Tumor-promoting effect of IL-23 in mammary cancer mediated by infiltration of M2 macrophages and neutrophils in tumor microenvironment.

Interleukin 23 (IL-23) is an inflammatory cytokine which plays a vital role in autoimmune diseases as well as in tumorigenesis. However, the role of IL-23 in tumor procession is still controversial and the underlying mechanism remains unclear. Here we established a stable cell line overexpressing IL-23 to prove that IL-23 promoted tumor growth and pulmonary metastasis through induction of tumor-related inflammation and absence of immune surveillance. IL-23 promotes tumor-associate inflammatory response such as infiltration of M2 macrophages, neutrophils and their elevated secretions of immunosuppressive cytokines transforming growth factor-ß (TGF-ß), IL-10 and vascular endothelial growth factor (VEGF) into tumor tissues, meanwhile the increase of the matrix metalloprotease MMP9. In addition, IL-23 increases the expression of the endothelial marker CD31 and proliferative marker Ki67 in tumors. Moreover, IL23 induces immunosuppression though reducing the infiltration of CD4+and CD8+T cells into tumor tissues. In conclusion, IL-23 is a considerable molecular in tumor progression, which simultaneously facilitates processes of pro-tumor inflammation, such as angiogenesis, immunosuppressive cytokines as well as infiltrations of M2 macrophages and neutrophils, and suppresses antitumor immune responses through reduction of CD4+ T cells and CD8+ T cells.

Extravascular red blood cells and hemoglobin promote tumor growth and therapeutic resistance as endogenous danger signals.

Hemorrhage is a common clinical manifestation in patients with cancer. Intratumor hemorrhage has been demonstrated to be a poor prognostic factor for cancer patients. In this study, we investigated the role of RBCs and hemoglobin (Hb) in the process of tumor progression and therapeutical response. RBCs and Hb potently promoted tumor cell proliferation and syngenic tumor growth. RBCs and Hb activated the reactive oxygen species-NF-κB pathway in both tumor cells and macrophages. RBCs and Hb also induced chemoresistance mediated, in part, by upregulating ABCB1 gene expression. Tumor growth induced by RBCs was accompanied by an inflammatory signature, increased tumor vasculature, and influx of M2 macrophages. In both the peritoneal cavity and tumor microenvironment, extravascular RBCs rapidly recruited monocyte-macrophages into the lesion sites. In addition, RBCs and Hb increased several nucleotide-binding oligomerization domain-like receptors' expression and induced IL-1ß release. Our results provide novel insights into the protumor function of RBCs and Hb as endogenous danger signals, which can promote tumor cell proliferation, macrophage recruitment, and polarization. Hemorrhage may represent a useful prognostic factor for cancer patients because of its role in tumor promotion and chemoresistance.

miR-1273g-3p participates in acute glucose fluctuation-induced autophagy, dysfunction, and proliferation attenuation in human umbilical vein endothelial cells.

Acute glucose fluctuations (AGF) often cause high mortality among critically ill patients, but the mechanisms induced by AGF are not clear. Recent studies suggest that endothelial dysfunction is a key factor that leads to high mortality among critically ill patients. Our goal is to evaluate the phenomenon and mechanisms of endothelial dysfunction induced by AGF. In this study, the functions of human umbilical vein endothelial cells (HUVECs) were compared after treatment with sustained high glucose (SHG), AGF in two groups (AGF1 fluctuations between 5 and 16 mM and AGF2 fluctuations between 5 and 25 mM), and normal glucose levels as a control group (CTR). The medium of the groups was changed every 4 h. The influence of AGF on wound healing was also tested on C57BL/6 mice. The results show that cell proliferation, angiogenesis, and migration functions were injured in the SHG and both AGF groups. AGF2 group shows the worse condition in vitro. In vivo, the wound healing was delayed after the AGF treatment. Furthermore, the markers of apoptosis and autophagy were analyzed. We observed that the autophagy changed in all treatment groups, but apoptosis showed no change. To get to know the mechanism of dysfunction and autophagy, we performed the microRNA chip assay and real-time PCR and found miR-1273g-3p remarkably changed in AGF2 group. After the mimic and inhibitor of miR-1273g-3p were transfected during the AGF2 treatment, we found that the dysfunction and autophagy were partially enhanced by miR-1273g-3p mimic and reversed by miR-1273g-3p inhibitor in AGF2 group. Thus, we conclude that AGF can induce more dysfunction and autophagy, and miR-1273g-3p is also an important factor that leads to the injury.

