Bisbenzylisoquinoline alkaloid fangchinoline derivative HY-2 inhibits breast cancer cells by suppressing BLM DNA helicase.

The high expression of BLM (Bloom syndrome) DNA helicase in tumors involves its strong association with cell expansion. Bisbenzylisoquinoline alkaloids own an antitumor property and have developed as candidates for anticancer drugs. This paper aimed to study the antitumor effect of fangchinoline derivative HY-2 by targeting BLM642-1290 DNA helicase, and then explore its inhibitory mechanism on proliferation of MDA-MB-435 breast cancer cells. We confirmed that the mRNA and protein levels of BLM DNA helicase in breast cancer were higher than those in normal tissues. HY-2 could inhibit the DNA binding, ATPase and DNA unwinding of BLM642-1290 DNA helicase with enzymatic assay. HY-2 could also inhibit the DNA unwinding of DNA helicase in cells. In addition, HY-2 showed an inhibiting the MDA-MB-435, MDA-MB-231, MDA-MB-436 breast cancer cells expansion. The mRNA and protein levels of BLM DNA helicase in MDA-MB-435 cells increased after HY-2 treatment, which might contribute to HY-2 inhibiting the DNA binding, ATPase and DNA unwinding of BLM DNA helicase. The mechanism of HY-2 inhibition on BLM DNA helicase was further confirmed with the effect of HY-2 on the ultraviolet spectrogram of BLM642-1290 DNA helicase and Molecular dynamics simulation of the interacting between HY-2 and BLM640-1291 DNA helicase. Our study provided some valuable clues for the exploration of HY-2 in the living body and developing it as an anticancer drug.

Downregulation of MAL2 inhibits breast cancer progression through regulating ß-catenin/c-Myc axis.

PURPOSE: Myelin and lymphocyte protein 2 (MAL2) is mainly involved in endocytosis under physiological conditions and mediates the transport of materials across the membranes of cell and organelle. It has been reported that MAL2 is significantly upregulated in diverse cancers. This study aimed to investigate the role of MAL2 in breast cancer (BC). METHODS: Bioinformatics analysis and Immunohistochemical assay were applied to detect the correlation between MAL2 expression in breast cancer tissues and the prognosis of breast cancer patients. Functional experiments were carried out to investigate the role of MAL2 in vitro and in vivo. The molecular mechanisms involved in MAL2-induced ß-catenin and c-Myc expression and ß-catenin/c-Myc-mediated enhancement of BC progression were confirmed by western blot, ß-catenin inhibitor and agonist, Co-IP and immunofluorescence colocalization assays. RESULTS: Results from the cancer genome atlas (TCGA) and clinical samples confirmed a significant upregulation of MAL2 in BC tissues than in adjacent non-tumor tissues. High expression of MAL2 was associated with worse prognosis. Functional experiments demonstrated that MAL2 knockdown reduced the migration and invasion associating with EMT, increased the apoptosis of BC cells in vitro and reduced the metastatic capacity in vivo. Mechanistically, MAL2 interacts with ß-catenin in BC cells. MAL2 silencing reduced the expression of ß-catenin and c-Myc, while the ß-catenin agonist SKL2001 partially rescued the downregulation of c-Myc and inhibition of migration and invasion caused by MAL2 knockdown in BC cells. CONCLUSION: These observations provided evidence that MAL2 acted as a potential tumor promoter by regulating EMT and ß-catenin/c-Myc axis, suggesting potential implications for anti-metastatic therapy for BC.

Histone demethylase KDM5D upregulation drives sex differences in colon cancer.

