Transgenic mouse model for breast cancer: induction of breast cancer in novel oncogene HCCR-2 transgenic mice

LETMD1 Regulates Phagocytosis and Inflammatory Responses to Lipopolysaccharide via Reactive Oxygen Species Generation and NF-κB Activation in Macrophages

LETM1 domain-containing protein 1 (LETMD1), also known as HCCR-1, is a mitochondrial protein and is known to regulate p53 and STAT3 activities in cancer cells. In this study, we present, for the first time (to our knowledge), data indicating that LETMD1 suppresses multiple immune responses in monocyte/macrophage lineage cells and mouse primary macrophages. Attenuation of LETMD1 expression with specific small interfering RNA and short hairpin RNA constructs enhanced LPS-induced expressions of inflammatory mediators in macrophages. In addition, LETMD1 attenuation caused potentiation of phagocytosis as well as migration in a macrophage-like cell line, U937. These enhancing effects were associated with altered activation of signaling adaptors (such as NF-κB, MAPKs, p53, and JAK-STAT) involved in TLR4 signaling. Especially, LETMD1 selectively regulated TLR4-induced NF-κB activation via MyD88 but not via TIR-domain-containing adapter-inducing IFN-β (TRIF). Attenuation of LETMD1 expression caused mitochondrial hyperpolarization and subsequent decrease in ATP production and increase in mitochondrial/cellular reactive oxygen species (ROS) and intracellular calcium levels. LETMD1 attenuation also enhanced LPS-induced expression of NADPH oxidase (NOX) 2, the main producer of cellular ROS in phagocytes, through augmenting IFN regulatory factor 1. Accordingly, treatment with ROS scavenger, NOX2 suppressing agents, or calcium chelators resulted in suppression of LPS-induced cytokine production as well as NF-κB activation in cells with LETMD1 attenuation. These findings reveal a previously unknown function of LETMD1 and provide evidences showing LETMD1 negatively regulates macrophage functions by modulating mitochondrial function, subsequent ROS generation, and NF-κB activation.

Cisatracurium Retards Cell Migration and Invasion Upon Upregulation of p53 and Inhibits the Aggressiveness of Colorectal Cancer

Colorectal cancer (CRC) is reported to be the third and fourth, most diagnosed and cause of cancer associated deaths respectively. In 2012 for instance, about 1.4 million new cases were reported, and approximately 700,000 deaths recorded. Survival from CRC is dependent on the stage at which it is diagnosed coupled with appropriate surgical and medical intervention. Cisatracurium is widely used for skeletal muscle relaxation during abdominal surgeries, including bowel and colon surgeries. Recent studies reported that cisatracurium inhibits progression of human cancer cells, however, the mechanisms leading to the inhibition are yet to be completely understood. To elucidate mechanisms resulting particularly in tumor cell growth and metastasis, we developed ex vivo and in in vivo xenograft models of CRC. Cisatracurium caused upregulation of p53 and its down-stream genes and proteins known to regulate proliferation and metastasis in vitro and in vivo. Genomic analyses of CRC following cisatracurium treatment revealed moderate to high DNA damage, while functional analyses demonstrated significant tumor cells growth regression, as well as repression of migration and invasion. Importantly, cisatracurium increased E-Cadherin and CALD-1 but decreased SNAI-1 and SLUG levels in vitro and in vivo. Together, the findings demonstrate that elevation of p53 upon cisatracurium-induced genomic injury, represent a potential mechanism by which cisatracurium result in the suppression of CRC progression and metastasis.

