Mucins are key components of the mucosal barrier in the stomach that protects epithelia from carcinogenic effects of chronic inflammation. Analysis of The Cancer Genome Atlas database indicated that mucin-17 (MUC17) was more highly expressed in gastric cancer (GC) specimens, with favourable prognosis for patients. To explore the underlying mechanisms, we investigated the potential role of MUC17 in controlling chronic gastric inflammation. We initially quantified the expression of MUC17 and inflammatory factor, as well as the association of MUC17 with survive in GC using immunohistochemistry. To establish how the inflammatory factors affect MUC17 expression, we explored luciferase reporter, chromatin immunoprecipitation (ChIP), and electrophoretic mobility shift (EMSA) assays. The role and mechanism that MUC17 plays in inflammation-induced cell proliferation was examined in AGS cells with reduced MUC17 expression and MKN45 cells overexpressing a truncated MUC17. We found MUC17 was induced by inflammatory cytokines in GC cells via CDX1upregulation. MUC17 thus inactivated NFκB to inhibit GC cell proliferation in response to pro-inflammatory cytokines. We also revealed that the function of MUC17 was dependent on its conserved epidermal growth factor domain and on downstream sequences to enable its interaction with myosin-9, resulting in a sustained regulatory feedback loop between myosin-9, p53, and RhoA, and then activation of p38 to negatively regulate the NFκB pathway in GC cells. This mechanism was also confirmed in vivo. Our study demonstrates MUC17 as a GC suppressor protein which has the therapeutic potential for human GC.

BACKGROUND: The use of programmed death-1 blockade has a significant therapeutic effect in patients with mismatch repair-deficient/microsatellite instability-high metastatic colorectal cancer. However, data on preoperative single-agent programmed death-1 blockade are rare. OBJECTIVE: This study aims to evaluate the effectiveness and safety of preoperative programmed death-1 blockade as a conversion strategy in patients with locally advanced and resectable metastatic mismatch repair-deficient/microsatellite instability-high colorectal cancer. DESIGN: This is a retrospective observational study. SETTINGS: This study was conducted at a high-volume tertiary referral cancer center in China. PATIENTS: Twenty-four patients of consecutive cases since 2020 to 2022 with mismatch repair-deficient/microsatellite instability-high colorectal cancer who received preoperative single-agent programmed death-1 blockade were retrospectively reviewed. These patients had either bulking tumors scheduled for multivisceral resection, a strong desire for organ preservation, or potentially resectable metastatic lesions. MAIN OUTCOME MEASURES: Pathological complete response, clinical complete response, toxicity, R0 resection rate, and complications were evaluated. RESULTS: Patients tolerated preoperative immunotherapy well. The R0 resection rate was 95.2%, and the pathological complete response rate was 47.6%. Three patients (12.5%) were evaluated as having a clinical complete response and then underwent “watch and wait.” One-half of the patients with cT4b were spared multivisceral resection, whereas 60% (3/5) achieved pathological complete response. All 3 patients with liver metastases obtained complete response of all liver lesions after programmed death-1 blockade treatment. Grade III postoperative complications occurred in 2 patients. LIMITATIONS: The limitations of this study are as follows: retrospective study, small sample size, and short follow-up. CONCLUSIONS: Preoperative anti–programmed death-1 therapy alone as a conversion strategy in initially resected difficult mismatch repair-deficient/microsatellite instability-high colorectal cancer can achieve a high tumor complete response. The use of immunopreoperative therapy in patients with T4b colon cancer or low rectal cancer can reduce multivisceral resection and achieve high organ function preservation. See the Video Abstract. INMUNOTERAPIA NEOADYUVANTE SOLA PARA PACIENTES CON CÁNCER COLORRECTAL LOCALMENTE AVANZADO Y METASTÁSICO RESECABLE CON ESTADO dMMR/MSI-H: ANTECEDENTES: El uso del bloqueo de muerte programada-1 tiene un efecto terapéutico significativo en pacientes con cáncer colorrectal metastásico deficiente en reparación de desajustes/inestabilidad de microsatélites-alta (dMMR/MSI-H). Sin embargo, los datos sobre el bloqueo preoperatorio de muerte programada-1 con un solo agente son escasos. OBJETIVO: Este estudio tiene como objetivo evaluar la eficacia y seguridad del bloqueo preoperatorio de muerte programada-1 como estrategia de conversión en pacientes con cáncer colorrectal localmente avanzado y metastásico resecable con dMMR/MSI-H. DISEÑO: Este es un estudio observacional retrospectivo. ESCENARIO: Este estudio se realizó en un centro oncológico terciario de referencia de gran volumen en China. PACIENTES: Se revisaron retrospectivamente veinticuatro pacientes de casos consecutivos desde 2020-2022 con cáncer colorrectal y dMMR/MSI-H que recibieron bloqueo preoperatorio de muerte programada-1 con un solo agente. Estos pacientes tenían un tumor voluminoso programado para resección multivisceral, un fuerte deseo de preservación del órgano o lesiones metastásicas potencialmente resecables. PRINCIPALES MEDIDAS DE RESULTADO: Se evaluaron la respuesta patológica completa, la respuesta clínica completa, la toxicidad, la tasa de resección R0 y las complicaciones. RESULTADOS: Los pacientes toleraron bien la inmunoterapia preoperatoria. La tasa de resección R0 fue del 95,2% y la tasa de respuesta patológica completa fue del 47,6%. Tres pacientes (12,5%) fueron evaluados como respuesta clínica completa y luego sometidos a “observar y esperar”. La mitad de los pacientes cT4b se salvaron de la resección multivisceral, mientras que el 60% (3/5) lograron una respuesta patológica completa. Los tres pacientes con metástasis hepáticas obtuvieron respuesta completa de todas las lesiones hepáticas después del tratamiento de bloqueo de muerte programada-1. En dos pacientes se produjeron complicaciones postoperatorias de grado III. LIMITACIONES: Las limitaciones de este estudio son las siguientes: estudio retrospectivo, tamaño de muestra pequeño y seguimiento corto. CONCLUSIONES: La terapia preoperatoria anti muerte programada-1 sola como estrategia de conversión en el cáncer colorrectal inicialmente difícil de resecar con dMMR/MSI-H puede lograr una alta respuesta completa tumoral. El uso de terapia inmunopreoperatoria en pacientes con cáncer de colon T4b o cáncer de recto bajo puede reducir la resección multivisceral y lograr una alta preservación de la función del órgano. (Traducción—Dr. Felipe Bellolio)

