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Carcinogenesis - RSS feed of current issue

Cancer is a multistep disease that begins with malignant cell transformation and frequently culminates in metastasis. MicroRNAs (miRNAs) are small regulatory 21–25 nt RNA molecules and are frequently deregulated in cancer. miR-200a is a member of the miR-200 family, which are known inhibitors of the epithelial-to-mesenchymal transition. As such, the tumor-suppressive role of miR-200a in oncogenesis has been well documented; however, recent studies have found a proliferative role for this miRNA as well as a prometastatic role in the later steps of cancer progression. Little is known about the role of this miRNA in the early stages of cancer, namely, malignant cell transformation. Here, we show that miR-200a alone transforms an immortalized rat epithelial cell line, and miR-200a cooperates with Ras to enhance malignant transformation of an immortalized human epithelial cell line. Furthermore, miR-200a induces cell transformation and tumorigenesis in immunocompromised mice by cooperating with a Ras mutant that activates only the RalGEF effector pathway, but not Ras mutants activating PI3K or Raf effector pathways. This transformative ability is in accordance with miR-200a targeting Fog2 and p53 to activate Akt and directly repress p53 protein levels, respectively. These results demonstrate an oncogenic role for miR-200a and provide a specific cellular context where miR-200a acts as an oncomiR rather than a tumor suppressor by cooperating with an oncogene in malignant cell transformation.

Poly (ADP-ribose) polymerase 1 (PARP1) inhibitors are actively under clinical trials for the treatment of breast and ovarian cancers that arise due to mutations in BRCA1 and BRCA2. The RAD51 paralog RAD51C has been identified as a breast and ovarian cancer susceptibility gene. The pathological RAD51C mutants that were identified in cancer patients are hypomorphic with partial repair function. However, targeting cancer cells that express hypomorphic mutants of RAD51C is highly challenging. Here, we report that RAD51C-deficient cells can be targeted by a ‘synthetic lethal’ approach using PARP inhibitor and this sensitivity was attributed to accumulation of cells in the G2/M and chromosomal aberrations. In addition, spontaneous hyperactivation of PARP1 was evident in RAD51C-deficient cells. Interestingly, RAD51C-negative cells exhibited enhanced recruitment of non-homologous end joining (NHEJ) proteins onto chromatin and this accumulation correlated with increased activity of error-prone NHEJ as well as genome instability leading to cell death. Notably, inhibition of DNA-PKcs or depletion of KU70 or Ligase IV rescued this phenotype. Strikingly, stimulation of NHEJ by low dose of ionizing radiation (IR) in the PARP inhibitor-treated RAD51C-deficient cells and cells expressing pathological RAD51C mutants induced enhanced toxicity ‘synergistically’. These results demonstrate that cancer cells arising due to hypomorphic mutations in RAD51C can be specifically targeted by a ‘synergistic approach’ and imply that this strategy can be potentially applied to cancers with hypomorphic mutations in other homologous recombination pathway genes.

Lgr5+ intestinal crypt base columnar cells function as stem cells whose progeny populate the villi, and Lgr5+ cells in which Apc is inactivated can give rise to tumors. Surprisingly, these Lgr5+ stem cell properties were abrogated by the lower dietary vitamin D and calcium in a semi-purified diet that promotes both genetically initiated and sporadic intestinal tumors. Inactivation of the vitamin D receptor in Lgr5+ cells established that compromise of Lgr5 stem cell function was a rapid, cell autonomous effect of signaling through the vitamin D receptor. The loss of Lgr5 stem cell function was associated with presence of Ki67 negative Lgr5+ cells at the crypt base. Therefore, vitamin D, a common nutrient and inducer of intestinal cell maturation, is an environmental factor that is a determinant of Lgr5+ stem cell functions in vivo. Since diets used in reports that establish and dissect mouse Lgr5+ stem cell activity likely provided vitamin D levels well above the range documented for human populations, the contribution of Lgr5+ cells to intestinal homeostasis and tumor formation in humans may be significantly more limited, and variable in the population, then suggested by published rodent studies.

