Evaluation of possible role of fluoride in pathogenesis of oral submucous fibrosis: A pilot study.

BACKGROUND: Oral submucous fibrosis (OSMF) is a potentially malignant disorder. Although areca nut chewing is an established risk factor, its low prevalence among nut chewers indicates additional factors likely facilitates pathogenesis. We recently demonstrated high fluoride levels in smokeless tobacco products and hypothesized a potential pathological role of fluoride in OSMF. Further exploring this novel role, this study compared fluoride levels in tissue, serum, and saliva samples from OSMF patients and healthy controls. METHODS: The ethically approved study included 25 clinically confirmed OSMF patients and 25 healthy matched controls. OSMF cases underwent buccal mucosal incisional biopsy, while controls had buccal mucosa tissue sampling during third molar removal. Fasting venous blood and unstimulated saliva were collected. Fluoride levels were analysed using ion chromatography and expressed as median (IQR). RESULTS: OSMF cases showed significantly higher fluoride concentrations compared with controls in tissue biopsies (30.1 vs. 0 mg/kg, p < 0.0001), serum (0.4 vs. 0 mg/L, p = 0.005) and saliva (1.3 vs. 0 mg/L, p < 0.0001). Majority (68%) of controls had undetectable fluoride levels across all samples. Tissue fluoride weakly correlated with OSMF severity (r = -0.158, p = 0.334). CONCLUSION: The preliminary findings demonstrated increased tissue fluoride levels in OSMF patients compared with healthy controls. Along with a previous study showing high fluoride content in smokeless tobacco products, these findings provided early evidence suggesting fluoride could play a contributory role in OSMF pathogenesis. Further large-scale investigation is warranted to definitively establish whether the association between fluoride exposure and OSMF is indicative of causation.

Landscape of clinically actionable mutations in breast cancer 'A cohort study'.

Breast cancer (BC) is a heterogeneous disease. Numerous chemotherapeutic agents are available for early stage or advanced/metastatic breast cancer to provide maximum benefit with minimum side effects. However, the clinical outcome of patients with the same clinical and pathological characteristics and treated with similar treatments may show major differences and a vast majority of patients still develop treatment resistance and eventually succumb to disease. It remains an unmet need to identify specific molecular defects, new biomarkers to enable clinicians to adopt individualized treatment for every patient in terms of endocrine, chemotherapy or targeted therapy which will improve clinical outcomes in BC. Our study aimed to identify frequent hotspot mutation profile in BC by targeted deep sequencing in cancer-related genes using Illumina Truseq amplicon/Swift Accel-Amplicon panel and MiSeq technology in an IRB-approved prospective study in a CLIA compliant laboratory. All the cases had pathology review for stage, histological type, hormonal status and Ki-67. Data was processed using Strand NGS™. Mutations identified in the tumor were assessed for 'actionability' i.e. response to therapy and impact on prognosis.

Mammalian lysine histone demethylase KDM2A regulates E2F1-mediated gene transcription in breast cancer cells.

It is established that histone modifications like acetylation, methylation, phosphorylation and ubiquitination affect chromatin structure and modulate gene expression. Lysine methylation/demethylation on Histone H3 and H4 is known to affect transcription and is mediated by histone methyl transferases and histone demethylases. KDM2A/JHDM1A/FBXL11 is a JmjC-containing histone demethylase that targets mono- and dimethylated Lys36 residues of Histone H3; its function in breast cancer is not fully understood. Here we show that KDM2A is strongly expressed in myoepithelial cells (MEPC) in breast cancer tissues by immunohistochemistry. Ductal cells from ductal carcinoma in situ (DCIS) and infiltrating ductal carcinoma (IDC) show positive staining for KDM2A, the expression decreases with disease progression to metastasis. Since breast MEPCs have tumor-suppressive and anti-angiogenic properties, we hypothesized that KDM2A could be contributing to some of these functions. Silencing KDM2A with small interfering RNAs demonstrated increased invasion and migration of breast cancer cells by suppressing a subset of matrix metalloproteinases (MMP-2, -9, -14 and -15), as seen by real-time PCR. HUVEC cells showed increased angiogenic tubule formation ability in the absence of KDM2A, with a concomitant increase in the expression of VEGF receptors, FLT-1 and KDR. KDM2A physically bound to both Rb and E2F1 in a cell cycle dependent manner and repressed E2F1 transcriptional activity. Chromatin immunoprecipitation (ChIP) assays revealed that KDM2A associates with E2F1-regulated proliferative promoters CDC25A and TS in early G-phase and dissociates in S-phase. Further, KDM2A could also be detected on MMP9, 14 and 15 promoters, as well as promoters of FLT1 and KDR. KDM2A could suppress E2F1-mediated induction of these promoters in transient transfection experiments. These results suggest a regulatory role for KDM2A in breast cancer cell invasion and migration, through the regulation of E2F1 function.