Sex exerts a profound impact on cancer incidence, spectrum and outcomes, yet the molecular and genetic bases of such sex differences are ill-defined and presumptively ascribed to X-chromosome genes and sex hormones1. Such sex differences are particularly prominent in colorectal cancer (CRC) in which men experience higher metastases and mortality. A murine CRC model, engineered with an inducible transgene encoding oncogenic mutant KRASG12D and conditional null alleles of Apc and Trp53 tumour suppressors (designated iKAP)2, revealed higher metastases and worse outcomes specifically in males with oncogenic mutant KRAS (KRAS*) CRC. Integrated cross-species molecular and transcriptomic analyses identified Y-chromosome gene histone demethylase KDM5D as a transcriptionally upregulated gene driven by KRAS*-mediated activation of the STAT4 transcription factor. KDM5D-dependent chromatin mark and transcriptome changes showed repression of regulators of the epithelial cell tight junction and major histocompatibility complex class I complex components. Deletion of Kdm5d in iKAP cancer cells increased tight junction integrity, decreased cell invasiveness and enhanced cancer cell killing by CD8+ T cells. Conversely, iAP mice engineered with a Kdm5d transgene to provide constitutive Kdm5d expression specifically in iAP cancer cells showed an increased propensity for more invasive tumours in vivo. Thus, KRAS*-STAT4-mediated upregulation of Y chromosome KDM5D contributes substantially to the sex differences in KRAS* CRC by means of its disruption of cancer cell adhesion properties and tumour immunity, providing an actionable therapeutic strategy for metastasis risk reduction for men afflicted with KRAS* CRC.

Immune checkpoint therapy-current perspectives and future directions.

Immune checkpoint therapy (ICT) has dramatically altered clinical outcomes for cancer patients and conferred durable clinical benefits, including cure in a subset of patients. Varying response rates across tumor types and the need for predictive biomarkers to optimize patient selection to maximize efficacy and minimize toxicities prompted efforts to unravel immune and non-immune factors regulating the responses to ICT. This review highlights the biology of anti-tumor immunity underlying response and resistance to ICT, discusses efforts to address the current challenges with ICT, and outlines strategies to guide the development of subsequent clinical trials and combinatorial efforts with ICT.

Ephrin receptor A10 monoclonal antibodies and the derived chimeric antigen receptor T cells exert an antitumor response in mouse models of triple-negative breast cancer.

Expression of the receptor tyrosine kinase ephrin receptor A10 (EphA10), which is undetectable in most normal tissues except for the male testis, has been shown to correlate with tumor progression and poor prognosis in several malignancies, including triple-negative breast cancer (TNBC). Therefore, EphA10 could be a potential therapeutic target, likely with minimal adverse effects. However, no effective clinical drugs against EphA10 are currently available. Here, we report high expression levels of EphA10 in tumor regions of breast, lung, and ovarian cancers as well as in immunosuppressive myeloid cells in the tumor microenvironment. Furthermore, we developed anti-EphA10 monoclonal antibodies (mAbs) that specifically recognize cell surface EphA10, but not other EphA family isoforms, and target tumor regions precisely in vivo with no apparent accumulation in other organs. In syngeneic TNBC mouse models, we found that anti-EphA10 mAb clone #4 enhanced tumor regression, therapeutic response rate, and T cell-mediated antitumor immunity. Notably, the chimeric antigen receptor T cells derived from clone #4 significantly inhibited TNBC cell viability in vitro and tumor growth in vivo. Together, our findings suggest that targeting EphA10 via EphA10 mAbs and EphA10-specific chimeric antigen receptor-T cell therapy may represent a promising strategy for patients with EphA10-positive tumors.

Quantification of strain analysis and late gadolinium enhancement in coronary chronic total occlusion: a cardiovascular magnetic resonance imaging follow-up study.

