Cdc6 and cyclin E2 are PTEN-regulated genes associated with human prostate cancer metastasis

Prostate cancer and the cell cycle: Focusing on the role of microRNAs

Prostate cancer is the most frequent solid tumor in terms of incidence and ranks second only to lung cancer in terms of cancer mortality among men. It has a considerably high mortality rate; around 375,000 deaths occurred worldwide in 2020. In 2024, the American Cancer Society estimated that the number of new prostate cancer cases will be around 299,010 cases, and the estimated deaths will be around 32,250 deaths only in the USA. Cell cycle dysregulation is inevitable in cancer etiology and is targeted by various therapies in cancer treatment. MicroRNAs (miRNAs) are small, endogenous, non-coding regulatory molecules involved in both normal and abnormal cellular events. One of the cellular processes regulated by miRNAs is the cell cycle. Although there are some exceptions, tumor suppressor miRNAs could potentially arrest the cell cycle by downregulating several molecular machineries involved in catalyzing the cell cycle progression. In contrast, oncogenic miRNAs (oncomirs) help the cell cycle to progress by targeting various regulatory proteins such as retinoblastoma (Rb) or cell cycle inhibitors such as p21 or p27, and hence may contribute to prostate cancer progression; however, this is not always the case. In this review, we emphasize how a dysregulated miRNA expression profile is linked to an abnormal cell cycle progression in prostate cancer, which subsequently paves the way to a new therapeutic option for prostate cancer.

PTEN Loss Enhances Error-Prone DSB Processing and Tumor Cell Radiosensitivity by Suppressing RAD51 Expression and Homologous Recombination

PTEN has been implicated in the repair of DNA double-strand breaks (DSBs), particularly through homologous recombination (HR). However, other data fail to demonstrate a direct role of PTEN in DSB repair. Therefore, here, we report experiments designed to further investigate the role of PTEN in DSB repair. We emphasize the consequences of PTEN loss in the engagement of the four DSB repair pathways-classical non-homologous end-joining (c-NHEJ), HR, alternative end-joining (alt-EJ) and single strand annealing (SSA)-and analyze the resulting dynamic changes in their utilization. We quantitate the effect of PTEN knockdown on cell radiosensitivity to killing, as well as checkpoint responses in normal and tumor cell lines. We find that disruption of PTEN sensitizes cells to ionizing radiation (IR). This radiosensitization is associated with a reduction in RAD51 expression that compromises HR and causes a marked increase in SSA engagement, an error-prone DSB repair pathway, while alt-EJ and c-NHEJ remain unchanged after PTEN knockdown. The G2-checkpoint is partially suppressed after PTEN knockdown, corroborating the associated HR suppression. Notably, PTEN deficiency radiosensitizes cells to PARP inhibitors, Olaparib and BMN673. The results show the crucial role of PTEN in DSB repair and show a molecular link between PTEN and HR through the regulation of RAD51 expression. The expected benefit from combination treatment with Olaparib or BMN673 and IR shows that PTEN status may also be useful for patient stratification in clinical treatment protocols combining IR with PARP inhibitors.

Non-canonical function of nuclear PTEN and its implication on tumorigenesis

Suppression of genomic instability is the key to prevent tumor development. PTEN is a unique tumor suppressor protein having both lipid and protein phosphatase activities. Interestingly though it is a cytoplasmic protein, but a significant pool of PTEN can also be localized in nucleus. The function of cytoplasmic PTEN is well defined and extensively studied in various literatures focusing mainly on the negative regulation of oncogenic PI-3Kinase-AKT pathway but functional regulation of nuclear PTEN is less defined and therefore it is a fascinating subject of research in cancer biology. Post-translation modulation of PTEN such as phosphorylation, sumorylation, acetylation and methylation also regulates its cellular localization, protein-protein association and catalytic function. Loss or mutation in PTEN is associated with the development of tumors in various tissues from the brain to prostate. Here we have summarized the role of nuclear PTEN and its epigenetic modulation in various DNA metabolic pathways, for example, DNA damage response, DNA repair, DNA replication, DNA segregation etc. Further, pathways involved in nuclear PTEN degradation are also discussed. Additionally, we also emphasize probable potential targets associated with PTEN pathway for chemotherapeutic purpose.

Novel chemotherapeutic agent FX-9 activates NF-κB signaling and induces G1 phase arrest by activating CDKN1A in a human prostate cancer cell line

Background

The aminoisoquinoline FX-9 shows pro-apoptotic and antimitotic effects against lymphoblastic leukemia cells and prostate adenocarcinoma cells. In contrast, decreased cytotoxic effects against non-neoplastic blood cells, chondrocytes, and fibroblasts were observed. However, the actual FX-9 molecular mode of action is currently not fully understood.

Methods

In this study, microarray gene expression analysis comparing FX-9 exposed and unexposed prostate cancer cells (PC-3 representing castration-resistant prostate cancer), followed by pathway analysis and gene annotation to functional processes were performed. Immunocytochemistry staining was performed with selected targets.

Results

Expression analysis revealed 0.83% of 21,448 differential expressed genes (DEGs) after 6-h exposure of FX-9 and 0.68% DEGs after 12-h exposure thereof. Functional annotation showed that FX-9 primarily caused an activation of inflammatory response by non-canonical nuclear factor-kappa B (NF-κB) signaling. The 6-h samples showed activation of the cell cycle inhibitor CDKN1A which might be involved in the secondary response in 12-h samples. This secondary response predominantly consisted of cell cycle-related changes, with further activation of CDKN1A and inhibition of the transcription factor E2F1, including downstream target genes, resulting in G1-phase arrest. Matching our previous observations on cellular level senescence signaling pathways were also found enriched. To verify these results immunocytochemical staining of p21 Waf1/Cip1 (CDKN1A), E2F1 (E2F1), PAI-1 (SERPNE1), and NFkB2/NFkB p 100 (NFKB2) was performed. Increased expression of p21 Waf1/Cip1 and NFkB2/NFkB p 100 after 24-h exposure to FX-9 was shown. E2F1 and PAI-1 showed no increased expression.

Conclusions

FX-9 induced G1-phase arrest of PC-3 cells through activation of the cell cycle inhibitor CDKN1A, which was initiated by an inflammatory response of noncanonical NF-κB signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08836-y.

