Biology subjects

Spurr, L. F.

Publications and source records attributed to Spurr, L. F..

2 recordsLinked to original sources

bioRxiv2021

Chromosomal instability mediates immune exclusion and response to cytotoxic chemotherapy in colorectal liver metastases

The genomic drivers of immune exclusion in colorectal cancer liver metastases (CRCLM) remain poorly understood. Chromosomal instability (CIN), resulting in aneuploidy and genomic rearrangements, is the central pathway of mismatch repair-proficient colorectal cancer pathogenesis; however, it is unknown whether CIN impacts the outcomes of patients with limited spread of CRCLM treated with curative intent cytotoxic chemotherapy and surgery. Herein, we examined the relationship between CIN and the molecular subtypes of CRCLM, immune signaling, treatment sensitivity, and patient outcomes in three independent CRCLM patient cohorts. We established that a previously developed 70-gene CIN signature (CIN70) is a reliable measure of CIN, encompassing features of both aneuploidy and cellular proliferation. We demonstrated that tumors with the canonical subtype of CRCLM exhibit elevated levels of CIN and aneuploidy. Genomically unstable tumors were associated with an immune-depleted tumor microenvironment, and patients with genomically unstable tumors were at increased risk for disease progression in adverse metastatic sites, resulting in poor progression-free and overall survival. However, high-CIN tumors were particularly susceptible to DNA-damaging chemotherapies, including topoisomerase inhibitors, as well as radiation therapy. Treatment with genotoxic agents depleted CIN-rich cell populations, which resulted in a concomitant increase in intratumoral CD8+ T-cells in patients with primary rectal, breast, and bladder cancer. Taken together, we propose a mechanistic explanation for why cytotoxic chemotherapy can augment anti-tumor immunity and improve outcomes in patients with genomically unstable cancers.

cancer biology↗

bioRxiv2020

Transcriptional subtype-specific microenvironmental crosstalk and tumor cell plasticity in metastatic pancreatic cancer

Bulk transcriptomic studies have defined classical and basal-like gene expression subtypes in pancreatic ductal adenocarcinoma (PDAC) that correlate with survival and response to chemotherapy; however, the underlying mechanisms that govern these subtypes and their heterogeneity remain elusive. Here, we performed single-cell RNA-sequencing of 23 metastatic PDAC needle biopsies and matched organoid models to understand how tumor cell-intrinsic features and extrinsic factors in the tumor microenvironment (TME) shape PDAC cancer cell phenotypes. We identify a novel cancer cell state that co-expresses basal-like and classical signatures, demonstrates upregulation of developmental and KRAS-driven gene expression programs, and represents a transitional intermediate between the basal-like and classical poles. Further, we observe structure to the metastatic TME supporting a model whereby reciprocal intercellular signaling shapes the local microenvironment and influences cancer cell transcriptional subtypes. In organoid culture, we find that transcriptional phenotypes are plastic and strongly skew toward the classical expression state, irrespective of genotype. Moreover, we show that patient-relevant transcriptional heterogeneity can be rescued by supplementing organoid media with factors found in the TME in a subtype-specific manner. Collectively, our study demonstrates that distinct microenvironmental signals are critical regulators of clinically relevant PDAC transcriptional states and their plasticity, identifies the necessity for considering the TME in cancer modeling efforts, and provides a generalizable approach for delineating the cell-intrinsic versus -extrinsic factors that govern tumor cell phenotypes.

cancer biology↗