BACKGROUND: The present study aimed to investigate the benefits of percutaneous coronary intervention (PCI) in patients with chronic total occlusions (CTOs) by using cardiac magnetic resonance imaging (CMR) feature tracking. METHODS: Fifty-five CTOs with successful CTO-PCI underwent CMR at baseline and 12 months. Feature tracking was applied to measure left ventricle strain index in CTOs with decreased and preserved left ventricular ejection fraction (LVEF). CTOs were also divided into two groups according to the infarct size of 10% or combined with multi-vessel disease. We also measured these parameters in 40 healthy subjects. RESULTS: Three quarters of CTOs showed preserved ejection fraction and no enlargement of left ventricle at baseline, but the global strains were lower than the controls (all P<0.01). In the entire CTO population, left ventricular ejection fraction did not show significant improvement in the 1-year follow-up (59.8%±11.3% vs. 62.0%±8.6%, P=0.08). However, global strains improved over time, and peak global radial strain and circumferential strain showed significant treatment effect of CTO-PCI in the entire CTO population (31.1%±9.9% vs. 34.3%±8.7%, P<0.01; -17.9±3.6 vs. -19.2±3.1, P<0.01), and the subgroup with decreased LVEF, infarct size less than 10%, or multi-vessel disease, but not with the 1-vessel disease. In the LAD and LCX CTO territory, radial and circumferential strain showed treatment effect of CTO-PCI on the recovery of strain parameters (P<0.01 for both). In the RCA CTO territory, circumferential and longitudinal strain showed treatment effect of CTO-PCI on the recovery of strain parameters (P<0.05 for both). CONCLUSIONS: In this single center study, global radial strain and circumferential strain showed treatment effect of successful CTO-PCI at 1-year follow-up in CTOs with the decreased LVEF, infarct size less than 10%, or multi-vessel disease, and the regional strain also showed a similar trend. However, the benefit of CTO-PCI on the strain recovery was not shown in patients with 1-vessel disease. Therefore, whether patients with CTO benefit from PCI still needs further verification.

C1q/TNF-related protein-9 is elevated in hypertension and associated with the occurrence of hypertension-related atherogenesis.

C1q-tumor necrosis factor-related protein-9 (CTRP9) is an important adipocytokine that is closely associated with cardiovascular disease. This study aimed to detect CTRP9 expression in hypertensive patients and mice and to analyze its effects on hypertension-related atherogenesis. First, circulating CTRP9 levels were detected in both nonhypertensive subjects and hypertensive patients. The results showed that plasma CTRP9 levels were increased in hypertension patients compared with control subjects and gradually elevated in the Grade I, Grade II, and Grade III groups. While nondipper state did not affect CTRP9 expression in hypertension patients. Hypertension patients with carotid atherosclerotic plaque (CAP) exhibited higher CTRP9 levels and the high CTRP9 group exhibited significantly higher CAP morbidity, CTRP9 levels were positively correlated with the occurrence of CAP. Then, effects of CTRP9 on angiotensin II (Ang II)-induced endothelial dysfunction were analyzed in vitro, and the results exhibited that treatment with Ang II significantly increased CTRP9 mRNA expression in endothelial cells (ECs), and downregulation of CTRP9 expression aggravated Ang II-induced endothelial dysfunction in ECs. Mice were infused with Ang II, and CTRP9 was also increased in Ang II-infused mice and mainly secreted by ECs. In Ang II-infused ApoE-/- mice, treatment with recombinant CTRP9 significantly reduced atherosclerotic area and alleviated endothelial dysfunction. In conclusion, our results may found that CTRP9 delayed the progression of hypertension-related arteriosclerosis by alleviating endothelial dysfunction.

Discovery of tetrandrine derivatives as tumor migration, invasion and angiogenesis inhibitors.

Metastatic progression of cancer is a complex and clinically daunting process, with migration, invasion and angiogenesis being the key features. Tetrandrine (TET) is a typical dibenzylisoquinoline alkaloid with promising anti-tumor activity. In our previous work, a number of TET derivatives were designed and synthesized with obvious anti-proliferation activities against cancer cells, however, the anti-metastatic effects of these compounds were not evaluated. In the current investigation, five TET derivatives (8, 18, 32, 71, and 72) with pronounced anti-proliferative activities (IC50 values of 1.00, 1.91, 3.43, 3.78, and 1.93 µM, respectively) against human umbilical vein endothelial cells (HUVECs) were screened out. Scratch assays showed that these compounds significantly suppressed the migration of HUVECs and induced their apoptosis. Among them, derivatives 8 and 72 obviously inhibited the proliferation, colony formation and invasion of HCT-15 cells. Tube formation assays revealed that 4 µM of 8 or 72 remarkably inhibited the tube forming capacity of HUVECs. Moreover, 8 and 72 surpressed the formation of filopodia in HUVECs and severely impaired their motility. Both compounds effectively inhibited the angiogenesis in the zebrafish model with low toxicities in vivo. These results indicated that TET derivatives 8 and 72 are promising anti-metastatic inhibitors.