Wogonin Induces Apoptosis and Reverses Sunitinib Resistance of Renal Cell Carcinoma Cells via Inhibiting CDK4-RB Pathway

Wogonin, an active component derived from Scutellaria baicalensis, has shown anti-tumor activities in several malignancies. However, the roles of wogonin in RCC cells remain elusive. Here, we explored the effects of wogonin on RCC cells and the underlying mechanisms. We found that wogonin showed significant cytotoxic effects against RCC cell lines 786-O and OS-RC-2, with much lower cytotoxic effects on human normal embryonic kidney cell line HEK-293 cells. Wogonin treatment dramatically inhibited the proliferation, migration, and invasion of RCC cells. We further showed that by inhibiting CDK4-RB pathway, wogonin transcriptionally down-regulated CDC6, disturbed DNA replication, induced DNA damage and apoptosis in RCC cells. Moreover, we found that the levels of p-RB, CDK4, and Cyclin D1 were up-regulated in sunitinib resistant 786-O, OS-RC-2, and TK-10 cells, and inhibition of CDK4 by palbociclib or wogonin effectively reversed the sunitinib resistance, indicating that the hyperactivation of CDK4-RB pathway may at least partially contribute to the resistance of RCC to sunitinib. Together, our findings demonstrate that wogonin could induce apoptosis and reverse sunitinib resistance of RCC cells via inhibiting CDK4-RB pathway, thus suggesting a potential therapeutic implication in the future management of RCC patients.

Chemotherapy exacerbates ovarian cancer cell migration and cancer stem cell-like characteristics through GLI1

BACKGROUND

Despite the great clinical response to the first-line chemotherapeutics, metastasis still happens among most of the ovarian cancer patients within 2 years.

METHODS

Using multiple human ovarian cancer cell lines, a transwell co-culture system of the carboplatin or VP-16-challenged feeder and receptor cells was established to demonstrate the chemotherapy-exacerbated migration. The migration and cancer stem cell (CSC)-like characteristics were determined by wound healing, transwell migration, flow cytometry and sphere formation. mRNA and protein expression were identified by qPCR and western blot. Bioinformatics analysis was used to investigate the differentially expressed genes. GLI1 expression in tissue samples was analysed by immunohistochemistry.

RESULTS

Chemotherapy was found to not only kill tumour cells, but also trigger the induction of CSC-like traits and the migration of ovarian cancer cells. EMT markers Vimentin and Snail in receptor cells were upregulated in the microenvironment of chemotherapy-challenged feeder cells. The transcription factor GLI1 was upregulated by chemotherapy in both clinical samples and cell lines. Follow-up functional experiments illustrated that inhibiting GLI1 reversed the chemotherapy-exacerbated CSC-like traits, including CD44 and CD133, as well as prevented the migration of ovarian cancer cells.

CONCLUSIONS

Targeting GLI1 may improve clinical benefits in the chemotherapy-exacerbated metastasis in ovarian cancer treatment.

Antibiotic tigecycline inhibits cell proliferation, migration and invasion via down-regulating CCNE2 in pancreatic ductal adenocarcinoma

Recently, many researches have reported that antibiotic tigecycline has significant effect on cancer treatment. However, biomedical functions and molecular mechanisms of tigecycline in human pancreatic ductal adenocarcinoma (PDAC) remain unclear. In the current study, we tried to assess the effect of tigecycline in PDAC cells. AsPC‐1 and HPAC cells were treated with indicated concentrations of tigecycline for indicated time, and then, MTT, BrdU and soft agar assay were used to test cell proliferation. The effect of tigecycline on cell cycle and cellular apoptosis was tested by cytometry. Migration and invasion were detected by wound healing assay and transwell migration/invasion assay. Expressions of cell cycle‐related and migration/invasion‐related protein were determined by using Western blot. The results revealed that tigecycline observably suppressed cell proliferation by inducing cell cycle arrest at G0/G1 phase and blocked cell migration/invasion via holding back the epithelial‐mesenchymal transition (EMT) process in PDAC. In addition, tigecycline also remarkably blocked tumorigenecity in vivo. Furthermore, the effects of tigecycline alone or combined with gemcitabine in vitro or on PDAC xenografts were also performed. The results showed that tigecycline enhanced the chemosensitivity of PDAC cells to gemcitabine. Interestingly, we found CCNE2 expression was declined distinctly after tigecycline treatment. Then, CCNE2 was overexpressed to rescue tigecycline‐induced effect. The results showed that CCNE2 overexpression significantly rescued tigecycline‐inhibited cell proliferation and migration/invasion. Collectively, we showed that tigecycline inhibits cell proliferation, migration and invasion via down‐regulating CCNE2, and tigecycline might be used as a potential drug for PDAC treatment alone or combined with gemcitabine.

Breast cancer pathogenesis is linked to the intra-tumoral estrogen sulfotransferase (hSULT1E1) expressions regulated by cellular redox dependent Nrf-2/NFκβ interplay

BACKGROUND

Estrogen sulfotransferase catalyzes conjugation of sulfuryl-group to estradiol/estrone and regulates E2 availability/activity via estrogen-receptor or non-receptor mediated pathways. Sulfoconjugated estrogen fails to bind estrogen-receptor (ER). High estrogen is a known carcinogen in postmenopausal women. Reports reveal a potential redox-regulation of hSULT1E1/E2-signalling. Further, oxidatively-regulated nuclear-receptor-factor 2 (Nrf2) and NFκβ in relation to hSULT1E1/E2 could be therapeutic-target via cellular redox-modification.

METHODS

Here, oxidative stress-regulated SULT1E1-expression was analyzed in human breast carcinoma-tissues and in rat xenografted with human breast-tumor. Tumor and its surrounding tissues were obtained from the district-hospital. Intracellular redox-environment of tumors was screened with some in vitro studies. RT-PCR and western blotting was done for SULT1E1 expression. Immunohistochemistry was performed to analyze SULT1E1/Nrf2/NFκβ localization. Tissue-histoarchitecture/DNA-stability (comet assay) studies were done.

RESULTS

Oxidative-stress induces SULT1E1 via Nrf2/NFκβ cooperatively in tumor-pathogenesis to maintain the required proliferative-state under enriched E2-environment. Higher malondialdehyde/non-protein-soluble-thiol with increased superoxide-dismutase/glutathione-peroxidase/catalase activities was noticed. SULT1E1 expression and E2-level were increased in tumor-tissue compared to their corresponding surrounding-tissues.

CONCLUSIONS

It may be concluded that tumors maintain a sustainable oxidative-stress through impaired antioxidants as compared to the surrounding. Liver-tissues from xenografted rat manifested similar E2/antioxidant dysregulations favoring pre-tumorogenic environment.