EML4-ALK induces epithelial-mesenchymal transition consistent with cancer stem cell properties in H1299 non-small cell lung cancer cells.

The echinoderm microtubule-associated protein-like 4(EML4)--anaplastic lymphoma kinase (ALK) fusion gene has been identified as a driver mutation in non-small-cell lung cancer (NSCLC). However, the role of EML4-ALK in malignant transformation is not entirely clear. Here, for the first time, we showed that H1299 NSCLC cells stably expressing EML4-ALK acquire EMT phenotype, associated with enhanced invasive migration and increased expression of EMT-inducing transcription factors. H1299-EML4-ALK cells also displayed cancer stem cell-like properties with a concomitant up-regulation of CD133 and enhanced ability of mammospheres formation. Moreover, we found that inhibition of ERK1/2 reversed EMT induced by EML4-ALK in H1299 cells. Taken together, these results suggested that EML4-ALK induced ERK activation is mechanistically associated with EMT phenotype. Thus, inhibition of ERK signaling pathway could be a potential strategy in treatment of NSCLC patients with EML4-ALK translocation.

[Infiltrated T Cells Induce the Accumulation of Myeloid-derived Suppressor Cells in Tumor Microenvironment].

OBJECTIVE: To determine the role of infiltrated T cells in the accumulation of myeloid-derived suppressor cells (MDSCs) in tumor microenvironment. METHODS: T-cell-deficient nude mice models were established using BALB/c mice. Growth of tumors was compared between those with and without adoptive transfer of T cells. Pathological changes of the tumors were examined with HE histological analysis. The levels of MDSCs were detected with flow cytometry (FACS). RESULTS: Tumor growth was promoted in T-cell-deficient nude mice, which was accompanied with lower levels of MDSCs compared with BALB/c mice (P < 0.05). T cell transfer increased the level of MDSCs significantly (P < 0.05). T cells depletion decreased the level of MDSCs (P < 0.05). CONCLUSION: Infiltrated T cells induce the accumulation of MDSCs in tumor microenvironment, and influence tumor growth.

Synthesis and biological evaluation of novel benzamide derivatives as potent smoothened antagonists.

A series of novel benzamide derivatives were prepared and evaluated using cell-based measurements. Among these compounds, 10f significantly inhibited Hedgehog signaling and showed equivalent or more potency than GDC-0449 in different tests. Furthermore, compound 10f potently inhibited the proliferation of Daoy, a medulloblastoma cell line that is reported to be resistant to GDC-0449, which indicated a promising prospect in the treatment of Hedgehog signaling pathway related cancer in clinical trial.

The diagnostic role of a short screening tool--the distress thermometer: a meta-analysis.

PURPOSE: The Distress Thermometer (the DT) is a commonly used screening tool to detect distress in cancer patients. This meta-analysis aims to examine the diagnostic role and the optimal cut-off score of the DT compared with various different reference standards. METHODS: We searched PubMed and Embase from 1997 to September 2013 for relevant studies. After extracting data, we estimated the pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratios, and constructed summary receiver operating characteristics curves to determine the optimal cut-off score. RESULTS: Forty-two relevant studies and 14,808 patients were included in total. When we pooled all the results together, the DT showed a good balance between pooled sensitivity (0.81, 95% confidence intervals (CI) 0.79-0.82) and pooled specificity (0.72, 95% CI 0.71-0.72) at the cut-off score of 4. The value of area under the curve (AUC) is 0.8321. When the DT is compared with the HADS-Total, the cut-off score of 4 maximized the balance between the pooled sensitivity (0.82, 95% CI 0.80-0.84) and pooled specificity (0.73, 95% CI 0.72-0.74). The AUC is 0.8432. CONCLUSIONS: This meta-analysis suggests that the DT is a valid tool to detect potential distress in cancer patients. According to our results, 4 as the optimal cut-off, is recommended. Further studies are needed to be done to examine the accuracy and optimal cut-off score in different regions globally and different cancer subtypes to guide the use of the DT for different patients.

Cathepsin B as a potential prognostic and therapeutic marker for human lung squamous cell carcinoma.