GM-CSF-dependent pSTAT5 sensitivity is a feature with therapeutic potential in chronic myelomonocytic leukemia.

Granulocyte-macrophage-colony-stimulating factor (GM-CSF) hypersensitivity is a hallmark of juvenile myelomonocytic leukemia (JMML) but has not been systematically shown in the related human disease chronic myelomonocytic leukemia (CMML). We find that primary CMML samples demonstrate GM-CSF-dependent hypersensitivity by hematopoietic colony formation assays and phospho-STAT5 (pSTAT5) flow cytometry compared with healthy donors. Among CMML patients, the pSTAT5 hypersensitive response positively correlated with high-risk disease, peripheral leukocytes, monocytes, and signaling-associated mutations. When compared with IL-3 and G-CSF, GM-CSF hypersensitivity was cytokine specific and thus a possible target for intervention in CMML. To explore this possibility, we treated primary CMML cells with KB003, a novel monoclonal anti-GM-CSF antibody, and JAK2 inhibitors. We found that an elevated proportion of immature GM-CSF receptor-α(R) subunit-expressing cells were present in the bone marrow myeloid compartment of CMML. In survival assays, we found that myeloid and monocytic progenitors were sensitive to GM-CSF signal inhibition. Our data indicate that a committed myeloid precursor expressing CD38 may represent the progenitor population with enhanced GM-CSF dependence in CMML, consistent with results in JMML. These preclinical data indicate that GM-CSF signaling inhibitors merit further investigation in CMML and that GM-CSFR expression on myeloid progenitors may be a biomarker for this therapy.

Nicotine, IFN-γ and retinoic acid mediated induction of MUC4 in pancreatic cancer requires E2F1 and STAT-1 transcription factors and utilize different signaling cascades.

BACKGROUND: The membrane-bound mucins are thought to play an important biological role in cell-cell and cell-matrix interactions, in cell signaling and in modulating biological properties of cancer cell. MUC4, a transmembrane mucin is overexpressed in pancreatic tumors, while remaining undetectable in the normal pancreas, thus indicating a potential role in pancreatic cancer pathogenesis. The molecular mechanisms involved in the regulation of MUC4 gene are not yet fully understood. Smoking is strongly correlated with pancreatic cancer and in the present study; we elucidate the molecular mechanisms by which nicotine as well as agents like retinoic acid (RA) and interferon-γ (IFN-γ) induce the expression of MUC4 in pancreatic cancer cell lines CD18, CAPAN2, AsPC1 and BxPC3. RESULTS: Chromatin immunoprecipitation assays and real-time PCR showed that transcription factors E2F1 and STAT1 can positively regulate MUC4 expression at the transcriptional level. IFN-γ and RA could collaborate with nicotine in elevating the expression of MUC4, utilizing E2F1 and STAT1 transcription factors. Depletion of STAT1 or E2F1 abrogated the induction of MUC4; nicotine-mediated induction of MUC4 appeared to require α7-nicotinic acetylcholine receptor subunit. Further, Src and ERK family kinases also mediated the induction of MUC4, since inhibiting these signaling molecules prevented the induction of MUC4. MUC4 was also found to be necessary for the nicotine-mediated invasion of pancreatic cancer cells, suggesting that induction of MUC4 by nicotine and other agents might contribute to the genesis and progression of pancreatic cancer. CONCLUSIONS: Our studies show that agents that can promote the growth and invasion of pancreatic cancer cells induce the MUC4 gene through multiple pathways and this induction requires the transcriptional activity of E2F1 and STAT1. Further, the Src as well as ERK signaling pathways appear to be involved in the induction of this gene. It appears that targeting these signaling pathways might inhibit the expression of MUC4 and prevent the proliferation and invasion of pancreatic cancer cells.

