FBXL5-mediated degradation of single-stranded DNA-binding protein hSSB1 controls DNA damage response.

Human single-strand (ss) DNA binding proteins 1 (hSSB1) has been shown to participate in DNA damage response and maintenance of genome stability by regulating the initiation of ATM-dependent signaling. ATM phosphorylates hSSB1 and prevents hSSB1 from ubiquitin-proteasome-mediated degradation. However, the E3 ligase that targets hSSB1 for destruction is still unknown. Here, we report that hSSB1 is the bona fide substrate for an Fbxl5-containing SCF (Skp1-Cul1-F box) E3 ligase. Fbxl5 interacts with and targets hSSB1 for ubiquitination and degradation, which could be prevented by ATM-mediated hSSB1 T117 phosphorylation. Furthermore, cells overexpression of Fbxl5 abrogated the cellular response to DSBs, including activation of ATM and phosphorylation of ATM targets and exhibited increased radiosensitivity, chemosensitivity and defective checkpoint activation after genotoxic stress stimuli. Moreover, the protein levels of hSSB1 and Fbxl5 showed an inverse correlation in lung cancer cells lines and clinical lung cancer samples. Therefore, Fbxl5 may negatively modulate hSSB1 to regulate DNA damage response, implicating Fbxl5 as a novel, promising therapeutic target for lung cancers.

17-AAG suppresses growth and invasion of lung adenocarcinoma cells via regulation of the LATS1/YAP pathway.

The large tumour suppressor 1 (LATS1) signalling network has been proved to be an essential regulator within the cell, participating in multiple cellular phenotypes. However, it is unclear concerning the clinical significance of LATS1 and the regulatory mechanisms of 17-Allylamino-17- demethoxygeldanamycin (17-AAG) in lung adenocarcinoma (LAC). The aim of the present study was to investigate the correlation of LATS1 and yes-associated protein (YAP) expression with clinicopathological characteristics in LAC patients, and the effects of 17-AAG on biological behaviours of LAC cells. Subcutaneous LAC tumour models were further established to observe the tumour growth in nude mice. The results showed that the positive expression of LATS1 was significantly lowered (26.7% versus 68.0%, P < 0.001), while that of YAP was elevated (76.0% versus 56.0%, P = 0.03) in LAC tissues compared to the adjacent non-cancerous tissues; LAST1 expression was negatively correlated with YAP expression (r = 0.432, P < 0.001) and lymphatic invasion of the tumour (P = 0.015). In addition, 17-AAG inhibited proliferation and invasion, and induced cell apoptosis and cycle arrest in LAC cells together with increased expression of E-cadherin and p-LATS1, and decreased expression of YAP and connective tissue growth factor. Tumour volumes and weight were much smaller in 17-AAG-treated groups than those in untreated group (P < 0.01). Taken together, our findings indicate that decreased expression of LATS1 is associated with lymphatic invasion of LAC, and 17-AAG suppresses growth and invasion of LAC cells via regulation of the LATS1/YAP pathway in vitro and in vivo, suggesting that we may provide a promising therapeutic strategy for the treatment of human LAC.

[Short-term intermittent prophylactic administration of recombinant human thrombopoietin attenuates chemotherapy-induced thrombocytopenia in lung cancer patients].

OBJECTIVE: To evaluate the efficacy of short-term intermittent prophylactic use of a recombinant human thrombopoietin (rhTPO) in chemotherapy-induced severe thrombocytopenia in lung cancer patients. METHODS: 24 advanced non-small cell lung cancer (NSCLC) patients who experienced severe thrombocytopenia in the last chemotherapy cycle received prophylactic rhTPO treatment in the next chemotherapy cycle (prophylactic treated cycle, PTC). rhTPO was given subcutaneously 300 U×kg(-1)×d(-1) on days 2, 4, 6, and 9 after the initiation of chemotherapy. Platelet count was monitored and compared with that in the previous treatment cycle (control cycle, CC). RESULTS: The lowest platelet count in the prophylactic rhTPO cycle was significantly higher than that in control cycle [(56 ± 16) × 10(9)/L vs. (28 ± 13) × 10(9)/L, P < 0.001]. The duration of thrombocytopenia was also shortened by the prophylactic rhTPO [(8 ± 2) d vs. (12 ± 3) d, P < 0.001]. The area under curve (AUC) of platelet count (21 days) was significantly increased [(3517 ± 685) × 10(9)/L vs. (2063 ± 436) × 10(9)/L, P < 0.001]. The time to platelet nadir and peak was not affected. CONCLUSION: Prophylactic use of rhTPO can attenuate the severity and shorten the duration of chemotherapy-induced thrombocytopenia in lung cancer patients.