Syndecan-1 (SDC1/CD138) is one of the main cell surface proteoglycans and is involved in crucial biological processes. Only a few studies have analyzed the role of SDC1 in mesenchymal tumor pathogenesis. In particular, its involvement in adipose tissue tumors has never been investigated. Dedifferentiated liposarcoma, one of the most frequent types of malignant adipose tumors, has a high potential of recurrence and metastastic evolution. Classical chemotherapy is inefficient in metastatic dedifferentiated liposarcoma and novel biological markers are needed for improving its treatment. In this study, we have analyzed the expression of SDC1 in well-differentiated/dedifferentiated liposarcomas and showed that SDC1 is highly overexpressed in dedifferentiated liposarcoma compared with normal adipose tissue and lipomas. Silencing of SDC1 in liposarcoma cells impaired cell viability and proliferation. Using the human multipotent adipose-derived stem cell model of human adipogenesis, we showed that SDC1 promotes proliferation of undifferentiated adipocyte progenitors and inhibits their adipogenic differentiation. Altogether, our results support the hypothesis that SDC1 might be involved in liposarcomagenesis. It might play a prominent role in the dedifferentiation process occurring when well-differentiated liposarcoma progress to dedifferentiated liposarcoma. Targeting SDC1 in these tumors might provide a novel therapeutic strategy.

Junctional adhesion molecule-A (JAM-A) is preferentially concentrated at tight junctions and influences epithelial cell morphology and migration. Epithelial-to-mesenchymal transition (EMT) is the conversion process of epithelial cells into mesenchymal cells, and it plays an important role in the invasiveness and metastasis of various cancers. However, the role of JAM-A in regulating the invasive behaviours of human nasopharyngeal carcinoma (NPC) is unknown. In this study, we found that JAM-A upregulation induced EMT, whereas silencing of endogenous JAM-A expression reversed EMT. Furthermore, upregulation of JAM-A led to EMT via activation phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway. PI3K inhibitors blocked JAM-A-induced EMT, suggesting that the kinase acts downstream of JAM-A. Finally, results from 172 human patients with NPC showed that high expression levels of JAM-A correlated with metastasis and poor prognosis in NPC. Taken together, these results suggest that high JAM-A expression positively correlates with poor prognosis in patients with NPC, and induces EMT of NPC cells in vitro and in vivo via the PI3K/Akt pathway. These data indicate novel functions in the JAM-A repertoire, and have clinical implications for the treatment of patients with NPC.

Inflammation, hormones and energy-related factors have been associated with colorectal cancer (CRC) and it has been proposed that convergence and interactions of these factors importantly influence CRC risk. We have previously hypothesized that genetic variation in the CHIEF (convergence of hormones, inflammation and energy-related factors) pathway would influence risk of CRC. In this paper, we utilize an Adaptive Rank Truncation Product (ARTP) statistical method to determine the overall pathway significance and then use that method to identify the key elements within the pathway associated with disease risk. Data from two population-based case–control studies of colon (n = 1555 cases and 1956 controls) and rectal (n = 754 cases and 959 controls) cancer were used. We use ARTP to estimate pathway and gene significance and polygenic scores based on ARTP findings to further estimate the risk associated with the pathway. Associations were further assessed based on tumor molecular phenotype. The CHIEF pathway was statistically significant for colon cancer (P ARTP = 0.03) with the most significant interferons (P ARTP = 0.0253), JAK/STAT/SOCS (P ARTP = 0.0111), telomere (P ARTP = 0.0399) and transforming growth factor β (P ARTP = 0.0043) being the most significant subpathways for colon cancer. For rectal cancer, interleukins (P ARTP = 0.0235) and selenoproteins (P ARTP = 0.0047) were statistically significant although the pathway overall was of borderline significance (P ARTP = 0.06). Interleukins (P ARTP = 0.0456) and mitogen-activated protein kinase (P ARTP = 0.0392) subpathways were uniquely significant for CpG island methylator phenotype-positive colon tumors. Increasing number of at-risk alleles was significantly associated with both colon [odds ratio (OR) = 6.21, 95% confidence interval (CI): 4.72, 8.16] and rectal (OR = 7.82, 95% CI: 5.26, 11.62) cancer. We conclude that elements of the CHIEF pathway are important for CRC risk.

