Investigating the role of Hedgehog/GLI1 signaling in glioblastoma cell response to temozolomide.

Resistance to chemotherapy substantially hinders successful glioblastoma (GBM) treatment, contributing to an almost 100% mortality rate. Resistance to the frontline chemotherapy, temozolomide (TMZ), arises from numerous signaling pathways that are deregulated in GBM, including Hedgehog (Hh) signaling. Here, we investigate suppression of Hh signaling as an adjuvant to TMZ using U87-MG and T98G cell lines as in vitro models of GBM. We found that silencing GLI1 with siRNA reduces cell metabolic activity by up to 30% in combination with TMZ and reduces multidrug efflux activity by 2.5-fold. Additionally, pharmacological GLI inhibition modulates nuclear p53 levels and decreases MGMT expression in combination with TMZ. While we surprisingly found that silencing GLI1 does not induce apoptosis in the absence of TMZ co-treatment, we discovered silencing GLI1 without TMZ co-treatment induces senescence as evidenced by a significant 2.3-fold increase in senescence associated β-galactosidase staining, and this occurs in a loss of PTEN-dependent manner. Finally, we show that GLI inhibition increases apoptosis in glioma stem-like cells by up to 6.8-fold in combination with TMZ, and this reduces the size and number of neurospheres grown from glioma stem-like cells. In aggregate, our data warrant the continued investigation of Hh pathway inhibitors as adjuvants to TMZ chemotherapy and highlight the importance of identifying signaling pathways that determine whether co-treatment will be successful

Strong Tumor Expression of ALDH1A1 is Associated with Black Race, Metabolic Disorders, and Poor Breast Cancer Outcomes

Racial differences in tumor biology may explain worse breast cancer outcomes in Black women relative to White women. This study provides a comparative racial analysis in Black and White women in terms of Aldehyde dehydrogenase 1 member A1 (ALDH1A1) expression and its association to clinicopathological features. Expression of ALDH1A1 in both tumor and stromal cells was assessed by immunohistochemistry in tissue microarrays containing 253 breast tumors including 161 tumors from White patients and 92 from Black patients. Relationships to clinicopathological features for strong and moderate to low ALDH1A1 staining were determined using Pearson’s Chi Square and an odds ratio was determined. Survival and recurrence were analyzed using Kaplan-Meier curves and Mantel Log-Rank tests. Multivariate analysis was conducted using Cox-proportional hazards tests.  Black, obese, and diabetic women showed higher staining intensity in both tumor and stromal tissue. Strong tumor staining was associated with Black race, advanced stage, high grade obesity and diabetes. Strong stromal expression was associated with estrogen receptor positivity, and prediabetes/diabetes. Patients with strong tumor ALDH1A1 had shorter recurrence free and overall survival compared to those with moderate to low expression. When stratified by race, Black women with strong tumor ALDH1A1 expression had shorter recurrence free survival compared to White women. Strong tumor ALDH1A1 staining was an independent predictor of poor overall survival in both Black and White women. These findings indicate that ALDH1A1 expression is associated with poor outcomes in breast cancer, particularly in Black women, and provide the first link between tumor ALDH1A1 expression, obesity, and diabetes

Detection of Canonical Hedgehog Signaling in Breast Cancer by 131-Iodine-Labeled Derivatives of the Sonic Hedgehog Protein

Activation of hedgehog (HH) pathway signaling is observed in many tumors. Due to a feedback loop, the HH receptor Patched (PTCH-1) is overexpressed in tumors with activated HH signaling. Therefore, we sought to radiolabel the PTCH-1 ligand sonic (SHH) for detection of cancer cells with canonical HH activity. Receptor binding of 131I-SHH was increased in cell lines with high HH pathway activation. Our findings also show that PTCH-1 receptor expression is decreased upon treatment with HH signaling inhibitors, and receptor binding of 131I-SHH is significantly decreased following treatment with cyclopamine. In vivo imaging and biodistribution studies revealed significant accumulation of 131I-SHH within tumor tissue as compared to normal organs. Tumor-to-muscle ratios were approximately 8 : 1 at 5 hours, while tumor to blood and tumor to bone were 2 : 1 and 5 : 1, respectively. Significant uptake was also observed in liver and gastrointestinal tissue. These studies show that 131I-SHH is capable of in vivo detection of breast tumors with high HH signaling. We further demonstrate that the hedgehog receptor PTCH-1 is downregulated upon treatment with hedgehog inhibitors. Our data suggests that radiolabeled SHH derivatives may provide a method to determine response to SHH-targeted therapies

Long-Term Survival, Toxicity Profile, and role of F-18 FDG PET/CT scan in Patients with Progressive Neuroendocrine Tumors Following Peptide Receptor Radionuclide Therapy with High Activity In-111 Pentetreotide

Aim: To study the long term benefits, toxicity and survival rate in patients with neuroendocrine tumors receiving multiple cycles of high activity In-111 Pentetreotide therapy. Moreover, our secondary aim was to evaluate the value of F-18 FDG PET-CT scan as prognostic indicator in this group of patients

BMI1 silencing enhances docetaxel activity and impairs antioxidant response in prostate cancer

