ABSTRACT
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 βarr2Y64A and βarr2Y250A 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.
ABSTRACT
Aim To evaluate the efficacy of TFU as a precursor of 5-FU on the growth inhibition of human gastric carcinoma cell lines SGC-7901 and MKN-45.Methods In vitro experiments,cell growth inhibition was measured by MTT assay.The rates were compared in the presence and Absence of liver microsomal enzymes.The morphology of apoptotic cells was detected by observation with a fluorescence microscope after staining by using adridine orange/ethidium bromide solution.DNA fragmentation was analyzed by agarose gel electrophoresis and flow cytometry respectively.Western blot was employed to analyze the expression of Bcl-2 and Bax.The in vivo efficacy of TFU was assessed in nude mice bearing tumours.The specimens were re-moved and the in situ cell apoptosis detection kit was employed for TUNEL staining.Results Growth of SGC-7901 and MKN-45 cells was remarkably suppressed by treatment with TFU in the presence of liver microsomal enzymes in vitro,suggesting that TFU might be converted to 5-FU by the enzymes.Similar treatment of TFU induced apoptosis of the cells,which was deduced from typical apoptotic features such as morphology,the formation of characteristic ladder pattern of DNA migration and the accumulation of sub-G1 phase.Furthermore,a significant inhibition of Bcl-2 expression and the up-regulation of Bax were observed after treatment with TFU in the presence of liver microsomal enzymes.Growth of human gastric carcinoma cells was significantly delayed by oral administration of TFU with low side effects.Apoptosis in xenografts was also observed by means of TUNEL staining method.Conclusion Treatment of TFU in the presence of liver microsomal enzymes could promote the inhibition of gastric carcinoma cell proliferation.TFU might sustain release of 5-FU mediated by liver microsomal enzymes.Low dose of 5-FU might trigger the carcinoma cells apoptosis via regulation of Bax and Bcl-2.
ABSTRACT
This paper describes the inhibitory effects of antineoplaston A10 with using different dosages against the mouse S180, rats W256 and Bca - P6 and MGC cell (human) in nude mouse. When the administered dosage of oral formulation antineoplaston A10 was 4000mg ? kg-1 ? 24h-1 against the S180 for 10d . inhibitory rate was 32. 5%( P