p16 INK4a is a tumor suppressor gene, frequently hypermethylated in breast cancer; this epigenetic silencing of p16 INK4a occurs early in carcinogenesis. The risk factors and functional consequences of p16 INK4a methylation are unknown. Alcohol consumption, a breast cancer risk factor, impedes folate metabolism and may thereby alter gene methylation since folate plays a pivotal role in DNA methylation. In a cross-sectional study of 138 women with no history of breast cancer who underwent reduction mammoplasty, we studied breast cancer risk factors, plasma and breast folate concentrations, variation in one-carbon metabolism genes, p16 INK4a promoter methylation and P16 protein expression. Logistic regression was used to estimate multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI). p16 INK4a methylation was negatively correlated with P16 expression (r = –0.28; P = 0.002). Alcohol consumption was associated with lower breast folate (P = 0.03), higher p16 INK4a promoter methylation (P = 0.007) and less P16 expression (P = 0.002). Higher breast folate concentrations were associated with lower p16 INK4a promoter methylation (P = 0.06). Genetic variation in MTRR (rs1801394) and MTHFD1 (rs1950902) was associated with higher p16 INK4a promoter methylation (OR = 2.66, 95% CI: 1.11–6.42 and OR = 2.72, 95% CI: 1.12–6.66, respectively), whereas variation in TYMS (rs502396) was associated with less P16 protein expression (OR = 0.22, 95% CI: 0.05–0.99). Given that this is the first study to indicate that alcohol consumption, breast folate and variation in one-carbon metabolism genes are associated with p16 INK4a promoter methylation and P16 protein expression in healthy tissues; these findings require replication.

Lung tumour subtyping, particularly the distinction between adenocarcinoma (AdC) and squamous cell carcinoma (SqCC), is a critical diagnostic requirement. In this work, the metabolic signatures of lung carcinomas were investigated through 1H NMR metabolomics, with a view to provide additional criteria for improved diagnosis and treatment planning. High Resolution Magic Angle Spinning Nuclear Magnetic Resonance (NMR) spectroscopy was used to analyse matched tumour and adjacent control tissues from 56 patients undergoing surgical excision of primary lung carcinomas. Multivariate modeling allowed tumour and control tissues to be discriminated with high accuracy (97% classification rate), mainly due to significant differences in the levels of 13 metabolites. Notably, the magnitude of those differences were clearly distinct for AdC and SqCC: major alterations in AdC were related to phospholipid metabolism (increased phosphocholine, glycerophosphocholine and phosphoethanolamine, together with decreased acetate) and protein catabolism (increased peptide moieties), whereas SqCC had stronger glycolytic and glutaminolytic profiles (negatively correlated variations in glucose and lactate and positively correlated increases in glutamate and alanine). Other tumour metabolic features were increased creatine, glutathione, taurine and uridine nucleotides, the first two being especially prominent in SqCC and the latter in AdC. Furthermore, multivariate analysis of AdC and SqCC profiles allowed their discrimination with a 94% classification rate, thus showing great potential for aiding lung tumours subtyping. Overall, this study has provided new, clear evidence of distinct metabolic signatures for lung AdC and SqCC, which can potentially impact on diagnosis and provide important leads for future research on novel therapeutic targets or imaging tracers.