Genetic and molecular determinants of prostate cancer among Iranian patients: An update

Prostate cancer (PCa) is one of the most common age-related cancers among men. Various environmental and genetic factors are involved in the development and progression of PCa. In most cases, the primary symptoms of disease are not severe. Therefore, it is common for patients to be referred with severe clinical manifestations at advanced stages of disease. Since this malignancy is age related and Iran will face a significant increase in the number of seniors, it is expected that the prevalence of PCa among Iranian men will rise. PCa progression has been observed to be associated with genetic and ethnic factors. It may therefore be clinically useful to determine a panel of genetic markers, in addition to routine diagnostic methods, to detect tumors in the early stages. In the present review, we have summarized the reported genetic markers in PCa Iranian patients to pave the way for the determination of an ethnic specific genetic marker panel for the early detection of PCa. To understand the genetic and molecular biology of PCa among Iranians, we have categorized these genetic markers based on their cellular functions.

Defined factors to reactivate cell cycle activity in adult mouse cardiomyocytes

Adult mammalian cardiomyocytes exit the cell cycle during the neonatal period, commensurate with the loss of regenerative capacity in adult mammalian hearts. We established conditions for long-term culture of adult mouse cardiomyocytes that are genetically labeled with fluorescence. This technique permits reliable analyses of proliferation of pre-existing cardiomyocytes without complications from cardiomyocyte marker expression loss due to dedifferentiation or significant contribution from cardiac progenitor cell expansion and differentiation in culture. Using this system, we took a candidate gene approach to screen for fetal-specific proliferative gene programs that can induce proliferation of adult mouse cardiomyocytes. Using pooled gene delivery and subtractive gene elimination, we identified a novel functional interaction between E2f Transcription Factor 2 (E2f2) and Brain Expressed X-Linked (Bex)/Transcription elongation factor A-like (Tceal) superfamily members Bex1 and Tceal8. Specifically, Bex1 and Tceal8 both preserved cell viability during E2f2-induced cell cycle re-entry. Although Tceal8 inhibited E2f2-induced S-phase re-entry, Bex1 facilitated DNA synthesis while inhibiting cell death. In sum, our study provides a valuable method for adult cardiomyocyte proliferation research and suggests that Bex family proteins may function in modulating cell proliferation and death decisions during cardiomyocyte development and maturation.

Importance of gene expression signatures in pancreatic cancer prognosis and the establishment of a prediction model

Background and aim

Pancreatic cancer (PC) is one of the most common tumors with a poor prognosis. The current American Joint Committee on Cancer (AJCC) staging system, based on the anatomical features of tumors, is insufficient to predict PC outcomes. The current study is endeavored to identify important prognosis-related genes and build an effective predictive model.

Methods

Multiple public datasets were used to identify differentially expressed genes (DEGs) and survival-related genes (SRGs). Bioinformatics analysis of DEGs was used to identify the main biological processes and pathways involved in PC. A risk score based on SRGs was computed through a univariate Cox regression analysis. The performance of the risk score in predicting PC prognosis was evaluated with survival analysis, Harrell's concordance index (C-index), area under the curve (AUC), and calibration plots. A predictive nomogram was built through integrating the risk score with clinicopathological information.

Results

A total of 945 DEGs were identified in five Gene Expression Omnibus datasets, and four SRGs (LYRM1, KNTC1, IGF2BP2, and CDC6) were significantly associated with PC progression and prognosis in four datasets. The risk score showed relatively good performance in predicting prognosis in multiple datasets. The predictive nomogram had greater C-index and AUC values, compared with those of the AJCC stage and risk score.

Conclusion

This study identified four new biomarkers that are significantly associated with the carcinogenesis, progression, and prognosis of PC, which may be helpful in studying the underlying mechanism of PC carcinogenesis. The predictive nomogram showed robust performance in predicting PC prognosis. Therefore, the current model may provide an effective and reliable guide for prognosis assessment and treatment decision-making in the clinic.

DNA replication licensing proteins: Saints and sinners in cancer

DNA replication is all-or-none process in the cell, meaning, once the DNA replication begins it proceeds to completion. Hence, to achieve maximum control of DNA replication, eukaryotic cells employ a multi-subunit initiator protein complex known as "pre-replication complex or DNA replication licensing complex (DNA replication LC). This complex involves multiple proteins which are origin-recognition complex family proteins, cell division cycle-6, chromatin licensing and DNA replication factor 1, and minichromosome maintenance family proteins. Higher-expression of DNA replication LC proteins appears to be an early event during development of cancer since it has been a common hallmark observed in a wide variety of cancers such as oesophageal, laryngeal, pulmonary, mammary, colorectal, renal, urothelial etc. However, the exact mechanisms leading to the abnormally high expression of DNA replication LC have not been clearly deciphered. Increased expression of DNA replication LC leads to licensing and/or firing of multiple origins thereby inducing replication stress and genomic instability. Therapeutic approaches where the reduction in the activity of DNA replication LC was achieved either by siRNA or shRNA techniques, have shown increased sensitivity of cancer cell lines towards the anti-cancer drugs such as cisplatin, 5-Fluorouracil, hydroxyurea etc. Thus, the expression level of DNA replication LC within the cell determines a cell's fate thereby creating a paradox where DNA replication LC acts as both "Saint" and "Sinner". With a potential to increase sensitivity to chemotherapy drugs, DNA replication LC proteins have prospective clinical importance in fighting cancer. Hence, in this review, we will shed light on importance of DNA replication LC with an aim to use DNA replication LC in diagnosis and prognosis of cancer in patients as well as possible therapeutic targets for cancer therapy.

An In Vivo Screen Identifies PYGO2 as a Driver for Metastatic Prostate Cancer

Advanced prostate cancer displays conspicuous chromosomal instability and rampant copy number aberrations, yet the identity of functional drivers resident in many amplicons remain elusive. Here, we implemented a functional genomics approach to identify new oncogenes involved in prostate cancer progression. Through integrated analyses of focal amplicons in large prostate cancer genomic and transcriptomic datasets as well as genes upregulated in metastasis, 276 putative oncogenes were enlisted into an in vivo gain-of-function tumorigenesis screen. Among the top positive hits, we conducted an in-depth functional analysis on Pygopus family PHD finger 2 (PYGO2), located in the amplicon at 1q21.3. PYGO2 overexpression enhances primary tumor growth and local invasion to draining lymph nodes. Conversely, PYGO2 depletion inhibits prostate cancer cell invasion in vitro and progression of primary tumor and metastasis in vivo In clinical samples, PYGO2 upregulation associated with higher Gleason score and metastasis to lymph nodes and bone. Silencing PYGO2 expression in patient-derived xenograft models impairs tumor progression. Finally, PYGO2 is necessary to enhance the transcriptional activation in response to ligand-induced Wnt/β-catenin signaling. Together, our results indicate that PYGO2 functions as a driver oncogene in the 1q21.3 amplicon and may serve as a potential prognostic biomarker and therapeutic target for metastatic prostate cancer.Significance: Amplification/overexpression of PYGO2 may serve as a biomarker for prostate cancer progression and metastasis. Cancer Res; 78(14); 3823-33. ©2018 AACR.