Nanoparticle-Mediated Therapeutic Agent Delivery for Treating Metastatic Breast Cancer-Challenges and Opportunities

Breast cancer (BC) is the second leading cause of cancer-related death in American women and more than 90% of BC-related death is caused by metastatic BC (MBC). This review stresses the limited success of traditional therapies as well as the use of nanomedicine for treating MBC. Understanding the biological barriers of MBC that nanoparticle in vivo trafficking must overcome could provide valuable new insights for translating nanomedicine from the bench side to the bedside. A view about nanomedicine applied in BC therapy has been summarized with their present status, which is gaining attention in the clinically-applied landscape. The progressions of drug/gene delivery systems, especially the status of their preclinical or clinical trials, are also discussed. Here we highlight that the treatment of metastasis, in addition to the extensively described inhibition of primary tumor growth, is an indispensable requirement for nanomedicine. Along with more innovations in material chemistry and more progressions in biology, nanomedicine will constantly supply more exciting new approaches for targeted drug/gene delivery against MBC.

Origin of Cancer: An Information, Energy, and Matter Disease

Cells are open, highly ordered systems that are far away from equilibrium. For this reason, the first function of any cell is to prevent the permanent threat of disintegration that is described by thermodynamic laws and to preserve highly ordered cell characteristics such as structures, the cell cycle, or metabolism. In this context, three basic categories play a central role: energy, information, and matter. Each of these three categories is equally important to the cell and they are reciprocally dependent. We therefore suggest that energy loss (e.g., through impaired mitochondria) or disturbance of information (e.g., through mutations or aneuploidy) or changes in the composition or distribution of matter (e.g., through micro-environmental changes or toxic agents) can irreversibly disturb molecular mechanisms, leading to increased local entropy of cellular functions and structures. In terms of physics, changes to these normally highly ordered reaction probabilities lead to a state that is irreversibly biologically imbalanced, but that is thermodynamically more stable. This primary change—independent of the initiator—now provokes and drives a complex interplay between the availability of energy, the composition, and distribution of matter and increasing information disturbance that is dependent upon reactions that try to overcome or stabilize this intracellular, irreversible disorder described by entropy. Because a return to the original ordered state is not possible for thermodynamic reasons, the cells either die or else they persist in a metastable state. In the latter case, they enter into a self-driven adaptive and evolutionary process that generates a progression of disordered cells and that results in a broad spectrum of progeny with different characteristics. Possibly, 1 day, one of these cells will show an autonomous and aggressive behavior—it will be a cancer cell.

Up-regulation of human cervical cancer proto-oncogene contributes to hepatitis B virus-induced malignant transformation of hepatocyte by down-regulating E-cadherin

Hepatocellular carcinoma (HCC) is one of the most fatal human malignancies, Human cervical cancer proto-oncogene (HCCR) aberrantly expressed in a number of malignant tumors, including HCC. HCC is associated with Hepatitis B virus (HBV) infection in a large percentage of cases. To explore the regulation and function of HCCR expression in the development of HCC, we detected HCCR expression in HBV expressing hepatocytes. Results showed that the expression of HCCR was higher in HBV-expressing hepatocytes than that in control cells. Examining different components of HBV revealed that the HBx promotes HCCR expression in hepatocytes via the T-cell factor (TCF)/β-catenin pathway. HCCR expression in HBx transgenic mice increased with as the mice aged and developed tumors. We also found that overexpression of HCCR in hepatocytes promoted cell proliferation, migration, and invasion and reduced cell adhesion. Suppressing HCCR expression abolished the effect of HBx-induced hepatocyte growth. In addition, HCCR represses the expression of E-cadherin by inhibition its promoter activity, which might correlate with the effects of HCCR in hepatocytes. Taken together, these results demonstrate that HBx-HCCR-E-cadherin regulation pathway might play an important role in HBV-induced hepatocarcinogenesis. They also imply that HCCR is a potential risk marker for HCC and/or a potential therapeutic target.

