MiR-1278 targets CALD1 and suppresses the progression of gastric cancer via the MAPK pathway.

This study aimed to investigate the interaction between miR-1278 and Caldesmon (CALD1) in gastric cancer (GC) and the regulatory mechanism. In both GC cells and tissues, the levels of CALD1, miR-1278, migration-related markers (E-cadherin, N-cadherin, and Snail), and MAPK signaling pathway-related proteins were clarified using quantitative real-time PCR and western blotting analyses. The effects of miR-1278 and CALD1 on GC cell viability and migration were analyzed using CCK-8 and Transwell assays, respectively. The targeting effect of miR-1278 on CALD1 was investigated using bioinformatics prediction and a dual luciferase reporter assay. The effect of miR-1278 on tumor growth was estimated in vivo using a tumor xenograft assay. In GC, miR-1278 expression decreased, whereas CALD1 was highly expressed. Transfecting an miR-1278 mimic into cells inhibited the viability as well as migration of GC cells, and suppressed Ras, phosphorylated (p)-P38, and p-ERK1/2 protein levels. Moreover, miR-1278 targeted and negatively regulated CALD1 expression. CALD1 overexpression promoted GC cell survival and migration and activated the MAPK pathway. Treatment with an miR-1278 mimic partially rescued the changes caused by CALD1 overexpression. Overall, our study revealed that miR-1278 suppresses the malignant behavior of GC cells by targeting CALD1 and regulating the MAPK pathway.

Family-based Helicobacter pylori infection status and transmission pattern in central China, and its clinical implications for related disease prevention.

BACKGROUND: Helicobacter pylori (H. pylori) has characteristics of family cluster infection; however, its family-based infection status, related factors, and transmission pattern in central China, a high-risk area for H. pylori infection and gastric cancer, have not been evaluated. We investigated family-based H. pylori infection in healthy households to understand its infection status, related factors, and patterns of transmission for related disease prevention. AIM: To investigate family-based H. pylori infection status, related factors, and patterns of transmission in healthy households for related disease prevention. METHODS: Blood samples and survey questionnaires were collected from 282 families including 772 individuals. The recruited families were from 10 selected communities in the greater Zhengzhou area with different living standards, and the family members' general data, H. pylori infection status, related factors, and transmission pattern were analyzed. H. pylori infection was confirmed primarily by serum H. pylori antibody arrays; if patients previously underwent H. pylori eradication therapy, an additional 13C-urea breath test was performed to obtain their current infection status. Serum gastrin and pepsinogens (PGs) were also analyzed. RESULTS: Among the 772 individuals examined, H. pylori infection rate was 54.27%. These infected individuals were from 246 families, accounting for 87.23% of all 282 families examined, and 34.55% of these families were infected by the same strains. In 27.24% of infected families, all members were infected, and 68.66% of them were infected with type I strains. Among the 244 families that included both husband and wife, spouse co-infection rate was 34.84%, and in only 17.21% of these spouses, none were infected. The infection rate increased with duration of marriage, but annual household income, history of smoking, history of alcohol consumption, dining location, presence of gastrointestinal symptoms, and family history of gastric disease or GC did not affect infection rates; however, individuals who had a higher education level showed lower infection rates. The levels of gastrin-17, PGI, and PGII were significantly higher, and PGI/II ratio was significantly lower in H. pylori-infected groups than in H. pylori-negative groups. CONCLUSION: In our study sample from the general public of central China, H. pylori infection rate was 54.27%, but in 87.23% of healthy households, there was at least 1 H. pylori-infected person; in 27.24% of these infected families, all members were infected. Type I H. pylori was the dominant strain in this area. Individuals with a higher education level showed significantly lower infection rates; no other variables affected infection rates.

Mesothelin-targeted CAR-T cells for adoptive cell therapy of solid tumors.

Significant progresses have been made in adoptive cell therapy with CAR-T cells for cancers, especially for hematological malignancies. However, the treatment of solid tumors still poses a tremendous challenge and remains an unmet medical need. Several factors are held responsible for the inadequate responses: tumor heterogeneity, inefficient homing of T cells to tumor tissues, immunosuppressive microenvironment and the shortage of specific antigens shortage. Mesothelin is a cell-surface glycoprotein highly expressed in many types of solid tumors. As such, it has attracted much attention as a molecular target in cancer immunotherapy. Here, we delineate the barriers imposed by solid tumors on CARs, outline the rationale of mesothelin as a target for immunotherapy, summarize the preclinical and clinical results of mesothelin-targeted therapies, and extrapolate the expected results of CAR-T cells directed against mesothelin for solid tumors.

hsa_circ_0006916 promotes hepatocellular carcinoma progression by activating the miR-337-3p/STAT3 axis.

