Extended Data Fig. 2: Dysregulated LIF is a key driver for STAT3 activation in PDACs.

a, Immunoblot analyses of the response of various human PCC and PSC cell lines to LIF stimulation using STAT3 phosphorylation at Y705 (pSTAT3) as a readout. b, Immunoblot analyses of LIF-stimulated downstream intracellular signalling changes in three representative PCC lines, KP4, MIA PaCa2 and PANC1, over a 2-h time course. Stimulation with recombinant human epidermal growth factor (EGF) 10 ng ml⁻¹ for 10 min was used as positive control for pAKT1 and pERK1/2 activation. c, d, Immunoblot analyses of pSTAT3 in MIA PaCa2 and PANC1 cells when LIF signalling was blocked by either shRNA knockdown of LIFR (c) or immune-inactivation of LIF using anti-LIF monoclonal antibody (d). For LIF stimulation (a–d), 1 ng ml⁻¹ recombinant human LIF was applied for 15 min, and at least three independent experiments were performed; representative images are presented. e, LIFR expression in PCCs by qPCR and its positive correlation with the response intensity to LIF as illustrated in the heat map. n = 2 biological replicates. f, LIF secretion by PCCs and PSCs quantified by ELISA, and its negative correlation with the corresponding response intensity to LIF. n = 2 biological replicates. g, Cellular localization of Lif mRNA in pancreatic tumour tissues from KP^f/fCL mice was examined by multiplex fluorescent RNAscope assays. Ptprc (also known as Cd45) mRNA was co-stained to mark immune cells, and KRT19 was stained by immunofluorescence to mark cancer cells. Scale bars: red, 200 µm; white, 50 µm. h–j, pSTAT3 analysed by immunoblotting (h) and immunohistochemistry (i) in mouse pancreatic tissues, and by immunohistochemistry in human pancreatic tissues during the pathogenesis of PDAC (j). Scale bars: black, 500 µm; blue, 100 µm. For the histology assays on tissue sections (g, i, j), at least three tumour samples were stained and analysed, and representative images are presented.

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