Da Song

Clinical and experimental evidence has shown that tumor-associated macrophages promote cancer initiation and progression. However, the macrophage-derived molecular determinants that regulate colorectal cancer metastasis have not been fully characterized. Here, we demonstrate that M2 macrophage-regulated colorectal cancer cells' migration and invasion is dependent upon M2 macrophage-derived exosomes (MDE). MDE displayed a high expression level of miR-21-5p and miR-155-5p, and MDE-mediated colorectal cancer cells' migration and invasion depended on these two miRNAs. Mechanistically, miR-21-5p and miR-155-5p were transferred to colorectal cancer cells by MDE and bound to the BRG1 coding sequence, downregulating expression of BRG1, which has been identified as a key factor promoting the colorectal cancer metastasis, yet is downregulated in metastatic colorectal cancer cells. Collectively, these findings show that M2 macrophages induce colorectal cancer cells' migration and invasion and provide significant plasticity of BRG1 expression in response to tumor microenvironments during malignant progression. This dynamic and reciprocal cross-talk between colorectal cancer cells and M2 macrophages provides a new opportunity for the treatment of metastatic colorectal cancer. SIGNIFICANCE: These findings report a functional role for miRNA-containing exosomes derived from M2 macrophages in regulating migration and invasion of colorectal cancer cells.

Extracellular cytokines are enriched in the tumor microenvironment and regulate various important properties of cancers, including autophagy. However, the precise molecular mechanisms underlying the link between autophagy and extracellular cytokines remain to be elucidated. In the present study, we demonstrate that IL-6 activates autophagy through the IL-6/JAK2/BECN1 pathway and promotes chemotherapy resistance in colorectal cancer (CRC). Mechanistically, IL-6 triggers the interaction between JAK2 and BECN1, where JAK2 phosphorylates BECN1 at Y333. We demonstrate that BECN1 Y333 phosphorylation is crucial for BECN1 activation and IL-6-induced autophagy by regulating PI3KC3 complex formation. Furthermore, we investigate BECN1 Y333 phosphorylation as a predictive marker for poor CRC prognosis and chemotherapy resistance. Combination treatment with autophagy inhibitors or pharmacological agents targeting the IL-6/JAK2/BECN1 signaling pathway may represent a potential strategy for CRC cancer therapy.

Immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) or programmed cell death 1 ligand 1 (PD-L1) have enabled some patients with cancer to experience durable, complete treatment responses; however, reliable anti-PD-(L)1 treatment response biomarkers are lacking. Our research found that PD-L1 K162 was methylated by SETD7 and demethylated by LSD2. Furthermore, PD-L1 K162 methylation controlled the PD-1/PD-L1 interaction and obviously enhanced the suppression of T cell activity controlling cancer immune surveillance. We demonstrated that PD-L1 hypermethylation was the key mechanism for anti-PD-L1 therapy resistance, investigated that PD-L1 K162 methylation was a negative predictive marker for anti-PD-1 treatment in patients with non-small cell lung cancer, and showed that the PD-L1 K162 methylation:PD-L1 ratio was a more accurate biomarker for predicting anti-PD-(L)1 therapy sensitivity. These findings provide insights into the regulation of the PD-1/PD-L1 pathway, identify a modification of this critical immune checkpoint, and highlight a predictive biomarker of the response to PD-1/PD-L1 blockade therapy.