High-fat diet promotes prostate cancer metastasis via RPS27.

BACKGROUND: Metastasis is the leading cause of death among prostate cancer (PCa) patients. Obesity is associated with both PCa-specific and all-cause mortality. High-fat diet (HFD) is a risk factor contributing to obesity. However, the association of HFD with PCa metastasis and its underlying mechanisms are unclear. METHODS: Tumor xenografts were conducted by intrasplenic injections. The ability of migration or invasion was detected by transwell assay. The expression levels of RPS27 were detected by QRT-PCR and western blot. RESULTS: The present study verified the increase in PCa metastasis caused by HFD in mice. Bioinformatics analysis demonstrated increased RPS27 in the experimentally induced PCa in HFD mice, indicating that it is an unfavorable prognostic factor. Intrasplenic injections were used to demonstrate that RPS27 overexpression promotes, while RPS27 knockdown significantly reduces, PCa liver metastasis. Moreover, RPS27 inhibition suppresses the effects of HFD on PCa metastasis. Further mRNA sequencing analysis revealed that RPS27 promotes PCa metastasis by selectively enhancing the expression of various genes. CONCLUSION: Our findings indicate that HFD increases the risk of PCa metastasis by elevating RPS27 expression and, subsequently, the expression of genes involved in PRAD progression. Therefore, RPS27 may serve as a novel target for the diagnosis and treatment of metastatic PCa.

Prostate cancer cells synergistically defend against CD8+ T cells by secreting exosomal PD-L1.

BACKGROUND: Metastatic castration-resistant prostate cancer (mCRPC) remains fatal and incurable, despite a variety of treatments that can delay disease progression and prolong life. Immune checkpoint therapy is a promising treatment. However, emerging evidence suggests that exosomal programmed necrosis ligand 1 (PD-L1) directly binds to PD-1 on the surface of T cells in the drain lineage lymph nodes or neutralizes administered PD-L1 antibodies, resulting in poor response to anti-PD-L1 therapy in mCRPC. MATERIALS AND METHODS: Western blotting and immunofluorescence were performed to compare PD-L1 levels in exosomes derived from different prostate cancer cells. PC3 cells were subcutaneously injected into nude mice, and then ELISA assay was used to detect human specific PD-L1 in exosomes purified from mouse serum. The function of CD8+ T cells was detected by T cell mediated tumor cell killing assay and FACS analysis. A subcutaneous xenograft model was established using mouse prostate cancer cell RM1, exosomes with or without PD-L1 were injected every 3 days, and then tumor size and weight were analyzed to evaluate the effect of exosomal PD-L1. RESULTS: Herein, we found that exosomal-PD-L1 was taken up by tumor cells expressing low levels of PD-L1, thereby protecting them from T-cell killing. Higher levels of PD-L1 were detected in exosomes derived from the highly malignant prostate cancer PC3 and DU145 cell lines. Moreover, exosomal PD-L1 was taken up by the PD-L1-low-expressing LNCaP cell line and inhibited the killing function of CD8-T cells on tumor cells. The growth rate of RM1-derived subcutaneous tumors was decreased after knockdown of PD-L1 in tumor cells, whereas the growth rate recovered following exosomal PD-L1 tail vein injection. Furthermore, in the serum of mice with PCa subcutaneous tumors, PD-L1 was mainly present on exosomes. CONCLUSION: In summary, tumor cells share PD-L1 synergistically against T cells through exosomes. Inhibition of exosome secretion or prevention of PD-L1 sorting into exosomes may improve the therapeutic response of prostate tumors to anti-PD-L1 therapy.

Indoleamine 2,3-dioxygenase 1 regulates breast cancer tamoxifen resistance through interleukin-6/signal transducer and activator of transcription.

Breast cancer is the primary cause of cancer-related deaths in women. Tamoxifen (TAM) is the preferred drug for treating premenopausal luminal-type breast cancer, but TAM resistance restricts its ability to benefit patients. To date, the mechanism of this resistance remains unclear, and there is currently no effective treatment for reversing it. The expression of indoleamine 2,3-dioxygenase 1 (IDO1) has been shown to be elevated in various malignancies. Here, we aimed to investigate the role of IDO1 in TAM-resistant breast cancer. We confirmed that IDO1 is strongly expressed in TAM-resistant breast cancer, and it mediates drug-resistant cell proliferation, metastasis, and TAM resistance in vivo and in vitro through interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3). We also found that the mechanism by which TAM upregulates IDO1 is dependent on STAT1 activation. In summary, IDO1 regulates TAM resistance and can serve as a novel target for treatment of TAM-resistant breast cancer.