Cdc6 contributes to cisplatin-resistance by activation of ATR-Chk1 pathway in bladder cancer cells

High activation of DNA damage response is implicated in cisplatin (CDDP) resistance which presents as a serious obstacle for bladder cancer treatment. Cdc6 plays an important role in the malignant progression of tumor. Here, we reported that Cdc6 expression is up-regulated in bladder cancer tissues and is positively correlated to high tumor grade. Cdc6 depletion can attenuate the malignant properties of bladder cancer cells, including DNA replication, migration and invasion. Furthermore, higher levels of chromatin-binding Cdc6 and ATR were detected in CDDP-resistant bladder cancer cells than in the parent bladder cancer cells. Intriguingly, down-regulation of Cdc6 can enhance sensitivity to CDDP both in bladder cancer cells and CDDP-resistant bladder cancer cells. Cdc6 depletion abrogates S phase arrest caused by CDDP, leading to aberrant mitosis by inactivating ATR-Chk1-Cdc25C pathway. Our results indicate that Cdc6 may be a promising target for overcoming CDDP resistance in bladder cancer.

Knockdown of Long Non-Coding RNA KCNQ1OT1 Restrained Glioma Cells' Malignancy by Activating miR-370/CCNE2 Axis

Accumulating evidence has highlighted the potential role of long non-coding RNAs (lncRNAs) as biomarkers and therapeutic targets in solid tumors. Here, we elucidated the function and possible molecular mechanisms of lncRNA KCNQ1OT1 in human glioma U87 and U251 cells. Quantitative Real-Time polymerase chain reaction (qRT-PCR) demonstrated that KCNQ1OT1 expression was up-regulated in glioma tissues and cells. Knockdown of KCNQ1OT1 exerted tumor-suppressive function in glioma cells. Moreover, a binding region was confirmed between KCNQ1OT1 and miR-370 by dual-luciferase assays. qRT-PCR showed that miR-370 was down-regulated in human glioma tissue and cells. In addition, restoration of miR-370 exerted tumor-suppressive function via inhibiting cell proliferation, migration and invasion, while promoting the apoptosis of human glioma cells. Knockdown of KCNQ1OT1 decreased the expression level of Cyclin E2 (CCNE2) by binding to miR-370. Further, miR-370 bound to CCNE2 3′UTR region and decreased the expression of CCNE2. These results provided a comprehensive analysis of KCNQ1OT1-miR-370-CCNE2 axis in human glioma cells and might provide a novel strategy for glioma treatment.

Downregulation of CREB Promotes Cell Proliferation by Mediating G1/S Phase Transition in Hodgkin Lymphoma

The cyclic-AMP response element-binding protein (CREB), a well-known nuclear transcription factor, has been shown to play an essential role in many cellular processes, including differentiation, cell survival, and cell proliferation, by regulating the expression of downstream genes. Recently, increased expression of CREB was frequently found in various tumors, indicating that CREB is implicated in the process of tumorigenesis. However, the effects of CREB on Hodgkin lymphoma (HL) remain unknown. To clarify the role of CREB in HL, we performed knockdown experiments in HL. We found that downregulation of CREB by short hairpin RNA (shRNA) resulted in enhancement of cell proliferation and promotion of G₁/S phase transition, and these effects can be rescued by expression of shRNA-resistant CREB. Meanwhile, the expression level of cell cycle-related proteins, such as cyclin D1, cyclin E1, cyclin-dependent kinase 2 (CDK2), and CDK4, was elevated in response to depletion of CREB. Furthermore, we performed chromatin immunoprecipitation (ChIP) assay and confirmed that CREB directly bound to the promoter regions of these genes, which consequently contributed to the regulation of cell cycle. Consistent with our results, a clinical database showed that high expression of CREB correlates with favorable prognosis in B-cell lymphoma patients, which is totally different from the function of CREB in other cancers such as colorectal cancer, acute myeloid leukemia, and some endocrine cancers. Taken together, all of these features of CREB in HL strongly support its role as a tumor suppressor gene that can decelerate cell proliferation by inhibiting the expression of several cell cycle-related genes. Our results provide new evidence for prognosis prediction of HL and a promising therapeutic strategy for HL patients.

PARP inhibitor increases chemosensitivity by upregulating miR-664b-5p in BRCA1-mutated triple-negative breast cancer

Emerging evidence has shown that adding poly(ADP-ribose) polymerase (PARP) inhibitors to chemotherapy regimens is superior to the control regimens alone in BRCA1-mutated triple-negative breast cancer (TNBC) patients, but their underlying mechanisms have not been fully elucidated. In this study, using miRNA microarray analysis of two BRCA1-mutated TNBC cell lines, we found that miR-664b-5p expression was increased after adding a PARP inhibitor, olaparib, to a carboplatin (CBP) plus gemcitabine (GEM) therapy regimen. Functional assays showed miR-664b-5p overexpression inhibited proliferation, migration and invasion in BRCA1-mutated TNBC cells. CCNE2 was identified as a novel functional target of miR-664b-5p, and CCNE2 knockdown revealed effects similar to those observed with miR-664b-5p overexpression. Both CCNE2 knockdown and miR-664b-5p overexpression significantly increased the chemosensitivity of BRCA1-mutated TNBC cells. In addition, in vivo studies indicated that miR-664b-5p inhibited tumour growth compared with the control in tumour xenograft models, and we also found that CCNE2 expression was inversely correlated with miR-664b-5p expression in 90 TNBC patient samples. In conclusion, miR-664b-5p functions as a tumour suppressor and has an important role in the regulation of PARP inhibitors to increase chemosensitivity by targeting CCNE2. This may be one of the possible mechanisms by which PARP inhibitors increase chemosensitivity in BRCA1-mutated TNBC.

