Guodong Xiao

Fibronectin protects lung cancer cells against docetaxel-induced apoptosis by promoting Src and caspase-8 phosphorylation

Fibronectin is involved in orchestrating many diverse cellular behaviors, including adhesion, invasion, differentiation, and proliferation and recently has also been shown to participate in the development of chemoresistance. In this study, we found that fibronectin expression was inversely correlated with clinical responses to docetaxel treatment in non-small cell lung cancer patients. Subsequently, we showed that fibronectin pretreatment could enhance cell viability and reduce apoptosis in docetaxel-treated lung cancer cells because fibronectin induced phosphorylated Src and caspase-8, rendering the later inactive, thus inhibiting docetaxel-induced apoptosis. The inhibition of apoptosis by fibronectin was found to be enhanced by Src overexpression and reversed by Src knockdown in lung cancer cells. Further investigation revealed that a downregulation of phospho-Src via treatment with a Src kinase inhibitor could also abolish fibronectin activity and recover docetaxel-induced apoptosis. Molecular studies revealed that this reversion was due to decreased phospho-Src levels rather than a reduction in total Src expression. Inhibition of phospho-Src reduced phospho-caspase-8 and promoted caspase-8 activity, restoring apoptosis following docetaxel and fibronectin co-treatment. Finally, xenografts experiments demonstrated that fibronectin promoted lung cancer cell proliferation during docetaxel treatment in vivo. Our findings indicate that fibronectin promotes Src and caspase-8 phosphorylation in lung cancer cells, which decreases caspase-8 activation and protects tumor cells from docetaxel-induced apoptosis. Therefore, the fibronectin/Src/caspase-8 pathway may play a crucial role in docetaxel resistance in lung cancer.

LCL161 increases paclitaxel-induced apoptosis by degrading cIAP1 and cIAP2 in NSCLC

BackgroundLCL161, a novel Smac mimetic, is known to have anti-tumor activity and improve chemosensitivity in various cancers. However, the function and mechanisms of the combination of LCL161 and paclitaxel in non-small cell lung cancer (NSCLC) remain unknown.MethodsCellular inhibitor of apoptotic protein 1 and 2 (cIAP1&2) expression in NSCLC tissues and adjacent non-tumor tissues were assessed by immunohistochemistry. The correlations between cIAP1&2 expression and clinicopathological characteristics, prognosis were analyzed. Cell viability and apoptosis were measured by MTT assays and Flow cytometry. Western blot and co-immunoprecipitation assay were performed to measure the protein expression and interaction in NF-kB pathway. siRNA-mediated gene silencing and caspases activity assays were applied to demonstrate the role and mechanisms of cIAP1&2 and RIP1 in lung cancer cell apoptosis. Mouse xenograft NSCLC models were used in vivo to determine the therapeutic efficacy of LCL161 alone or in combination with paclitaxel.ResultsThe expression of cIAP1 and cIAP2 in Non-small cell lung cancer (NSCLC) tumors was significantly higher than that in adjacent normal tissues. cIAP1 was highly expressed in patients with late TNM stage NSCLC and a poor prognosis. Positivity for both cIAP1 and cIAP2 was an independent prognostic factor that indicated a poorer prognosis in NSCLC patients. LCL161, an IAP inhibitor, cooperated with paclitaxel to reduce cell viability and induce apoptosis in NSCLC cells. Molecular studies revealed that paclitaxel increased TNFα expression, thereby leading to the recruitment of various factors and the formation of the TRADD-TRAF2-RIP1-cIAP complex. LCL161 degraded cIAP1&2 and released RIP1 from the complex. Subsequently, RIP1 was stabilized and bound to caspase-8 and FADD, thereby forming the caspase-8/RIP1/FADD complex, which activated caspase-8, caspase-3 and ultimately lead to apoptosis. In nude mouse xenograft experiments, the combination of LCL161 and paclitaxel degraded cIAP1,2, activated caspase-3 and inhibited tumor growth with few toxic effects.ConclusionThus, LCL161 could be a useful agent for the treatment of NSCLC in combination with paclitaxel.

MiR-129 blocks estrogen induction of NOTCH signaling activity in breast cancer stem-like cells

Stem-like cells in tumor group featured the major role in the chemotherapy resistance of breast cancer, and the reduction of stem-like cells helped to perish the tumor when receiving chemotherapy. Smaller stem cells number indicated better therapeutic effect in vitro and in clinics, but how did miR-129 and Notch signaling function in breast cancer stem-like cells (BrCSCs) were unclear yet. Through using sphere forming assay and FACS sorting, we found that miR-129 decreased the proportion of stem-like cells in breast cancer cells. Results further indicated that miR-129 degraded the Estrogen Receptor 1 (ESR1) mRNA through a post-translational manner and contributed to the decline of stem-like cells number, preventing tumor regeneration. Cyclin d1 and DICER 1 were proved to promote Let-7 maturation, and in present study, we proved that miR-129 exhibited inhibition on ESR1 and halted the cyclin d1/DICER 1 sustaining of Let-7, which consequently released the Let-7 degradation of NUMB. The restoration of suppressive NUMB by upregulating miR-129 resulted in NOTCH signaling inhibition. In conclusion, we demonstrated the negative regulation of miR-129 on NOTCH signaling activation in BrCSCs’ renewal, which was achieved via continuous suppression on cyclin d1/DICER1 sustaining of Let-7 level, and eventually rescued the targeted inhibition of NUMB. The miR-129/ESR1 signaling played pivotal role in controlling DICER1/Let-7/NOTCH cascade via cyclin d1, revealing the novel mechanism of dual Let-7 in non-coding genes network.