Targeting Glycosylated PD-1 Induces Potent Antitumor Immunity.

Immunotherapies targeting programmed cell death protein 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1) immune checkpoints represent a major breakthrough in cancer treatment. PD-1 is an inhibitory receptor expressed on the surface of activated T cells that dampens T-cell receptor (TCR)/CD28 signaling by engaging with its ligand PD-L1 expressed on cancer cells. Despite the clinical success of PD-1 blockade using mAbs, most patients do not respond to the treatment, and the underlying regulatory mechanisms of PD-1 remain incompletely defined. Here we show that PD-1 is extensively N-glycosylated in T cells and the intensities of its specific glycoforms are altered upon TCR activation. Glycosylation was critical for maintaining PD-1 protein stability and cell surface localization. Glycosylation of PD-1, especially at the N58 site, was essential for mediating its interaction with PD-L1. The mAb STM418 specifically targeted glycosylated PD-1, exhibiting higher binding affinity to PD-1 than FDA-approved PD-1 antibodies, potently inhibiting PD-L1/PD-1 binding, and enhancing antitumor immunity. Together, these findings provide novel insights into the functional significance of PD-1 glycosylation and offer a rationale for targeting glycosylated PD-1 as a potential strategy for immunotherapy. SIGNIFICANCE: These findings demonstrate that glycosylation of PD-1 is functionally significant and targeting glycosylated PD-1 may serve as a means to improve immunotherapy response.

Oncogenic KRAS-Driven Metabolic Reprogramming in Pancreatic Cancer Cells Utilizes Cytokines from the Tumor Microenvironment.

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is an exuberant stroma comprised of diverse cell types that enable or suppress tumor progression. Here, we explored the role of oncogenic KRAS in protumorigenic signaling interactions between cancer cells and host cells. We show that KRAS mutation (KRAS*) drives cell-autonomous expression of type I cytokine receptor complexes (IL2rγ-IL4rα and IL2rγ-IL13rα1) in cancer cells that in turn are capable of receiving cytokine growth signals (IL4 or IL13) provided by invading Th2 cells in the microenvironment. Early neoplastic lesions show close proximity of cancer cells harboring KRAS* and Th2 cells producing IL4 and IL13. Activated IL2rγ-IL4rα and IL2rγ-IL13rα1 receptors signal primarily via JAK1-STAT6. Integrated transcriptomic, chromatin occupancy, and metabolomic studies identified MYC as a direct target of activated STAT6 and that MYC drives glycolysis. Thus, paracrine signaling in the tumor microenvironment plays a key role in the KRAS*-driven metabolic reprogramming of PDAC. SIGNIFICANCE: Type II cytokines, secreted by Th2 cells in the tumor microenvironment, can stimulate cancer cell-intrinsic MYC transcriptional upregulation to drive glycolysis. This KRAS*-driven heterotypic signaling circuit in the early and advanced tumor microenvironment enables cooperative protumorigenic interactions, providing candidate therapeutic targets in the KRAS* pathway for this intractable disease.

Screening antiproliferative drug for breast cancer from bisbenzylisoquinoline alkaloid tetrandrine and fangchinoline derivatives by targeting BLM helicase.

