As the use of zinc oxide nanoparticles (ZnO NPs) in everyday products grows, so does concern about health risks. However, no findings on the gastrointestinal toxicity of ZnO NPs have been published. We investigated the possible malignant transformation of ZnO NPs in the mice's colonic tissues using the APC^min/+ mouse model with a premalignant lesion in intestinal epithelial cells. Higher doses and long-term oral exposure to ZnO NPs were found to mildly promote colonic inflammation in WT mice, while they moderately or strongly exacerbated the severity of chronic inflammation and tumorigenesis in APC^min/+ mice with intestinal adenomatous polyposis. The ZnO NPs-induced inflammation and tumorigenesis in colonic epithelial cells was linked to the activation of CXCR2/NF-κB/STAT3/ERK and AKT pathways. Analysis of the ZnO NPs-exacerbated intestinal adenomatous polyposis in APC^min/+ mice revealed that ZnO NPs could activate the APC-driven Wnt/β-catenin signaling pathway, exacerbating intestinal tumorigenesis. In fact, ZnO NPs have been shown to increase intestinal inflammation and tumorigenesis in APC^min/+ mice by releasing free Zn²⁺. In WT mice, a low dose of ZnO NPs (26 mg/kg/day) did not cause intestinal inflammation. In conclusion, higher doses and prolonged exposure to ZnO NPs promote the malignant transformation of precancerous epithelial cells.

Insulin-like growth factor-1 receptor (IGF-1R) has been made an attractive anticancer target due to its overexpression in cancers. However, targeting it has often produced the disappointing results as the role played by cross talk with numerous downstream signalings. Here, we report a disobliging IGF-1R signaling which promotes growth of cancer through triggering the E3 ubiquitin ligase MEX3A-mediated degradation of RIG-I. The active β-arrestin-2 scaffolds this disobliging signaling to talk with MEX3A. In response to ligands, IGF-1Rβ activated the basal βarr2 into its active state by phosphorylating the interdomain domain on Tyr64 and Tyr250, opening the middle loop (Leu130‒Cys141) to the RING domain of MEX3A through the conformational changes of βarr2. The models of βarr2/IGF-1Rβ and βarr2/MEX3A could interpret the mechanism of the activated-IGF-1R in triggering degradation of RIG-I. The assay of the mutants βarr2^Y64A and βarr2^Y250A further confirmed the role of these two Tyr residues of the interlobe in mediating the talk between IGF-1Rβ and the RING domain of MEX3A. The truncated-βarr2 and the peptide ATQAIRIF, which mimicked the RING domain of MEX3A could prevent the formation of βarr2/IGF-1Rβ and βarr2/MEX3A complexes, thus blocking the IGF-1R-triggered RIG-I degradation. Degradation of RIG-I resulted in the suppression of the IFN-I-associated immune cells in the TME due to the blockade of the RIG-I-MAVS-IFN-I pathway. Poly(I:C) could reverse anti-PD-L1 insensitivity by recovery of RIG-I. In summary, we revealed a disobliging IGF-1R signaling by which IGF-1Rβ promoted cancer growth through triggering the MEX3A-mediated degradation of RIG-I.

The well-known insulin-like growth factor 1 (IGF1)/IGF-1 receptor (IGF-1R) signaling pathway is overexpressed in many tumors, and is thus an attractive target for cancer treatment. However, results have often been disappointing due to crosstalk with other signals. Here, we report that IGF-1R signaling stimulates the growth of hepatocellular carcinoma (HCC) cells through the translocation of IGF-1R into the ER to enhance sarco-endoplasmic reticulum calcium ATPase 2 (SERCA2) activity. In response to ligand binding, IGF-1Rβ is translocated into the ER by β-arrestin2 (β-arr2). Mass spectrometry analysis identified SERCA2 as a target of ER IGF-1Rβ. SERCA2 activity is heavily dependent on the increase in ER IGF-1Rβ levels. ER IGF-1Rβ phosphorylates SERCA2 on Tyr⁹⁹⁰ to enhance its activity. Mutation of SERCA2-Tyr⁹⁹⁰ disrupted the interaction of ER IGF-1Rβ with SERCA2, and therefore ER IGF-1Rβ failed to promote SERCA2 activity. The enhancement of SERCA2 activity triggered Ca²⁺_ER perturbation, leading to an increase in autophagy. Thapsigargin blocked the interaction between SERCA2 and ER IGF-1Rβ and therefore SERCA2 activity, resulting in inhibition of HCC growth. In conclusion, the translocation of IGF-1R into the ER triggers Ca²⁺_ER perturbation by enhancing SERCA2 activity through phosphorylating Tyr⁹⁹⁰ in HCC.

Dihydropyrimidine dehydrogenase (DPD) is a major determinant of cancer 5-fluorouracyl (5-FU) resistance via its direct degradation. However, the mechanisms of tumoral DPD upregulation have not been fully understood. This study aimed to explore the role of S1PR2 in the regulation of tumoral DPD expression, identifying S1PR2 as the potential target for reversing 5-FU resistance. Western blot was used to analyze S1PR2 expression in cultured cancer cells and human colorectal cancer (CRC) tissues. 5-FU resistance was estimated in mouse xenografts of HT-29^sh-S1PR2 and SW480^S1PR2 cells. HPLC-UV was used to measure 5-FU levels in the xenografts. Chromatin immunoprecipitation (ChIP) was used to analyze the binding of YAP1/TEAD1 to the TWIST1 promoter. A luciferase reporter was used to analyze the binding of TWIST1 to the DPYD promoter. S1PR2 was highly expressed in cancer cell lines and human CRC tissues. Activation of S1PR2 upregulated DPD expression, leading to 5-FU resistance. Mechanistically, activated S1PR2 upregulated nuclear TWIST1 by activating the Hippo/TEAD1-TWIST1 pathway. Nuclear TWIST1 interacted with the JMJD3-RNA Pol II complex, resulting in the interaction of TWIST1 with the DPYD promoter, thus increasing H3K27me3-enriched DPYD transcription. These findings were confirmed in xenografted human colon cancer cells in nude mice. Transfection with an S1PR2 expression vector led to the upregulation of DPD, blunting the sensitivity of SW480^S1PR2 cells to 5-FU by 45.14 %. Conversely, knockdown of S1PR2 resulted in a decrease of DPD, thus increasing the sensitivity of HT-29^sh-S1PR2 cells to 5-FU by 62.12 %. Molecular analysis of these xenografts confirmed the role of S1PR2 in upregulating DPD expression by activating the Hippo/TEAD1-JMJD3 pathway. Activation of S1PR2 upregulated DPD expression by activating the Hippo/TWIST1-JMJD3 pathway. S1PR2 is therefore a potential target for novel inhibitors that may reverse 5-FU resistance in cancer therapy.