Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies worldwide, with a five-year survival rate remaining in the single digits.

Gemcitabine has long been a cornerstone of systemic therapy for PDAC, yet most patients eventually develop resistance, leading to disease progression and poor outcomes.

Despite decades of clinical use, the biological mechanisms underlying gemcitabine resistance have remained incompletely understood.

In a new study, researchers combined cutting-edge transcriptomic technologies with experimental validation to reveal how interactions between specific tumour and immune cell populations drive chemotherapy resistance in pancreatic cancer.

The work provides a comprehensive view of the cellular ecosystem that supports drug resistance and identifies new therapeutic vulnerabilities.

The study was published in Chinese Medical Journal.

Mapping resistance at single-cell resolution

To dissect the complexity of gemcitabine resistance, the research team integrated bulk RNA sequencing, single-cell RNA sequencing, and spatial transcriptomics from pancreatic cancer samples.

This multi-layered approach allowed them to not only identify resistance-associated gene programmes, but also pinpoint the exact cell types and spatial contexts in which these programmes operate.

The analysis revealed two cell populations that were consistently enriched in gemcitabine-resistant tumours: PRRX2+ epithelial cancer cells and SPP1+ tumour-associated macrophages (TAMs).

Importantly, these cells were not acting in isolation.

Computational modelling of cell–cell communication showed strong bidirectional signalling between the two populations, suggesting a coordinated resistance programme.

A TGF-β–driven resistance circuit

Further investigation identified the TGFB1/TGFBR2 signalling axis as the molecular bridge linking PRRX2+ epithelial cells (EC) and SPP1+ macrophages.

PRRX2, a transcription factor known to regulate cell plasticity, emerged as a central driver of this process.

In epithelial tumour cells, PRRX2 amplified TGF-β signalling, inducing epithelial–mesenchymal transition, a programme associated with enhanced invasiveness and drug tolerance.

At the same time, PRRX2 promoted extracellular matrix remodelling through activation of genes such as FN1, reshaping the tumour microenvironment into a dense, immunosuppressive niche.

This remodelled environment further supported the accumulation and activation of SPP1+ macrophages, which in turn reinforced resistance-promoting signals back to tumour cells.

Experimental and clinical validation

The researchers validated these findings using a combination of in vitro experiments and multicolor immunofluorescence analysis of patient samples.

Suppressing PRRX2 expression in pancreatic cancer cell lines significantly reduced cell migration, supporting its functional role in tumour aggressiveness.

In clinical cohorts, tumours with high levels of PRRX2+ epithelial cells and SPP1+ macrophages were associated with poorer prognosis, underscoring the clinical relevance of the identified axis.

Implications for treatment

Beyond mechanistic insight, the study points to potential therapeutic strategies.

Drug sensitivity analyses suggested that tumours enriched for the PRRX2+ EC/SPP1+ TAM signature may respond to dasatinib, a multi-kinase inhibitor, as well as antibody–drug conjugates targeting epithelial markers such as TROP2, MUC1, and CEACAM5.

These findings support the rationale for combination or precision therapies aimed at both tumour cells and their microenvironment.

A step toward precision therapy in PDAC

By revealing how specific epithelial and immune cell populations cooperate to drive gemcitabine resistance, this study advances understanding of pancreatic cancer biology and highlights the importance of tumour microenvironmental interactions.

The results suggest that overcoming drug resistance in PDAC will require strategies that disrupt these cellular communication networks, rather than targeting tumour cells alone.

As pancreatic cancer continues to pose a major clinical challenge, insights from integrative, single-cell–based studies such as this offer new hope for designing more effective, personalised treatment approaches.

Source: Chinese Medical Journals Publishing House Co., Ltd.