Pancreatic ductal adenocarcinoma (PDAC) is characterized by a KRAS-driven inflammatory program and a desmoplastic stroma, which contribute to the profoundly chemoresistant phenotype. The tumor stroma contains an abundance of cancer-associated fibroblasts (CAF), which engage in extensive paracrine cross-talk with tumor cells to perpetuate protumorigenic inflammation. IL1α, a pleiotropic, tumor cell–derived cytokine, plays a critical role in shaping the stromal landscape. To provide insights into the molecular mechanisms regulating IL1A expression in PDAC, we performed transcriptional profiling of The Cancer Genome Atlas datasets and pharmacologic screening in PDAC cells and identified p38α MAPK as a key positive regulator of IL1A expression. Both genetic and pharmacologic inhibition of p38 MAPK significantly diminished IL1α production in vitro. Chromatin- and coimmunoprecipitation analyses revealed that p38 MAPK coordinates the transcription factors Sp1 and the p65 subunit of NFκB to drive IL1A overexpression. Single-cell RNA sequencing of a highly desmoplastic murine PDAC model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), confirmed that p38 MAPK inhibition significantly decreases tumor cell–derived Il1a and attenuates the inflammatory CAF phenotype in a paracrine IL1α-dependent manner. Furthermore, p38 MAPK inhibition favorably modulated intratumoral immunosuppressive myeloid populations and augmented chemotherapeutic efficacy to substantially reduce tumor burden and improve overall survival in PKT mice. These findings illustrate a cellular mechanism of tumor cell–intrinsic p38-p65/Sp1-IL1α signaling that is responsible for sustaining stromal inflammation and CAF activation, offering an attractive therapeutic approach to enhance chemosensitivity in PDAC. Significance: Inhibition of p38 MAPK suppresses tumor cell–derived IL1α and attenuates the inflammatory stroma and immunosuppressive tumor microenvironment to overcome chemotherapeutic resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a KRAS-driven inflammatory program and a desmoplastic stroma, which contribute to the profoundly chemoresistant phenotype. The tumor stroma contains an abundance of cancer-associated fibroblasts (CAF), which engage in extensive paracrine cross-talk with tumor cells to perpetuate protumorigenic inflammation. IL1α, a pleiotropic, tumor cell–derived cytokine, plays a critical role in shaping the stromal landscape. To provide insights into the molecular mechanisms regulating IL1A expression in PDAC, we performed transcriptional profiling of The Cancer Genome Atlas datasets and pharmacologic screening in PDAC cells and identified p38α MAPK as a key positive regulator of IL1A expression. Both genetic and pharmacologic inhibition of p38 MAPK significantly diminished IL1α production in vitro. Chromatin- and coimmunoprecipitation analyses revealed that p38 MAPK coordinates the transcription factors Sp1 and the p65 subunit of NFκB to drive IL1A overexpression. Single-cell RNA sequencing of a highly desmoplastic murine PDAC model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), confirmed that p38 MAPK inhibition significantly decreases tumor cell–derived Il1a and attenuates the inflammatory CAF phenotype in a paracrine IL1α-dependent manner. Furthermore, p38 MAPK inhibition favorably modulated intratumoral immunosuppressive myeloid populations and augmented chemotherapeutic efficacy to substantially reduce tumor burden and improve overall survival in PKT mice. These findings illustrate a cellular mechanism of tumor cell–intrinsic p38-p65/Sp1-IL1α signaling that is responsible for sustaining stromal inflammation and CAF activation, offering an attractive therapeutic approach to enhance chemosensitivity in PDAC.Significance:Inhibition of p38 MAPK suppresses tumor cell–derived IL1α and attenuates the inflammatory stroma and immunosuppressive tumor microenvironment to overcome chemotherapeutic resistance in pancreatic cancer.

Roughly 100,000 new cases of melanoma are diagnosed yearly in the United States, the majority of which are early-stage disease with excellent prognosis. However, a subset of patients harbors clinically occult aggressive biology that can go undetected on standard clinicopathologic analyses. Gene expression profiling (GEP) assays have emerged as molecular adjuncts to risk stratification, aiming to improve sentinel lymph node biopsy (SLNB) decision-making and surveillance planning. Two commercial tests are widely available: the 31-gene expression profile (31-GEP, DecisionDx-Melanoma, Castle Biosciences) and the clinicopathologic gene expression profile (CP-GEP, Merlin, SkylineDx). This review summarizes the current evidence for each assay regarding their performance and utility, with a focus on potentially actionable use cases, limitations, and the practical context in which these tools are most valuable.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a KRAS-driven inflammatory program and a desmoplastic stroma, which contribute to the profoundly chemoresistant phenotype. The tumor stroma contains an abundance of cancer-associated fibroblasts (CAF), which engage in extensive paracrine cross-talk with tumor cells to perpetuate protumorigenic inflammation. IL1α, a pleiotropic, tumor cell–derived cytokine, plays a critical role in shaping the stromal landscape. To provide insights into the molecular mechanisms regulating IL1A expression in PDAC, we performed transcriptional profiling of The Cancer Genome Atlas datasets and pharmacologic screening in PDAC cells and identified p38α MAPK as a key positive regulator of IL1A expression. Both genetic and pharmacologic inhibition of p38 MAPK significantly diminished IL1α production in vitro. Chromatin- and coimmunoprecipitation analyses revealed that p38 MAPK coordinates the transcription factors Sp1 and the p65 subunit of NFκB to drive IL1A overexpression. Single-cell RNA sequencing of a highly desmoplastic murine PDAC model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), confirmed that p38 MAPK inhibition significantly decreases tumor cell–derived Il1a and attenuates the inflammatory CAF phenotype in a paracrine IL1α-dependent manner. Furthermore, p38 MAPK inhibition favorably modulated intratumoral immunosuppressive myeloid populations and augmented chemotherapeutic efficacy to substantially reduce tumor burden and improve overall survival in PKT mice. These findings illustrate a cellular mechanism of tumor cell–intrinsic p38-p65/Sp1-IL1α signaling that is responsible for sustaining stromal inflammation and CAF activation, offering an attractive therapeutic approach to enhance chemosensitivity in PDAC.Significance:Inhibition of p38 MAPK suppresses tumor cell–derived IL1α and attenuates the inflammatory stroma and immunosuppressive tumor microenvironment to overcome chemotherapeutic resistance in pancreatic cancer.

Supplementary data for TCGA analysis in Figure 1 without the normalized tumor cellularity analysis

Supplementary Data for figure 3