Targeting HCCR expression resensitizes gastric cancer cells to chemotherapy via down-regulating the activation of STAT3

The human cervical cancer oncogene (HCCR) has been found to be overexpressed in a variety of human cancers. However, the level of expression of HCCR and its biological function in gastric cancer are largely unknown. In this study, we evaluated HCCR expression in several gastric cancer cell lines and in one normal gastric mucosal cell line. We established a 5-FU-resistant gastric cancer cell subline, and we evaluated its HCCR expression. HCCR expression levels were high in gastric cancer lines, and expression was significantly increased in the 5-FU-resistant cancer cell subline. HCCR expression affected cell growth by regulating apoptosis in the cancer cells, and it had a positive correlation with p-STAT3 expression. Western blot and luciferase reporter assays showed that the activation of STAT3 upregulated HCCR expression in a positive feedback loop model. In vivo and in vitro studies showed that HCCR plays an important role in the apoptosis induced by 5-FU. Our data demonstrate that HCCR is probably involved in apoptosis and cancer growth and that it functions as a p-STAT3 stimulator in a positive feedback loop model. In gastric cancer cells, HCCR confers a more aggressive phenotype and resistance to 5-FU-based chemotherapy.

Quantitative detection of the human cervical cancer oncogene for monitoring the minimal residual disease in acute leukemia

The human cervical cancer oncogene (HCCR) has been shown to be over-expressed in some solid tumors, and its function is involved in negative regulation of p53 tumor suppressor gene. However, the roles of HCCR in leukemia remain unclear. The present study is to investigate whether the expression levels of HCCR mRNA are associated with clinical prognosis in patients with acute leukemia (AL) and to explore the potential use as a biomarker for monitoring minimal residual disease (MRD) in AL. The mRNA levels of HCCR1 and HCCR2 were quantified by real-time reverse transcription polymerase chain reaction in bone marrow samples from 80 adult de novo AL patients and 20 normal healthy donors. The expressions of HCCR1 and HCCR2 were significantly higher in patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) than those in healthy donors (P < 0.01), but there was no significant difference between AML and ALL (P > 0.05). Besides white blood cell count, we did not find any significant correlation between HCCR expression and clinical characteristics, such as age, sex, CD34 antigen expression, and response to chemotherapy. HCCR was monitored in 12 cases during remission and/or relapse. Significant reductions of both HCCR1 and HCCR2 mRNA levels were observed in patients who had achieved complete remission after chemotherapy but not in patients with non-responsive. However, an increased HCCR expression was detected in these patients who relapsed. Our findings suggest that HCCR gene is over-expressed in AL patients and may be as a useful biomarker for monitoring MRD in AL.

HCCRBP-3 induces tumorigenesis through direct interaction with HCCR-1 in human cancers

Human cervical cancer oncogene 1, HCCR-1, is over-expressed in various human tumors and appears to serve as a negative regulator of the p53 gene. HCCR-1 transgenic mice developed breast cancers but it is unknown how HCCR-1 contributes to tumorigenesis. We identified the HCCR-1 binding protein 3 (HCCRBP-3) as a binding partner for HCCR-1. These two proteins co-localized to the mitochondria. HCCRBP-3 over-expressed in various human tumors converted normal cells into tumor cells in vitro. Nude mice injected with NIH/3T3 cells stably transfected with HCCRBP-3 also induced the tumor formation. In addition, p53 showed the functional impairment in HCCRBP-3-transfected cells as accompanied with defective induction of p21 and bax. In support of this, p21 promoter activities containing p53 responsive elements were inhibited by HCCRBP-3 in a dose-dependent manner. Therefore, our study suggests that HCCRBP-3 contributes to the HCCR-1 induced tumorigenesis by interrupting the p53 function.

Clinical implication of elevated human cervical cancer oncogene-1 expression in esophageal squamous cell carcinoma

The human cervical cancer oncogene 1 (HCCR-1), a novel human oncoprotein, has been shown to be upregulated in various human tumors and plays a critical role in tumorigenesis and tumor progression. Here, the authors investigated HCCR-1 level in esophageal squamous cell carcinoma (ESCC) tissues and assessed the correlation between HCCR-1 level and prognosis of the patients with ESCC. HCCR-1 levels were investigated by immunohistochemistry, in situ hybridization, real-time quantitative RT-PCR and Western blotting methods; Kaplan-Meier curve was used to evaluate the prognostic value of HCCR-1 level in patients with ESCC using log-rank test. HCCR-1 displayed high levels in ESCC tissues compared to squamous dysplasia tissues and normal esophageal epithelial tissues. No significant correlation was observed between the levels of HCCR-1 mRNA and protein and gender and age (all p>0.05) but obviously related to histological grade, clinical stage, and lymph node metastasis (all p<0.001). Moreover, the survival rate of the patients with low HCCR-1 levels was higher than that of the patients with high HCCR-1 levels (both p<0.05). These data demonstrate that HCCR-1 may be used as a novel predictor for the prognosis of the patients with ESCC.