BRCA1-associated protein-1 (BAP1) mutations cause a new cancer syndrome, with a high rate of malignant mesothelioma (MM). Here, we tested the hypothesis that MM associated with germline BAP1 mutations has a better prognosis compared with sporadic MM. We compared survival among germline BAP1 mutation MM patients with that of all MM (N = 10 556) recorded in the United States Surveillance, Epidemiology, and End Results (SEER) data from 1973 to 2010. We identified 23 MM patients—11 alive—with germline BAP1 mutations and available data on survival. Ten patients had peritoneal MM, ten pleural MM and three MM in both locations. Thirteen patients had one or more malignancies in addition to MM. Actuarial median survival for the MM patients with germline BAP1 mutations was 5 years, as compared with <1 year for the median survival in the United States SEER MM group. Five-year survival was 47%, 95% confidence interval (24–67%), as compared with 6.7% (6.2–7.3%) in the control SEER group. Analysis of the pooled cohort of germline BAP1 mutation MM showed that patients with peritoneal MM (median survival of 10 years, P = 0.0571), or with a second malignancy in addition to MM (median survival of 10 years, P = 0.0716), survived for a longer time compared with patients who only had pleural MM, or MM patients without a second malignancy, respectively. In conclusion, we found that MM patients with germline BAP1 mutations have an overall 7-fold increased long-term survival, independently of sex and age. Appropriate genetic counseling and clinical management should be considered for MM patients who are also BAP1 mutation carriers.

Colorectal cancer (CRC) is one of the most frequently diagnosed malignancies worldwide. It is routinely cured by a 5-fluorouracil (5-FU)-based chemotherapy which improves outcomes in patients. We investigated the effect of single nucleotide polymorphisms (SNPs) in two microRNA (miRNA)-encoding genes that have been previously reported as important in prognosis in patients with stage III CRC and treated with 5-FU-based chemotherapy. Two SNPs (rs4919510 in miR-608 and rs213210 in miR-219-1) were genotyped in 1083 CRC patients recruited in the Czech Republic to evaluate their effect on clinical outcomes. Carriers of the variant T allele in rs213210 and receiving 5-FU chemotherapy were associated with a significantly worse survival [hazard ratio (HR) = 2.18; 95% confidence interval (CI): 1.20–3.98; adjusted P = 0.01] and an increased risk of relapse (HR = 1.94; 95% CI: 1.16–3.25; adjusted P = 0.01). After further stratification for tumor grading, stage III patients carrying the G allele of rs4919510 and undergoing adjuvant chemotherapy were at decreased risk of relapse (HR = 0.44; 95% CI: 0.20–0.94; adjusted P = 0.03). The present study confirms that variations in miRNA-encoding genes may be an important factor for modulating CRC prognosis and predicting therapy response.

Cell free circulating microRNAs (cfmiRNAs) have been recognized as robust and stable biomarkers of cancers. However, little is known about the prognostic significance of cfmiRNAs in esophageal adenocarcinoma (EA). In this study, we explored whether specific cfmiRNA profiles could predict EA prognosis and whether Helicobacter pylori (HP) infection status could influence the association between cfmiRNAs and EA survival outcome. We profiled 1075 miRNAs in pooled serum samples from 30 EA patients and 30 healthy controls. The most relevant cfmiRNAs were then assessed for their associations with EA survival in an independent cohort of 82 patients, using Log-rank test and multivariate Cox regression models. Quantitative real-time PCR (qRT-PCR) was used for cfmiRNA profiling. HP infection status was determined by immunoblotting assay. We identified a panel of 18 cfmiRNAs that could distinguish EA patients from healthy subjects (P = 3.0E–12). In overall analysis and in HP-positive subtype patients, no cfmiRNA was significantly associated with EA prognosis. In HP-negative patients, however, 15 cfmiRNAs were significantly associated with overall survival (OS) (all P < 0.05). A combined 2-cfmiRNA (low miR-3935 and high miR-4286) risk score was constructed; that showed greater risk for worse OS (HR = 2.22, P = 0.0019) than individual cfmiRNA alone. Patients with high-risk score had >10-fold increased risk of death than patients with low risk score (P = 0.0302; HR = 10.91; P = 0.0094). Our findings suggest that dysregulated cfmiRNAs may contribute to EA survival outcome and HP infection status may modify the association between cfmiRNAs and EA survival.