BACKGROUND: Circular RNAs (circRNAs) are thought to be involved in the development of various malignancies. The expression and function of hsa_circ_0006916, a newly identified circRNA, in hepatocellular carcinoma remain unclear. METHODS: Quantitative RT-PCR was used to detect hsa_circ_0006916 in hepatocellular carcinoma. In vitro function assays were conducted to explore growth and invasion of hepatocellular carcinoma cells. Next, the mechanism of hsa_circ_0006916 function in hepatocellular carcinoma was determined by luciferase reporter and RIP assays. RESULTS: Hsa_circ_0006916 was substantially overexpressed in hepatocellular carcinoma tissues and cells. High levels of hsa_circ_0006916 in hepatocellular carcinoma patients were associated with advanced clinical characteristics. Down-regulation of hsa_circ_0006916 decreased the growth and invasion of hepatocellular carcinoma cells in vitro. The results suggested that hsa_circ_0006916 acted as a sponge of miR-337-3p and had an important functional use in the regulation of STAT3 levels in hepatocellular carcinoma cells. Moreover, miR-337-3p inhibition or STAT3 overexpression abolished the effect of hsa_circ_0006916 suppression on the progression of hepatocellular carcinoma cells. CONCLUSIONS: Our data suggest a novel hsa_circ_0006916/miR-337-3p/STAT3 axis in hepatocellular carcinoma, and provide a new target for treatment.

EGFRvIII-specific CAR-T cells produced by piggyBac transposon exhibit efficient growth suppression against hepatocellular carcinoma.

Adoptive cellular immunotherapy employing chimeric antigen receptors-modified T (CAR-T) cells has demonstrated promising antitumor effects in hematologic cancers. However, CAR-T therapy confront many challenges in solid tumors like immunosuppressive microenvironment, molecular heterogeneity, etc. The cancer genome atlas (TCGA) of hepatocellular carcinoma (HCC) revealed many genetic characteristic and molecular tumorigenesis. EGFRvIII is a tumor specific antigen widely expressed in a variety of cancers including HCC and an ideal therapeutic target for cancer therapy. The liver cancer cell line SMMC7721 express high level EGFRvIII and widely applied in HCC investigations. Herein, we developed EGFRvIII CAR-T cells by piggyBac transposon system, and detected its specific killing effect against SMMC7721 cells in vitro and in vivo. Results indicated that transduction efficiency of CAR reached 53.1%. Expression of CAR protein was verified by immunoblotting as a band of approximate 57KD. The killing effect of CAR-T cells against SMMC7721 was positively correlated with E/T ratio (E:T=5:1, 10:1, 20:1, 40:1), and exceeded 50% at 20:1 ratio. Significant increase in IFN-γ and TNF-α secretion were detected in the co-culture supernatant of CAR-T cells and SMMC7721, comparable to the level of exogenous EGFRvIII-expressing U87 cells. The killing activity and cytokine secretion were both dependent on the expression level of EGFRvIII in target cells. In HCC xenograft models, CAR-T cells could effectively suppress the growth of SMMC7721. In conclusion, EGFRvIII CAR-T cells demonstrated specific antitumor effect against SMMC7721 in vitro and in vivo, providing basis for immunotherapy of HCC in future clinical use.

PiggyBac transposon system with polymeric gene carrier transfected into human T cells.

CAR-T cell-based immunotherapy has shown great promise in clinical trials for the treatment of hematological malignancies. The majority of these trials utilize retroviral and lentiviral vectors to introduce CAR transgene. In spite of its satisfactory efficiency, the concerns about the potential carcinogenicity and complicated synthesis procedure restrict widespread clinical applications of viral vectors. Recent studies show that transposon-based gene transfer is a safer and simpler non-viral approach for stable transgene expression. Here, we developed an in house made polymeric nanomicelles carrier for piggyBac (PB) transposon delivery to primary T lymphocytes. The properties, transfection efficiency and toxicity of this carrier was analyzed. Results indicated that nanomicelles produced in our study were stable and reduction-sensitive. These micelles can completely condense DNA and mediate transfection with efficiency of average 30.2% with high cell viability (> 80%). Furthermore, incorporating piggyBac transposase elements into polyplexes promoted persistent expression of the transgene (up to 55%). At the end of culture, CAR-T cells mainly exhibited memory phenotype and consisted of CD3+CD8+ T cells. The cytotoxicity of these CAR-T cells was average 17% at 20:1 ratio. In conclusion, polymeric nanomicelles provide a flexible and safe method for gene delivery to T lymphocytes.