Reduced abundance of the E3 ubiquitin ligase E6AP contributes to decreased expression of the INK4/ARF locus in non-small cell lung cancer

The tumor suppressor p16^INK4a, one protein encoded by the INK4/ARF locus, is frequently absent in multiple cancers, including non-small cell lung cancer (NSCLC). Whereas increased methylation of the encoding gene (CDKN2A) accounts for its loss in a third of patients, no molecular explanation exists for the remainder. We unraveled an alternative mechanism for the silencing of the INK4/ARF locus involving the E3 ubiquitin ligase and transcriptional cofactor E6AP (also known as UBE3A). We found that the expression of three tumor suppressor genes encoded in the INK4/ARF locus (p15^INK4b, p16^INK4a, and p19^ARF) was decreased in E6AP^-/- mouse embryo fibroblasts. E6AP induced the expression of the INK4/ARF locus at the transcriptional level by inhibiting CDC6 transcription, a gene encoding a key repressor of the locus. Luciferase assays revealed that E6AP inhibited CDC6 expression by reducing its E2F1-dependent transcription. Chromatin immunoprecipitation analysis indicated that E6AP reduced the amount of E2F1 at the CDC6 promoter. In a subset of NSCLC samples, an E6AP-low/CDC6-high/p16^INK4a-low protein abundance profile correlated with low methylation of the gene encoding p16^INK4a (CDKN2A) and poor patient prognosis. These findings define a previously unrecognized tumor-suppressive role for E6AP in NSCLC, reveal an alternative silencing mechanism of the INK4/ARF locus, and reveal E6AP as a potential prognostic marker in NSCLC.

Mice lacking β-carotene-15,15'-dioxygenase exhibit reduced serum testosterone, prostatic androgen receptor signaling, and prostatic cellular proliferation

β-Carotene-15,15'-dioxygenase (BCO1) cleaves dietary carotenoids at the central 15,15' double bond, most notably acting on β-carotene to yield retinal. However, Bco1 disruption also impacts diverse physiological end points independent of dietary carotenoid feeding, including expression of genes controlling androgen metabolism. Using the Bco1^-/- mouse model, we sought to probe the effects of Bco1 disruption on testicular steroidogenesis, prostatic androgen signaling, and prostatic proliferation. Male wild-type (WT) and Bco1^-/- mice were raised on carotenoid-free AIN-93G diets before euthanasia between 10 and 14 wk of age. Weights of the prostate and seminal vesicles were significantly lower in Bco1^-/- than in WT mice (-18% and -29%, respectively). Serum testosterone levels in Bco1^-/- mice were significantly reduced by 73%. Bco1 disruption significantly reduced Leydig cell number and decreased testicular mRNA expression of Hsd17b3, suggesting inhibition of testicular testosterone synthesis. Immunofluorescent staining of the androgen receptor (AR) in the dorsolateral prostate lobes of Bco1^-/- mice revealed a decrease in AR nuclear localization. Analysis of prostatic morphology suggested decreases in gland size and secretion. These findings were supported by reduced expression of the proliferation marker Ki-67 in Bco1^-/- prostates. Expression analysis of 200 prostate cancer- and androgen-related genes suggested that Bco1 loss significantly disrupted prostatic androgen receptor signaling, cell cycle progression, and proliferation. This is the first demonstration that Bco1 disruption lowers murine circulating testosterone levels and thereby reduces prostatic androgen receptor signaling and prostatic cellular proliferation, further supporting the role of this protein in processes more diverse than carotenoid cleavage.

Cell Division Cycle 6 Promotes Mitotic Slippage and Contributes to Drug Resistance in Paclitaxel-Treated Cancer Cells

Paclitaxel (PTX) is an antimitotic drug that possesses potent anticancer activity, but its therapeutic potential in the clinic has been hindered by drug resistance. Here, we report a mechanism by which cancer cells can exit from the PTX-induced mitotic arrest, i.e. mitotic slippage, and avoid subsequent death resulting in drug resistance. In cells experiencing mitotic slippage, Cdc6 protein level was significantly upregulated, Cdk1 activity was inhibited, and Cohesin/Rad21 was cleaved as a result. Cdc6 depletion by RNAi or Norcantharidin inhibited PTX-induced Cdc6 up-regulation, maintained Cdk1 activity, and repressed Cohesin/Rad21 cleavage. In all, this resulted in reduced mitotic slippage and reversal of PTX resistance. Moreover, in synchronized cells, the role of Cdc6 in mitotic exit under PTX pressure was also confirmed. This study indicates that Cdc6 may promote mitotic slippage by inactivation of Cdk1. Targeting of Cdc6 may serve as a promising strategy for enhancing the anticancer activity of PTX.

Expression of CDc6 after acute spinal cord injury in adult rats

The cell division cycle 6 (CDc6) protein has been primarily investigated as a component of the pre-replicative complex for the initiation of DNA replication. Some studies have shown that CDc6 played a critical role in the development of human carcinoma. However, the expression and roles of CDc6 in the central nervous system remain unknown. We have performed an acute spinal cord injury (SCI) model in adult rats and investigated the dynamic changes of CDc6 expression in spinal cord. Western blot have found that CDc6 protein levels first significantly increase, reach a peak at day 3, and then gradually return to normal level at day 14 after SCI. Double immunofluorescence staining showed that CDc6 immunoreactivity was found in neurons, astrocytes, and microglia. Additionally, colocalization of CDc6/active caspase-3 has been detected in neurons and colocalization of CDc6/proliferating cell nuclear antigen has been detected in astrocytes and microglial. In vitro, CDc6 depletion by short interfering RNA inhibits astrocyte proliferation and reduces cyclin A and cyclin D1 protein levels. CDc6 knockdown also decreases neuronal apoptosis. We speculate that CDc6 might play crucial roles in CNS pathophysiology after SCI.

Estimation of High-Dimensional Graphical Models Using Regularized Score Matching

Graphical models are widely used to model stochastic dependences among large collections of variables. We introduce a new method of estimating undirected conditional independence graphs based on the score matching loss, introduced by Hyvärinen (2005), and subsequently extended in Hyvärinen (2007). The regularized score matching method we propose applies to settings with continuous observations and allows for computationally efficient treatment of possibly non-Gaussian exponential family models. In the well-explored Gaussian setting, regularized score matching avoids issues of asymmetry that arise when applying the technique of neighborhood selection, and compared to existing methods that directly yield symmetric estimates, the score matching approach has the advantage that the considered loss is quadratic and gives piecewise linear solution paths under ℓ₁ regularization. Under suitable irrepresentability conditions, we show that ℓ₁-regularized score matching is consistent for graph estimation in sparse high-dimensional settings. Through numerical experiments and an application to RNAseq data, we confirm that regularized score matching achieves state-of-the-art performance in the Gaussian case and provides a valuable tool for computationally efficient estimation in non-Gaussian graphical models.

