MicroRNAs (miRNAs) are small noncoding RNAs that potentially play a critical role in tumorigenesis. Mounting evidence indicates that one specific miRNA: miR-320b is down regulated in numerous human cancers, including colorectal cancer (CRC); making the hypothesis that miR-320b may play a key role in tumorigenesis plausible. However, its role in carcinogenesis remains poorly defined. The goal of this study is to better clarify the role of miR-320b in tumor growth of CRC. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-320b in CRC tissues and 5 CRC cell lines. The effect of miR-320b on cell proliferation was analyzed in vitro and in vivo. Furthermore, a luciferase reporter assay was performed to measure the target effects of miR-320b. Lastly, the messenger RNA (mRNA) and protein levels of the gene c-MYC were measured in CRC cell lines and tissues by qRT-PCR, and confirmed via Western blot and Immunohistochemical (IHC) staining. The results presented here showed that miR-320b expression was down regulated in both CRC tissues and cells. Overexpression of miR-320b in CRC cells was statistically correlated with a decrease of cell growth in vitro and in vivo, while c-MYC was identified as a target gene of miR-320b in CRC. Furthermore, it was found that up-regulation of c-Myc can attenuate the effects induced by miR-320b. Our identification of c-MYC as a target gene of miR-320b provides new insights into the pathophysiology of CRC proliferation, and identifies miR-320b as a novel therapeutic target for the treatment of CRC.

Colorectal Cancer (CRC) is one of the most common gastrointestinal tumors, and its high tumor heterogeneity makes traditional sequencing methods incapable of obtaining information about the heterogeneity of individual cancer cells in CRC. Therefore, single-cell sequencing technology can be applied to better analyze the differences in genetic and protein information between cells, to obtain genomic sequence information of single cells, and to more thoroughly analyze the cellular characteristics and interactions in the CRC microenvironment. This will provide a more comprehensive understanding of colorectal cancer development and metastasis and indicate the treatment plan and prognosis. In this study, we review the application of single-cell sequencing to analyze the tumor microenvironment of CRC, explore the mechanisms involved in CRC metastasis and progression, and provide a reference for potential treatment options.

: The tumor microenvironment (TME) plays a critical role in shaping tumor progression and determining the outcome of the therapeutic response. In this study, we aimed to generate a comprehensive cellular landscape of the colorectal cancer (CRC) TME. : We generated a comprehensive single-cell atlas by collecting CRC cases that have been uploaded to the online database and conducting an in-depth secondary analysis. We then carried out spatial transcriptomic sequencing and multiple immunohistochemical analyses to verify the results of the single-cell analysis. Moreover, we applied our findings to the TCGA database and used tissue microarray (TMA) on CRC tissue specimens to validate clinical prognosis. We re-analyzed the transcriptomes of 23785 cells, revealing a pattern of cell heterogeneity in the tumor region, leading-edge region, and non-tumor region. A subtype of COL11A1+INHBA+ tumor-resident cancer-associated fibroblasts (CAFs) was identified, and marker genes, transcription factors, and tissue-specific expression differences were noted and suggested to have potential roles in promoting cancer. We further confirmed that COL11A1+INHBA+ tumor-resident CAFs are mainly located in the hypoxic TME and we propose that they interact with CD44+ CRC cells via INHBA. Elevation of INHBA in CRC is associated with a poor prognosis. : Our results demonstrated a single cell landscape of CRC in different regions and identified in hypoxic TME a special subtype of CAFs producing INHBA, which promotes CRC development and correlates with poor prognosis. This special subtype of CAFs is a candidate target for translational research.