Identification of a potential tumor suppressor gene, UBL3, in non-small cell lung cancer.

Objective: Oncogenes have been shown to be drivers of non-small cell lung cancer (NSCLC), yet the tumor suppressing genes involved in lung carcinogenesis remain to be systematically investigated. This study aimed to identify tumor suppressing ubiquitin pathway genes (UPGs) that were critical to lung tumorigenesis. Methods: The 696 UPGs were silenced by an siRNA screening in NSCLC cells; the potential tumor suppressing UPGs were analyzed, and their clinical significance was investigated. Results: We reported that silencing of 11 UPGs resulted in enhanced proliferation of NSCLC cells, and four UPGs (UBL3, TRIM22, UBE2G2, and MARCH1) were significantly downregulated in tumor samples compared to that in normal lung tissues and their expression levels were positively associated with overall survival (OS) of NSCLC patients. Among these genes, UBL3 was the most significant one. UBL3 expression was decreased in tumor samples compared to that in paired normal lung tissues in 59/86 (68.6%) NSCLCs, was correlated with TNM stage and sex of NSCLC patients, and was significantly higher in non-smoking patients than in smoking patients. Silencing UBL3 accelerated cell proliferation and ectopic expression of UBL3 suppressed NSCLC in vitro and in vivo. Conclusions: These results showed that UBL3 represented a tumor suppressor in NSCLC and may have potential for use in therapeutics and for the prediction of clinical outcome of patients.

Systematic identification of CDC34 that functions to stabilize EGFR and promote lung carcinogenesis.

BACKGROUND: How the oncoprotein epidermal growth factor receptor (EGFR) evades proteolytic degradation and accumulates in non-small cell lung cancer (NSCLC) remains unclear, and ubiquitin pathway genes (UPGs) that are critical to NSCLC needs to be systematically identified. METHODS: A total of 696 UPGs (including E1, E2, E3, and deubiquitinases) were silenced by small interfering RNA (siRNA) library in NSCLC cells, the candidates were verified, and their significance was evaluated in patients with NSCLC. The effects of a candidate gene on EGFR were investigated in vitro and in vivo. FINDINGS: We report 31 candidates that are required for cell proliferation, with the E2 ubiquitin conjugase CDC34 as the most significant one. CDC34 is elevated in tumor tissues in 76 of 114 (66.7%) NSCLCs and inversely associated with prognosis, is higher in smoker patients than nonsmoker patients, and is induced by tobacco carcinogens in normal human lung epithelial cells. Forced expression of CDC34 promotes, whereas knockdown of CDC34 inhibits, NSCLC cell proliferation in vitro and in vivo. CDC34 competes with c-Cbl to bind Y1045 to inhibit polyubiquitination and degradation of EGFR. In EGFR-L858R and EGFR-T790M/Del (exon 19)-driven lung tumor growth in mouse models, knockdown of CDC34 significantly inhibits tumor formation. INTERPRETATION: These results demonstrate that an E2 enzyme is capable of competing with E3 ligase to stabilize substrates, and CDC34 represents an attractive therapeutic target for NSCLCs. FUNDING: National Key Research and Development Program of China, National Natural Science Foundation of China, and the CAMS Innovation Fund for Medical Sciences.

Identification of an E3 ligase-encoding gene RFWD3 in non-small cell lung cancer.

