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Xie Y.,McMaster University | Xie Y.,Father Sean OSullivan Research Institute | Xie Y.,St Josephs Hospital | Xie Y.,Central South University | And 22 more authors.
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2012

Loss of IQGAP2 contributes to the tumorigenesis of hepatocellular carcinoma and gastric cancer. However, whether IQGAP2 also suppresses prostate tumorigenesis remains unclear. We report here that IQGAP2 is a candidate tumour suppressor of prostate cancer (PC). Elevated IQGAP2 was detected in prostatic intraepithelial neoplasia (PIN), early stages of PCs (Gleason score ≤ 3), and androgen-dependent LNCaP PC cells. However, IQGAP2 was expressed at substantially reduced levels not only in prostate glands and non-tumorigenic BPH-1 prostate epithelial cells but also in advanced (Gleason score 4 or 5) and androgen-independent PCs. Furthermore, xenograft tumours that were derived from stem-like DU145 cells displayed advanced features and lower levels of IQGAP2 in comparison to xenograft tumours that were produced from non stem-like DU145 cells. Collectively, these results suggest that IQGAP2 functions in the surveillance of prostate tumorigenesis. Consistent with this concept, ectopic IQGAP2 reduced the proliferation of DU145, PC3, and 293. T cells as well as the invasion ability of DU145 cells. While ectopic IQGAP2 up-regulated E-cadherin in DU145 and PC3 cells, knockdown of IQGAP2 reduced E-cadherin expression. In primary PC and DU145 cells-derived xenograft tumours, the majority of tumours with high levels of IQGAP2 were strongly-positive for E-cadherin. Therefore, IQGAP2 may suppress PC tumorigenesis, at least in part, by up-regulation of E-cadherin. Mechanistically, overexpression of IQGAP2 significantly reduced AKT activation in DU145 cells and inhibition of AKT activation upregulated E-cadherin, suggesting that IQGAP2 increases E-cadherin expression by inhibiting AKT activation. Taken together, we demonstrate here that IQGAP2 is a candidate tumour suppressor of PC. © 2012 Elsevier B.V.


Ojo D.,McMaster University | Ojo D.,Father Sean OSullivan Research Institute | Ojo D.,St Josephs Hospital | Wei F.,Institute of Women and Childrens Health | And 14 more authors.
Current Medicinal Chemistry | Year: 2015

Estrogen receptor-alpha positive (ER+) breast cancer constitutes 70-75% of the disease incidence. Tamoxifen has been the basis of endocrine therapy for patients with ER+ breast cancer for more than three decades. The treatment reduces the annual mortality rate of breast cancer by 31%, and remains the most effective targeted cancer therapy. However, approximately one-third of patients treated with adjuvant tamoxifen suffer from aggressive recurrent disease. Resistance to tamoxifen, thus, remains a major challenge in providing effective treatments for these patients. In an effort to overcome the resistance, intensive research has been conducted to understand the underlying mechanisms; this has resulted in the identification of complex factors/pathways contributing to tamoxifen resistance, including modulations of the ERsignaling, upregulation of a set of growth factor receptor networks (HER2, EGFR, FGFR, and IGF1R), alterations of the PI3K-PTEN/AKT/mTOR pathway, and an elevation of the NF-κB signaling. Despite these advances, our understanding of the acquired resistance remains fragmented and there is a lack of a platform to integrate these diversified molecular factors/pathways into a cohesive mechanistic model. Nonetheless, at the cellular level, it is becoming increasingly recongnized that cancer stem cells (CSCs) are key in driving cancer metastasis and therapy resistance. Likewise, evidence is emerging for the critical contributions of breast cancer stem cells (BCSCs) to tamoxifen resistance. In this review, we will discuss these recent developments of BCSC-mediated resistance to tamoxifen and the contributions of those demonstrated molecular factors/pathways to BCSC expansion during the emergency of tamoxifen resistance. © 2015 Bentham Science Publishers.