The BMI1 oncogene promotes prostate cancer (PC) progression. High B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1) expression predicts poor prognosis in PC patients. Recent evidence suggests that BMI1 may also play a role in docetaxel chemoresistance. However, mechanisms and clinical significance of BMI1-related chemoresistance have not been investigated. For this purpose, BMI1 was silenced in 2 PC cell lines (LNCaP and DU 145). Cell proliferation and apoptosis after docetaxel treatment were measured. Guanine oxidation was assessed by in-cell western. Global gene expression analysis was performed on BMI1 silenced cells. Oncomine database was used to compare in vitro data with gene expression in PC samples. BMI1 silencing had no effect on cell proliferation but significantly enhanced docetaxel-induced antitumor activity. Gene expression analysis demonstrated that BMI1 silencing downregulates a set of antioxidant genes. Docetaxel treatment increased guanine oxidation, whereas the antioxidant N-acetyl cysteine rescued docetaxel-induced cell death. Examination of clinical datasets revealed a positive correlation of BMI1 and antioxidant gene expression. BMI1-controlled antioxidant genes were predictive of poor prognosis in PC patients. In conclusion, BMI1 enhances antioxidant response, thereby allowing PC survival after docetaxel-based chemotherapy. BMI1-controlled antioxidant genes are overexpressed in aggressive PC and should be tested as predictors of chemotherapy failure

Small-Molecule Synthetic Compound Norcantharidin Reverses Multi-Drug Resistance by Regulating Sonic Hedgehog Signaling in Human Breast Cancer Cells

Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells

Targeting the hedgehog transcription factors GLI1 and GLI2 restores sensitivity to vemurafenib-resistant human melanoma cells

BRAF inhibitor (BRAFi) therapy for melanoma patients harboring the V600E mutation is initially highly effective, but almost all patients relapse within a few months. Understanding the molecular mechanisms underpinning BRAFi-based therapy is therefore an important issue. Here we identified a previously unsuspected mechanism of BRAFi resistance driven by elevated Hedgehog (Hh) pathway activation that is observed in a cohort of melanoma patients after vemurafenib treatment. Specifically, we demonstrate that melanoma cell lines, with acquired in vitro-induced vemurafenib resistance, show increased levels of glioma-associated oncogene homolog 1 and 2 (GLI1/GLI2) compared with naive cells. We also observed these findings in clinical melanoma specimens. Moreover, the increased expression of the transcription factors GLI1/GLI2 was independent of canonical Hh signaling and was instead correlated with the noncanonical Hh pathway, involving TGF beta/SMAD (transforming growth factor-beta/Sma- and Mad-related family) signaling. Knockdown of GLI1 and GLI2 restored sensitivity to vemurafenib-resistant cells, an effect associated with both growth arrest and senescence. Treatment of vemurafenib-resistant cells with the GLI1/GLI2 inhibitor Gant61 led to decreased invasion of the melanoma cells in a three-dimensional skin reconstruct model and was associated with a decrease in metalloproteinase (MMP2/MMP9) expression and microphthalmia transcription factor upregulation. Gant61 monotherapy did not alter the drug sensitivity of naive cells, but could reverse the resistance of melanoma cells chronically treated with vemurafenib. We further noted that alternating dosing schedules of Gant61 and vemurafenib prevented the onset of BRAFi resistance, suggesting that this could be a potential therapeutic strategy for the prevention of therapeutic escape. Our results suggest that targeting the Hh pathway in BRAFi-resistant melanoma may represent a viable therapeutic strategy to restore vemurafenib sensitivity, reducing or even inhibiting the acquired chemoresistance in melanoma patients.Fapesp-grant number 2012/04194-1, 2013/05172-4, 2014/24400-0 and 2015/10821-7, CNPq-grant number 150447/2013-2 and 471512/2013-3 and PRODOC-grant no 3193-32/2010. Work in the lab of KS Smalley was supported by the National Institutes of Health grants R01 CA161107, R21 CA198550, and Skin SPORE grant P50 CA168536info:eu-repo/semantics/publishedVersio

Discrepancies in the Tumor Microenvironment of Spontaneous and Orthotopic Murine Models of Pancreatic Cancer Uncover a New Immunostimulatory Phenotype for B Cells.

B cells are salient features of pancreatic ductal adenocarcinoma (PDAC) tumors, yet their role in this disease remains controversial. Murine studies have indicated a protumoral role for B cells, whereas clinical data show tumor-infiltrating B cells are a positive prognostic factor, both in PDAC and other cancers. This disparity needs to be clarified in order to develop effective immunotherapies. In this study, we provide new evidence that reconcile human and mouse data and highlight the importance of using relevant preclinical tumor models when assessing B cell function. We compared B cell infiltration and activation in both a genetic model of murine PDAC (KPC mouse) and an injectable orthotopic model. A pronounced B cell infiltrate was only observed in KPC tumors and correlated with T cell infiltration, mirroring human disease. In contrast, orthotopic tumors exhibited a relative paucity of B cells. Accordingly, KPC-derived B cells displayed markers of B cell activation (germinal center entry, B cell memory, and plasma cell differentiation) accompanied by significant intratumoral immunoglobulin deposition, a feature markedly weaker in orthotopic tumors. Tumor immunoglobulins, however, did not appear to form immune complexes. Furthermore, in contrast to the current paradigm that tumor B cells are immunosuppressive, when assessed as a bulk population, intratumoral B cells upregulated several proinflammatory and immunostimulatory genes, a distinctly different phenotype to that of splenic-derived B cells; further highlighting the importance of studying tumor-infiltrating B cells over B cells from secondary lymphoid organs. In agreement with the current literature, genetic deletion of B cells (μMT mice) resulted in reduced orthotopic tumor growth, however, this was not recapitulated by treatment with B-cell-depleting anti-CD20 antibody and, more importantly, was not observed in anti-CD20-treated KPC mice. This suggests the result from B cell deficient mice might be caused by their altered immune system, rather than lack of B cells. Therefore, our data indicate B cells do not favor tumor progression. In conclusion, our analysis of relevant preclinical models shows B cells to be active members of the tumor microenvironment, producing immunostimulatory factors that might support the adaptive antitumor immune response, as suggested by human PDAC studies