Combinatorial PX-866 and Raloxifene Decrease Rb Phosphorylation, Cyclin E2 Transcription, and Proliferation of MCF-7 Breast Cancer Cells

As a potential means to reduce proliferation of breast cancer cells, a multiple-pathway approach with no effect on control cells was explored. The human interactome being constructed by the Center for Cancer Systems Biology will prove indispensable to understanding composite effects of multiple pathways, but its discovered protein-protein interactions require characterization. Accordingly, we explored the effects of regulators of one protein on downstream targets of the other protein. MCF-7 estrogen receptor-positive (ER+) breast cancer cells were treated with raloxifene to upregulate the TGF-β pathway and PX-866 to down-regulate the PI3K/Akt pathway. This resulted in highly significant downstream reduction of cell cycle proliferation in breast cancer cells with no significant proliferation reduction following similar treatment of noncancerous MCF10A breast epithelial cells. Reduced phosphorylation of p107 and substantial reduction of Rb phosphorylation were observed in response. The effects of reduced Rb and p107 phosphorylation were reflected in significant decline in E2F-1 transcriptional activity, which is dependent on pocket protein phosphorylation status. The reduced proliferation was related to decreased expression of cyclins, including E2F-1-regulated Cyclin E2, which was also in response to raloxifene and PX-866. All combinations of raloxifene and PX-866 produced significant or highly significant results for reduced MCF-7 cell proliferation, reduced Cyclin E2 transcription, and reduced Rb phosphorylation. These studies demonstrated that uncontrolled proliferation of ER+ breast cancer cells can be significantly reduced by combinational targeting of two relevant pathways. J. Cell. Biochem. 117: 1688-1696, 2016. © 2015 Wiley Periodicals, Inc.

High expression of CDC6 is associated with accelerated cell proliferation and poor prognosis of epithelial ovarian cancer

Cell division cycle 6 (CDC6) is an essential regulator of DNA replication and plays important roles in the activation and maintenance of the checkpoint mechanisms in the cell cycle. CDC6 has been associated with the oncogenic activities in human cancers, but the biological function and clinical significance of CDC6 in EOC remain unclear. The aim of the present study is to examine the effect of CDC6 on epithelial ovarian cancer (EOC) cells proliferation. We found that CDC6 protein level was up-regulated in EOC tissues compared with the normal ovary tissues. CDC6 expression correlated significantly with FIGO stage (p<0.001), differentiation grade (p=0.002), ascites (p<0.001), malignant tumor cells in ascites (p=0.004), and lymph node status (p<0.001). In vitro, after the release of ovarian cancer cell line (HO8910) from serum starvation, the expression of CDC6, cyclinD1, and PCNA was up-regulated, whereas p16 expression was down-regulated. Furthermore, down-regulation of CDC6 in HO8910 cells decreased cell proliferation and colony formation. HO8910 cells transfected with sh CDC6#1 underwent G1 phase cell cycle arrest. Collectively, this study provides a novel regulatory signaling pathway of CDC6-regulated EOC growth and a new potential therapeutic target for EOC patients.

MicroRNA-26a/b regulate DNA replication licensing, tumorigenesis, and prognosis by targeting CDC6 in lung cancer

Cancer is characterized by mutations, genome rearrangements, epigenetic changes, and altered gene expression that enhance cell proliferation, invasion, and metastasis. To accommodate deregulated cellular proliferation, many DNA replication-initiation proteins are overexpressed in human cancers. However, the mechanism that represses the expression of these proteins in normal cells and the cellular changes that result in their overexpression are largely unknown. One possible mechanism is through miRNA expression differences. Here, it is demonstrated that miR26a and miR26b inhibit replication licensing and the proliferation, migration, and invasion of lung cancer cells by targeting CDC6. Importantly, miR26a/b expression is significantly decreased in human lung cancer tissue specimens compared with the paired adjacent normal tissues, and miR26a/b downregulation and the consequential upregulation of CDC6 are associated with poorer prognosis of patients with lung cancer. These results indicate that miR26a/b repress replication licensing and tumorigenesis by targeting CDC6.

IMPLICATIONS

The current study suggests that miR26a, miR26b, and CDC6 and factors regulating their expression represent potential cancer diagnostic and prognostic markers as well as anticancer targets.

Visual gene-network analysis reveals the cancer gene co-expression in human endometrial cancer

Background

Endometrial cancers (ECs) are the most common form of gynecologic malignancy. Recent studies have reported that ECs reveal distinct markers for molecular pathogenesis, which in turn is linked to the various histological types of ECs. To understand further the molecular events contributing to ECs and endometrial tumorigenesis in general, a more precise identification of cancer-associated molecules and signaling networks would be useful for the detection and monitoring of malignancy, improving clinical cancer therapy, and personalization of treatments.

Results

ECs-specific gene co-expression networks were constructed by differential expression analysis and weighted gene co-expression network analysis (WGCNA). Important pathways and putative cancer hub genes contribution to tumorigenesis of ECs were identified. An elastic-net regularized classification model was built using the cancer hub gene signatures to predict the phenotypic characteristics of ECs. The 19 cancer hub gene signatures had high predictive power to distinguish among three key principal features of ECs: grade, type, and stage. Intriguingly, these hub gene networks seem to contribute to ECs progression and malignancy via cell-cycle regulation, antigen processing and the citric acid (TCA) cycle.

Conclusions

The results of this study provide a powerful biomarker discovery platform to better understand the progression of ECs and to uncover potential therapeutic targets in the treatment of ECs. This information might lead to improved monitoring of ECs and resulting improvement of treatment of ECs, the 4^th most common of cancer in women.

Sparstolonin B inhibits pro-angiogenic functions and blocks cell cycle progression in endothelial cells

Sparstolonin B (SsnB) is a novel bioactive compound isolated from Sparganium stoloniferum, an herb historically used in Traditional Chinese Medicine as an anti-tumor agent. Angiogenesis, the process of new capillary formation from existing blood vessels, is dysregulated in many pathological disorders, including diabetic retinopathy, tumor growth, and atherosclerosis. In functional assays, SsnB inhibited endothelial cell tube formation (Matrigel method) and cell migration (Transwell method) in a dose-dependent manner. Microarray experiments with human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells (HCAECs) demonstrated differential expression of several hundred genes in response to SsnB exposure (916 and 356 genes, respectively, with fold change ≥2, p<0.05, unpaired t-test). Microarray data from both cell types showed significant overlap, including genes associated with cell proliferation and cell cycle. Flow cytometric cell cycle analysis of HUVECs treated with SsnB showed an increase of cells in the G1 phase and a decrease of cells in the S phase. Cyclin E2 (CCNE2) and Cell division cycle 6 (CDC6) are regulatory proteins that control cell cycle progression through the G1/S checkpoint. Both CCNE2 and CDC6 were downregulated in the microarray data. Real Time quantitative PCR confirmed that gene expression of CCNE2 and CDC6 in HUVECs was downregulated after SsnB exposure, to 64% and 35% of controls, respectively. The data suggest that SsnB may exert its anti-angiogenic properties in part by downregulating CCNE2 and CDC6, halting progression through the G1/S checkpoint. In the chick chorioallantoic membrane (CAM) assay, SsnB caused significant reduction in capillary length and branching number relative to the vehicle control group. Overall, SsnB caused a significant reduction in angiogenesis (ANOVA, p<0.05), demonstrating its ex vivo efficacy.