Human bone marrow-derived mesenchymal stem cell-secreted exosomes overexpressing microRNA-34a ameliorate glioblastoma development via down-regulating MYCN.

PURPOSE: Exosomes play important roles in intercellular communication through signaling pathways affecting tumor microenvironment modulation and tumor proliferation, including those in glioblastoma (GBM). As yet, however, limited studies have been conducted on the inhibitory effect of human bone marrow-derived mesenchymal stem cell (hBMSC)-derived exosomes on GBM development. Therefore, we set out to assess the role of hBMSC secreted exosomes, in particular those carrying microRNA-34a (miR-34a), in the development of GBM. METHODS: Microarray-based expression analysis was employed to identify differentially expressed genes and to predict miRNAs regulating MYCN expression. Next, hBMSCs were transfected with a miR-34a mimic or inhibitor after which exosomes were isolated. Proliferation, apoptosis, migration, invasion and temozolomide (TMZ) chemosensitivity of exosome-exposed GBM cells (T-98G, LN229 and A-172) were measured in vitro. The mechanism underlying MYCN regulation was investigated using lentiviral transfections. The in vivo inhibitory effect of exosomal miR-34a was measured in nude mice xenografted with GBM cells through subcutaneous injection of hBMSCs with an upregulated miR34a content. RESULTS: We found that poorly-expressed miR-34a specifically targeted and negatively regulated the expression of MYCN in GBM cells. In addition we found that miR-34a was delivered to T-98G, LN229 and A-172 GBM cells via hBMSC-derived exosomes. Exogenous overexpression of miR-34a in hBMSC-derived exosomes resulted in inhibition of GBM cell proliferation, invasion, migration and tumorigenesis in vitro and in vivo, while promoting the chemosensitivity of GBM cells to TMZ by silencing MYCN. CONCLUSIONS: From our data we conclude that hBMSC-derived exosomes overexpressing miR-34a may be instrumental for the therapeutic targeting and clinical management of GBM.

Resveratrol restores sensitivity of glioma cells to temozolamide through inhibiting the activation of Wnt signaling pathway.

Malignant gliomas are aggressive primary neoplasms that originate in the glial cells of the brain or the spine with notable resistance to standard treatment options. We carried out the study with the aim to shed light on the sensitization of resveratrol to temozolomide (TMZ) against glioma through the Wnt signaling pathway. Initially, glioma cell lines with strong resistance to TMZ were selected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Then, the glioma cells were subjected to resveratrol, TMZ, Wnt signaling pathway inhibitors, and activators. Cell survival rate and inhibitory concentration at half maximum value were detected by MTT, apoptosis by flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, in vitro proliferation by hanging drop method and ß-catenin translocation into nuclei by TOP/FOP-FLASH assay. The expressions of the Wnt signaling pathway-related and apoptosis-related factors were determined by western blot analysis. Nude mice with glioma xenograft were established to detect tumorigenic ability. Glioma cell lines T98G and U138 which were highly resistant to TMZ were selected for subsequent experiments. Resveratrol increased the efficacy of TMZ by restraining cell proliferation, tumor growth, and promoting cell apoptosis in glioma cells. Resveratrol inhibited Wnt2 and ß-catenin expressions yet elevated GSK-3ß expression. Moreover, the Wnt signaling pathway participates in the sensitivity enhancing of resveratrol to TMZ via regulating O 6 -methylguanine-DNA methyltransferase (MGMT) expression. Resveratrol sensitized TMZ-induced glioma cell apoptosis by repressing the activation of the Wnt signaling pathway and downregulating MGMT expression, which may confer new thoughts to the chemotherapy of glioma.

Generation of regulable EGFRvIII targeted chimeric antigen receptor T cells for adoptive cell therapy of glioblastoma.

Adoptive immunotherapy using chimeric antigen receptors-modified T cells (CAR-T) is a promising approach for cancer treatment. However, CARs currently applied in the clinics cannot be effectively regulated and the safety of CAR-T cell therapies remains a major concern. To improve the safety of CAR-T cells, we designed a synthetic splitting CAR (ssCAR) that can regulate T cell functions exogenously. Epidermal growth factor receptor variant III (EGFRvIII) was used as a molecular target for ssCAR. Our results indicate that both EGFRvIII and small molecule are needed for the activation of the ssCAR-T cells. AP21967 dose-dependently increased the expression of T cell activation, production of cytokines and extent of cell lysis. In conclusion, the gene switch designed in this study allows for temporal and spatial control over engineered T cells in a dose-and time-dependent manner by AP21967. Our work demonstrates the feasibility and improved safety profile of this novel treatment approach.