BACKGROUND: The lung squamous cell carcinoma survival rate is very poor despite multimodal treatment. It is urgent to discover novel candidate biomarkers for prognostic assessment and therapeutic targets to lung squamous cell carcinoma (SCC). RESULTS: Herein a two-dimensional gel electrophoresis and ESI-Q-TOF MS/MS-based proteomic approach was used to identify differentially expressed proteins between lung SCC and adjacent normal tissues. 31 proteins with significant alteration were identified. These proteins were mainly involved in metabolism, calcium ion binding, signal transduction and so on. Cathepsin B (CTSB) was one of the most significantly altered proteins and was confirmed by western blotting. Immunohistochemistry showed the correlation between higher CTSB expression and lower survival rate. No statistically significant difference between CTSB-shRNA treated group and the controls was observed in tumor volume, tumor weight, proliferation and apoptosis. However, the CTSB-shRNA significantly inhibited tumor metastases and prolonged survival in LL/2 metastatic model. Moreover, CTSB, Shh and Ptch were up-regulated in patients with metastatic lung SCC, suggesting that hedgehog signaling might be activated in metastatic lung SCC which could affect the expression of CTSB that influence the invasive activity of lung SCC. CONCLUSIONS: These data suggested that CTSB might serve as a prognostic and therapeutic marker for lung SCC.

Which is false: oxaliplatin or fluoropyrimidine? An analysis of patients with KRAS wild-type metastatic colorectal cancer treated with first-line epidermal growth factor receptor monoclonal antibody.

This meta-analysis was performed to determine whether the addition of monoclonal antibodies (mAbs) of epidermal growth factor receptor (EGFR) to oxaliplatin-based chemotherapy treatment improves efficacy in KRAS wild-type metastatic colorectal cancer (mCRC), and whether infusional 5-fluorouracil (5-FU) and oxaliplatin is a preferred combination for EGFR mAbs. Oxaliplatin (including treatment), EGFR mAbs, first-line treatment, KRAS wild-type, and mCRC were used as key words. The PRIME, OPUS, COIN, and NORDIC VII trials were identified by two independent authors. Time-to-event outcomes of overall survival (OS) and progression-free survival (PFS) were analyzed using HRs (hazard ratios) with fixed effect, and response rate (RR) using odd ratios (OR) with fixed effect. A total of 1767 patients who were KRAS wild-type were included in this meta-analysis, with 866 patients in the mAbs and chemotherapy combination group and 901 patients in the chemotherapy alone group. The addition of mAbs to oxaliplatin-based chemotherapy in patients with KRAS wild-type mCRC as first-line treatment resulted in significant improvements in PFS (HR = 0.88; 95% confidence interval (CI), 0.79-0.99; P = 0.03) and response rate (RR) (OR = 1.38; 95% CI, 1.14-1.66; P = 0.009) compared with chemotherapy alone, but the difference in OS was not significant (HR = 0.96; 95% CI, 0.85-1.08; P = 0.48). However, the differences in OS and PFS were not significant when mAbs were added to bolus 5-FU or capecitabine-based regimens compared with chemotherapy alone, whereas PFS improved with an infusional 5-FU and oxaliplatin combination (P = 0.06; PFS, HR = 0.76; 95% CI, 0.65-0.86; P = 0.0002), and even OS was marginally significant, which was consistent with the subgroup analysis of cetuximab and panitumumab. EGFR mAbs combined with oxaliplatin and an infusional 5-FU regimen was associated with significantly improved RR, PFS and OS as first-line treatment in KRAS wild-type mCRC.

Inhibition of tumor growth and alteration of associated macrophage cell type by an HO-1 inhibitor in breast carcinoma-bearing mice.

Heme oxygenase-1 [HO-1, also called heat shot protein 32 (HSP32)] can specifically metabolize heme to carbon monoxide, biliverdin, and ferrous iron and plays an important role in the processes of anti-inflammation, tissue protection, and antioxidative stress reaction. It has been reported that HO-1 can promote tumorigenesis and metastasis of many tumors. However, the detailed mechanisms of how HO-1 affects tumor progress are not clear. Here, we used ZnPPIX (a specific inhibitor of HO-1) to evaluate its potential effects on mouse breast cancer and tumor-associated macrophages (TAMs). We found out that mouse 4T1 breast cancer growth can be effectively suppressed through inhibition of HO-1 in vitro and in vivo. Moreover, in the 4T1 mouse model, when HO-1 was suppressed in TAMs, alternatively activated macrophages (M2 type) switched to classically activated macrophages (M1 type). In conclusion, 4T1 breast cancer growth was modulated by HO-1 expression. Furthermore, inhibition of HO-1 may induce tumor-associated immune response by activating TAMs' alternative proliferation. These data suggest that HO-1 may be an important target of breast cancer treatment.

Apatinib vs Placebo in Patients With Locally Advanced or Metastatic, Radioactive Iodine-Refractory Differentiated Thyroid Cancer: The REALITY Randomized Clinical Trial.