Nicotine induces inhibitor of differentiation-1 in a Src-dependent pathway promoting metastasis and chemoresistance in pancreatic adenocarcinoma.

Smoking is a significant risk factor for pancreatic cancer, but the molecular mechanisms by which tobacco smoke components promote the growth and progression of these cancers are not fully understood. While nicotine, the addictive component of tobacco smoke, is not a carcinogen, it has been shown to promote the growth of non-small cell lung and pancreatic cancers in a receptor-dependent fashion. Here, we show that stimulation of pancreatic cancer cells with nicotine concentrations that are within the range of human exposure results in activation of Src kinase, which facilitated the induction of the inhibitor of differentiation-1 (Id1) transcription factor. Depletion of Id1 prevented nicotine-mediated induction of proliferation and invasion of pancreatic cancer cells, indicating that it is a major mediator of nicotine function. Nicotine could promote the growth and metastasis of pancreatic cancers orthotopically implanted into SCID mice; in addition, cells stably expressing a short hairpin RNA for Id1 did not grow or metastasize in response to nicotine. Nicotine could also confer resistance to apoptosis induced by gemcitabine in pancreatic cancer cells in vitro and depletion of Src or Id1 rendered the cells sensitive to gemcitabine. Further, nicotine could effectively inhibit the chemotherapeutic effects of gemcitabine on pancreatic tumors xenografted into mice. Clinical analyses of resected pancreatic cancer specimens demonstrated a statistically significant correlation between Id1 expression and phospho-Src, tumor grade/differentiation, and worsening overall patient survival. These results demonstrate that exposure to tobacco smoke components might promote pancreatic cancer progression, metastasis, and chemoresistance and highlight the role of Id1 in these processes.

Stat3-siRNA induces Fas-mediated apoptosis in vitro and in vivo in breast cancer.

Stat3, a member of the signal transducer and activator of transcription family, has the potential to mediate cell survival, growth and differentiation. Stat3 is constitutively activated in numerous cancers, including >50% of breast cancers. Previous studies demonstrated that constitutively activated Stat3 plays an important role in breast cancer development and progression by promoting cell proliferation and inhibiting apoptosis. The present study was designed to investigate the potential use of RNA interference (RNAi) to block Stat3 expression and activation, as well as the subsequent effect on human breast cancer cell growth. Our studies show that knockdown of STAT3 expression by siRNA reduced expression of Bcl-xL and survivin in MDA-MB-231 cells, and also led to Fas mediated intrinsic apoptotic pathway by activating caspases -8, -9, -3 and PARP1 cleavage. In nude mice, pRNAi-Stat3 significantly suppressed tumor growth compared with controls. It also suppressed Stat3 expression, and downregulated BcL-xL and upregulated Fas, Fas-L and cleaved caspase-3 expression within the tumor, which significantly induced apoptosis and led to tumor suppression. Thus, targeting Stat3 signaling using siRNA may serve as a novel therapeutic strategy for the treatment of breast cancers expressing constitutively activated Stat3.

Tissue inhibitor of metalloproteinase 3 suppresses tumor angiogenesis in matrix metalloproteinase 2-down-regulated lung cancer.

Matrix metalloproteinase-2 (MMP-2) expression is often up-regulated in advanced cancers and known to play an important role in tumor angiogenesis. We previously showed that adenoviral-mediated delivery of siRNA for MMP-2 (Ad-MMP-2-Si) inhibited lung cancer growth, angiogenesis, and metastasis. In this study, we investigated the signaling mechanisms involved in Ad-MMP-2-Si-mediated inhibition of angiogenesis. Ad-MMP-2-Si treatment inhibited neovascularization in vivo as determined by mouse dorsal air sac model, and conditioned medium from Ad-MMP-2-Si-infected A549 lung cancer cells (Ad-MMP-2-Si-CM) inhibited endothelial tube formation in vitro. Ad-MMP-2-Si-CM decreased proliferation as determined by Ki-67 immunofluorescence and induced apoptosis in endothelial cells as determined by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) assay. Furthermore, Ad-MMP-2-Si-CM inhibited AKT phosphorylation and induced phosphorylation of extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase in endothelial cells. Overexpression of constitutively active AKT reversed the Ad-MMP-2-Si-CM-mediated inhibition of tube formation and induction of ERK phosphorylation. Conversely, Ad-MMP-2-Si-CM induced tissue inhibitor of metalloproteinase (TIMP) 3 expression, and the interaction of vascular endothelial growth factor 2 and TIMP-3 was determined by coimmunoprecipitation experiments. TIMP-3 induction was mediated by ERK activation. In addition, electrophoretic mobility shift and chromatin immunoprecipitation assays show that Sp1 transcription factor mediated Ad-MMP-2-Si-CM-stimulated increase of TIMP-3. Vasculature destruction was confirmed with colocalization studies with TUNEL and an endothelial marker, CD31, in tumor sections of Ad-MMP-2-Si-treated mice. Our data collectively suggest that MMP-2 inhibition induces endothelial apoptosis in vivo and inhibits endothelial tube formation. These experiments provide the first evidence that inhibition of p-AKT and induction of p-ERK1/2 are crucial events in the induction of TIMP-3-mediated endothelial apoptosis in MMP-2 inhibited lung tumors.