BACKGROUND: The high expression of BLM (Bloom syndrome) helicase in tumors involves its strong association with cell expansion. Bisbenzylisoquinoline alkaloids own an antitumor property and have developed as candidates for anticancer drugs. This paper aimed to screen potential antiproliferative small molecules from 12 small molecules (the derivatives of bisbenzylisoquinoline alkaloids tetrandrine and fangchinoline) by targeting BLM642-1290 helicase. Then we explore the inhibitory mechanism of those small molecules on proliferation of MDA-MB-435 breast cancer cells. METHODS: Fluorescence polarization technique was used to screen small molecules which inhibited the DNA binding and unwinding of BLM642-1290 helicase. The effects of positive small molecules on the ATPase and conformation of BLM642-1290 helicase were studied by the malachite green-phosphate ammonium molybdate colorimetry and ultraviolet spectral scanning, respectively. The effects of positive small molecules on growth of MDA-MB-435 cells were studied by MTT method, colony formation and cell counting method. The mRNA and protein levels of BLM helicase in the MDA-MB-435 cells after positive small molecule treatments were examined by RT-PCR and ELISA, respectively. RESULTS: The compound HJNO (a tetrandrine derivative) was screened out which inhibited the DNA binding, unwinding and ATPase of BLM642-1290 helicase. That HJNO could bind BLM642-1290helicase to change its conformationcontribute to inhibiting the DNA binding, ATPase and DNA unwinding of BLM642-1290 helicase. In addition, HJNO showed its inhibiting the growth of MDA-MB-435 cells. The values of IC50 after drug treatments for 24 h, 48 h and 72 h were 19.9 µmol/L, 4.1 µmol/L and 10.9 µmol/L, respectively. The mRNA and protein levels of BLM helicase in MDA-MB-435 cells increased after HJNO treatment. Those showed a significant difference (P < 0.05) compared with negative control when the concentrations of HJNO were 5 µmol/L and 10 µmol/L, which might contribute to HJNO inhibiting the DNA binding, ATPase and DNA unwinding of BLM helicase. CONCLUSION: The small molecule HJNO was screened out by targeting BLM642-1290 helicase. And it showed an inhibition on MDA-MB-435 breast cancer cells expansion.

Selective ERK1/2 agonists isolated from Melia azedarach with potent anti-leukemic activity.

BACKGROUND: MAPK/ERK kinases transmit signals from many growth factors/kinase receptors during normal cell growth/differentiation, and their dysregulation is a hallmark of diverse types of cancers. A plethora of drugs were developed to block this kinase pathway for clinical application. With the exception of a recently identified agent, EQW, most of these inhibitors target upstream factors but not ERK1/2; no activator of ERK1/2 is currently available. METHOD: A library of compounds isolated from medicinal plants of China was screened for anti-cancer activities. Three limonoid compounds, termed A1541-43, originally isolated from the plant Melia azedarach, exhibiting strong anti-leukemic activity. The anti-neoplastic activity and the biological target of these compounds were explored using various methods, including western blotting, flow cytometry, molecular docking and animal model for leukemia. RESULTS: Compounds A1541-43, exhibiting potent anti-leukemic activity, was shown to induce ERK1/2 phosphorylation. In contrast, the natural product Cedrelone, which shares structural similarities with A1541-43, functions as a potent inhibitor of ERK1/2. We provided evidence that A1541-43 and Cedrelone specifically target ERK1/2, but not the upstream MAPK/ERK pathway. Computational docking analysis predicts that compounds A1541-43 bind a region in ERK1/2 that is distinct from that to which Cedrelone and EQW bind. Interestingly, both A1541-43, which act as ERK1/2 agonists, and Cedrelone, which inhibit these kinases, exerted strong anti-proliferative activity against multiple leukemic cell lines, and induced robust apoptosis as well as erythroid and megakaryocytic differentiation in erythroleukemic cell lines. These compounds also suppressed tumor progression in a mouse model of erythroleukemia. CONCLUSIONS: This study identifies for the first time activators of ERK1/2 with therapeutic potential for the treatment of cancers driven by dysregulation of the MAPK/ERK pathway and possibly for other disorders.

IL-6/JAK1 pathway drives PD-L1 Y112 phosphorylation to promote cancer immune evasion.