IMPORTANCE: Patients with radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) have a poor prognosis and limited treatment options. OBJECTIVE: To assess the efficacy and safety of apatinib, a highly selective vascular endothelial growth factor (VEGFR-2) inhibitor, in patients with progressive locally advanced or metastatic RAIR-DTC. DESIGN, SETTING, AND PARTICIPANTS: This randomized, double-blind, placebo-controlled, phase 3 trial (Efficacy of Apatinib in Radioactive Iodine-refractory Differentiated Thyroid Cancer [REALITY]) was conducted in 92 patients with progressive locally advanced or metastatic RAIR-DTC between February 17, 2017, and March 2, 2020, at 21 sites within China, and the data cutoff date for this analysis was March 25, 2020. INTERVENTIONS: Patients were randomly assigned (1:1) to apatinib, 500 mg/d, or placebo. Patients who developed progression while receiving placebo were allowed to cross over to apatinib. MAIN OUTCOMES AND MEASURES: The primary end point was investigator-assessed progression-free survival (PFS). Secondary end points included overall survival, objective response rate (ORR), disease control rate (DCR), duration of response, time to objective response, and safety. Intention-to-treat analyses were performed to evaluate efficacy. RESULTS: Of the 92 patients included in the trial, 56 were women (60.9%); mean (SD) age at baseline was 55.7 (10.6) years. Patients were randomized to the apatinib (n = 46) or placebo (n = 46) group. The median follow-up duration was 18.1 (IQR, 12.7-22.2) months. The median PFS was 22.2 (95% CI, 10.91-not reached) months for apatinib vs 4.5 (95% CI, 1.94-9.17) months for placebo (hazard ratio, 0.26; 95% CI, 0.14-0.47; P < .001). The confirmed ORR was 54.3% (95% CI, 39.0%-69.1%) and the DCR was 95.7% (95% CI, 85.2%-99.5%) in the apatinib group vs an ORR of 2.2% (95% CI, 0.1%-11.5%) and DCR of 58.7% (95% CI, 43.2%-73.0%) in the placebo group. The median overall survival was not reached for apatinib (95% CI, 26.25-not reached) and was 29.9 months (95% CI, 18.96-not reached) for placebo (hazard ratio, 0.42; 95% CI, 0.18-0.97; P = .04). The most common grade 3 or higher-level treatment-related adverse events in the apatinib group were hypertension (16 [34.8%]), hand-foot syndrome (8 [17.4%]), proteinuria (7 [15.2%]), and diarrhea (7 [15.2%])-none of which occurred in the placebo group. CONCLUSIONS AND RELEVANCE: The REALITY trial met its primary end point of PFS at the prespecified interim analysis. Apatinib showed significant clinical benefits in both prolonged PFS and overall survival with a manageable safety profile in patients with progressive locally advanced or metastatic RAIR-DTC. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03048877.

A study of ALK-positive pulmonary squamous-cell carcinoma: From diagnostic methodologies to clinical efficacy.

BACKGROUND: High concordance has been observed between Ventana D5F3 ALK immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH) in lung adenocarcinoma (LADC). However, whether a similar conclusion can be applied to lung squamous-cell carcinoma (LSCC) has remained unclear. We therefore evaluated the ALK (anaplastic lymphoma kinase) status and the therapeutic effect of an ALK tyrosine kinase inhibitor (TKI) in IHC- or FISH-positive LSCC. MATERIALS AND METHODS: A total of 2403 LSCC patients from three institutions were screened for ALK aberration by IHC. All IHC-positive cases were subjected to FISH (with an approximately equal number of negative cases as a control group) and next-generation sequencing (NGS). Clinical efficacy was evaluated for the patients who received TKI therapy. RESULTS: In 2403 cases of LSCC, 37 cases were identified as ALK-positive by IHC. After quality control, 28 cases were succeeded by FISH (six with insufficient tissue, three with lack of signals) and 13 by NGS (24 failed due to insufficient samples or poor DNA quality); the percentage of non-diagnostic tests was 24.3% (9/37) and 64.9% (24/37), respectively. Four cases (4/2394, 0.17%) analyzed by FISH were determined as ALK-positive. For the control group (40 ALK IHC), FISH demonstrated no samples with ALK gene fusion. The concordance between ALK IHC- and ALK FISH-positive results was 14.3% (4/28). In the 13 cases studied by NGS, two cases showed ALK-EML4 fusion (consistent with two FISH-positive results), and two cases were interpreted as harboring an ALK-association gene mutation. Among four patients (two FISH-positive and two IHC-positive only cases) receiving TKI therapy, two patients had stable disease and the other two had progressive disease. CONCLUSIONS: The positive concordance rate of ALK IHC and FISH in LSCC is far less than that reported for LADC. Therefore, ALK IHC detection in LSCC cannot be used as a diagnostic method for ALK rearrangement.