In order to unveil ubiquitin pathway genes (UPGs) that are essential for non-small cell lung cancer (NSCLC) cell proliferation, we recently conducted a siRNA screening experiment to knockdown the expression of 696 UPGs found in the human genome in A549 and H1975 NSCLC cells. We found that silencing of one of the candidates, RFWD3 that encodes an E3 ubiquitin ligase essential for the repair of DNA interstrand cross-links in response to DNA damage, led to dramatic inhibition of NSCLC cell proliferation with significant Z-scores. Knockdown of RFWD3 suppressed colony forming activity of NSCLC cells.We further evaluated the significance of RFWD3 in NSCLCs and found that this gene was more elevated in tumor samples than in paired normal lung tissues and was inversely associated with the clinical outcome of patients with NSCLC. Moreover, RFWD3 expression was significantly higher in smokers than in non-smokers. These results show for the first time that RFWD3 is required for NSCLC cell proliferation and may have an important role in lung carcinogenesis.

The Aryl hydrocarbon receptor mediates tobacco-induced PD-L1 expression and is associated with response to immunotherapy.

Whether tobacco carcinogens enable exposed cells immune escape resulting in carcinogenesis, and why patients who smoke respond better to immunotherapies than non-smokers, remains poorly understood. Here we report that cigarette smoke and the carcinogen benzo(a)pyrene (BaP) induce PD-L1 expression on lung epithelial cells in vitro and in vivo, which is mediated by aryl hydrocarbon receptor (AhR). Anti-PD-L1 antibody or deficiency in AhR significantly suppresses BaP-induced lung cancer. In 37 patients treated with anti-PD-1 antibody pembrolizumab, 13/16 (81.3%) patients who achieve partial response or stable disease express high levels of AhR, whereas 12/16 (75%) patients with progression disease exhibit low levels of AhR in tumor tissues. AhR inhibitors exert significant antitumor activity and synergize with anti-PD-L1 antibody in lung cancer mouse models. These results demonstrate that tobacco smoke enables lung epithelial cells to escape from adaptive immunity to promote tumorigenesis, and AhR predicts the response to immunotherapy and represents an attractive therapeutic target.

The red wine component ellagic acid induces autophagy and exhibits anti-lung cancer activity in vitro and in vivo.

Red wine consists of a large amount of compounds such as resveratrol, which exhibits chemopreventive and therapeutic effects against several types of cancers by targeting cancer driver molecules. In this study, we tested the anti-lung cancer activity of 11 red wine components and reported that a natural polyphenol compound ellagic acid (EA) inhibited lung cancer cell proliferation at an efficacy approximately equal to that of resveratrol. EA markedly increased the expression of the autophagosomal marker LC3-II as well as inactivation of the mechanistic target of rapamycin signalling pathway. EA elevated autophagy-associated cell death by down-regulating the expression of cancerous inhibitor of protein phosphatase 2A (CIP2A), and CIP2A overexpression attenuated EA-induced autophagy of lung cancer cells. Treating tumour-bearing mice with EA resulted in significant inhibition of tumour growth with suppression of CIP2A levels and increased autophagy. In addition, EA potentiated the inhibitory effects of the natural compound celastrol on lung cancer cells in vitro and in vivo by enhancing autophagy and down-regulating CIP2A. These findings indicate that EA may be a promising chemotherapeutic agent for lung cancer, and that the combination of EA and celastrol may have applicability for the treatment of this disease.

Genome-wide identification of transcription factors that are critical to non-small cell lung cancer.

To systematically unveil transcription factors (TFs) that are critical to lung carcinogenesis, here we conducted a genome-wide lethality screening in non-small cell lung cancer (NSCLC) cells and reported that among the 1530 TFs tested, 21 genes were required for NSCLC cell proliferation and were negatively or positively associated with overall survival (OS) of patients with NSCLC. These included 11 potential tumor suppressing genes (AFF3, AhR, AR, CBFA2T3, CHD4, KANK2, NR3C2, PTEN, PRDM16, RB1, and STK11) and 10 potential oncogenic TFs (BARX1, DLX6, ELF3, EN1, ETV1, FOXE1, HOXB7, IRX4, IRX5, and SALL1). The expression levels of IRX5 were positively associated with OS of smoker and inversely associated with OS of non-smoker patients with lung adenocarcinoma. We showed that tobacco carcinogen benzo(a)pyrene (BaP) induced upregulation of IRX5 in lung epithelial cells, and Cyclin D1 was a downstream target of IRX5. Furthermore, silencing of IRX5 by lentivirus mediated transfection of short hairpin RNA significantly inhibited tumor growth in nude mice. These results indicate that tobacco smoke can modulate TFs to facilitate lung carcinogenesis, and inhibition of IRX5 may have therapeutic potentials in NSCLCs.