Women born from a preeclamptic (PE) pregnancy are associated with a lower risk of breast cancer. Prenatal and early-life exposures are hypothesized to influence breast cancer susceptibility through their effect on stem cells. We examined stem cell populations in umbilical cord blood from PE pregnancies and compared with those from pregnancies without this condition. We isolated mononuclear cells from 58 PE and 197 normotensive (non-PE) umbilical cord blood samples and examined the different stem cell populations. Hematopoietic (CD34+ and CD34+CD38), endothelial (CD34+CD133+, CD34+VEGFR2+, CD133+VEGFR2+ and CD34+CD133+VEGFR2+), and putative breast (EpCAM+, EpCAM+CD49f+, EpCAM+CD49f+CD117+, CD49f+CD24+, CD24+CD29+ and CD24+CD29+CD49f+) stem/progenitor cell subpopulations were quantified by flow cytometry and compared between PE and non-PE samples. Hematopoietic CD34+ cell counts were significantly lowered in PE compared with non-PE samples (P = 0.039, Kruskal–Wallis test). Levels of CD34+CD133+ endothelial progenitor cells were also lower in PE samples (P = 0.032, multiple regression analysis). EpCAM+ and EpCAM+CD49f+ putative breast stem cell levels were significantly lowered in PE subjects (multiple regression analysis: P = 0.038 and 0.007, respectively). Stratifying by newborn gender, EpCAM+ and EpCAM+CD49f+ stem cells were significantly lowered in PE samples of female, but not male, newborns. Umbilical cord blood samples from pregnancies complicated by preeclampsia thus had significantly lower levels of hematopoietic, endothelial, and putative breast stem cells than non-PE controls. With a lowered breast cancer risk for offspring of a PE pregnancy, our findings provide support to the hypothesis that susceptibility to breast oncogenesis may be affected by conditions and processes during the prenatal period.

We investigated genetic variation in CYP2A6 in relation to lung cancer risk among African American smokers, a high-risk population. Previously, we found that CYP2A6, a nicotine/nitrosamine metabolism gene, was associated with lung cancer risk in European Americans, but smoking habits, lung cancer risk and CYP2A6 gene variants differ significantly between European and African ancestry populations. Herein, African American ever-smokers, drawn from two independent lung cancer case–control studies, were genotyped for reduced activity CYP2A6 alleles and grouped by predicted metabolic activity. Lung cancer risk in the Southern Community Cohort Study (n = 494) was lower among CYP2A6 reduced versus normal metabolizers, as estimated by multivariate conditional logistic regression [odds ratio (OR) = 0.44; 95% confidence interval (CI) = 0.26–0.73] and by unconditional logistic regression (OR = 0.62; 95% CI = 0.41–0.94). The association was replicated in an independent study from MD Anderson Cancer Center (n = 407) (OR = 0.64; 95% CI = 0.42–0.98), and pooling the studies yielded an OR of 0.64 (95% CI = 0.48–0.86). Exploratory analyses revealed a significant interaction between CYP2A6 genotype and sex on the risk for lung cancer (Southern Community Cohort Study: P = 0.04; MD Anderson: P = 0.03; Pooled studies: P = 0.002) with a CYP2A6 effect in men only. These findings support a contribution of genetic variation in CYP2A6 to lung cancer risk among African American smokers, particularly men, whereby CYP2A6 genotypes associated with reduced metabolic activity confer a lower risk of developing lung cancer.

