Kristian Pietras lab

*The implications*
These results position CAF niches—not just CAF types—as actionable units. Precision targeting of CAF-defined functional niches may rewire tumor–immune interactions and enhance therapeutic responses in breast cancer.

*The novelty*
Spatial context matters: immunomodulatory CAFs co-localize with immune cells, whereas myofibroblastic CAFs form a barrier around the tumor core, limiting immune infiltration. CAF transcriptional programs are shaped by their local cellular neighborhoods.

*The findings*
By integrating scRNA-seq, multiplex immunostaining, and spatial analysis in murine and human breast tumors, we identified six CAF substates that occupy distinct, stage-dependent spatial niches within tumors.

*The scene*
Cancer-associated fibroblasts (CAFs) are major architects of the breast cancer microenvironment, yet how CAF heterogeneity emerges over time and space during tumor progression has remained unclear.

Spatial and temporal dynamics of cancer-associated fibroblast niches in breast cancer - Breast Cancer Research Breast Cancer Research - Cancer-associated fibroblasts (CAFs) are the main constituents of the tumor microenvironment. Several studies have delineated CAF heterogeneity in different types of...

Starting 2026 in style 🕺💃! New paper out from talented PhD-student @jessicapantaleo.bsky.social who conceptualized the breast tumor microenvironment to visualize architectural structure in cancer-associated fibroblast niches. Thanks to all funders and collaborators😇
link.springer.com/article/10.1...

Check this out👇
Our neighbors @pietraslab.bsky.social has just published a new preprint detailing high-resolution profiling of the irradiated GBM microenvironment. ❄️Cool reading for the holidays❄️ Thanks for including us!

Thanks for inspiring collaborations with @pietraslab.bsky.social @jonssonmelanomalab.bsky.social

We are grateful for generous support from @vetenskapsradet.bsky.social #Barncancerfonden #Cancerfonden #L2CancerBridge

7/ Therapeutic & translational implications
Strategies that preserve pericyte function might reinforce vascular and immune barriers against GBM progression.
Conversely, therapies that inadvertently deplete pericytes might worsen disease by unleashing immuno-suppressive and invasive programs.

6/ Take-home message
Pericytes are not merely passive structural cells — in GBM, they act as central conductors of microenvironmental signaling that restrain tumor growth and invasion. Their loss rewires the vasculature + immune microenvironment, fueling aggressive mesenchymal, MET-driven GBM.

5/ Clinical relevance
In human GBM, low expression of a pericyte core gene signature was observed more often in recurrent tumors vs primary. Also, the prevalence of FOSL1⁺ GBM cells correlated with poor patient survival. Pericyte loss may thus contribute to aggressive relapse of GBM.

4/ HGF → MET activation → mesenchymal invasion
TAMs express HGF, which boosts activation of the receptor MET on GBM cells — notably in those with a mesenchymal phenotype regulated by FOSL1. Thus: loss of pericytes → vascular & immune remodeling → HGF-MET signaling → mesenchymal, invasive GBM.

3/ What happens when pericytes are lost?
Genetic depletion of pericytes in mouse GBM models dramatically accelerated tumor growth and shortened survival. Mechanistically, pericyte loss remodels the tumor vasculature, recruiting tumor-associated immunosuppressive macrophages (TAMs).

2/ Pericytes = central communication nodes
By scRNAseq + cell-cell communication inference, we found that pericytes exhibit the highest paracrine signaling activity in human high-grade glioma. Thus, pericytes are not just passive structural cells; they are active “conductors” of signaling in GBM.

1/ What’s new?
Glioblastoma (GBM) is notoriously aggressive, driven by complex crosstalk between malignant cells and their microenvironment. Our work shows that pericytes, long-viewed mainly as vascular support cells, act as a major paracrine signaling hub that restrains tumor growth.

Pericytes orchestrate a tumor-restraining microenvironment in glioblastoma - Nature Communications Improved understanding of the tumor ecosystem in glioblastoma is critical for developing new treatment strategies for the disease. Here, the authors identify pericytes as an active paracrine signaling...