XIAP inhibits mature Smac-induced apoptosis by degrading it through ubiquitination in NSCLC

X-linked inhibitor of apoptosis protein (XIAP) and second mitochondrial-derived activator of caspase (Smac) are two important prognostic biomarkers for cancer. They are negatively correlated in many types of cancer. However, their relationship is still unknown in lung cancer. In the present study, we found that there was a negative correlation between Smac and XIAP at the level of protein but not mRNA in NSCLC patients. However, XIAP overexpression had no effect on degrading endogenous Smac in lung cancer cell lines. Therefore, we constructed plasmids with full length of Smac (fSmac) and mature Smac (mSmac) which located in cytoplasm instead of original mitochondrial location, and was confirmed by immunofluorescence. Subsequently, we found that mSmac rather than fSmac was degraded by XIAP and inhibited cell viability. CHX chase assay and ubiquitin assay were performed to illustrate XIAP degraded mSmac through ubiquitin pathway. Overexpression of XIAP partially reverted apoptotic induction and cell viability inhibition by mSmac, which was due to inhibiting caspase-3 activation. In nude mouse xenograft experiments, mSmac inhibited Ki-67 expression and slowed down lung cancer growth, while XIAP partially reversed the effect of mSmac by degrading it. In conclusion, XIAP inhibits mature Smac-induced apoptosis by degrading it through ubiquitination in NSCLC.

Analysis of risk factors for post‑operative complications and prognostic predictors of disease recurrence following definitive treatment of patients with esophageal cancer from two medical centers in Northwest China

Evaluating the clinicopathological features of patients receiving definitive treatment for esophageal cancer may facilitate the identification of patterns and factors associated with post-operative complications, and enable the development of a surveillance strategy for surviving patients at a higher risk of disease recurrence. In the present study, clinical data from 579 patients with esophageal cancer that underwent radical resection of esophagus were collected. These patients were admitted to two medical centers in Northwest China, and information regarding the presence or absence of basic chronic diseases and post-operative results were retrospectively analyzed. The level of selected stem cell markers, including aldehyde dehydrogenase 1, CD133, integrin subunit α 6, integrin subunit β 4 and T-cell factor-4, were determined in esophageal cancer tissue samples in order to determine whether these markers may be useful predictors of disease prognosis and recurrence. Post-operative complications in patients receiving radical resection of the esophagus included respiratory system complications, cardiovascular abnormalities and esophageal anastomotic fistulae. Diabetes, basic respiratory disease and lower pre-surgical serum albumin levels were observed to be individual risk factors associated with post-operative complications, including respiratory system complications of acute respiratory failure and pulmonary infection, cardiovascular abnormalities of atrial fibrillation and arrhythmia, as well as the development of esophageal anastomotic fistulae. Diagnosis of esophageal cancer at later stage was significantly correlated with anastomotic fistula. Molecular detection of stem cell markers for prognosis prediction was achieved by immunohistochemical and immunofluorescence staining assays. The results demonstrated that the presence of stem-like cells in cancer tissues was associated with poor disease prognosis and a high recurrence ratio. In conclusion, the results of the current study suggested that post-operative complications were more likely to occur in patients with diabetes, basic respiratory disease or lower serum albumin levels prior to surgery. Therefore, sufficient intensive peri-operative care, rigorous operative risk assessments, and the selection of the patients with early or mid-stage esophageal cancer, may decrease the risk of post-surgical complications in patients receiving radical resection of the esophagus. In addition, a high ratio of esophageal cancer stem-like cells was associated with cancer recurrence. These results suggest that an intensive surveillance strategy should be implemented in order to facilitate early detection of disease recurrence and improve the clinical management of these patients post-surgery.

Clinical Application of Detecting 21-Gene Recurrence Score in Predicating Prognosis and Therapy Response of Patients with Breast Cancer from Two Medical Centers

ABSTRACT To determine the most suitable strategy in treating patients with invasive breast cancer from Northwest China. Lower recurrence score (RS) correlated with lower recurrence ratio. Patients having a medium-high 21-gene RS who received adjuvant therapy presented lower recurrence risk. Younger patients having RS results (⩾31) tended to accept adjuvant therapy more often, however, those having intermediate RS results were inclined to wait and did not receive chemotherapy. These results suggested that RS-based precision medicine will allow individualized diagnosis and treatment, resulting in better outcomes and preserved medical resources.