Glycosylation of immune receptors and ligands, such as T cell receptor and coinhibitory molecules, regulates immune signaling activation and immune surveillance. However, how oncogenic signaling initiates glycosylation of coinhibitory molecules to induce immunosuppression remains unclear. Here we show that IL-6-activated JAK1 phosphorylates programmed death-ligand 1 (PD-L1) Tyr112, which recruits the endoplasmic reticulum-associated N-glycosyltransferase STT3A to catalyze PD-L1 glycosylation and maintain PD-L1 stability. Targeting of IL-6 by IL-6 antibody induced synergistic T cell killing effects when combined with anti-T cell immunoglobulin mucin-3 (anti-Tim-3) therapy in animal models. A positive correlation between IL-6 and PD-L1 expression was also observed in hepatocellular carcinoma patient tumor tissues. These results identify a mechanism regulating PD-L1 glycosylation initiation and suggest the combination of anti-IL-6 and anti-Tim-3 as an effective marker-guided therapeutic strategy.

[Preparation, characterization and application of monoclonal antibody against RecQ helicase].

Objective To prepare monoclonal antibodies (mAb) against RecQ helicase, characterize their biological properties, and then investigate their activity against RecQ helicase in tumor cells. Methods BALB/c mice were immunized with purified recombinant RecQ helicase from E.coli. Hybridoma technique was used to generate the mAb against RecQ helicase. The chromosome karyotype analysis of the hybridoma cells was performed by colchicine blocking. The Ig subtype and titer of mAb in ascitic fluid were determined by ELISA. The biological properties of mAb were detected via Western blotting and fluorescence polarization. Immunofluorescence was used to detect the interactions of mAb with BLM, RecQ4 and RecQ5 helicases in human breast cancer MDA-MB-231 cells. Immunohistochemistry was applied to detect the binding of mAb and RecQ helicase in K562 tumor cells and the corresponding stem cells. Results One stable hybridoma cell line expressing anti-RecQ mAb was obtained and named 6H5. The number of chromosomes was from 94 to 104, and Ig subtype was IgG1. The titer of 6H5 in ascitic fluid was 1×10-7. The mAb could specifically recognize E. coli RecQ helicase and thus inhibit its DNA binding activity. Besides, the mAb could also recognize BLM, RecQ4 and RecQ5 in MDA-MB-231 cells, and sensitively detect the expression of the RecQ helicase in K562 tumor cells and the corresponding stem cells. Conclusion The mAb against RecQ helicase was successfully prepared with a high titer and specificity.

Recent development of risk-prediction models for incident hypertension: An updated systematic review.

BACKGROUND: Hypertension is a leading global health threat and a major cardiovascular disease. Since clinical interventions are effective in delaying the disease progression from prehypertension to hypertension, diagnostic prediction models to identify patient populations at high risk for hypertension are imperative. METHODS: Both PubMed and Embase databases were searched for eligible reports of either prediction models or risk scores of hypertension. The study data were collected, including risk factors, statistic methods, characteristics of study design and participants, performance measurement, etc. RESULTS: From the searched literature, 26 studies reporting 48 prediction models were selected. Among them, 20 reports studied the established models using traditional risk factors, such as body mass index (BMI), age, smoking, blood pressure (BP) level, parental history of hypertension, and biochemical factors, whereas 6 reports used genetic risk score (GRS) as the prediction factor. AUC ranged from 0.64 to 0.97, and C-statistic ranged from 60% to 90%. CONCLUSIONS: The traditional models are still the predominant risk prediction models for hypertension, but recently, more models have begun to incorporate genetic factors as part of their model predictors. However, these genetic predictors need to be well selected. The current reported models have acceptable to good discrimination and calibration ability, but whether the models can be applied in clinical practice still needs more validation and adjustment.

Tbx5 and Osr1 interact to regulate posterior second heart field cell cycle progression for cardiac septation.