Carcinogens that induce the A:T > T:A nucleotide substitutions in the genome.

Recently, Ng et al. reported that the A:T > T:A substitutions, proposed to be a signature of aristolochic acid (AA) exposure, were detected in 76/98 (78%) of patients with hepatocellular carcinoma (HCC) from the Taiwan Province of China, and 47% to 1.7% of HCCs from the Chinese mainland and other countries harbored the nucleotide changes. However, other carcinogens, e.g., tobacco carcinogens 4-aminobiphenyl and 1,3-butadiene, air toxic vinyl chloride and its reactive metabolites chloroethylene oxide, melphalan and chlorambucil, also cause this signature in the genome. Since tobacco smoke is a worldwide public health threat and vinyl chloride distributes globally and is an air pollutant in Taiwan Province, the estimation of the patients' exposure history is the key to determine the "culprit" of the A:T > T:A mutations. Apparently, without estimation of the patients' exposure history, the conclusion of Ng et al. is unpersuasive and misleading.

Long non-coding RNA stabilizes the Y-box-binding protein 1 and regulates the epidermal growth factor receptor to promote lung carcinogenesis.

Indoor and outdoor air pollution has been classified as group I carcinogen in humans, but the underlying tumorigenesis remains unclear. Here, we screened for abnormal long noncoding RNAs (lncRNAs) in lung cancers from patients living in Xuanwei city which has the highest lung cancer incidence in China due to smoky coal combustion-generated air pollution. We reported that Xuanwei patients had much more dysregulated lncRNAs than patients from control regions where smoky coal was not used. The lncRNA CAR intergenic 10 (CAR10) was up-regulated in 39/62 (62.9%) of the Xuanwei patients, which was much higher than in patients from control regions (32/86, 37.2%; p=0.002). A multivariate regression analysis showed an association between CAR10 overexpression and air pollution, and a smoky coal combustion-generated carcinogen dibenz[a,h]anthracene up-regulated CAR10 by increasing transcription factor FoxF2 expression. CAR10 bound and stabilized transcription factor Y-box-binding protein 1 (YB-1), leading to up-regulation of the epidermal growth factor receptor (EGFR) and proliferation of lung cancer cells. Knockdown of CAR10 inhibited cell growth in vitro and tumor growth in vivo. These results demonstrate the role of lncRNAs in environmental lung carcinogenesis, and CAR10-YB-1 represents a potential therapeutic target.

The combination therapy of high-intensity focused ultrasound with radiotherapy in locally advanced pancreatic carcinoma.

BACKGROUND: The aim of the present study is to evaluate the effectiveness of the combined application of high-intensity focused ultrasound (HIFU) and radiotherapy in the treatment of locally advanced pancreatic carcinoma (LAPC). METHODS: A total number of sixteen patients with LAPC started treatment beginning with HIFU and radiotherapy 1 week after the HIFU treatment. Evaluation of the effectiveness of treatment was performed using main clinical symptoms, serum levels of CA-19-9, Response Evaluation Criteria in Solid Tumors (RECIST) guidelines, and the Kaplan-Meier method for estimating median overall survival (OS). The occurrence of adverse reactions was recorded. RESULTS: The main clinical symptoms including abdominal pain and lower back pain were alleviated, and the mean visual analog scale (VAS) pain score declined from 5.1 points to just 3.3 points immediately after the HIFU treatment. The median pain relief time was 5.6 months after radiotherapy, serum CA-19-9 levels began to decrease significantly 1 week after the HIFU treatment, from 102.1 to 60.8 U/ml, and the median continuous decline time was 4.3 months after radiotherapy. Partial response (PR) was observed in seven of sixteen patients, with stable disease (SD) in four patients, and progressive disease (PD) in the remaining five patients at 6 months after radiotherapy. Serum levels of amylopsin and lipase were not elevated to abnormal levels. The median OS was 14 months. No serious adverse reactions occurred. CONCLUSIONS: Treatment with both HIFU and radiotherapy can quickly improve symptoms and the quality of life and prolong survival lengths. This combination might be a promising therapeutic treatment for patients with LAPC.