Matrix metalloproteinase-9 inhibition down-regulates radiation-induced nuclear factor-kappa B activity leading to apoptosis in breast tumors.

PURPOSE: Novel strategies are needed to prevent the high mortality rates of several types of cancer. These high rates stem from tumor resistance to radiation therapy, which is thought to result from the induction of matrix metalloproteinases (MMP) and plasminogen activators. In the present study, we show that the modulation of MMP-9 expression, using adenoviral-mediated transfer of the antisense MMP-9 gene (MMP-9 adenoviral construct, Ad-MMP-9), affects breast cancer sensitivity to radiation. EXPERIMENTAL DESIGN: In the present study, we used antisense Ad-MMP-9 to down-regulate the expression of MMP-9 in MDA MB 231 breast cancer cell lines in vitro before irradiation and subsequently incubated cells in hypoxic condition. In vivo studies were done with orthotopic breast tumors, and radiosensitivity was evaluated both in vitro and in vivo. RESULTS: Ad-MMP-9 infection resulted in down-regulation of radiation-induced levels of hypoxia-inducible factor 1 alpha and MMP-9 under hypoxic conditions in MDA MB 231 breast cancer cells. In addition, Ad-MMP-9, in combination with radiation, decreased levels of the transcription factors nuclear factor-kappaB and activator protein 1, both of which contribute to the radioresistance of breast tumors. Finally, the triggering of the Fas-Fas ligand apoptotic cascade, which resulted in the cleavage of PARP-1 and caspase-10, caspase-3, and caspase-7, signifies the efficiency of combined treatment of Ad-MMP-9 and radiation. Treatment with Ad-MMP-9 plus radiation completely regressed tumor growth in orthotopic breast cancer model. CONCLUSIONS: In summary, integrating gene therapy (adenovirus-mediated inhibition of MMP-9) with radiotherapy could have a synergistic effect, thereby improving the survival of patients with breast cancer.

Blockade of tumor growth due to matrix metalloproteinase-9 inhibition is mediated by sequential activation of beta1-integrin, ERK, and NF-kappaB.

We previously showed that matrix metalloproteinase (MMP)-9 inhibition using an adenovirus-mediated delivery of MMP-9 small interfering RNA (Ad-MMP-9), caused senescence in medulloblastoma cells. Regardless of whether or not Ad-MMP-9 would induce apoptosis, the possible signaling mechanism is still obscure. In this report, we demonstrate that Ad-MMP-9 induced apoptosis in DAOY cells as determined by propidium iodide and terminal deoxynucleotidyltransferase-mediated nick end labeling staining. Ad-MMP-9 infection induced the release of cytochrome c, activation of caspase-9 and -3, and cleavage of poly(ADP-ribose) polymerase. Ad-MMP-9 infection stimulated ERK, and electrophoretic mobility shift assay indicated an increase in NF-kappaB activation. ERK inhibition, using a kinase-dead mutant for ERK, ameliorated NF-kappaB activation and caspase-mediated apoptosis in Ad-MMP-9-infected cells. beta1-Integrin expression in Ad-MMP-9-infected cells also increased, and this increase was reversed by the reintroduction of MMP-9. We found that the addition of beta1 blocking antibodies inhibited Ad-MMP-9-induced ERK activation. Taken together, our results indicate that MMP-9 inhibition induces apoptosis due to altered beta1-integrin expression in medulloblastoma. In addition, ERK activation plays an active role in this process and functions upstream of NF-kappaB activation to initiate the apoptotic signal.

