Novel morphological and genetic analysis of cancer cells in a 3D microenvironment identifies STAT3 as a regulator of tumor permeability barrier function


Min Chul Park, Hyobin Jeong, Sung Hwa Son, Youn Ha Kim, Daeyoung Han, Peter C Goughnour, Taehee Kang, Nam Hoon Kwon, Hyo Eun Moon, Sun Ha Paek, Daehee Hwang, Ho Jun Seol, Do-Hyun Nam, and Sunghoon Kim

Tumor permeability is a critical determinant of drug delivery and sensitivity, but systematic methods to identify factors that perform permeability barrier functions in the tumor microenvironment are not yet available. Multicellular tumor spheroids have become tractable in vitro models in which to study the impact of a three-dimensional (3D) environment on cellular behavior. In this study, we characterized the spheroid-forming potential of cancer cells and correlated the resulting spheroid morphologies with genetic information to identify conserved cellular processes associated with spheroid structure. Spheroids generated from 100 different cancer cell lines were classified into four distinct groups based on morphology. In particular, round and compact spheroids exhibited highly hypoxic inner cores and permeability barriers against anticancer drugs. Through systematic and correlative analysis, we reveal JAK-STAT signaling as one of the signature pathways activated in round spheroids. Accordingly, STAT3 inhibition in spheroids generated from the established cancer cells and primary glioblastoma patient-derived cells altered the rounded morphology and increased drug sensitivity. Furthermore, combined administration of the STAT3 inhibitor and 5-FU to a mouse xenograft model markedly reduced tumor growth compared to monotherapy. Collectively, our findings demonstrate the ability to integrate 3D culture and genetic profiling to determine the factors underlying the integrity of the permeability barrier in the tumor microenvironment, and may help to identify and exploit novel mechanisms of drug resistance.

Keywords: Cancer spheroid; Tumor permeability; STAT3; Drug sensitivity