Silencing of the HCCR2 gene induces apoptosis and suppresses the aggressive phenotype of hepatocellular carcinoma cells in culture

BACKGROUND

The human cervical cancer oncogene HCCR-2 is overexpressed in various malignant tumors and cell lines, and might function as a negative regulator of the p53 tumor suppressor. Here, we used RNA interference strategies to evaluate the role of HCCR-2 in liver cancer, and to explore its potential therapeutic effect.

METHODS

Changes of HepG2 cells stably transfected by an HCCR-2 RNA interference vector were detected by real-time PCR, MTT staining, plate colony formation, flow cytometry, and cell migration experiments. Apoptosis-related protein Bcl-2 and Bax levels were measured by Western blot.

RESULTS

Our results showed that of the three siRNA-expressing vectors, siRNA-H3 had a suppressive effect on the expression of HCCR-2 mRNA, interfering with proliferation and migration of HCCR-2. Moreover, the apoptotic rate also increased, and cells transfected by siRNA-H3 were blocked in the G0/G1 stage. Plate colony formation experiments demonstrated that the single cell clone formation capacity of HepG2-H3 cells was clearly lower than that of HepG2 and HepG2-N cells. Western blot results indicated that the expression of Bcl-2 was inhibited, and the expression of Bax was increased.

CONCLUSIONS

In summary, RNAi targeting HCCR-2 could be an effective means for suppressing malignant features of hepatocellular carcinoma cells.

Construction of eukaryotic expression vectors expressing siRNAs targeting the HCCR2 gene and their transfection into PANC1 cells

AIM: To construct eukaryotic expression vectors expressing small interfering RNAs (siRNAs) targeting the human cervical cancer oncogene 2 (HCCR2) gene and transfect them into human pancreatic cancer cell line PANC1 to obtain a cell line stably transfected with the HCCR2 siRNA plasmid.

METHODS: Multiple siRNAs targeting the HCCR2 gene were designed, chemically synthesized, and cloned into the eukaryotic expression vector pGCsi-H1/Hygro/NEGative. The resulting recombinant vectors were identified by direct sequencing. After the recombinant pGCsi-HCCR plasmids were co-transfected with an HCCR eukaryotic expression vector into 293T cells, the protein expression of HCCR-2 was analyzed by Western blotting to identify the pGCsi-HCCR vector that had the highest gene knockdown efficiency. This recombinant vector was then transfected into PANC1 cells with LipofectamineTM 2000. G418-resistant clones were selected to obtain a stably transfected cell line. The expression of HCCR2 protein in stably transfected cell line was detected by Western blot.

RESULTS: The pGCsi-HCCR-3 plasmid had the highest gene knockdown efficiency and was used to transfect PANC1 cells. Western blotting analysis demonstrated that HCCR2 expression was significantly inhibited in PANC-1 cells stably transfected with the pGCsi-HCCR-3 plasmid compared to cells transfected with the empty vector.

CONCLUSION: Eukaryotic expression vectors expressing siRNAs targeting the HCCR2 gene were successfully constructed and a PANC-1 cell line stably transfected with the pGCsi-HCCR-3 plasmid was successfully established.

