Primary tumor resection in colorectal cancer patients with unresectable distant metastases: a minireview.

Colorectal cancer (CRC) is the second most common cause of cancer-related death among both men and women worldwide and the third most common cancer overall. About 20% of patients diagnosed with CRC were discovered to have distant metastatic lesions, the majority of which were located in the liver. For the optimum treatment of CRC patients with hepatic metastases, interventional radiologists, medical oncologists, and surgeons must all collaborate. The surgical excision of the primary tumor is an important part of CRC treatment since it has been found to be curative in cases of CRC with minimal metastases. However, given the evidence to date was gathered from retrospective data, there is still controversy over the effectiveness of primary tumor resection (PTR) in improving the median overall survival (OS) and quality of life. Patients who have hepatic metastases make up a very tiny fraction of those who are candidates for resection. With a focus on the PTR, this minireview attempted to review the current advancements in the treatment options for hepatic colorectal metastatic illness. This evaluation also included information on PTR's risks when performed on individuals with stage IV CRC.

"Cold" colorectal cancer faces a bottleneck in immunotherapy.

The advent of immunotherapy and the development of immune checkpoint inhibitors (ICIs) are changing the way we think about cancer treatment. ICIs have shown clinical benefits in a variety of tumor types, and ICI-based immunotherapy has shown effective clinical outcomes in immunologically "hot" tumors. However, for immunologically "cold" tumors such as colorectal cancer (CRC), only a limited number of patients are currently benefiting from ICIs due to limitations such as individual differences and low response rates. In this review, we discuss the classification and differences between hot and cold CRC and the current status of research on cold CRC, and summarize the treatment strategies and challenges of immunotherapy for cold CRC. We also explain the mechanism, biology, and role of immunotherapy for cold CRC, which will help clarify the future development of immunotherapy for cold CRC and discovery of more emerging strategies for the treatment of cold CRC.

The miR-145-MMP1 axis is a critical regulator for imiquimod-induced cancer stemness and chemoresistance.

Cancer stemness, chemoresistance, and metastasis are related biological events. However, whether they have common molecular mechanisms remains to be determined. Here, we report that imiquimod (IMQ) facilitates the acquisition of stem-cell-like properties and chemoresistance via the upregulation of matrix metalloproteinase 1 (MMP1) and downregulation of microRNA-145 (miR-145). MiR-145-5p was found to suppress MMP1 expression through direct binding, and miR-145-mediated downregulation of MMP1 reversed the effects of IMQ. In addition, IMQ downregulated miR-145 by promoting DNA methylation at its promoter. DNA methyltransferase inhibitors limited IMQ-induced MMP1 expression, stemness, and chemoresistance. Collectively, our results highlight the miR-145-MMP1 axis as a potential coordinator of cancer stemness and chemoresistance. Given the role of MMP1 in the initiation of metastasis, the miR-145-MMP1 axis serves as a promising therapeutic target for improved cancer treatment.

Relationship between microsatellite status and immune microenvironment of colorectal cancer and its application to diagnosis and treatment.

Due to advances in understanding the immune microenvironment of colorectal cancer (CRC), microsatellite classification (dMMR/MSI-H and pMMR/MSS) has become a key biomarker for the diagnosis and treatment of CRC patients and therefore has important clinical value. Microsatellite status is associated with a variety of clinicopathological features and affects drug resistance and the prognosis of patients. CRC patients with different microsatellite statuses have different compositions and distributions of immune cells and cytokines within their tumor microenvironments (TMEs). Therefore, there is great interest in reversing or reshaping CRC TMEs to transform immune tolerant "cold" tumors into immune sensitive "hot" tumors. This requires a thorough understanding of differences in the immune microenvironments of MSI-H and MSS type tumors. This review focuses on the relationship between CRC microsatellite status and the immune microenvironment. It focuses on how this relationship has value for clinical application in diagnosis and treatment, as well as exploring the limitations of its current application.

Colorectal cancer-derived exosomal miR-106b-3p promotes metastasis by down-regulating DLC-1 expression.

Cancer-derived exosomal miRNAs play an important role in the development of metastasis, but the effects and underlying mechanisms remain unclear. In the present study, we investigated the miRNA expression profiles of 5 paired serum exosomal samples from metastatic colorectal cancer (mCRC) and non-mCRC patients via RNA sequencing. After we evaluated the differentially expressed miRNAs in 80 CRC patients, miR-106b-3p was selected as a metastasis-associated miRNA of CRC. We showed that the expression level of serum exosomal miR-106b-3p was significantly higher in CRC patients with metastasis than those without metastasis. Additionally, high serum exosomal miR-106b-3p expression in patients was correlated with a poor prognosis. Coculture of low-metastatic CRC cells with high-metastatic CRC cell-derived exosomes promoted cell migration, invasion, and epithelial-to-mesenchymal transition (EMT), which was caused by the transport and transduction of miR-106b-3p in vitro. Moreover, exosomal miR-106b-3p promoted lung metastasis of CRC cells in vivo. In addition, we demonstrated that miR-106b-3p regulated metastasis by targeting deleted in liver cancer-1 (DLC-1). A negative correlation was also identified between miR-106b-3p and DLC-1 expression in human CRC tumour tissues and in mouse lung metastatic lesions. Collectively, our study indicated that metastasis-associated miR-106b-3p from serum exosomes could be used as a potential prognostic biomarker and therapeutic target for CRC patients.