An In Vitro and In Vivo Study of Combination Therapy with Photogem®-Mediated Photodynamic Therapy and Cisplatin on Mouse Cancer Cells (CT-26)

Abstract Background Identification of genomic biomarkers to predict the anticancer effects of indicated drugs is considered a promising strategy for the development of precision medicine. DNA endonuclease MUS81 plays a pivotal role in various biological processes during malignant diseases, mainly in DNA damage repair and replication fork stability. Our previous study reported that MUS81 was highly expressed and linked to tumor metastasis in gastric cancer; however, its therapeutic value has not been fully elucidated. Methods Bioinformatics analysis was used to define MUS81-related differential genes, which were further validated in clinical tissue samples. Gain or loss of function MUS81 cell models were constructed to elucidate the effect and mechanism of MUS81 on WEE1 expression. Moreover, the antitumor effect of targeting MUS81 combined with WEE1 inhibitors was verified using in vivo and in vitro assays. Thereafter, the cGAS/STING pathway was evaluated, and the therapeutic value of MUS81 for immunotherapy of gastric cancer was determined. Results In this study, MUS81 negatively correlated with the expression of cell cycle checkpoint kinase WEE1. Furthermore, we identified that MUS81 regulated the ubiquitination of WEE1 via E-3 ligase β-TRCP in an enzymatic manner. In addition, MUS81 inhibition could sensitize the anticancer effect of the WEE1 inhibitor MK1775 in gastric cancer in vitro and in vivo. Interestingly, when MUS81 was targeted, it increased the accumulation of cytosolic DNA induced by MK1775 treatment and activated the DNA sensor STING-mediated innate immunity in the gastric cancer cells. Thus, the WEE1 inhibitor MK1775 specifically enhanced the anticancer effect of immune checkpoint blockade therapy in MUS81 deficient gastric cancer cells. Conclusions Our data provide rational evidence that targeting MUS81 could elevate the expression of WEE1 by regulating its ubiquitination and could activate the innate immune response, thereby enhancing the anticancer efficacy of WEE1 inhibitor and immune checkpoint blockade combination therapy in gastric cancer cells.

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Nano-Mediated Photodynamic Therapy for Cancer: Enhancement of Cancer Specificity and Therapeutic Effects

10.20944/preprints201810.0271.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Ivan Mfouo Tynga ◽

Heidi Abrahamse

Keyword(s):

Photodynamic Therapy ◽

Cancer Cells ◽

Treatment Options ◽

Therapeutic Effects ◽

Drug Resistant ◽

Severe Condition ◽

Cell Niche ◽

Extended Exposure

Deregulation of cell growth and development lead to cancer, a severe condition that claims millions of lives worldwide. Targeted or selective approaches used during cancer treatment determine the efficacy and outcome of the therapy. In order to enhance specificity and targeting and better treatment options for cancer, novel and alternative modalities are currently under development. Photodynamic therapy has the potential to eradicate cancer and combination therapy would yield even greater outcomes. Nanomedicine-aided cancer therapy shows enhanced specificity for cancer cells and minimal side-effects coupled with effective cancer destruction both in vitro and in vivo. Nanocarriers used in drug-delivery systems are well able to penetrate cancer stem cell niche, simultaneously killing cancer cells and eradicate drug-resistant cancer stem cells, yielding therapeutic efficiency up to 100 fold against drug-resistant cancer in comparison with free drugs. Safety precautions should be considered when using Nano-mediated therapy as the effects of extended exposure to biological environments are still to be determined.

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