The novel metastasis promoter Merm1/Wbscr22 enhances tumor cell survival in the vasculature by suppressing Zac1/p53-dependent apoptosis

Understanding metastasis is integral to curative cancer treatments. Using a mouse genetic screening model, we identified Merm1/Wbscr22 as a novel metastasis promoter that includes a methyltransferase fold in its structure. Merm1 showed high levels of expression in invasive breast cancer. Ectopic expression of Merm1 in nonmetastatic cells enhanced metastasis formation without affecting cell growth and motility. The intact methyltransferase fold of Merm1 was required for metastasis formation. Interestingly, Merm1 expression promoted cell survival after entrapment in the lung microvasculature. Consistent with these results, knockdown of endogenous Merm1 in tumor cells reduced lung retention and metastasis formation. On the basis of comparative transcriptome analysis, Merm1 expression was negatively correlated with the expression of tumor suppressor Zac1. We confirmed that Merm1 suppressed Zac1 expression with histone H3 methylation at Lys(9) in the Zac1 promoter region. Zac1 can induce apoptosis through its ability to transcriptionally coactivate p53, which regulates apoptosis in the vasculature and is often downregulated in metastasis. We found that Zac1 knockdown reduced the p53-dependent apoptosis that was enhanced by Merm1 knockdown, thereby increasing lung retention of metastatic cells. Our findings show that Merm1 enhances cancer cell survival in the vasculature by suppressing Zac1/p53-dependent apoptosis, thereby enhancing metastasis.

Transdifferentiation-inducing HCCR-1 oncogene

Background

Cell transdifferentiation is characterized by loss of some phenotypes along with acquisition of new phenotypes in differentiated cells. The differentiated state of a given cell is not irreversible. It depends on the up- and downregulation exerted by specific molecules.

Results

We report here that HCCR-1, previously shown to play an oncogenic role in human cancers, induces epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) in human and mouse, respectively. The stem cell factor receptor CD117/c-Kit was induced in this transdifferentiated (EMT) sarcoma tissues. This MET occurring in HCCR-1 transfected cells is reminiscent of the transdifferentiation process during nephrogenesis. Indeed, expression of HCCR-1 was observed during the embryonic development of the kidney. This suggests that HCCR-1 might be involved in the transdifferentiation process of cancer stem cell.

Conclusions

Therefore, we propose that HCCR-1 may be a regulatory factor that stimulates morphogenesis of epithelia or mesenchyme during neoplastic transformation.

Epidermal growth factor induces HCCR expression via PI3K/Akt/mTOR signaling in PANC-1 pancreatic cancer cells

BACKGROUND

Human cervical cancer oncoprotein 1 (HCCR-1), reported as a negative regulator of p53, is over-expressed in a variety of human cancers. However, it is yet unknown whether HCCR-1 plays any role in pancreatic cancer development. The aim of this study was to investigate the effect of epidermal growth factor on the expression of HCCR in pancreatic cancer cells, and to explore if PI3K/Akt/mTOR signaling pathway mediated this expression.

METHODS

A polyclonal antibody against HCCR protein was raised by immunizing Balb/c mice with the purified recombinant protein pMBPc-HCCR. Tissue samples were constructed on a tissue chip, and the expression of HCCR was investigated by immunohistochemistry assay and Western blotting. Pancreatic cell line, PANC-1 cells were stably transfected with plasmids containing sense-HCCR-1 fragment and HCCR siRNA fragment. MTT and transwell assay were used to investigate the proliferation and invasion of stable tansfectants. The specific inhibitor of PI3K and mTOR was used to see if PI3K/mTOR signal transduction was involved in the induction of HCCR gene expression. A Luciferase assay was used to see if Akt can enhance the HCCR promoter activity.

RESULTS

HCCR was up-regulated in pancreatic tumor tissues (mean Allred score 4.51+/-1.549 vs. 2.87+/-2.193, P<0.01), especially with high expression in poorly differentiated pancreatic cancer. The growth of cells decreased in HCCR-1 siRNA transfected cells compared with vector transfectants. The number of invasion cells was significantly lower in HCCR-1 siRNA transfected cells (24.4+/-9.9) than that in vector transfectants (49.1+/-15.4). Treatment of PANC-1 cells with epidermal growth factor increased HCCR protein level in a dose- and time-dependent manner. However, application of LY294002 and rapamycin caused a dramatic reduction of epidermal growth factor-induced HCCR expression. Over-expression of exogenous constitutively active Akt increased the HCCR promoter activity; in contrast, dominant negative Akt decreased the promoter activity.