Genomic profiling of oral squamous cell carcinoma by array-based comparative genomic hybridization

We designed a study to investigate genetic relationships between primary tumors of oral squamous cell carcinoma (OSCC) and their lymph node metastases, and to identify genomic copy number aberrations (CNAs) related to lymph node metastasis. For this purpose, we collected a total of 42 tumor samples from 25 patients and analyzed their genomic profiles by array-based comparative genomic hybridization. We then compared the genetic profiles of metastatic primary tumors (MPTs) with their paired lymph node metastases (LNMs), and also those of LNMs with non-metastatic primary tumors (NMPTs). Firstly, we found that although there were some distinctive differences in the patterns of genomic profiles between MPTs and their paired LNMs, the paired samples shared similar genomic aberration patterns in each case. Unsupervised hierarchical clustering analysis grouped together 12 of the 15 MPT-LNM pairs. Furthermore, similarity scores between paired samples were significantly higher than those between non-paired samples. These results suggested that MPTs and their paired LNMs are composed predominantly of genetically clonal tumor cells, while minor populations with different CNAs may also exist in metastatic OSCCs. Secondly, to identify CNAs related to lymph node metastasis, we compared CNAs between grouped samples of MPTs and LNMs, but were unable to find any CNAs that were more common in LNMs. Finally, we hypothesized that subpopulations carrying metastasis-related CNAs might be present in both the MPT and LNM. Accordingly, we compared CNAs between NMPTs and LNMs, and found that gains of 7p, 8q and 17q were more common in the latter than in the former, suggesting that these CNAs may be involved in lymph node metastasis of OSCC. In conclusion, our data suggest that in OSCCs showing metastasis, the primary and metastatic tumors share similar genomic profiles, and that cells in the primary tumor may tend to metastasize after acquiring metastasis-associated CNAs.

Release of macrophage migration inhibitory factor by neuroendocrine-differentiated LNCaP cells sustains the proliferation and survival of prostate cancer cells

The acquisition of neuroendocrine (NE) characteristics by prostate cancer (PCa) cells is closely related to tumour progression and hormone resistance. The mechanisms by which NE cells influence PCa growth and progression are not fully understood. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine involved in oncogenic processes, and MIF serum levels correlate with aggressiveness of PCa. Here, we investigated the regulation and the functional consequences of MIF expression during NE transdifferentiation of PCa cells. NE differentiation (NED) of LNCaP cells, initiated either by increasing intracellular levels of cAMP or by culturing cells in an androgen-depleted medium, was associated with markedly increased MIF release. Yet, intracellular MIF protein and mRNA levels and MIF gene promoter activity decreased during NED of LNCaP cells, suggesting that NED favours MIF release despite decreasing MIF synthesis. Adenoviral-mediated forced MIF expression in NE-differentiated LNCaP cells increased cell proliferation without affecting the expression of NE markers. Addition of exogenous recombinant MIF to LNCaP and PC-3 cells stimulated the AKT and ERK1/2 signalling pathways, the expression of genes involved in PCa, as well as proliferation and resistance to paclitaxel and thapsigargin-induced apoptosis. Altogether, these data provide evidence that increased MIF release during NED in PCa may facilitate cancer progression or recurrence, especially following androgen deprivation. Thus, MIF could represent an attractive target for PCa therapy.

Genomic deletion of PTEN is associated with tumor progression and early PSA recurrence in ERG fusion-positive and fusion-negative prostate cancer

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene is often altered in prostate cancer. To determine the prevalence and clinical significance of the different mechanisms of PTEN inactivation, we analyzed PTEN deletions in TMAs containing 4699 hormone-naïve and 57 hormone-refractory prostate cancers using fluorescence in situ hybridization analysis. PTEN mutations and methylation were analyzed in subsets of 149 and 34 tumors, respectively. PTEN deletions were present in 20.2% (458/2266) of prostate cancers, including 8.1% heterozygous and 12.1% homozygous deletions, and were linked to advanced tumor stage (P < 0.0001), high Gleason grade (P < 0.0001), presence of lymph node metastasis (P = 0.0002), hormone-refractory disease (P < 0.0001), presence of ERG gene fusion (P < 0.0001), and nuclear p53 accumulation (P < 0.0001). PTEN deletions were also associated with early prostate-specific antigen recurrence in univariate (P < 0.0001) and multivariate (P = 0.0158) analyses. The prognostic impact of PTEN deletion was seen in both ERG fusion-positive and ERG fusion-negative tumors. PTEN mutations were found in 4 (12.9%) of 31 cancers with heterozygous PTEN deletions but in only 1 (2%) of 59 cancers without PTEN deletion (P = 0.027). Aberrant PTEN promoter methylation was not detected in 34 tumors. The results of this study demonstrate that biallelic PTEN inactivation, by either homozygous deletion or deletion of one allele and mutation of the other, occurs in most PTEN-defective cancers and characterizes a particularly aggressive subset of metastatic and hormone-refractory prostate cancers.

The interconnectedness of cancer cell signaling

The elegance of fundamental and applied research activities have begun to reveal a myriad of spatial and temporal alterations in downstream signaling networks affected by cell surface receptor stimulation including G protein-coupled receptors and receptor tyrosine kinases. Interconnected biochemical pathways serve to integrate and distribute the signaling information throughout the cell by orchestration of complex biochemical circuits consisting of protein interactions and covalent modification processes. It is clear that scientific literature summarizing results from both fundamental and applied scientific research activities has served to provide a broad foundational biologic database that has been instrumental in advancing our continued understanding of underlying cancer biology. This article reflects on historical advances and the role of innovation in the competitive world of grant-sponsored research.