Helicobacter pylori infection-induced H3Ser10 phosphorylation in stepwise gastric carcinogenesis and its clinical implications.

BACKGROUND: Our previous works have demonstrated that Helicobacter pylori (Hp) infection can alter histone H3 serine 10 phosphorylation status in gastric epithelial cells. However, whether Helicobacter pylori-induced histone H3 serine 10 phosphorylation participates in gastric carcinogenesis is unknown. We investigate the expression of histone H3 serine 10 phosphorylation in various stages of gastric disease and explore its clinical implication. MATERIALS AND METHODS: Stomach biopsy samples from 129 patients were collected and stained with histone H3 serine 10 phosphorylation, Ki67, and Helicobacter pylori by immunohistochemistry staining, expressed as labeling index. They were categorized into nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia, and intestinal-type gastric cancer groups. Helicobacter pylori infection was determined by either 13 C-urea breath test or immunohistochemistry staining. RESULTS: In Helicobacter pylori-negative patients, labeling index of histone H3 serine 10 phosphorylation was gradually increased in nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia groups, peaked at low-grade intraepithelial neoplasia, and declined in high-grade intraepithelial neoplasia and gastric cancer groups. In Helicobacter pylori-infected patients, labeling index of histone H3 serine 10 phosphorylation followed the similar pattern as above, with increased expression over the corresponding Helicobacter pylori-negative controls except in nonatrophic gastritis patient whose labeling index was decreased when compared with Helicobacter pylori-negative control. Labeling index of Ki67 in Helicobacter pylori-negative groups was higher in gastric cancer than chronic atrophic gastritis and low-grade intraepithelial neoplasia groups, and higher in intestinal metaplasia group compared with chronic atrophic gastritis group. In Helicobacter pylori-positive groups, Ki67 labeling index was increased stepwise from nonatrophic gastritis to gastric cancer except slightly decrease in chronic atrophic gastritis group. In addition, we noted that histone H3 serine 10 phosphorylation staining is accompanied with its location changes from gastric gland bottom expanded to whole gland as disease stage progress. CONCLUSIONS: These results indicate that stepwise gastric carcinogenesis is associated with altered histone H3 serine 10 phosphorylation, Helicobacter pylori infection enhances histone H3 serine 10 phosphorylation expression in these processes; it is also accompanied with histone H3 serine 10 phosphorylation location change from gland bottom staining expand to whole gland expression. The results suggest that epigenetic dysregulation may play important roles in Helicobacter pylori-induced gastric cancer.

MicroRNA-21 promotes glioma cell proliferation and inhibits senescence and apoptosis by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway.

AIMS: Our study aims to investigate the effect of microRNA-21 (miR-21) on the proliferation, senescence, and apoptosis of glioma cells by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway. METHODS: Glioma tissues and brain tissues were collected for this study after surgical decompression for traumatic brain injury. RT-qPCR was employed to measure mRNA levels of miR-21, SPRY1, PTEN, PI3K, and AKT, and Western blotting was conducted to determine protein levels of SPRY1, PTEN, PI3K, AKT, p-AKT, Caspase-3, Caspase-9, P53, GSK3, and p-GSK3. Human glioma U87 cells were assigned into the blank, negative control (NC), miR-21 mimics, miR-21 inhibitors, siRNA-SPRY1, and miR-21 inhibitors + siRNA-SPRY1 groups, with human HEB cells serving as the normal group. Cell proliferation, cell cycle, and apoptosis were determined by MTT and flow cytometry, respectively. RESULTS: Compared with control group, an increased expression of miR-21, PI3K, AKT, p-AKT, P53, and p-GSK3, and a decreased expression of SPRY1, PTEN, Caspase-3, and Caspase-9 were observed in the glioma group, and no significant differences were found in the expression of GSK3. SPRY1 was verified to be the target gene of miR-21. Compared with the blank and NC groups, levels of PI3K, AKT, p-AKT, P53, and p-GSK3 increased while levels of SPRY1, PTEN, Caspase-3, and Caspase-9 decreased in the miR-21 mimics and siRNA-SPRY1 groups; the miR-21 inhibitors group reversed the tendency; furthermore, the miR-21 inhibitors group showed decreased cell proliferation but promoted apoptosis, which were opposite to the results of the miR-21 mimics and siRNA-SPRY1 groups. CONCLUSION: MicroRNA-21 might promote cell proliferation and inhibit cell senescence and apoptosis of human glioma cells by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway.

