Radioresistance is one of the primary causes responsible for therapeutic failure and recurrence of cancer. It is well documented that reactive oxygen species (ROS) contribute to the initiation and development of gastric cancer (GC), and the levels of ROS are significantly increased in patients with GC accompanied with abnormal expressions of multiple inflammatory factors. It is also well documented that ROS can activate cancer cells and inflammatory cells, stimulating the release of a variety of inflammatory cytokines, which subsequently mediates the tumor microenvironment (TME) and promotes cancer stem cell (CSC) maintenance as well as renewal and epithelial‐mesenchymal transition (EMT), ultimately resulting in radioresistance and recurrence of GC.

Penile squamous cell carcinoma (PSCC) accounts for over 95% of penile malignancies and causes significant mortality and morbidity in developing countries. Molecular mechanisms and therapies of PSCC are understudied, owing to scarcity of laboratory models. Herein, we describe a genetically engineered mouse model of PSCC, by co-deletion of Smad4 and Apc in the androgen-responsive epithelium of the penis. Mouse PSCC fosters an immunosuppressive microenvironment with myeloid-derived suppressor cells (MDSCs) as a dominant population. Preclinical trials in the model demonstrate synergistic efficacy of immune checkpoint blockade with the MDSC-diminishing drugs cabozantinib or celecoxib. A critical clinical problem of PSCC is chemoresistance to cisplatin, which is induced by Pten deficiency on the backdrop of Smad4/Apc co-deletion. Drug screen studies informed by targeted proteomics identify a few potential therapeutic strategies for PSCC. Our studies have established what we believe to be essential resources for studying PSCC biology and developing therapeutic strategies.

The noninflamed microenvironment in prostate cancer represents a barrier to immunotherapy. Genetic alterations underlying cancer cell–intrinsic oncogenic signaling are increasingly appreciated for their role in shaping the immune landscape. Recently, we identified Pygopus 2 ( PYGO2 ) as the driver oncogene for the amplicon at 1q21.3 in prostate cancer. Here, using transgenic mouse models of metastatic prostate adenocarcinoma, we found that Pygo2 deletion decelerated tumor progression, diminished metastases, and extended survival. Pygo2 loss augmented the activation and infiltration of cytotoxic T lymphocytes (CTLs) and sensitized tumor cells to T cell killing. Mechanistically, Pygo2 orchestrated a p53/Sp1/Kit/Ido1 signaling network to foster a microenvironment hostile to CTLs. Genetic or pharmacological inhibition of Pygo2 enhanced the antitumor efficacy of immunotherapies using immune checkpoint blockade (ICB), adoptive cell transfer, or agents inhibiting myeloid-derived suppressor cells. In human prostate cancer samples, Pygo2 expression was inversely correlated with the infiltration of CD8 ⁺ T cells. Analysis of the ICB clinical data showed association between high PYGO2 level and worse outcome. Together, our results highlight a potential path to improve immunotherapy using Pygo2-targeted therapy for advanced prostate cancer.

Background. The mechanisms of crosstalk between depression and gastric cancer (GC) remain ill defined. Given that reactive oxygen species (ROS) is involved in the pathophysiology of both GC and depression, we try to explore the activities of ROS in the development of GC and GC-related depression. Methods. 110 patients with newly diagnosed GC were recruited in our study. The clinical characteristics of these patients were recorded. Inflammation and oxidative stress markers were detected by ELISA. The depression status of patients with GC was assessed during follow-up. The association between ROS, ABL1, and inflammation factors was evaluated in H₂O₂-treated GC cell lines and The Cancer Genome Atlas (TCGA) database. The effect of ABL1 on inflammation was detected with Imatinib/Nilotinib-treated GC cell lines. A chronic mild stress- (CMS-) induced patient-derived xenograft (PDX) mice model was established to assess the crosstalk between depression and GC. Results. Depression was correlated with poor prognosis of patients with GC. GC patients with depression were under a high level of oxidative status as well as dysregulated inflammation. In the CMS-induced GC PDX mice model, CMS could facilitate the development of GC. Additionally, tumor bearing could induce depressive-like behaviors of mice. With the treatment of ROS, the activities of ABL1 and inflammatory signaling were enhanced both in vitro and in vivo, and blocking the activities of ABL1 inhibited inflammatory signaling. Conclusions. ROS-activated ABL1 mediates inflammation through regulating NF-κB1 and STAT3, which subsequently leads to the development of GC and GC-related depression.

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Radiotherapy is used to treat gastric cancer (GC); however, radioresistance challenges the clinical outcomes of GC, and the mechanisms of radioresistance in GC remain poorly understood. Here, we report that the TGF-β receptor inhibitor, LY2109761 (LY), is a potential radiosensitizer both in vitro and in vivo. As per the Cancer Genome Atlas database, TGF-β overexpression is significantly related to poor overall survival in GC patients. We demonstrated that the TGF-β/SMAD4 signaling pathway was activated in both radioresistant GC cells and radioresistant GC patients. As a TGF-β receptor inhibitor, LY can enhance the activities of irradiation by inhibiting cell proliferation, decreasing clonogenicity and increasing apoptosis. Moreover, LY attenuated the radiation-induced migration and invasion, epithelial-mesenchymal transition (EMT), inflammatory factor activation, immunosuppression, and cancer stem cell characteristics of GC cells, thus leading to radiosensitization of the GC cells. We confirmed that LY reduced tumor growth, inhibited TGF-β/SMAD4 pathway activation and reversed irradiation-induced EMT in a tumor xenograft model. Our findings indicate that the novel TGF-β receptor inhibitor, LY, increases GC radiosensitivity by directly regulating the TGF-β/SMAD4 signaling pathway. These findings provide new insight for radiotherapy in GC patients.