De Melo J.,McMaster University | De Melo J.,St Josephs Hospital | Lin X.,McMaster University | Lin X.,St Josephs Hospital | And 9 more authors.
Cellular Signalling | Year: 2014

PTEN is post-translationally modified by ubiquitin via association with multiple E3 ubiquitin ligases, including NEDD4-1, XIAP, and WWP2. Despite the rapid progress made in researching the impact of ubiquitination on PTEN function, our understanding remains fragmented. Building on the previously observed interaction between SIPL1 and PTEN, we report here that SIPL1 promotes PTEN polyubiquitination via lysine 48 (K48)-independent polyubiquitin chains. Substitution of the K48 residue of ubiquitin with arginine (R) enhanced SIPL1-mediated PTEN polyubiquitination. In contrast, the K63R substitution significantly reduced it. The ubiquitin-like (UBL) domain is required for SIPL1-induced PTEN polyubiquitination. This post-translational modification promoted the association of SIPL1 with PTEN. Elevated amounts of the SIPL1/PTEN complex were precipitated in 293T cells co-transfected with PTEN, SIPL1, and ubiquitin compared to cells co-transfected with SIPL1 and PTEN only. Additionally, formation of the SIPL1/PTEN complex was inhibited when either lysine-less (K0) ubiquitin or K63R ubiquitin was co-transfected together with SIPL1. +. PTEN. The PTEN component in the SIPL1/PTEN complex contained polyubiquitin chains. The ubiquitination reaction may play a structural role, stabilizing the SIPL1/PTEN complex, as a ubiquitin binding-defective SIPL1 mutant (TFLV) is proficient in PTEN association. Collectively, we demonstrate that SIPL1 binds PTEN and enhances PTEN polyubiquitination which in turn promotes the interaction between SIPL1 and PTEN. © 2014.


Wei F.,McMaster University | Wei F.,Father Sean OSullivan Research Institute | Wei F.,St Josephs Hospital | Wei F.,Institute of Women and Childrens Health | And 23 more authors.
Oncogene | Year: 2015

The BMI1 protein contributes to stem cell pluripotency and oncogenesis via multiple functions, including its newly identified role in DNA damage response (DDR). Although evidence clearly demonstrates that BMI1 facilitates the repair of double-stranded breaks via homologous recombination (HR), it remains unclear how BMI1 regulates checkpoint activation during DDR. We report here that BMI1 has a role in G2/M checkpoint activation in response to etoposide (ETOP) treatment. Ectopic expression of BMI1 in MCF7 breast cancer and DU145 prostate cancer cells significantly reduced ETOP-induced G2/M arrest. Conversely, knockdown of BMI1 in both lines enhanced the arrest. Consistent with ETOP-induced activation of the G2/M checkpoints via the ATM pathway, overexpression and knockdown of BMI1, respectively, reduced and enhanced ETOP-induced phosphorylation of ATM at serine 1981 (ATM pS1981). Furthermore, the phosphorylation of ATM targets, including γH2AX, threonine 68 (T68) on CHK2 (CHK2 pT68) and serine 15 (S15) on p53 were decreased in overexpression and increased in knockdown BMI1 cells in response to ETOP. In line with the requirement of NBS1 in ATM activation, we were able to show that BMI1 associates with NBS1 and that this interaction altered the binding of NBS1 with ATM. BMI1 consists of a ring finger (RF), helix-turn-helix-turn-helix-turn (HT), proline/serine (PS) domain and two nuclear localization signals (NLS). Although deletion of either RF or HT did not affect the association of BMI1 with NBS1, the individual deletions of PS and one NLS (KRMK) robustly reduced the interaction. Stable expression of these BMI1 mutants decreased ETOP-induced ATM pS1981 and CHK2 pT68, but not ETOP-elicited γH2AX in MCF7 cells. Furthermore, ectopic expression of BMI1 in non-transformed breast epithelial MCF10A cells also compromised ETOP-initiated ATM pS1981 and γH2AX. Taken together, we provide compelling evidence that BMI1 decreases ETOP-induced G2/M checkpoint activation via reducing NBS1-mediated ATM activation. © 2015 Macmillan Publishers Limited.


