Antitumor activity of iNGR-GRIM-19 in colorectal cancer

Autophagy: A Versatile Player in the Progression of Colorectal Cancer and Drug Resistance

Colorectal cancer (CRC) is among the topmost malignancies for both genders. Despite the high incidence rate and advances in diagnostic tools, treatment in many cases is still ineffective. Most cancerous lesions in CRC begin as benign, followed by the development of invasive forms and metastases. The development of CRC has been linked to defects in autophagy, which plays both a pro-and anti-tumor role and is mainly context-dependent. Autophagy suppression could enhance apoptosis via p53 activation, or autophagy also promotes tumor progression by maintaining tumor growth and increasing resistance to chemotherapy. Autophagy promotes the invasion and metastasis of CRC cells via increased epithelial-mesenchymal transition (EMT). Moreover, dysbiosis of gut microbiota upregulated autophagy and metastasis markers. Autophagy responses may also modulate the tumor microenvironment (TME) via regulating the differentiation process of several innate immune cells. Treatments that promote tumor cell death by stimulating or inhibiting autophagy could be beneficial if used as an adjunct treatment, but the precise role of various autophagy-modulating drugs in CRC patients is needed to be explored. In this article, we present an overview of the autophagy process and its role in the pathogenesis and therapeutic resistance of CRC. Also, we focused on the current understanding of the role of the EMT and TME, including its relation to gut microbiota and immune cells, in autophagic manipulation of CRC. We believe that there is a potential link between autophagy, TME, EMT, and drug resistance, suggesting that further studies are needed to explore this aspect.

GRIM-19 inhibits proliferation and induces apoptosis in a p53-dependent manner in colorectal cancer cells through the SIRT7/PCAF/MDM2 axis

Colorectal cancer (CRC) is the leading deadly cancer worldwide. Gene associated with retinoid-IFN-induced mortality-19 (GRIM-19), a novel tumor suppressor, has been reported to be expressed at low levels in human CRC. However, the role of GRIM-19 in CRC progression and the corresponding detailed mechanisms are unclear. The results of this study indicated that GRIM-19 expression is related to CRC progression. Overexpression of GRIM-19 was found to inhibit CRC cell proliferation and induce apoptosis in vitro and in vivo. Our results demonstrated that GRIM-19 suppresses CRC through posttranslational regulation of p53, in which SIRT7 is activated by GRIM-19 and triggers PCAF-mediated MDM2 ubiquitination, eventually stabilizing the p53 protein. We also observed that GRIM-19 enhances the effect of oxaliplatin against CRC. In conclusion, GRIM-19 plays an important role in CRC development and is a potential biomarker and therapeutic target for clinical treatment of CRC.

GRIM-19 repressed hypoxia-induced invasion and EMT of colorectal cancer by repressing autophagy through inactivation of STAT3/HIF-1α signaling axis

Hypoxia leads to cancer progression and promotes the metastatic potential of cancer cells. Thereby, the aim of the present study was to investigate the detailed effects of gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) in colorectal cancer (CRC) cell lines under hypoxia conditions and explore the potential molecular mechanisms. Here, we observed that GRIM-19 expression was downregulated in several CRC cell lines as well as in HCT116 and Caco-2 cells under a hypoxic microenvironment. Additionally, the introduction of GRIM-19 obviously suppressed cell invasive ability and epithelial-mesenchymal transition (EMT) through modulating EMT markers as reflected by the upregulation of E-cadherin along with the downregulation of vimentin and N-cadherin under hypoxic conditions. Moreover, the addition of GRIM-19 repressed hypoxia-induced autophagy through modulating autophagy associated proteins as reflected by the downregulation of LC3-II/LC3-I ratio and Beclin-1 expression, as well as the increased of p62 expression. Interestingly, overexpression of GRIM-19 markedly ameliorated the accumulation of HIF-1α triggered by hypoxia accompanied by an inhibition of vascular endothelial growth factor (VEGF) production and phospho-signal transducer and activator of transcription 3 (p-STAT3) expression. Further data demonstrated that GRIM-19 have a negative feedback effect on the expression of HIF-1α. Mechanistically, re-expression of HIF-1α completely reversed the inhibitory effects of GRIM-19 on hypoxia-induced invasion and EMT. Taken all data together, our findings established that GRIM-19 suppresses hypoxia-triggered invasion and EMT by inhibiting hypoxia-induced autophagy through inactivation HIF-1α/STAT3 signaling pathway, indicating that GRIM-19 may serve as a potential predictive factor and therapeutic target for CRC treatment.

Molecular Imaging of Aminopeptidase N in Cancer and Angiogenesis

This review focuses on recent advances in the molecular imaging of aminopeptidase N (APN, also known as CD13), a zinc metalloenzyme that cleaves N-terminal neutral amino acids. It is overexpressed in multiple cancer types and also on the surface of vasculature undergoing angiogenesis, making it a promising target for molecular imaging and targeted therapy. Molecular imaging probes for APN are divided into two large subgroups: reactive and nonreactive. The structures of the reactive probes (substrates) contain a reporter group that is cleaved and released by the APN enzyme. The nonreactive probes are not cleaved by the enzyme and contain an antibody, peptide, or nonpeptide for targeting the enzyme exterior or active site. Multivalent homotopic probes utilize multiple copies of the same targeting unit, whereas multivalent heterotopic molecular probes are equipped with different targeting units for different receptors. Several recent preclinical cancer imaging studies have shown that multivalent APN probes exhibit enhanced tumor specificity and accumulation compared to monovalent analogues. The few studies that have evaluated APN-specific probes for imaging angiogenesis have focused on cardiac regeneration. These promising results suggest that APN imaging can be expanded to detect and monitor other diseases that are associated with angiogenesis.