Chemokines modulate angiogenesis and metastasis that dictate cancer development in tumor microenvironment. Osteosarcoma is the most frequent bone tumor and is characterized by a high metastatic potential. Chemokine CCL5 (previously called RANTES) has been reported to facilitate tumor progression and metastasis. However, the crosstalk between chemokine CCL5 and vascular endothelial growth factor (VEGF) as well as tumor angiogenesis in human osteosarcoma microenvironment has not been well explored. In this study, we found that CCL5 increased VEGF expression and production in human osteosarcoma cells. The conditioned medium (CM) from CCL5-treated osteosarcoma cells significantly induced tube formation and migration of human endothelial progenitor cells. Pretreatment of cells with CCR5 antibody or transfection with CCR5 specific siRNA blocked CCL5-induced VEGF expression and angiogenesis. CCL5/CCR5 axis demonstrably activated protein kinase C (PKC), c-Src and hypoxia-inducible factor-1 alpha (HIF-1α) signaling cascades to induce VEGF-dependent angiogenesis. Furthermore, knockdown of CCL5 suppressed VEGF expression and attenuated osteosarcoma CM-induced angiogenesis in vitro and in vivo. CCL5 knockdown dramatically abolished tumor growth and angiogenesis in the osteosarcoma xenograft animal model. Importantly, we demonstrated that the expression of CCL5 and VEGF were correlated with tumor stage according the immunohistochemistry analysis of human osteosarcoma tissues. Taken together, our findings provide evidence that CCL5/CCR5 axis promotes VEGF-dependent tumor angiogenesis in human osteosarcoma microenvironment through PKC/c-Src/HIF-1α signaling pathway. CCL5 may represent a potential therapeutic target against human osteosarcoma.

Activation of the NOTCH pathway occurs commonly in T acute lymphoblastic leukemia (T-ALL) mainly due to mutations in NOTCH1 or alterations in FBW7 and is involved in the regulation of cell proliferation and survival. Since mutations hit different domains of the receptor, they are predicted to heterogeneously perturb ligand-induced NOTCH1 activity. Moreover, T-ALL cells also co-express NOTCH3 receptors which could be triggered by different ligands. In this study, we aimed to investigate the role of DLL4 in the regulation of NOTCH signaling in T-ALL cells in the context of different types of NOTCH1 mutation or wild-type NOTCH receptor, as well as the effects of DLL4 neutralization on T-ALL engraftment in mice.

We found that NOTCH signaling can be stimulated in T-ALL cells in vitro by either human or murine DLL4 with heterogeneous effects, according to NOTCH1/FBW7 mutation status, and that these effects can be blocked by antibodies neutralizing DLL4, NOTCH1 or NOTCH2/3. In vivo, DLL4 is expressed in the spleen and the bone marrow (BM) of NOD/SCID mice bearing T-ALL xenografts as well as the BM of T-ALL patients. Importantly, DLL4 blockade impaired growth of T-ALL cells in NOD/SCID mice and increased leukemia cell apoptosis. These results show that DLL4 is an important component of the tumor microenvironment which contributes to the early steps of T-ALL cell growth.

Response to breast cancer chemoprevention can depend upon host genetic makeup and initiating events leading up to preneoplasia. Increased expression of aromatase and estrogen receptor (ER) is found in conjunction with breast cancer. To investigate response or resistance to endocrine therapy, mice with targeted overexpression of Esr1 or CYP19A1 to mammary epithelial cells were employed, representing two direct pathophysiological interventions in estrogen pathway signaling. Both Esr1 and CYP19A1 overexpressing mice responded to letrozole with reduced hyperplastic alveolar nodule prevalence and decreased mammary epithelial cell proliferation. CYP19A1 overexpressing mice were tamoxifen sensitive but Esr1 overexpressing mice were tamoxifen resistant. Increased ER expression occurred with tamoxifen resistance but no consistent changes in progesterone receptor, pSTAT3, pSTAT5, cyclin D1 or cyclin E levels in association with response or resistance were found. RNA-sequencing (RNA-seq) was employed to seek a transcriptome predictive of tamoxifen resistance using these models and a second tamoxifen-resistant model, BRCA1 deficient/Trp53 haploinsufficient mice. Sixty-eight genes associated with immune system processing were upregulated in tamoxifen-resistant Esr1- and Brca1-deficient mice, whereas genes related to aromatic compound metabolic process were upregulated in tamoxifen-sensitive CYP19A1 mice. Interferon regulatory factor 7 was identified as a key transcription factor regulating these 68 immune processing genes. Two loci encoding novel transcripts with high homology to human immunoglobulin lambda-like polypeptide 1 were uniquely upregulated in the tamoxifen-resistant models. Letrozole proved to be a successful alternative to tamoxifen. Further study of transcriptional changes associated with tamoxifen resistance including immune-related genes could expand our mechanistic understanding and lead to biomarkers predictive of escape or response to endocrine therapies.