Xie Y.,Central South University | Xie Y.,McMaster University | Xie Y.,Father Sean OSullivan Research Institute | Xie Y.,St Josephs Hospital | And 27 more authors.
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2016

Cervical cancer is caused by infections with human papillomaviruses (HPV) and genetic alternations in the cervical epithelium. While the former is well studied, the latter remains unclear. We report here that CYB5D2/Neuferricin possesses tumor suppressing activity towards cervical tumorigenesis. Ectopic expression of CYB5D2 did not affect HeLa cell proliferation and the cell's ability to form xenograft tumors, but significantly inhibited HeLa cell invasion in vitro and the cell-produced lung metastasis in NOD/SCID mice. Knockdown of CYB5D2 enhanced HeLa cell invasion. Two mutations in CYB5D2, the substitutions of arginine (R) 7 with either proline (P) or glycine (G), were reported in colon cancer. Both CYB5D2(R7P) and CYB5D2(R7G) were incapable of inhibiting HeLa cell invasion. CYB5D2 binds heme, in which aspartate (D) 86 is required. While CYB5D2(D86G) is heme-binding defective, it inhibited HeLa cell invasion. On the other hand, CYB5D2(R7P) and CYB5D2(R7G) bound heme but did not inhibit HeLa cell invasion. Collectively, CYB5D2 inhibits HeLa cell invasion independently of its heme binding. Furthermore, immunohistochemistry examination of CYB5D2 expression in 20 normal cervical tissues and 40 cervical squamous cell carcinomas (SCC) revealed a CYB5D2 reduction in 87.5% (35/40) of SCC. Analysis of CYB5D2 gene expression and genomic alteration data available from Oncomeine™ detected significant reductions of CYB5D2 mRNA in 40 SCCs and CYB5D2 gene copy number in 107 SCCs. Collectively, we provide evidence that CYB5D2 is a candidate tumor suppressor of cervical tumorigenesis. © 2015 Elsevier B.V.


Wei F.,McMaster University | Wei F.,St Josephs Hospital | Wei F.,Institute of Women and Childrens Health | Yan J.,McMaster University | And 3 more authors.
Current Medicinal Chemistry | Year: 2011

The Raf-MEK-ERK pathway is commonly activated in human cancers, largely attributable to the extracellular signal-regulated kinases (ERKs) being a common downstream target of growth factor receptors, Ras, and Raf. Elevation of these up-stream signals occurs frequently in a variety of malignancies and ERK kinases play critical roles in promoting cell proliferation. Therefore, inhibition of MEK-mediated ERK activation is very appealing in cancer therapy. Consequently, numerous MEK inhibitors have been developed over the years. However, clinical trials have yet to produce overwhelming support for using MEK inhibitors in cancer therapy. Although complex reasons may have contributed to this outcome, an alternative possibility is that the MEK-ERK pathway may not solely provide proliferation signals to malignancies, the central scientific rationale in developing MEK inhibitors for cancer therapy. Recent developments may support this alternative possibility. Accumulating evidence now demonstrated that the MEK-ERK pathway contributes to the proper execution of cellular DNA damage response (DDR), a major pathway of tumor suppression. During DDR, the MEK-ERK pathway is commonly activated, which facilitates the proper activation of DDR checkpoints to prevent cell division. Inhibition of MEK-mediated ERK activation, therefore, compromises checkpoint activation. As a result, cells may continue to proliferate in the presence of DNA lesions, leading to the accumulation of mutations and thereby promoting tumorigenesis. Alternatively, reduction in checkpoint activation may prevent efficient repair of DNA damages, which may cause apoptosis or cell catastrophe, thereby enhancing chemotherapy's efficacy. This review summarizes our current understanding of the participation of the ERK kinases in DDR. © 2011 Bentham Science Publishers.