Detection of Helicobacter pylori in dental plaque using a DNA biosensor for noninvasive diagnosis.

Noninvasive diagnosis of Helicobacter pylori (H. pylori) infection is very attractive. This study investigated the single strand DNA (ssDNA) acquisition method from H. pylori in dental plaque, and the integration of our previously developed 43-mer H. pylori DNA biosensor with the obtained target ssDNA (tDNA). Dental plaque samples were collected from 34 patients/volunteers, whose gastric H. pylori infection statuses were tested with the 13C urea breath test (UBT). The samples were treated with colony polymerase chain reaction (PCR) to obtain double strand DNA (dsDNA) of 104 basepairs (bp) long. A blocker ssDNA was designed and used in thermal treatment of the dsDNA to release the 104-mer tDNA, which contains the 43-mer DNA sequence in the middle. PCR primers were designed, and the tDNA releasing and detection conditions with the biosensor were optimized. The limit of detection with the biosensor was 12 fM dsDNA. The dental plaque detection results correlated quite well with the UBT results, with a sensitivity of 100%, and specificity of 97%. These results indicate that the residence of H. pylori in dental plaque is highly associated with gastric H. pylori infection, and detection of dental plaque samples with our DNA biosensor is promisingly applicable in noninvasive diagnosis of H. pylori infection.

Safety Strategies of Genetically Engineered T Cells in Cancer Immunotherapy.

T-cell therapy using genetically engineered T cells modified with either T cell receptor or chimeric antigen receptor holds great promise for cancer immunotherapy. The concerns about its toxicities still remain despite recent successes in clinical trials. Temporal and spatial control of the engineered therapeutic T cells may improve the safety profile of these treatment regimens. To achieve these goals, numerous approaches have been tested and utilized including the incorporation of a suicide gene, the switch-mediated activation, the combinatorial antigen recognition, etc. This review will summarize the toxicities caused by engineered T cells and novel strategies to overcome them.

Anti-EGFRvIII Chimeric Antigen Receptor-Modified T Cells for Adoptive Cell Therapy of Glioblastoma.

Glioblastoma (GBM) is one of the most devastating brain tumors with poor prognosis and high mortality. Although radical surgical treatment with subsequent radiation and chemotherapy can improve the survival, the efficacy of such regimens is insufficient because the GBM cells can spread and destroy normal brain structures. Moreover, these non-specific treatments may damage adjacent healthy brain tissue. It is thus imperative to develop novel therapies to precisely target invasive tumor cells without damaging normal tissues. Immunotherapy is a promising approach due to its capability to suppress the growth of various tumors in preclinical model and clinical trials. Adoptive cell therapy (ACT) using T cells engineered with chimeric antigen receptor (CAR) targeting an ideal molecular marker in GBM, e.g. epidermal growth factor receptor type III (EGFRvIII) has demonstrated a satisfactory efficacy in treating malignant brain tumors. Here we summarize the recent progresses in immunotherapeutic strategy using CAR-modified T cells oriented to EGFRvIII against GBM.

Expression and diagnostic value of CCT3 and IQGAP3 in hepatocellular carcinoma.

BACKGROUND: To evaluate plasma chaperonin containing TCP1 complex subunit 3 (CCT3) and IQ-motif-containing GTPase-activating protein-3 (IQGAP3) as biomarker for hepatocellular carcinoma (HCC) screening and diagnosis. METHODS: Blood samples were collected from 126 HCC patients with HCC, 88 patients with cirrhosis and 50 healthy volunteers to detect plasma α-fetoprotein (AFP), CCT3 and IQGAP3 levels. Plasma AFP, CCT3 and IQGAP3 protein levels were measured by enzyme linked immunosorbent assay (ELISA). RESULTS: In the plasma of HCC patients, both CCT3 and IQGAP3 were significantly higher than in patients with cirrhosis and in healthy controls (P < 0.01). CCT3 and IQGAP3 protein level correlated well with HCC etiology, tumor size, TNM stage, and child-pugh classification. CCT3 protein had higher sensitivity in the diagnosis of HCC when compared with AFP (87.3 vs 69.8 %). In addition, CCT3 and IQGAP3 protein were able to complement AFP in detecting AFP-negative HCC patients with sensitivity and specificity of 92.1 and 70.5 % and 81.6 and 71.6 %, respectively. In the small HCC group, CCT3 and IQGAP3 protein had sensitivity of 76.6 and 74.5 %, respectively. The combination of AFP + CCT3 + IQGAP3 (0.954) had significantly superior discriminative ability than AFP alone (0.815; P < 0.01). CONCLUSIONS: CCT3 and IQGAP3 are novel complementary biomarkers for HCC screening and diagnosis, especially for AFP-negative and small HCC patients.