Cancer-associated fibroblasts (CAFs) have recently been linked to the invasion and metastasis of gastric cancer. In addition, the microRNA (miR)-200 family plays a central role in the regulation of the epithelial–mesenchymal transition process during cancer metastasis, and aberrant DNA methylation is one of the key mechanisms underlying regulation of the miR-200 family. In this study, we clarified whether epigenetic changes of miR-200b by CAFs stimulate cancer invasion and peritoneal dissemination in gastric cancer. We evaluated the relationship between miR-200b and CAFs using a coculture model. In addition, we established a peritoneal metastasis mouse model and investigated the expression and methylation status of miR-200b. We also investigated the expression and methylation status of miR-200b and CAFs expression in primary gastric cancer samples. CAFs (CAF-37 and CAF-50) contributed to epigenetic changes of miR-200b, reduced miR-200b expression and promoted tumor invasion and migration in NUGC3 and OCUM-2M cells in coculture. In the model mice, epigenetic changes of miR-200b were observed in the inoculated high-frequency peritoneal dissemination cells. In the 173 gastric cancer samples, the low miR-200b expression group demonstrated a significantly poorer prognosis compared with the high miR-200b expression group and was associated with peritoneal metastasis. In addition, downregulation of miR-200b in cancer cells was significantly correlated with alpha-smooth muscle actin expression. Our data provide evidence that CAFs reduce miR-200b expression and promote tumor invasion through epigenetic changes of miR-200b in gastric cancer. Thus, CAFs might be a therapeutic target for inhibition of gastric cancer.

Tumor cells need to attain anoikis resistance to survive prior to metastasis making it a vital trait of malignancy. The mechanism by which pancreatic cancer cells resist anoikis and metastasize is not well established. Significant proportion of pancreatic cancer cells resisted anoikis when grown under anchorage-independent conditions. The cells that resisted anoikis showed higher migratory and invasive characteristics than the cells that were cultured under anchorage-dependent condition. Interestingly, anoikis-resistant cells exhibited significantly increased expression and phosphorylation of signal transducer and activation of transcription 3 (STAT3) at Tyr 705, as compared to adherent cells. AG 490 and piplartine (PL) induced significant anoikis in anoikis-resistant pancreatic cancer cells. Silencing STAT3 not only reduced the capacity of pancreatic cancer cells to resist anoikis but also reversed its invasive characteristics. Interleukin-6 treatment and overexpression of STAT3 enhanced anoikis resistance and protected the cells from PL-induced anoikis. PL-treated cells completely failed to develop tumors when injected subcutaneously in immune-compromised mice. Moreover, these cells also failed to metastasize when injected intravenously. On the other hand, untreated anoikis-resistant cells not only formed aggressive tumors but also metastasized substantially to lungs and liver when injected intravenously. Metastatic nodules formed by untreated anoikis-resistant cells in lungs exhibited significant phosphorylation of STAT3 at Tyr705. Taken together, our results established the critical involvement of STAT3 in conferring anoikis resistance to pancreatic cancer cells and increased metastasis.

