The role and clinical significance of LIF protein in paracrine signaling in pancreatic cancer

The poor prognosis of pancreatic ductal adenocarcinoma is primarily due to low diagnostic efficiency and strong tumor drug resistance. The activation of pancreatic stellate cells and the formation of dense stroma are key factors contributing to the aggressiveness of this tumor. The interaction between pancreatic stellate cells and pancreatic cancer cells not only promotes tumor progression and metastasis but also maintains the viability of both cell types, exacerbating tumor progression and drug resistance. Since pancreatic stellate cell activation occurs early in pancreatic ductal adenocarcinoma development and the tumor parenchyma largely consists of activated pancreatic stellate cells, it provides a rich source for detection. Therefore, elucidating the communication mechanisms between pancreatic stellate cells and pancreatic cancer cells holds promise for developing new strategies for the treatment and diagnosis of pancreatic ductal adenocarcinoma.

Using systemic proteomics techniques, researchers analyzed secretory disease mediators and potential molecular mechanisms, revealing a key paracrine factor from activated pancreatic stellate cells—LIF protein. Through mass spectrometry-based co-immunoprecipitation-mass spectrometry detection and quantitative proteomic analysis, it was found that STAT3 activation in pancreatic cancer cells was the sole response to stimulation by pancreatic stellate cell-conditioned medium, with the LIF receptor co-receptor IL6ST being the only protein interacting with it. Secretory protein analysis of human pancreatic cancer cell lines and human pancreatic stellate cell lines showed that only the latter produced high levels of LIF protein, indicating that LIF is the key paracrine factor responsible for STAT3 activation in pancreatic cancer cells.

LIF protein is a pleiotropic cytokine that regulates cell differentiation, proliferation, and survival and is involved in cancer development. In vitro assessments revealed that pancreatic cancer cells universally respond to LIF protein. Knocking out the LIF receptor in pancreatic cancer cells to block the LIF signaling pathway or immunodepleting the LIF ligand in pancreatic stellate cell-conditioned medium effectively inhibited STAT3 activation, further confirming LIF as the key paracrine factor for STAT3 activation in pancreatic cancer cells. In vivo validation showed that LIF protein was undetectable in normal pancreatic tissue but significantly present in pancreatic ductal adenocarcinoma tissues, indicating its association with the pathogenesis of pancreatic ductal adenocarcinoma.

Using gene knockout mouse models to evaluate the effect of intrinsic LIF receptor signaling in pancreatic cancer cells on pancreatic ductal adenocarcinoma, it was found that LIF receptor-deficient mice exhibited significantly increased overall survival, indicating that LIF receptor signaling in pancreatic cancer cells plays a clear role in pancreatic ductal adenocarcinoma development. Administration of antitumor drugs further prolonged mouse survival, suggesting that the LIF receptor contributes to increased chemotherapy resistance. Correspondingly, drug-treated LIF receptor-deficient mice showed reduced relative abundance of pancreatic cancer cells in tumors, indicating that LIF protein acts on pancreatic cancer cells to promote tumor progression.

The feasibility of LIF protein as a clinical therapeutic target was assessed using LIF-neutralizing monoclonal antibodies. Similar to LIF receptor depletion, LIF blockade increased overall mouse survival, and combined treatment with LIF blockade and antitumor drugs further prolonged survival and reduced tumor burden, confirming the significant role of LIF protein in pancreatic ductal adenocarcinoma progression and chemotherapy resistance. This treatment regimen significantly decreased pancreatic cancer cell abundance but had minimal impact on pancreatic stellate cells. Evaluation of pancreatic cancer cells revealed enhanced proliferation accompanied by increased apoptosis, which may enhance susceptibility to chemotherapy drugs, thereby alleviating chemotherapy resistance. Mechanistic studies found that combined therapy downregulated the expression of key genes involved in epithelial-mesenchymal transition and largely suppressed the Hippo, Wnt, and STAT3 signaling pathways.

Since LIF protein mediates tumor progression and pancreatic stellate cells are activated early in pancreatic ductal adenocarcinoma development, producing LIF protein with gradually increasing abundance, LIF levels are already significantly elevated in the early lesion stages of pancreatitis and small tumor nodules and steadily increase during tumor progression. Among various pathological parameters, LIF protein levels correlate with the differentiation status of pancreatic ductal adenocarcinoma and overall survival. The correlation between LIF protein and tumor pathology in both mouse and human pancreatic ductal adenocarcinoma suggests that LIF protein is a potential disease monitoring biomarker. Given the clinical requirement for easily collectable samples, ELISA assessment of LIF protein levels in blood samples revealed significant elevation in the context of pancreatic ductal adenocarcinoma, further supporting LIF protein's potential as a biomarker for monitoring pancreatic ductal adenocarcinoma status.

Nanjing UA-Biotech Co., Ltd. (UA-Bio) has independently developed "LIF Protein, Mouse" (Catalog No.: UA040061), a high-quality recombinant protein reagent specifically designed for mouse embryonic stem cell culture, pluripotency maintenance, and developmental biology research. This protein is mouse-derived leukemia inhibitory factor (LIF), which efficiently activates the LIF receptor signaling pathway, promotes embryonic stem cell self-renewal, inhibits differentiation, and participates in hematopoietic development, neural differentiation, and bone metabolism regulation. It provides a stable and reliable standardized tool for research in mouse embryonic stem cells, developmental biology exploration, and regenerative medicine.