 microtumour (v). Dotted circles, cell-adherable circular islands 30 µm in diameter. Time shown as hh:mm. (b) Schematic overview. The micro-patterned plate with nanoscale roughness (micro/nanoplate) was prepared according to a standard photography method (i). Etching both the Parylene and MPC polymer with oxygen (O2) plasma (ii). Removal of PR before use (iii). (c,d) Quantitative analysis of roughness in patterned circular islands with roughness (micro/nanoplate) compared with areas without roughness (conventional microplate) using laser scanning microscopy. Roughness images were magnified by ×10000; graphs of height differences are shown (c). Graphs of quantitative roughness analysis (n = 6) (d). Surface roughness parameters: arithmetical mean height (Ra) and maximum height of profile (Rz). Area roughness parameters: arithmetic mean peak curvature (Spc) and developed interfacial area ratio (Sdr). **P < 0.01, ***P < 0.001. (e) Differential interference contrast images (upper panels) and fluorescence for Hoechst 33342, Phalloidin, and anti α-tubulin antibody (lower panels). Green dots indicate estimated cell-adherable circular islands of 30 µm in diameter. (f) Circularity of microtumours anchored to the micro/nanoplate when exceeding a single circular island. (g) Percentage of occupancy by adherent cells patterned on circular islands of 30 µm, 95 µm, and 300 µm in diameter. The roughness of circular islands is necessary for cell adhesion. n.s: not significant. (h) Bottom size of PCI-55 microtumours. Roughness (−): n = 440, Roughness: (+) n = 1084.