CONCLUSIONS

EGF-induced HCCR-1 over-expression is mediated by PI3K/AKT/mTOR signaling which plays a pivotal role in pancreatic tumor progression, suggesting that HCCR-1 could be a potential target for cancer therapeutics.

TCF/beta-catenin plays an important role in HCCR-1 oncogene expression

Background

Oncogene HCCR-1 functions as a negative regulator of the p53 and contributes to tumorigenesis of various human tissues. However, it is unknown how HCCR-1 contributes to the cellular and biochemical mechanisms of human tumorigenesis.

Results

In this study, we showed how the expression of HCCR-1 is modulated. The luciferase activity assay indicated that the HCCR-1 5'-flanking region at positions -166 to +30 plays an important role in HCCR-1 promoter activity. Computational analysis of this region identified two consensus sequences for the T-cell factor (TCF) located at -26 to -4 (Tcf1) and -136 to -114 (Tcf2). Mutation at the Tcf1 site led to a dramatic decrease in promoter activity. Mobility shift assays (EMSA) revealed that nuclear proteins bind to the Tcf1 site, but not to the Tcf2 site. LiCl, Wnt signal activator by GSK-3β inhibition, significantly increased reporter activities in wild-type Tcf1-containing constructs, but were without effect in mutant Tcf1-containing constructs in HEK/293 cells. In addition, endogenous HCCR-1 expression was also increased by treatment with GSK-3β inhibitor, LiCl or AR-A014418 in HEK/293 and K562 cells. Finally, we also observed that the transcription factor, TCF, and its cofactor, β-catenin, bound to the Tcf1 site.

Conclusion

These findings suggest that the Tcf1 site on the HCCR-1 promoter is a major element regulating HCCR-1 expression and abnormal stimulation of this site may induce various human cancers.

HCCRBP-1 directly interacting with HCCR-1 induces tumorigenesis through P53 stabilization

Oncogene HCCR-1 functions as a negative regulator of the p53 and contributes to tumorigenesis of various human tissues. HCCR transgenic mice developed breast cancers but it is unknown how HCCR-1 contributes to human tumorigenesis. This study identified a HCCR-1-binding protein 1 (HCCRBP-1) as an HCCR binding partner by performing yeast two hybrid screening. Their endogenous interaction was further confirmed by coimmunoprecipitation experiments. These two proteins colocalized in the mitochondria. HCCRBP-1 was overexpressed in various human tumors. In addition, HCCRBP-1 alone converted NIH/3T3 cells into tumor cells in combination with no other oncogenes. HCCRBP-1 induced tumorigenesis by markedly activating PKC activities but decreasing the pro-apoptotic PKC alpha and PKC delta isoform levels. We observed that p53 stabilization also occurred with functional impairment in HCCRBP-1-transfected 293 cells, as indicated by defective induction of p21, MDM2 and bax. Indeed, HCCRBP-1 decreased p21 promoter activity probably via p53 stabilization leading to the defective function. These results indicate that HCCRBP-1 oncogene induces p53 stabilization and thereby contributes to tumorigenesis.

HCCR-1, a novel oncogene, encodes a mitochondrial outer membrane protein and suppresses the UVC-induced apoptosis

Background

The Human cervical cancer oncogene (HCCR-1) has been isolated as a human oncoprotein, and has shown strong tumorigenic features. Its potential role in tumorigenesis may result from a negative regulation of the p53 tumor suppressor gene.