Targeting a glioblastoma cancer stem-cell population defined by EGF receptor variant III.

The relationship between mutated proteins and the cancer stem-cell population is unclear. Glioblastoma tumors frequently express EGFRvIII, an EGF receptor (EGFR) variant that arises via gene rearrangement and amplification. However, expression of EGFRvIII is restricted despite the prevalence of the alteration. Here, we show that EGFRvIII is highly coexpressed with CD133 and that EGFRvIII(+)/CD133(+) defines the population of cancer stem cells (CSC) with the highest degree of self-renewal and tumor-initiating ability. EGFRvIII(+) cells are associated with other stem/progenitor markers, whereas markers of differentiation are found in EGFRvIII(-) cells. EGFRvIII expression is lost in standard cell culture, but its expression is maintained in tumor sphere culture, and cultured cells also retain the EGFRvIII(+)/CD133(+) coexpression, self-renewal, and tumor initiating abilities. Elimination of the EGFRvIII(+)/CD133(+) population using a bispecific antibody reduced tumorigenicity of implanted tumor cells better than any reagent directed against a single epitope. This work demonstrates that a mutated oncogene can have CSC-specific expression and be used to specifically target this population.

Chimeric antigen receptor-engineered T cells for cancer immunotherapy: progress and challenges.

Recent years have witnessed much progress in both basic research and clinical trials regarding cancer immunotherapy with chimeric antigen receptor (CAR)-engineered T cells. The unique structure of CAR endows T cell tumor specific cytotoxicity and resistance to immunosuppressive microenvironment in cancers, which helps patients to better tackle the issue of immunological tolerance. Adoptive immunotherapy (AIT) using this supernatural T cell have gained momentum after decades of intense debates because of the promising results obtained from preclinical models and clinical trials. However, it is very important for us to evaluate thoroughly the challenges/obstacles before widespread clinical application, which clearly warrants more studies to improve our understanding of the mechanism underlying AIT. In this review, we focus on the critical issues related to the clinical outcomes of CAR-based adoptive immunotherapy and discuss the rationales to refine this new cancer therapeutic modality.

Anti-apoptotic proteins and catalase-dependent apoptosis resistance in nickel chloride-transformed human lung epithelial cells.

Chronic exposure to nickel compounds is associated with increased incidence of certain types of human cancer, including lung and nasal cancers. Despite intensive investigation, the oncogenic processes remain poorly understood. Apoptosis resistance is a key feature for tumor cells to escape physiological surveillance and acquire growth advantage over normal cells. Although NiCl2 exposure induces transformation of human lung epithelial cells, little information is available with regard to its molecular mechanisms, it is also not clear if the transformed cells are apoptosis resistant and tumorigenic. We explored the apoptosis resistance properties of nickel chloride­transformed human lung epithelial cells and the underlying mechanisms. The results showed that transformed BEAS-2B human lung epithelial cells are resistant to NiCl2-induced apoptosis. They have increased Bcl-2, Bcl-xL and catalase protein levels over the passage matched non­transformed counterparts. The mechanisms of apoptosis resistance are mitochondria­mediated and caspase-dependent. Forced overexpression of Bcl-2, Bcl-xL and catalase proteins reduced NiCl2-induced cell death; siRNA­mediated knockdown of their expression sensitized the cells to nickel-induced apoptosis, suggesting that Bcl-2, Bcl-xl and catalase protein expression plays a critical role in apoptosis resistance. Akt also participates in this process, as its overexpression increases Bcl-xL protein expression levels and attenuates NiCl2-induced apoptosis. Furthermore, transformed cells are tumorigenic in a xenograft model. Together, these results demonstrate that nickel-transformed cells are apoptosis­resistant and tumorigenic. Increased expression of Bcl-2, Bcl-xL and catalase proteins are important mechanisms contributing to transformed cell oncogenic properties.