SIRT1 deacetylates WEE1 and sensitizes cancer cells to WEE1 inhibition.

The cell-cycle checkpoint kinase WEE1 is emerging as a therapeutic target for cancer treatment. However, how its catalytic activity is regulated remains poorly understood, and reliable biomarkers for predicting response to WEE1 inhibitor remain to be identified. Here we identify an evolutionarily conserved segment surrounding its Lys177 residue that inhibits WEE1 activity through an intermolecular interaction with the catalytic kinase domain. Upon DNA damage, CHK1-dependent phosphorylation of WEE1 at Ser642 primes GCN5-mediated acetylation at Lys177, resulting in dissociation of the inhibitory segment from the kinase domain and subsequent activation of WEE1 and cell-cycle checkpoints. Conversely, SIRT1 associates with and deacetylates WEE1, which maintains it in an inactive state. Consequently, SIRT1 deficiency induces WEE1 hyperacetylation and activation, rendering cancer cells resistant to WEE1 inhibition. These results suggest that SIRT1 expression level and abundance of WEE1 Lys177 acetylation in tumor cells can serve as useful biomarkers for predicting WEE1 inhibitor sensitivity or resistance.

Ulva pertusa lectin 1 delivery through adenovirus vector affects multiple signaling pathways in cancer cells.

Ulva pertusa lectin 1 (UPL1) is a N-acetyl-D-glucosamine (GlcNAc) binding lectin in marine green alga Ulva pertusa. Exogenous UPL1 colocalized with protein arginine methyltransferase 5 (PRMT5), methylosome protein 50 (MEP50), ß-actin and ß-tubulin, indicating the interaction of UPL1 with the methylosome and cytoskeleton. UPL1 delivery through adenovirus vector (Ad-UPL1) dramatically induced extracellularly regulated protein kinases 1/2 (ERK1/2) phosphorylation in liver cancer cell lines BEL-7404 and Huh7. Signaling pathways including p38 mitogen-activated protein kinase (MAPK), and Akt were also affected by Ad-UPL1 in a cell type dependent manner. MEK1/2 inhibitor U0126, as well as to a lesser extent p38 MAPK inhibitor SB203580 and phosphoinositide 3-kinase (PI3K) inhibitor LY294002, completely eliminated a higher molecular weight isoform of ß-tubulin induced by Ad-UPL1, and significantly enhanced the cytotoxicity of Ad-UPL1 in Huh7 cells, suggesting that the inhibition of MEK1/2, p38 MAPK, and PI3K enhanced antiproliferative effect of Ad-UPL1 possibly through regulating the modification of ß-tubulin. Ad-UPL1 completely inhibited the expression of autophagy-related factor Beclin1, but induced LC3-II expression in Huh7 cells. In addition, Ad-UPL1 significantly enhanced starvation induced survival suppression in Huh7 cells. Our data elucidated intracellular signaling pathways affected by exogenous UPL1, and may provide insights into a novel way of UPL1 delivery through adenovirus vectors combined with survival signaling inhibitors for cancer treatment.

Oncolytic vaccine virus harbouring the IL-24 gene suppresses the growth of lung cancer by inducing apoptosis.

Lung cancer has an especially high incidence rate worldwide, and its resistance to cell death and chemotherapeutic drugs increases its intractability. The vaccinia virus has been shown to destroy neoplasm within a short time and disseminate rapidly and extensively as an enveloped virion throughout the circulatory system, and this virus has also demonstrated a strong ability to overexpress exogenous genes. Interleukin-24 (IL-24/mda-7) is an important cytokine that belongs to the activating caspase family and facilitates the inhibition of STAT3 when a cell enters the apoptosis pathway. In this study, we constructed a cancer-targeted vaccinia virus carrying the IL-24 gene knocked in the region of the viral thymidine kinase (TK) gene (VV-IL-24). Our results showed that VV-IL-24 efficiently infected and destroyed lung cancer cells via caspase-dependent apoptosis and decreased the expression of STAT3. In vivo, VV-IL-24 expressed IL-24 at a high level in the transplanted tumour, reduced STAT3 activity, and eventually led to apoptosis. In conclusion, we demonstrated that vv-IL-24 has the potential for use as a new human lung cancer treatment.