Background: The inflammatory response plays an essential role in the tumor microenvironment (TME) of colorectal cancer (CRC) by modulating tumor growth, progression, and response to therapy through the recruitment of immune cells, production of cytokines, and activation of signaling pathways. However, the molecular subtypes and risk score prognostic model based on inflammatory response remain to be further explored.Methods: Inflammation-related genes were collected from the molecular signature database and molecular subtypes were identified using nonnegative matrix factorization based on the TCGA cohort. We compared the clinicopathological features, immune infiltration, somatic mutation profile, survival prognosis, and drug sensitivity between the subtypes. The risk score model was developed using LASSO and multivariate Cox regression in the TCGA cohort. The above results were independently validated in the GEO cohort. Moreover, we explored the biological functions of the hub gene, receptor interacting protein kinase 2 (RIPK2), leveraging proteomics data, in vivo, and in vitro experiments.Results: We identified two inflammation-related subtypes (inflammation-low and inflammation-high) and have excellent internal consistency and stability. Inflammation-high subtype showed higher immune cell infiltration and increased sensitivity to common chemotherapeutic drugs, while inflammation-low subtype may be more suitable for immunotherapy. Besides, the two subtypes differ significantly in pathway enrichment and biological functions. In addition, the 11-gene signature prognostic model constructed from inflammation-related genes showed strong prognostic assessment power and could serve as a novel prognostic marker to predict the survival of CRC patients. Finally, RIPK2 plays a crucial role in promoting malignant proliferation of CRC cell validated by experiment.Conclusions: This study provides new insights into the heterogeneity of CRC and provides novel opportunities for treatment development and clinical decision making.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease, characterized by relapsing and remitting colon mucosal inflammation. For patients suffering from UC, a higher risk of colon cancer has been widely recognized. Here, we found that Elf4(-/-) mice developed colon tumors with 3 cycles of dextran sulfate sodium salt (DSS) treatment alone. We further showed that ELF4 suppression was prevalent in both patients with UC and DSS-induced mice models, and this suppression was caused by promoter region methylation. ELF4, upon PARylation by PARP1, transcriptionally regulated multiple DNA damage repair machinery components. Consistently, ELF4 deficiency leads to more severe DNA damage both in vitro and in vivo. Oral administration of montmorillonite powder can prevent the reduction of ELF4 in DSS-induced colitis models and lower the risk of colon tumor development during azoxymethane (AOM) and DSS induced colitis-associated cancer (CAC). These data provided additional mechanism of CAC initiation and supported the "epigenetic priming model of tumor initiation''.

Efficacy and safety of preoperative immunotherapy in patients with mismatch repair-deficient or microsatellite instability-high gastrointestinal malignancies

In vitro patient tumor models such as patient-derived organoids (PDO) and conditionally reprogrammed (CR) cell culture are important for translational research and pre-clinical drug testing. In this study we present a personalized drug sensitivity test for late stage, potentially operable colorectal cancer (CRC) using patient-derived primary tumor cells isolated with i-CR technology, an optimized CR method. We explored the clinical feasibility of using i-CR platform to guide CRC chemotherapy, and established the correlation between in vitro drug sensitivity and patient clinical response. Primary CRC tumor cells were isolated and cultured with the i-CR technology. NGS was performed and the WES and CNV results of i-CR cells were compared with that of the original patient tumor samples. In vitro drug screenings were done with guideline chemotherapy drugs for CRC. In vivo drug response was examined with paired PDX mouse models. A double-blind co-clinical cohort study was carried out and the clinical outcomes of the enrolled patients were compared with the i-CR results. i-CR platform could be used to rapidly propagate primary colorectal tumor cells that represent individual patient tumors effectively by keeping the clonal heterogeneity and the genetic characteristics. Chemotherapy drug screenings with i-CR cells were comparable with that of PDX models. More importantly, i-CR results showed high accordance with the clinical outcomes of the enrolled CRC patients. i-CR platform was capable to test and optimize therapeutic regimens pre-clinically, study cancer cell biology, and model tumor re-emergence to identify new targeted therapeutics from an effective personalized medicine standpoint.