RATIONALE: Mutations of TBX5 cause Holt-Oram syndrome (HOS) in humans, a disease characterized by atrial or occasionally ventricular septal defects in the heart and skeletal abnormalities of the upper extremity. Previous studies have demonstrated that Tbx5 regulates Osr1 expression in the second heart field (SHF) of E9.5 mouse embryos. However, it is unknown whether and how Tbx5 and Osr1 interact in atrial septation. OBJECTIVE: To determine if and how Tbx5 and Osr1 interact in the posterior SHF for cardiac septation. METHODS AND RESULTS: In the present study, genetic inducible fate mapping showed that Osr1-expressing cells contribute to atrial septum progenitors between E8.0 and E11.0. Osr1 expression in the pSHF was dependent on the level of Tbx5 at E8.5 and E9.5 but not E10.5, suggesting that the embryo stage before E10.5 is critical for Tbx5 interacting with Osr1 in atrial septation. Significantly more atrioventricular septal defects (AVSDs) were observed in embryos with compound haploinsufficiency for Tbx5 and Osr1. Conditional compound haploinsufficiency for Tbx5 and Osr1 resulted in a significant cell proliferation defect in the SHF, which was associated with fewer cells in the G2 and M phases and a decreased level of Cdk6 expression. Remarkably, genetically targeted disruption of Pten expression in atrial septum progenitors rescued AVSDs caused by Tbx5 and Osr1 compound haploinsufficiency. There was a significant decrease in Smo expression, which is a Hedgehog (Hh) signaling pathway modulator, in the pSHF of Osr1 knockout embryos at E9.5, implying a role for Osr1 in regulating Hh signaling. CONCLUSIONS: Tbx5 and Osr1 interact to regulate posterior SHF cell cycle progression for cardiac septation.

Mitofusin-2 over-expresses and leads to dysregulation of cell cycle and cell invasion in lung adenocarcinoma.

Mitofusin-2 (MFN2) is a mitochondrial protein associated with mitochondrial fusion process. It was initially identified as a hyperplasia suppressor and implicated in Charcot-Marie-Tooth disease. Recent studies showed that MFN2 played important roles in the development of multiple tumors. Here we examined MFN2 expression in 30 lung adenocarcinoma samples and revealed that the expression of MFN2 was significantly higher in lung adenocarcinoma tissues as compared to adjacent normal tissues. We then investigated the impact of MFN2 knockdown on A549 human lung adenocarcinoma cells and showed that cell proliferation, cell cycle and invasion behavior were all deregulated by MFN2 knockdown. And deregulation of cell cycle pathway after MFN2 knockdown was confirmed by microarray analysis. Furthermore, microarray analysis also revealed that different oncogenes such as RAP1A, RALB and ITGA2 were oppositely regulated by MFN2, which provided molecular clues for the paradoxical functions of MFN2 in tumor development. Taken together, our study unraveled the tumor-promoting functions of MFN2 in lung adenocarcinoma and implicated that the role of MFN2 in cancer development might be more complicated than expected and should be explored in detail in the future.

Cross-drug resistance to sunitinib induced by doxorubicin in endothelial cells.

Multiple drug resistance remains an unsolved problem in cancer therapy. A previous study has demonstrated that the chemotherapeutic drug doxorubicin (Dox) induced upregulation of P-glycoprotein in endothelial cells, resulting in a 20-fold increase in drug resistance and reduced efficiency of doxorubicin treatment in a mouse tumor model. In the present study, the cross-resistance and sensitivity of HMECd1 and HMECd2 established cell lines to anti-angiogenic drugs, particularly sunitinib, was explored. The results revealed that Dox treatment induced a significant increase in the breast cancer resistance protein (ABCG2) gene transcription and protein expression. This increase gave rise to a 4- to 5-fold increase in the half maximal inhibitory concentration of the HMECd1 and HMECd2 cells in response to sunitinib treatment in vitro. Functionally, the role of ABCG2 in the resistance to sunitinib was confirmed by the use of the ABCG2 inhibitors fumitremorgin C and diethylstilbestrol, which blocked cell resistance. The present study indicates that endothelial cells exhibit cross-resistance between cytotoxic drugs and anti-angiogenic drugs. This suggests that multiple drug resistance induced by chemotherapy in endothelial cells may affect the efficiency of anti-angiogenic drugs.