GATA6-CRT axis promotes stress-associated autophagy, EMT, and stemness-associated traits in pancreatic cancer.

Pancreatic cancer (PC) remains a major therapeutic challenge because of its profound plasticity and adaptability. Although our previous studies established that calreticulin (CRT) promotes epithelial-mesenchymal transition (EMT), its role in linking endoplasmic reticulum stress (ERS), autophagy-associated responses, and tumor cell plasticity has remained incompletely defined. The functional role of CRT was examined using in vitro and in vivo PC models, together with CRISPR/Cas9-mediated gene silencing, overexpression approaches, and pharmacological modulation of ERS and autophagy. Clinical relevance was evaluated in human PC specimens and correlated with patient survival. Thapsigargin-induced ERS activated autophagy-associated signaling through the PERK/eIF2α-ATG5/ATG12/LC3B axis and promoted EMT in a CRT-dependent manner. Under serum-free conditions, CRT was required for AMPK/mTOR/ULK1-associated autophagy activation and stemness-associated traits. Mechanistically, CRT interacted with LC3 through a conserved LC3-interacting region (LIR; WDFL), and this interaction contributed to stress-associated autophagy and malignant phenotypes. Furthermore, GATA6 was identified as a direct transcriptional activator of CRT, defining a GATA6-CRT regulatory axis. In vivo, targeting this axis through CRT silencing or autophagy inhibition by chloroquine or ATG5 knockdown suppressed tumor growth and metastasis. Clinically, high CRT expression was associated with GATA6, LC3B, and markers linked to stemness and EMT, as well as poor prognosis. Together, these findings support a model in which the GATA6-CRT axis functions as an important stress-responsive regulator associated with autophagy, phenotypic plasticity, and aggressiveness in PC, and nominate this axis as a potential therapeutic vulnerability while highlighting the need for further work to define its full mechanistic scope.