Results

To investigate the biological function of HCCR-1 in the cell, we predicted biological features using bioinformatic tools, and have identified a LETM1 homologous domain at position 75 to 346 of HCCR-1. This domain contains proteins identified from diverse species predicted to be mitochondrial proteins. Fluorescence microscopy and fractionation experiments showed that HCCR-1 is located in mitochondria in the COS-7, MCF-7 and HEK/293 cell lines, and subcompartamentally at the outer membrane in the HEK/293 cell line. The topological structure was revealed as the NH₂-terminus of HCCR-1 oriented toward the cytoplasm. We also observed that the D1-2 region, at position 1 to 110 of HCCR-1, was required and sufficient for posttranslational mitochondrial import. The function of HCCR-1 on mitochondrial membrane is to retard the intrinsic apoptosis induced by UVC and staurosporine, respectively.

Conclusion

Our experiments show the biological features of HCCR-1 in the cell, and suggest that uncontrolled expression of HCCR-1 may cause mitochondrial dysfunction that can result in resisting the UVC or staurosporine-induced apoptosis and progressing in the tumor formation.

A concise review of serum markers for hepatocellular cancer

BACKGROUND

The rising incidence of hepatocellular cancer in the US and worldwide has sparked a renewed interest in HCC serum markers. HCC typically develops in patients with chronic liver disease and cirrhosis. It is in these target populations that serum markers are most urgently needed. Unfortunately, the currently available markers lack sensitivity and specificity. A number of novel candidate markers have recently been introduced.

METHODS

We performed a review of the literature (2001-2006) of traditional and novel serum markers for hepatocellular cancer.

RESULTS

Several promising new HCC markers have been identified over the past 5 years. They include single proteins, complex proteomics features, and tumor-specific autoantibodies. The excitement about the new markers is tempered by the realization that none of them have yet met the most stringent criteria defined by the Early Detection Research Network (EDRN).

CONCLUSION

A new generation of HCC serum markers awaits validation in properly controlled clinical studies.

The phosphatidylinositol 3-kinase/Akt pathway regulates the HCCR-1 oncogene expression

The human cervical cancer oncogene HCCR-1 is overexpressed in various human cancers, and might function as a negative regulator of the p53 tumor suppressor. To determine the regulatory pathway involved in the HCCR-1 gene expression, we searched the 5' flanking region of HCCR-1 and identified HCCR-1 promoter including putative homeodomain protein binding sites. The level of HCCR-1 expression was increased during the mouse embryogenesis. Expression of phosphatidylinositol 3-kinase (PI3K) in NIH/3T3 cells activated the HCCR-1 promoter. This promoter was also activated by wild type Akt but not by dominant negative Akt in K562 cells. In addition, the level of HCCR-1 was decreased by PI3K inhibitor, LY-294002, in a dose dependent manner. Northern blot analysis revealed that the HCCR-1 gene expression was down-regulated by LY-294002. These results suggest that the HCCR-1 oncogene expression was regulated by the PI3K/Akt signaling pathway.

Metastasis: a question of life or death

The metastatic process is highly inefficient--very few of the many cells that migrate from the primary tumour successfully colonize distant sites. One proposed mechanism to explain this inefficiency is provided by the cancer stem cell model, which hypothesizes that micrometastases can only be established by tumour stem cells, which are few in number. However, recent in vitro and in vivo observations indicate that apoptosis is an important process regulating metastasis. Here we stress that the inhibition of cell death, apart from its extensively described function in primary tumour development, is a crucial characteristic of metastatic cancer cells.

HCCR-1-interacting molecule "deleted in polyposis 1" plays a tumor-suppressor role in colon carcinogenesis

BACKGROUND & AIMS

Human cervical cancer oncogene (HCCR-1) has appeared to act as a negative regulator of p53 and contributes to tumorigenesis of various organs including the colon. We identified the HCCR-1 binding protein deleted in polyposis 1 (DP1) and accessed the role of HCCR-1 and DP1 in colon tumorigenesis.

METHODS

Yeast 2-hybrid was used to identify HCCR-1 interacting proteins. Various molecular biological approaches were used to examine the expression profile of HCCR-1 and DP1, subcellular localization, epitope mapping, the biological role of DP1, and the serum HCCR-1 level. Loss of heterozygosity frequency around DP1 also was examined.