The efficacy and safety of anti-PD-1/PD-L1 antibody therapy versus docetaxel for pretreated advanced NSCLC: a meta-analysis

Antibodies against the immune checkpoint proteins PD-1 and PD-L1 are novel therapeutic drugs for the treatment of advanced non-small cell lung cancer (NSCLC). Many clinical trials involving these drugs achieved breakthroughs in patients previously treated for advanced NSCLC. However, the results of these clinical studies are not consistent. In this report, we performed a meta-analysis to assess the efficacy and safety of anti-PD-1/PD-L1 antibodies compared with docetaxel treatment for advanced NSCLC patients from 5 randomized clinical trials. We demonstrated that the patients in anti-PD-1/PD-L1 antibody therapy groups had significantly longer overall survival (OS) (HR = 0.69, 95% CI 0.63–0.75, P < 0.05) and progression-free survival (PFS) (HR = 0.76, 95% CI 0.63–0.92, P < 0.05) than those in chemotherapy groups, especially PD-L1 positive patients. Anti-PD-1/PD-L1 antibodies improved the objective response rate (ORR) compared with docetaxel (OR = 1.64, 95% CI 1.19–2.26, p < 0.05). In addition, the anti-PD-1/PD-L1 antibody therapy had fewer treatment-related adverse events (AEs) (OR = 0.33, 95% CI 0.28–0.39, P < 0.05) than docetaxel, especially the grade ≥3 AEs (OR = 0.18, 95% CI 0.12–0.28, P < 0.001). In conclusion, our study revealed that, compared with docetaxel, anti-PD-1/PD-L1 antibody therapy improved clinical efficacy and safety in previously treated advanced NSCLC patients. This therapy may be a promising treatment for advanced NSCLC patients.

MYC and DNMT3A-mediated DNA methylation represses microRNA-200b in triple negative breast cancer

Triple‐negative breast cancer (TNBC) is the most aggressive breast cancer subtype with a poor prognosis. The microRNA‐200 (miR‐200) family has been associated with breast cancer metastasis. However, the epigenetic mechanisms underlying miR‐200b repression in TNBC are not fully elucidated. In this study, we found that MYC proto‐oncogene, bHLH transcription factor (MYC) and DNA methyltransferase 3A (DNMT3A) were highly expressed in TNBC tissues compared with other breast cancer subtypes, while miR‐200b expression was inhibited significantly. We demonstrated that MYC physically interacted with DNMT3A in MDA‐MB‐231 cells. Furthermore, we demonstrated that MYC recruited DNMT3A to the miR‐200b promoter, resulting in proximal CpG island hypermethylation and subsequent miR‐200b repression. MiR‐200b directly inhibited DNMT3A expression and formed a feedback loop in TNBC cells. MiR‐200b overexpression synergistically repressed target genes including zinc‐finger E‐box‐binding homeobox factor 1, Sex determining region Y‐box 2 (SOX2), and CD133, and inhibited the migration, invasion and mammosphere formation of TNBC cells. Our findings reveal that MYC can collaborate with DNMT3A on inducing promoter methylation and miR‐200b silencing, and thereby promotes the epithelial to mesenchymal transition and mammosphere formation of TNBC cells.

Breast cancer stem-like cells are sensitized to tamoxifen induction of self-renewal inhibition with enforced Let-7c dependent on Wnt blocking

Let-7 microRNAs have been reported to have tumor suppressive functions; however, the effect of Let-7 when used in combination with chemotherapies is uncertain, but may have potential for use in clinical practice. In this study, we used RT-qPCR, western blot analysis, cell proliferation assay, flow cytometry analysis, immunohistochemistry (IHC) staining, luciferase assays, cell sorting analysis and xenografted tumor model to explore the role of Let-7 in the chemotherapy sensitivity of breast cancer stem cells. The findings of the current study indicated that Let-7 enhances the effects of endocrine therapy potentially by regulating the self-renewal of cancer stem cells. Let-7c increased the anticancer functions of tamoxifen and reduced the ratio of cancer stem-like cells (CSCs), sensitizing cells to therapy-induced repression in an estrogen receptor (ER)-dependent manner. Notably, Let-7 decreased the tumor formation ability of estrogen-treated breast CSCs in vivo and suppressed Wnt signaling, which further consolidated the previously hypothesis that Let-7 decreases the self-renewal ability, contributing to reduced tumor formation ability of stem cells. The suppressive effects exerted by Let-7 on stem-like cells involved Let-7c/ER/Wnt signaling, and the functions of Let-7c exerted with tamoxifen were dependent on ER. Taken together, the findings identified a biochemical and functional link between Let-7 and endocrine therapy in breast CSCs, which may facilitate clinical treatment in the future using delivery of suppressive Let-7.

FBXW7 suppresses epithelial-mesenchymal transition and chemo-resistance of non-small-cell lung cancer cells by targeting snai1 for ubiquitin-dependent degradation

FBXW7 acts as a tumour suppressor by targeting at various oncoproteins for ubiquitin‐mediated degradation. However, the clinical significance and the involving regulatory mechanisms of FBXW7 manipulation of NSCLC regeneration and therapy response are not clear.