MiR-516a-5p inhibits the proliferation of non-small cell lung cancer by targeting HIST3H2A.

The dysregulation of microRNAs (miRNAs) is associated with the pathogenesis of non-small cell lung cancer (NSCLC). However, the mechanisms by which miR-516a-5p contributes to NSCLC remain unclear. The association between miR-516a-5p expression and the clinicopathological characteristics and prognosis in patients with NSCLC was analyzed by The Cancer Genome Atlas (TCGA) data set. The targets of miR-516a-5p were identified by bioinformatic analysis and luciferase report assay. MTT and soft agar assays were conducted to investigate the function of miR-516a-5p in NSCLC cells. We found that the expression of miR-516a-5p was decreased in NSCLC tissues and associated with the age, pathological stage, and tumor size, acting as an independent prognostic factor of tumor recurrence in patients with NSCLC. Restoration of miR-516a-5p inhibited the cell viability and anchorage-independent growth of NSCLC cells, but its inhibitor had the opposite effects. Histone cluster 3 H2A (HIST3H2A) was further identified as a direct target of miR-516a-5p and displayed a negative correlation with miR-516a-5p expression in NSCLC tissues. Overexpression of HIST3H2A reversed the anti-proliferation effects induced by miR-516a-5p and acted as an independent prognostic factor of poor survival in patients with NSCLC. Altogether, our findings demonstrate that miR-516a-5p may function as a tumor suppressive factor in NSCLC cells by targeting HIST3H2A and might represent a potential indicator of tumor recurrence in patients with NSCLC.

C3: Consensus Cancer Driver Gene Caller.

Next-generation sequencing has allowed identification of millions of somatic mutations in human cancer cells. A key challenge in interpreting cancer genomes is to distinguish drivers of cancer development among available genetic mutations. To address this issue, we present the first web-based application, consensus cancer driver gene caller (C3), to identify the consensus driver genes using six different complementary strategies, i.e., frequency-based, machine learning-based, functional bias-based, clustering-based, statistics model-based, and network-based strategies. This application allows users to specify customized operations when calling driver genes, and provides solid statistical evaluations and interpretable visualizations on the integration results. C3 is implemented in Python and is freely available for public use at http://drivergene.rwebox.com/c3.

[Evaluation of recombinant human thrombopoietin in the treatment of chemotherapy-induced thrombocytopenia in lung cancer patients].

OBJECTIVE: To evaluate the efficacy and safety of recombinant human thrombopoietin (rhTPO) in treatment for chemotherapy-induced thrombocytopenia in patients with lung cancer. METHODS: Fifty-one lung cancer patients with platelet count < 100 x 10(9)/L after chemotherapy were enrolled into this study. They were divided into three groups: mild, moderate and severe thrombocytopenia groups according to the platelet count. rhTPO was subcutaneously administered at a dosage of 300 microg kg(-1) d(-1) until the platelet count >or= 100 x 10(9)/L or absolute value of platelet count >or= 50 x 10(9)/L. Laboratory tests included routine blood count, serum biochemistry, and blood coagulation test. RESULTS: The duration of the chemotherapy-induced thrombocytopenia was significantly shorter in the mild group than that in the moderate and severe groups (P < 0.01). After administration of rhTPO, the time of declined platelet count beginning to recover was also significantly shorter in the mild group than that in the moderate and severe groups (P < 0.01). There was a statistically significant difference in platelet transfusion needed among the three groups (P < 0.01). However, no significant difference was found among the three groups in the time of rhTPO treatment (P > 0.05) and platelet count improvement (P > 0.05). CONCLUSION: Recombinant human thrombopoietin can be effectively and safely administered to deal with grade III/IV chemotherapy-induced thrombocytopenia in lung cancer patients with mild adverse effects.