New paper alert 🚨
We are delighted to present our latest paper in @natcomms.nature.com through fabulous work from co-first authors Sebastian Braun and Paulina Bolivar! Big thanks to all expert collaborators for taking this long journey with us!
Tweetorial in comments 🧵
www.nature.com/articles/s41...

Reflecting on the 2025 EACR Cancer Neuroscience Conference in Bilbao- what a friendly, inspiring meeting with many opportunities to increase connectivity, in that case to fight tumors. Big ‘Thank you’ to the organizers!

Don’t miss a joint LUCC-LBIC-ZEISS-ACD seminar on visualization of gene expression and biomarker localization in 2D, 3D and 4D. 16th June, BMC, Lund.

Doctoral Student in Tumor Biology Description of the workplace The research group conducts experimental research on brain tumors and is led by Associate Professor Alexander Pietras. The group consists of a bioinformatician, two postdo

🚨 We’re hiring a bioinformatics-focused PhD student for our ERC-funded project on recurrent GBM! Focus: tumor-supportive microenvironment 🔬 Experience with scRNA-seq, spatial transcriptomics & Python/R a plus. Must be self-motivated & driven. DM for details! Repost=❤️ lu.varbi.com/en/what:job/...

Swedish Childhood Cancer Fund (BCF) is raising awareness and support: today it is #Fotbollströjefredagen (Football shirt Friday)

Postdoc in Experimental Oncology - Lund (Stad), Skåne (SE) job with Lund University | 12838990 Lunds universitet, 009999 LUNDS UNIVERSITET, 310000 MED Lund University was founded in 1666 and is repeatedly ranked among the world’s top universi...

Join us for innovative explorations of the tumor microenvironment🔬 Learn cutting-edge technologies and grow in a dynamic environment💡 The postdoc will work alongside a doctoral student from @adaptmet.bsky.social, gaining access to collaborative partners across 🇪🇺.
Apply now👇
tinyurl.com/4mby45hf

Targeting the most immune-suppressive macrophage with ALK1 inhibitors in malignant breast cancer!
@kpietraslab.bsky.social & team @lund-university.bsky.social target the most immune-suppressive macrophage with ALK1 inhibitors in malignant breast cancer models!
buff.ly/FXssb1x

Congratulations Kristian! @lundsuniversitet.bsky.social @lunduniversity-med.bsky.social

Kristian Pietras – Årets cancerforskare 2025 Kristian Pietras forskar om hur celler i blodkärl och bindväv påverkar cancerns möjlighet att växa eller dö. Nu tilldelas han utmärkelsen Årets cancerforskare.

We are proud to share that our PI has been named Cancer Researcher of the Year by @Cancerfonden! This well-deserved recognition highlights not only his outstanding contributions to cancer research but also his creativity in tackling scientific challenges and his inspiring leadership within our team.

🎉 Today, we gathered online for the #AdaptMet Kick-Off Meeting! A fantastic start to this journey, bringing together top researchers & partners to train the next generation of metastasis experts. Exciting discussions & collaborations ahead—stay tuned! 🔬✨ #CancerResearch

At the Brain Tumor Microenvironment Symposium @institutducerveau.bsky.social, Sebastian Braun presented our comprehensive study of pericytes in GBM 🤩. Pericytes act as guardians of the peri-vascular niche to prevent malignant cell invasion, read more at www.biorxiv.org/content/10.1...

@jessicapantaleo.bsky.social making us proud at the @lund-university.bsky.social Cancer Centre Tumor Microenvironment retreat by presenting our latest findings on CAF subtype spatial organization across longitudinally sampled experimental breast cancers.

Cancer-associated fibroblasts rewire the estrogen receptor response in luminal breast cancer, enabling estrogen independence - Oncogene Oncogene - Cancer-associated fibroblasts rewire the estrogen receptor response in luminal breast cancer, enabling estrogen independence

www.nature.com/articles/s41...

Readers Choice: The best of Oncogene 2024 In this collection we highlight a selection of articles from 2024, which top the list of the journal’s most cited, downloaded and most shared (including press ...

Thanks @oncogenejournal for highlighting our work on cancer-associated fibroblasts that enable endocrine resistance in luminal breast cancer
www.nature.com/collections/...