OBJECTIVETo investigate the role of type I collagen as an autocrine protein in promoting the growth lung cancer cells in a three-dimensional (3D) culture system.

METHODSImmunohistochemistry and RT-PCR were used to detect the expression of type I collagen in lung cancer specimens and 5 lung cancer cell lines. The lung cancer cell lines in 3D cultures were treated with vectors harboring short hairpin RNA (shRNA) targeting type I collagen, and the cell growth suppression was evaluated using MTT assay and colony formation assay. The lung cancer cells stimulated with supernatant from lung cancer-derived fibroblasts were tested for the expression of type I collagen mRNA.

RESULTSType I collagen expressions were detected in both the lung cancer tissues and the cell lines. In the 3D culture system, the growth of the cancer cell lines was obviously suppressed by shRNA-mediated type I collagen knockdown evidenced by lowered cell growth rate and colony formation ability. Stimulation with fibroblast culture supernatant resulted in enhanced expressions of type I collagen in the cancer cell lines.

CONCLUSIONAutocrine of type I collagen I is required for maintaining lung cancer cell growth in 3D cultures, and its expression is regulated by fibroblasts. These findings provide new insights into the role of type I collagen I in the tumor microenvironment and point a new direction for targeted therapy of tumors.