Ser289 phosphorylation activates both DAPK1 and DAPK2 but in response to different intracellular signaling pathways

The microRNA-520a-3p inhibits invasion and metastasis by targeting NF-kappaB signaling pathway in non-small cell lung cancer

PURPOSE

To identify the expression of miR-520a-3p and AKT1 in non-small cell lung cancer cells (NSCLC) and the mechanism in inhibiting cell invasion and metastasis by targeting NF-kappaB signaling pathway.

METHODS

Bioinformatics analysis and dual luciferase reporter gene assay were used to predict and verify the targeting relationship between miR-520a-3p and AKT1. EdU assay was used to detect the proliferation of NSCLC cells. Flow cytometry detected the apoptosis of NSCLC cells. Transwell assay tested the invasion ability of NSCLC cells. qRT-PCR measured the expression of miR-520a-3p and AKT1 mRNA in NSCLC cells; while western blotting was adopted to detect the protein expressions of AKT1, Ki67, CyclinD1, Bax, Bcl-2, MMP-2, MMP-9, NF-kB p65, IkBs kinase (IKK), NF-kB inducing kinase (NIK).

RESULTS

Bioinformatics analysis suggested that miR-520a-3p could target AKT1. miR-520a-3p could regulate the expression of AKT1 negatively. Compared to mimic-NC group, miR-520a-3p mimic group had increased expressions of miR-520a-3p and Bax, while decreased expressions of AKT1, Ki67, CyclinD1, Bcl-2, MMP-2, MMP-9, NF-kB p65, IKK and NIK, reduced cell proliferation, invasion, and increased cell apoptosis rate (all P < 0.05). Compared to inhibitor NC group, miR-520a-3p inhibitor group had decreased expressions of miR-520a-3p and Bax, but increased expressions of AKT1, Ki67, CyclinD1, Bcl-2, MMP-2, MMP-9, NF-kB p65, IKK and NIK, promoted cell proliferation, invasion, and suppressed cell apoptosis rate (all P < 0.05).

CONCLUSION

Overexpression of miR-520a-3p can target and downregulate the expression of AKT1 to inhibit the invasion and metastasis of NSCLC via suppressing the activation of NF-kappaB signaling pathway.

The impact of DAPK1 and mTORC1 signaling association on autophagy in cancer

BACKGROUND

The autophagy pathway is used by eukaryotic cells to maintain metabolic homeostasis. Autophagy has two functions in cancerous cells which could inhibit tumorigenesis or lead to cancer progression by increasing cell survival and proliferation.

METHODS AND RESULTS

In this review article, Web of Science, PubMed, Scopus,  and Google Scholar were searched and summarized published studies to explore the relationship between DAPK1 and mTORC1 signaling association on autophagy in cancer. Autophagy is managed through various proteins including the mTOR, which is two separated structural and functional complexes known as mTORC1 and mTORC2. MTORC1 is an important component of the regulatory pathway affecting numerous cellular functions including proliferation, migration, invasion, and survival. This protein plays a key role in human cancers. The activity level of mTORC1 is regulated by the death-associated protein kinases (DAPks) family, especially DAPK1. In many cancers, DAPK1 acts as a tumor suppressor which can be attributed to its ability to suppress cellular transformation and to inhibit metastasis.

CONCLUSIONS

A deep investigation not only will reveal more about the function of DAPK1 but also might provide insights into novel therapies aimed to modulate the autophagy pathway in cancer and to achieve better cancer therapy.

DAPK2 activates NF-κB through autophagy-dependent degradation of I-κBα during thyroid cancer development and progression

Background

Death-associated protein kinase 2 (DAPK2) is a serine/threonine kinase, which has been implicated in autophagy and apoptosis. DAPK2 functions as a tumor suppressor in various cancers. However, the role of DAPK2 in thyroid cancer (TC) is unclear.

Methods

RNA sequencing of human TC samples was performed to identify differentially expressed genes that may play a role in TC development. The messenger RNA (mRNA) expression of DAPK2 was verified by quantitative real-time polymerase chain reaction (qRT-PCR). To investigate the role of DAPK2 in TC development, DAPK2 was knocked down and overexpressed in a TTA1 cell line. The effect of DAPK2 on cell proliferation, sensitization of TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis and tumor growth was examined. The effect of DAPK2 on autophagy and NF-κB activation was investigated to address the underlying mechanism.

Results

DAPK2 was upregulated in TC. Knockdown of DAPK2 in TTA1 cells led to reduced cell proliferation, sensitization of TRAIL-induced apoptosis, and restricted tumor growth both in vitro and in vivo, while overexpression of DAPK2 exhibited the opposite effect. Mechanistically, DAPK2 promoted autophagy as demonstrated by the accumulation of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, which correlated with the level of nuclear factor-κB (NF-κB) activation. Knockdown of inhibitory-κBα (I-κBα) in short hairpin (sh) DAPK2 TTA1 cells restored the activity of NF-κB, suggesting DAPK2 activated NF-κB through autophagy-mediated I-κBα degradation.

Conclusions

Our findings revealed a pivotal role of DAPK2 in thyroid carcinogenesis, being required for tumor growth and for resistance to TRAIL-induced apoptosis through autophagy-mediated I-κBα degradation. This result provides a novel target for the therapy of TC.