ROS enhances CXCR4-mediated functions through inactivation of PTEN in prostate cancer cells

Inactivation of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is heavily implicated in the tumorigenesis of prostate cancer. Conversely, the upregulation of the chemokine (CXC) receptor 4 (CXCR4) is associated with prostate cancer progression and metastasis. Studies have shown that loss of PTEN permits CXCR4-mediated functions in prostate cancer cells. Loss of PTEN function is typically due to genetic and epigenetic modulations, as well as active site oxidation by reactive oxygen species (ROS); likewise ROS upregulates CXCR4 expression. Herein, we show that ROS accumulation permitted CXCR4-mediated functions through PTEN catalytic inactivation. ROS increased p-AKT and CXCR4 expression, which were abrogated by a ROS scavenger in prostate cancer cells. ROS mediated PTEN inactivation but did not affect expression, yet enhanced cell migration and invasion in a CXCR4-dependent manner. Collectively, our studies add to the body of knowledge on the regulatory role of PTEN in CXCR4-mediated cancer progression, and hopefully, will contribute to the development of therapies that target the tumor microenvironment, which have great potential for the better management of a metastatic disease.

Dinosaurs and ancient civilizations: reflections on the treatment of cancer

Research efforts in the area of palaeopathology have been seen as an avenue to improve our understanding of the pathogenesis of cancer. Answers to questions of whether dinosaurs had cancer, or if cancer plagued ancient civilizations, have captured the imagination as well as the popular media. Evidence for dinosaurian cancer may indicate that cancer may have been with us from the dawn of time. Ancient recorded history suggests that past civilizations attempted to fight cancer with a variety of interventions. When contemplating the issue why a generalized cure for cancer has not been found, it might prove useful to reflect on the relatively limited time that this issue has been an agenda item of governmental attention as well as continued introduction of an every evolving myriad of manmade carcinogens relative to the total time cancer has been present on planet Earth. This article reflects on the history of cancer and the progress made following the initiation of the "era of cancer chemotherapy."

Metastasis suppressors in human benign prostate, intraepithelial neoplasia, and invasive cancer: their prospects as therapeutic agents

Despite advances in diagnosis and treatment of prostate cancer, development of metastases remains a major clinical challenge. Research efforts are dedicated to overcome this problem by understanding the molecular basis of the transition from benign cells to prostatic intraepithelial neoplasia (PIN), localized carcinoma, and metastatic cancer. Identification of proteins that inhibit dissemination of cancer cells will provide new perspectives to define novel therapeutics. Development of antimetastatic drugs that trigger or mimic the effect of metastasis suppressors represents new therapeutic approaches to improve patient survival. This review focuses on different biochemical and cellular functions of metastasis suppressors known to play a role in prostate carcinogenesis and progression. Ten putative metastasis suppressors implicated in prostate cancer are discussed. CD44s is decreased in both PIN and cancer; Drg-1, E-cadherin, KAI-1, RKIP, and SSeCKS show similar expression between benign epithelia and PIN, but are downregulated in invasive cancer; whereas, maspin, MKK4, Nm23 and PTEN are upregulated in PIN and downregulated in cancer. Moreover, the potential role of microRNA in prostate cancer progression, the understanding of the cellular distribution and localization of metastasis suppressors, their mechanism of action, their effect on prostate invasion and metastasis, and their potential use as therapeutics are addressed.

Loss of PTEN permits CXCR4-mediated tumorigenesis through ERK1/2 in prostate cancer cells

Loss of PTEN is frequently observed in androgen-independent prostate cancer, resulting in the deregulation of metastatic events. SDF1α activation of CXCR4 induces signaling pathways that have been implicated in prostate metastasis and progression to an advanced disease. The pathways of CXCR4 and PTEN converge, leading to the promotion and regulation of tumorigenesis, respectively. However, loss of PTEN may permit CXCR4 to progress prostate cancer to an advanced disease. In the present study, we investigated the involvement of PTEN in CXCR4-mediated tumorigenesis. When screening advanced metastatic prostate cancer cell lines for PTEN, we observed a loss of expression in PC3 and LNCaP cells whereas Du145 expressed wild-type PTEN. All three cell lines were positive for surface expression of CXCR4. Reconsitution of PTEN induced a mesenchymal to epithelial like morphologic change and inhibited CXCR4-mediated migration and proliferation in PC3 cells. Downregulation of PTEN by siRNA enhanced the CXCR4-mediated migratory behavior of Du145 cells. By Western blot analysis, we observed that PTEN inhibited basal AKT phosphorylation but not ERK1/2 phosphorylation in PTEN-expressing cells. Upon CXCR4 stimulation, PTEN inhibited ERK1/2 phosphorylation but not phosphorylation of AKT. The CXCR4-mediated migration of PC3 cells was through the ERK1/2 pathway, as confirmed by chemical inhibitors. On the basis of these studies, we suggest that loss of PTEN permits CXCR4-mediated functions in prostate cancer cells through the ERK1/2 pathway. Antagonizing CXCR4 and downstream signaling cascades may provide an efficient approach for treating patients with advanced prostate cancer when hormone therapy fails to the stop the growth and containment of tumors.

The War on Cancer rages on

In 1971, the "War on Cancer" was launched by the US government to cure cancer by the 200-year anniversary of the founding of the United States of America, 1976. This article briefly looks back at the progress that has been made in cancer research and compares progress made in other areas of human affliction. While progress has indeed been made, the battle continues to rage on.

Distinct and redundant functions of cyclin E1 and cyclin E2 in development and cancer

The highly conserved E-type cyclins are core components of the cell cycle machinery, facilitating the transition into S phase through activation of the cyclin dependent kinases, and assembly of pre-replication complexes on DNA. Cyclin E1 and cyclin E2 are assumed to be functionally redundant, as cyclin E1-/- E2-/- mice are embryonic lethal while cyclin E1-/- and E2-/- single knockout mice have primarily normal phenotypes. However more detailed studies of the functions and regulation of the E-cyclins have unveiled potential additional roles for these proteins, such as in endoreplication and meiosis, which are more closely associated with either cyclin E1 or cyclin E2. Moreover, expression of each E-cyclin can be independently regulated by distinct transcription factors and microRNAs, allowing for context-specific expression. Furthermore, cyclins E1 and E2 are frequently expressed independently of one another in human cancer, with unique associations to signatures of poor prognosis. These data imply an absence of co-regulation of cyclins E1 and E2 during tumorigenesis and possibly different contributions to cancer progression. This is supported by in vitro data identifying divergent regulation of the two genes, as well as potentially different roles in vivo.

Molecular imaging of prostate cancer: a concise synopsis

Prostate cancer is the most common malignancy in men and continues to be a major public health problem. Imaging of prostate cancer remains particularly challenging owing to disease heterogeneity. Molecular imaging can provide unprecedented opportunities for deciphering the molecular mechanisms that are involved in the development and natural progression of prostate cancer from a localized process to the hormone-refractory metastatic disease. Such understanding will be the key for targeted imaging and therapy and for predicting and evaluating treatment response and prognosis. In this article, we review briefly the contribution of multimodality molecular imaging methods for the in vivo characterization of the pathophysiology of prostate cancer.