RESULTS

We identified that HCCR-1 interacted with DP1. These 2 proteins colocalized in mitochondria but the expression of HCCR-1 showed negative correlation with that of DP1 in colorectal cancer (CRC). DP1 played a tumor-suppressor role in colon tumorigenesis (ie, DP1-transfected RKO cells showed growth inhibition, apoptosis, decreased telomerase activity, and up-regulation of p53). These phenomena were reversed when HCCR-1 was overexpressed. Loss of heterozygosity around the DP1 gene was observed frequently (50%) in CRCs. We examined the use of serum HCCR-1 in CRC patients. The sensitivity of HCCR-1 (76.0%) for detecting CRC was proven to be much higher than that of CA19-9 (32.0%).

CONCLUSIONS

DP1 plays a tumor-suppressor role in CRC. DP1 and HCCR-1 are supposed to regulate each other negatively by interaction, but further study is required to get better insight into the biological significance of the interaction.

The HCCR oncoprotein as a biomarker for human breast cancer

PURPOSE

HCCR oncoprotein is reported to be related to tumorigenesis, including breast cancer, functioning as a negative regulator of p53. Mice transgenic for HCCR developed breast cancers. The objective of this study was to validate the HCCR oncoprotein as a candidate biomarker for breast cancer.

EXPERIMENTAL DESIGN

HCCR expression in breast cancer cells was analyzed by quantitative PCR, ELISA, immunohistochemistry, Western blotting, fluorescence-activated cell sorting, and confocal microscopy. Epitope areas were determined using mass spectrometry through the analysis of time-dependent tryptic fragment patterns of HCCR. HCCR expression profiles in breast cancer patient sera were analyzed, and correlations with clinicopathologic data and carbohydrate antigen 15-3 (CA15-3) levels were determined.

RESULTS

HCCR was up-regulated in breast cancer cells and tissues. The epitope regions of HCCR recognized by monoclonal antibody (BCS-1) were HFWTPK and QQTDFLDIYHAFR. According to fluorescence-activated cell sorting and confocal microscopic analysis, BCS-1 was bound to HCCR antigen on the cell surface. Serum HCCR concentrations were measured using ELISA from 299 subjects, including 129 patients with breast cancer, 24 patients with benign breast disease, and 158 normal volunteers, and comparisons were made to CA15-3. Serologic studies revealed an 86.8% sensitivity for HCCR in breast cancer, which was higher than 21.0% for CA15-3. Eighty-six of 98 (87.8%) patients with breast cancers that were negative for CA15-3 were positive for HCCR-1. A positive response rate of 83.3% was identified even at early stages for pathologic factors in breast cancer.

CONCLUSIONS

The HCCR assay has an advantage over CA15-3 in diagnosing breast cancer and detecting early stages of the disease.

Transgenic mouse models for the prevention of breast cancer

Breast cancer prevention research has made remarkable progress in the past decade. Much of this progress has come from clinical trials. However, in the future to test the many promising agents that are now available, pre-clinical models of breast cancer are needed. Such models are now available. Useful models include rat and mouse models, particularly, the genetically engineered mice (GEM). Many transgenic mouse models have been generated by manipulating growth factors and their receptors, cell cycle regulators, signal transduction pathways, cellular differentiation, oncogenes and tumor suppressor genes. The transgenes are induced to express in the mouse mammary glands under the control of various transgenic promoters, which have respective characteristics in expression pattern and other biological attributes. These models are providing invaluable insight on the molecular mechanisms of breast tumorigenesis. In this review, we discuss the relative relevance of the most commonly used transgenic mouse models for breast cancer prevention studies, and provide examples of how these transgenic models can be used to conduct cancer prevention research. Due to the multi-factor, multi-step nature of breast cancer, many factors should be incorporated into a valid prevention study. However, many barriers to progress must be overcome, including access to and availability of new cancer preventive drugs, and difficulties in conducting studies of combinations of preventive agents.