RNAi-mediated downregulation of urokinase plasminogen activator receptor and matrix metalloprotease-9 in human breast cancer cells results in decreased tumor invasion, angiogenesis and growth.

The serine protease urokinase-type plasminogen activator (uPA) plays a significant role in tumor cell invasion and metastasis when bound to its specific receptor, uPAR (also known as CD87). In addition to the uPA-uPAR system, matrix metalloproteinases (MMPs) are involved in tumor cell invasion and metastasis. In this study, we achieved specific inhibition of uPAR and MMP-9 using RNAi technology. We introduced small interfering RNA to downregulate the expression of uPAR and MMP-9 (pUM) in breast cancer cell lines (MDA MB 231 and ZR 75 1). In vitro angiogenesis studies indicated a decrease in the angiogenic potential of the treated cells; in particular, a remarkable decrease was observed in the cells treated with bicistronic construct (pUM) in comparision to the controls. Additionally, bicistronic construct inhibited the formation of capillary-like structures in in vivo models of angiogenesis. Similarly, the invasive potential and migration decreased dramatically when treated with the bicistronic construct as shown by matrigel invasion and migration assays. These results suggest a synergistic effect from the simultaneous downregulation of uPAR and MMP-9. We also assessed the levels of phosphorylated forms of MAPK, ERK and AKT signaling pathway molecules and found reduction in the levels of these molecules in cells treated with the bicistronic construct as compared to the control cells. Furthermore, targeting both uPAR and MMP-9 totally regressed orthotopic breast tumors in nude mice. In conclusion, our results provide evidence that the simultaneous downregulation of uPAR and MMP-9 using RNAi technology may provide an effective tool for breast cancer therapy.

SPARC-induced migration of glioblastoma cell lines via uPA-uPAR signaling and activation of small GTPase RhoA.

Secreted protein acidic and rich in cysteine (SPARC) is highly expressed in human gliomas where it promotes invasion and delays tumor growth, both in vitro and in vivo. SPARC, which interacts at the cell surface, has an impact on intracellular signaling and downstream gene expression changes, which might account for some of its effects on invasion and growth. Additionally in vitro studies demonstrated that SPARC delays growth, increases attachment, and modulates migration of tumor cells in an extracellular matrix-specific and concentration-dependent manner. Because the signaling aspect of this migration is neither well understood nor characterized, we overexpressed SPARC in both the minimally-invasive U87 cell line and in the most aggressive invasive cell line, SNB19. We first performed RT-PCR analysis and observed an upregulation of uPA and its receptor, uPAR. We also observed increased expression levels of matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9). Western blot analysis confirmed these results, and the enzymatic activity of the metalloproteinases and uPA was further supported by zymography. Downstream of the uPA-uPAR interaction, upregulation of PI3-K occurred in cells overexpressing SPARC. Using GST-TRBD, we showed the upregulation of active GTP-bound RhoA, but neither Rac1 nor Cdc42 were activated. The inhibition of uPA and uPAR downregulated PI3-K activity and cell migration, as shown by matrigel invasion assay. A dorsal skin-fold chamber model revealed the high angiogenic activity of SPARC, though the proliferation of SPARC overexpressing cells was unaffected. Our results show that the small GTPase RhoA was a critical mediator of invasion or migration in the uPA-uPAR/PI3-K signaling pathway.

Monocyte-expressed urokinase inhibits vascular smooth muscle cell growth by activating Stat1.

After vascular injury, a remodeling process occurs that features leukocyte migration and infiltration. Loss of endothelial integrity allows the leukocytes to interact with vascular smooth muscle cells (VSMCs) and to elicit "marching orders"; however, the signaling processes are poorly understood. We found that human monocytes inhibit VSMC proliferation and induce a migratory potential. The monocytes signal the VSMCs through the urokinase-type plasminogen activator (uPA). The VSMC uPA receptor (uPAR) receives the signal and activates the transcription factor Stat1 that, in turn, mediates the antiproliferative effects. These results provide the first evidence that monocytes signal VSMCs by mechanisms involving the fibrinolytic system, and they imply an important link between the uPA/uPAR-related signaling machinery and human vascular disease.