A comparison of QuantStudio™ 3D Digital PCR and ARMS-PCR for measuring plasma EGFR T790M mutations of NSCLC patients.

BACKGROUND: The AURA3 clinical trial has shown that advanced non-small cell lung cancer (NSCLC) patients with EGFR T790M mutations in circulating tumor DNA (ctDNA) could benefit from osimertinib. PURPOSE: The aim of this study was to assess the usefulness of QuantStudio™ 3D Digital PCR System platform for the detection of plasma EGFR T790M mutations in NSCLC patients, and compare the performances of 3D Digital PCR and ARMS-PCR. PATIENTS AND METHODS: A total of 119 Chinese patients were enrolled in this study. Mutant allele frequency of plasma EGFR T790M was detected by 3D Digital PCR, then 25 selected samples were verified by ARMS-PCR and four of them were verified by next generation sequencing (NGS). RESULTS: In total, 52.94% (69/119) had EGFR T790M mutations detected by 3D Digital PCR. In 69 positive samples, the median mutant allele frequency (AF) was 1.09% and three cases presented low concentration (AF <0.1%). Limited by the amount of plasma DNA, 17 samples (AF <2.5%) and eight samples (T790M-) were selected for verification by ARMS-PCR. Four of those samples were verified by NGS as a third verification method. Among the selected 17 positive cases, ten samples presented mutant allele frequency <0.5%, and seven samples presented intermediate mutant allele frequency (0.5% AF 2.5%). However, only three samples (3/17) were identified as positive by ARMS-PCR, namely, P6 (AF =1.09%), P7 (AF =2.09%), and P8 (AF =2.21%). It is worth mentioning that sample P9 (AF =2.05%, analyzed by 3D Digital PCR) was identified as T790M- by ARMS-PCR. Four samples were identified as T790M+ by both NGS and 3D Digital PCR, and typically three samples (3/4) presented at a low ratio (AF <0.5%). CONCLUSION: Our study demonstrated that 3D Digital PCR is a novel method with high sensitivity and specificity to detect EGFR T790M mutation in plasma.

Adenomatous polyposis coli genotype-dependent toll-like receptor 4 activity in colon cancer.

Toll-like receptors (TLRs)/NF-κB activation stimulated by lipopolysaccharide (LPS) was associated with diverse biological response in colon cancer, but the underlying mechanism was largely unknown. In the current study, we reported cell proliferation was elevated in adenomatous polyposis coli (APC) mutated- and APC knockdown cell lines, while the proliferation was inhibited in APC wild-type cell lines. Besides, in vivo experiments showed that LPS promoted APC knockdown tumor growth while inhibited proliferation of APC wild type. Further study confirmed that activation of TLRs/NF-κB signaling pathway by LPS cross regulated with APC/GSK-3ß/ß-catenin pathway, which were depend on APC status of cell lines. Taken together, APC genotypes play a key role in LPS induced different colon cancer biological response by cross-regulating ß-catenin and NF-κB, which may provide a novel strategy for carcinogenesis prevention.

Forced co-expression of IL-21 and IL-7 in whole-cell cancer vaccines promotes antitumor immunity.

Genetic modification of whole-cell cancer vaccines to augment their efficacies has a history of over two and a half decades. Various genes and gene combinations, targeting different aspects of immune responses have been tested in pursuit of potent adjuvant effects. Here we show that co-expression of two cytokine members of the common cytokine receptor γ-chain family, IL-21 and IL-7, in whole-cell cancer vaccines boosts antitumor immunity in a CD4(+) and CD8(+) T cell-dependent fashion. It also generates effective immune memory. The vaccine-elicited short-term effects positively correlated with enhanced infiltration of CD4(+) and CD8(+) effector T cells, and the long-term effects positively correlated with enhanced infiltration of effector memory T cells, especially CD8(+) effector memory T cells. Preliminary data suggested that the vaccine exhibited good safety profile in murine models. Taken together, the combination of IL-21 and IL-7 possesses potent adjuvant efficacy in whole-cell vaccines. This finding warrants future development of IL-21 and IL-7 co-expressing whole-cell cancer vaccines and their relevant combinatorial regimens.

