Cross‐Talk Signaling Between Non‐Small Cell Lung Cancer Cell Lines and Fibroblasts Attenuates the Cytotoxic Effect of Cisplatin

Fibroblasts represent one of the most crucial cell types in the tumor microenvironment (TME), playing a major role in chemoresistance development. This study investigated the ability of fibroblasts to alter the response of non-small cell lung cancer (NSCLC) cell lines to cisplatin exposure. A cytotoxicity assay was performed to determine the IC₅₀ of cisplatin using MTT. The assay was performed on NSCLC cell lines A549 and H1299 monocultures and co-cultures with fibroblasts. The co-culture was performed directly with the HSF cell line and indirectly through conditioned media. The ELISA technique was then used to determine the expression of biochemical markers at various time points of co-culture before and after cisplatin exposure. We observed a time-dependent evolution in the fibroblast-cancer cell interplay. Initially, fibroblast co-culture enhanced the cytotoxic effect of cisplatin, as reflected by decreased IC₅₀ values after 24 h of co-culture. However, prolonged co-culture durations (48-96 h) led to the emergence of cisplatin resistance, coinciding with increased IC₅₀ values and altered expression of key biochemical markers. The findings suggest that fibroblasts undergo a potential identity switch over time, transitioning from a tumor-restrictive to a tumor-promoting phenotype. This switch was associated with the activation of EGFR and FGF signaling pathways, increased expression of angiogenic and metastasis markers (e.g., VEGF, MMP2 & MMP9), and inhibition of apoptosis (e.g., reduced caspase expression). Our results suggest that fibroblasts may initially potentiate the effect of cisplatin on NSCLC cells; however, in a time-dependent manner, fibroblast co-culture attenuates the cytotoxic efficacy of cisplatin.