Interferons (IFNs) have been used to treat epithelial lesions caused by human papillomavirus (HPV) persistence. Here, we exposed primary human keratinocytes (HFKs) immortalized by persistently replicating HPV-16 plasmid genomes to increasing levels of IFN-. While untreated HFKs retained replicating HPV-16 plasmids for up to 60–120 population doublings, IFN led to rapid HPV-16 plasmid loss. However, treated cultures eventually gave rise to outgrowth of clones harboring integrated HPV-16 genomes expressing viral E6 and E7 oncogenes from chimeric virus-cell mRNAs similar to those in cervical and head and neck cancers. Surprisingly, every HPV-16 integrant that arose after IFN exposure stemmed from an independent integration event into a different cellular gene locus, even within parallel cultures started from small cell inocula and cultured separately for ≥25 doublings to permit the rise and expansion of spontaneous integrants. While IFN treatment conferred a growth advantage upon preexisting integrants added to mixed control cultures, our results indicate that IFN exposure directly or indirectly induces HPV-16 integration, rather than only selects preexisting, spontaneous integrants that appear to be much less frequent. We estimate that IFN exposure increased integration rates by ≥100-fold. IFN-induced HPV-16 integration involved a wide range of chromosomal loci with less apparent selection for recurrent insertions near genes involved in cancer-related pathways. We conclude that IFNs and other potential treatments targeting high-risk HPV persistence that disrupt viral genome replication may promote increased high-risk HPV integration as a step in cancer progression. Therapies against high-risk HPV persistence thus need to be evaluated for their integration-inducing potential.

Formaldehyde (FA) is an economically important industrial chemical to which millions of people worldwide are exposed environmentally and occupationally. Recently, the International Agency for Cancer Research concluded that there is sufficient evidence that FA causes leukemia, particularly myeloid leukemia. To evaluate the biological plausibility of this association, we employed a chromosome-wide aneuploidy study approach, which allows the evaluation of aneuploidy and structural chromosome aberrations (SCAs) of all 24 chromosomes simultaneously, to analyze cultured myeloid progenitor cells from 29 workers exposed to relatively high levels of FA and 23 unexposed controls. We found statistically significant increases in the frequencies of monosomy, trisomy, tetrasomy and SCAs of multiple chromosomes in exposed workers compared with controls, with particularly notable effects for monosomy 1 [P = 6.02E-06, incidence rate ratio (IRR) = 2.31], monosomy 5 (P = 9.01E-06; IRR = 2.24), monosomy 7 (P = 1.57E-05; IRR = 2.17), trisomy 5 (P = 1.98E-05; IRR = 3.40) and SCAs of chromosome 5 (P = 0.024; IRR = 4.15). The detection of increased levels of monosomy 7 and SCAs of chromosome 5 is particularly relevant as they are frequently observed in acute myeloid leukemia. Our findings provide further evidence that leukemia-related cytogenetic changes can occur in the circulating myeloid progenitor cells of healthy workers exposed to FA, which may be a potential mechanism underlying FA-induced leukemogenesis.

Identification of early perturbations induced in cells from non-cancerous breast tissue is critical for understanding possible breast cancer risk from chemical exposure. We have demonstrated previously that exposure to the ubiquitous xenoestrogens, bisphenol A (BPA) and methyl paraben, promotes the hallmarks of cancer in non-malignant human high-risk donor breast epithelial cells (HRBECs) isolated from several donors. Here we show that terephthalic acid (TPA), a major chemical precursor of polyethylene terephthalate (PET) containers used for the storage of food and beverages, increased the ERα: ERβ ratio in multiple HRBEC samples, suggesting an estrogenic effect. Although, like BPA and methyl paraben, TPA also promoted resistance to tamoxifen-induced apoptosis, unlike these chemicals instead of inducing an increased S-phase fraction, TPA treatment arrested cell proliferation. DNA-PK, ATM and members of the MRN complex, known to be involved in DNA damage sensor and effector proteins, were elevated indicating induction of DNA strand breaks. Early DNA damage checkpoint response, mediated through p53/p21, led to G1 arrest in TPA-exposed cells. Removal of TPA from the growth medium resulted in the rapid induction of BCL2, increasing the ratio of anti-: pro-apoptotic proteins, together with overexpression of Cyclin A/CDK2 proteins. Consequently, despite elevated p53pSer15 and H2AXpSer139, indicating sustained DNA damage, TPA exposed cells resumed robust growth rates seen prior to TPA exposure. The propensity for the perpetuation of DNA aberrations that activate DNA damage pathways in non-malignant breast cells justifies careful consideration of human exposure to TPA, particularly at vulnerable life stages.