Ovarian cancer treatment with a tumor-targeting and gene expression-controllable lipoplex.

Overexpression of folate receptor alpha (FRα) and high telomerase activity are considered to be the characteristics of ovarian cancers. In this study, we developed FRα-targeted lipoplexes loaded with an hTERT promoter-regulated plasmid that encodes a matrix protein (MP) of the vesicular stomatitis virus, F-LP/pMP(2.5), for application in ovarian cancer treatment. We first characterized the pharmaceutical properties of F-LP/pMP(2.5). The efficient expression of the MP-driven hTERT promoter in SKOV-3 cells was determined after an in-vitro transfection assay, which was significantly increased compared with a non-modified LP/pMP(2.5) group. F-LP/pMP(2.5) treatment significantly inhibited the growth of tumors and extended the survival of mice in a SKOV-3 tumor model compared with other groups. Such an anti-tumor effect was due to the increased expression of MP in tumor tissue, which led to the induction of tumor cell apoptosis, inhibition of tumor cell proliferation and suppression of tumor angiogenesis. Furthermore, a preliminary safety evaluation demonstrated a good safety profile of F-LP/pMP(2.5) as a gene therapy agent. Therefore, FRα-targeted lipoplexes with therapeutic gene expression regulated by an hTERT promoter might be a promising gene therapy agent and a potential translational candidate for the clinical treatment of ovarian cancer.

Immunotherapy of tumors with human telomerase reverse transcriptase immortalized human umbilical vein endothelial cells.

Human umbilical endothelial cells (HUVECs) have been proven to be effective in tumor anti-angiogenesis but the mechanism remained to be further demonstrated. The restricted ability of HUVECs to proliferate in vitro also limits their application on a large scale. In the present study, we immortalized HUVECs with hTERT genes by lentiviral infection and explored the antitumor immunity of hTERT-expressing HUVECs (HUVEC-TERTs). Results showed that HUVEC-TERTs maintained high telomere activity and expressed CD31, VEGFR-II and integrin α5. Passage-30 HUVEC-TERTs were able to form vascular tubes in vitro without showing signs of senescence. In vivo HUVEC-TERTs elicited antitumor immunity in mouse LL2 and CT26 models protectively and therapeutically. Both humoral and cellular immunity participated in the tumor anti-angiogenesis as HUVEC-neutralizing sera antibodies and HUVEC-specific CTL were detected. The subsets of activated spleen T lymphocytes included both CD4(+) T cells and CD8(+) T cells. Moreover, MDSCs and Tregs were decreased while T lymphocytes were aggregated in the tumor microenvironment. Collectively, the present study is the first to confirm the antitumor immunity of hTERT-immortalized HUVECs. Both anti-angiogenesis and tumor microenvironmental regulation participated in the antitumor activity. Transducing hTERT genes might be a new strategy to allow HUVECs to be applied on a large scale in cancer immunotherapy.

Knockdown of SUMO-activating enzyme subunit 2 (SAE2) suppresses cancer malignancy and enhances chemotherapy sensitivity in small cell lung cancer.

BACKGROUND: SUMO-activating enzyme subunit 2 (SAE2) is the sole E1-activating enzyme required for numerous important protein SUMOylation, abnormal of which is associated with carcinogenesis. SAE2 inactivation was recently reported to be a therapeutic strategy in cancers with Myc overexpression. However, the roles of SAE2 in small cell lung cancer (SCLC) are largely unknown. METHODS: Stably SAE2 knockdown in H446 cells were established with a lentiviral system. Cell viability, cell cycle, and apoptosis were analyzed using MTT assay and flow cytometric assay. Expression of SAE2 mRNA and protein were detected by qPCR, western blotting, and immunohistochemical staining. Cell invasion and migration assay were determined by transwell chamber assay. H446 cells with or without SAE2 knockdown, nude mice models were established to observe tumorigenesis. RESULTS: SAE2 was highly expressed in SCLC and significantly correlated with tumorigenesis in vivo. Cancer cells with RNAi-mediated reduction of SAE2 expression exhibited growth retardation and apoptosis increasing. Furthermore, down-regulation of SAE2 expression inhibited migration and invasion, simultaneously increased the sensitivity of H446 to etoposide and cisplatin. CONCLUSIONS: SAE2 plays an important role in tumor growth, metastasis, and chemotherapy sensitivity of H446 and is a potential clinical biomarker and therapeutic target in SCLC with high c-Myc expression.