Ren C.-M.,Sun Yat Sen University | Liang Y.,Maoming Peoples Hospital | Wei F.,Institute of Women and Childrens Health | Zhang Y.-N.,Sun Yat Sen University | And 8 more authors.
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2013

Intellectual disability (ID) is a common disease. While the etiology remains incompletely understood, genetic defects are a major contributor, which include mutations in genes encoding zinc finger proteins. These proteins modulate gene expression via binding to DNA. Consistent with this knowledge, we report here the identification of mutations in the ZNF407 gene in ID/autistic patients. In our study of an ID patient with autism, a reciprocal translocation 46,XY,t(3;18)(p13;q22.3) was detected. By using FISH and long-range PCR approaches, we have precisely mapped the breakpoints associated with this translocation in a gene-free region in chromosome 3 and in the third intron of the ZNF407 gene in chromosome18. The latter reduces ZNF407 expression. Consistent with this observation, in our subsequent investigation of 105 ID/autism patients with similar clinical presentations, two missense mutations Y460C and P1195A were identified. These mutations cause non-conservative amino acid substitutions in the linker regions between individual finger structures. In line with the linker regions being critical for the integrity of zinc finger motifs, both mutations may result in loss of ZNF407 function. Taken together, we demonstrate that mutations in the ZNF407 gene contribute to the pathogenesis of a group of ID patients with autism. © 2012 Elsevier B.V.


Liu X.,CAS National Center for Nanoscience and Technology | Liu X.,Jiamusi University | Su S.,CAS National Center for Nanoscience and Technology | Wei F.,Institute of Women and Childrens Health | And 5 more authors.
Journal of Colloid and Interface Science | Year: 2014

A novel amphiphilic copolymer (γ-PGA-co-PLA-DPPE) containing poly(γ-glutamic acid) (γ-PGA), polylactide (PLA), and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were characterized by Fourier-transform infrared spectroscopy (FT-IR), NMR (1H NMR, 13C NMR, 31P NMR), and thermogravimetric analysis (TGA). In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug, doxorubicin hydrochloride salt (DOX) was encapsulated into the copolymers nanoparticles (NPs) by double emulsion and nanoprecipitation methods. The influence of processing factors on encapsulation efficiency and particle size using double emulsion and nanoprecipitation technique were studied. In addition, the DOX-loaded NPs exhibited pH-dependent drug release profiles in vitro. The cumulative release of DOX-loaded NPs was much faster at pH 5.0 than that at pH 7.4. In vitro cytotoxicity test of DOX-loaded NPs against Hela and C666-1 cells demonstrated that DOX-loaded NPs exhibited effectively time-delayed cytotoxicity. Confocal laser scanning microscopy (CLSM) showed that DOX-loaded NPs accumulated mostly in lysosomes instead of cell nucleus, in contrast to free DOX. Therefore, the copolymer nanoparticles were proved to be an available carrier for anti-tumor drug delivery. © 2013 Elsevier Inc.


Yan J.,McMaster University | Ojo D.,McMaster University | Kapoor A.,McMaster University | Lin X.,McMaster University | And 12 more authors.
Cancer Research | Year: 2016

Prostate cancer metastasis is the main cause of disease-related mortality. Elucidating the mechanisms underlying prostate cancer metastasis is critical for effective therapeutic intervention. In this study, we performed gene-expression profiling of prostate cancer stem-like cells (PCSC) derived from DU145 human prostate cancer cells to identify factors involved in metastatic progression. Our studies revealed contactin 1 (CNTN1), aneuralcell adhesion protein, to be a prostate cancer-promoting factor. CNTN1 knockdown reduced PCSC-mediated tumor initiation, whereas CNTN1 overexpression enhanced prostate cancer cell invasion in vitro and promoted xenograft tumor formation and lung metastasis in vivo. In addition, CNTN1 overexpression in DU145 cells and corresponding xenograft tumors resulted in elevated AKT activation and reduced E-cadherin (CDH1) expression. CNTN1 expression was not readily detected in normal prostate glands, but was clearly evident on prostate cancer cells in primary tumors and lymph node and bone metastases. Tumors from 637 patients expressing CNTN1 were associated with prostate cancer progression and worse biochemical recurrence-free survival following radical prostatectomy (P < 0.05). Collectively, our findings demonstrate that CNTN1 promotes prostate cancer progression and metastasis, prompting further investigation into the mechanisms that enable neural proteins to become aberrantly expressed in non-neural malignancies. © 2016 American Association for Cancer Research.

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