Heregulin regulates the actin cytoskeleton and promotes invasive properties in breast cancer cell lines

The metastatic process requires changes in tumor cell adhesion properties, cell motility and remodeling of the extracellular matrix. The erbB2 proto-oncogene is overexpressed in approximately 30% of breast cancers and is a major prognostic parameter when present in invasive disease. A ligand for the erbB2 receptor has not yet been identified but it can be activated by heterodimerization with heregulin (HRG)-stimulated erbB3 and erbB4 receptors. The HRGs are a family of polypeptide growth factors that have been shown to play a role in embryogenesis, tumor formation, growth and differentiation of breast cancer cells. The erbB3 and erbB4 receptors are involved in transregulation of erbB2 signaling. The work presented here suggests biological roles for HRG including regulation of the actin cytoskeleton and induction of motility and invasion in breast cancer cells. HRG-expressing breast cancer cell lines are characterized by low erbB receptor levels and a high invasive and metastatic index, while those which overexpress erbB2 demonstrate minimal invasive potential in vitro and are non-tumorigenic in vivo. Treatment of the highly tumorigenic and metastatic HRG-expressing breast cancer cell line MDA-MB-231 with an HRG-neutralizing antibody significantly inhibited proliferation in culture and motility in the Boyden chamber assay. Addition of exogenous HRG to non-invasive erbB2 overexpressing cells (SKBr-3) at low concentrations induced formation of pseudopodia, enhanced phagocytic activity and increased chemomigration and invasion in the Boyden chamber assay. The specificity of the chemomigration response to HRG is demonstrated by inhibition with the anti-HRG neutralizing antibody. These results suggest that either HRG can act as an autocrine or paracrine ligand to promote the invasive behavior of breast cancer cells in vitro or thus may enhance the metastatic process in vivo.

ST7-mediated suppression of tumorigenicity of prostate cancer cells is characterized by remodeling of the extracellular matrix

Multiple lines of evidence have provided compelling evidence for the existence of a tumor suppressor gene (TSG) on chromosome 7q31.1. ST7 may be the target of this genetic instability but its designation as a TSG is controversial. In this study, we show that, functionally, ST7 behaves as a tumor suppressor in human cancer. ST7 suppressed growth of PC-3 prostate cancer cells inoculated subcutaneously into severe combined immunodeficient mice, and increased the latency of tumor detection from 13 days in control tumors to 23 days. Re-expression of ST7 was also associated with suppression of colony formation under anchorage-independent conditions in MDA-MB-231 breast cancer cells and ST7 mRNA expression was downregulated in 44% of primary breast cancers. Expression profiling of PC-3 cells revealed that ST7 predominantly induces changes in genes involved in re-modeling the extracellular matrix such as SPARC, IGFBP5 and several matrix metalloproteinases. These data indicate that ST7 may mediate tumor suppression through modification of the tumor microenvironment.

Tumor cells are the source of osteopontin and bone sialoprotein expression in human breast cancer

Bone sialoprotein (BSP) and osteopontin (OPN) are secreted glycoproteins with a conserved Arg-Gly-Asp (RGD) integrin-binding motif and are expressed predominantly in bone. The RGD tripeptide is commonly present in extracellular attachment proteins and has been shown to mediate the attachment of osteosarcoma cells and osteoclasts. To determine the origin and incidence of BSP and OPN mRNA expression in primary tumor, a cohort of archival, primary invasive breast carcinoma specimens was analyzed. BSP transcripts were detected in 65% and OPN transcripts in 77% of breast cancers examined. In general, BSP and OPN transcripts were detected in both invasive and in situ carcinoma components. The transcripts were not detected in surrounding stromal cells or in peritumoral macrophages. Despite its abundance in carcinomas, BSP expression was not detected in a panel of 11 human breast cancer cell lines (MCF-7, T47D, SK-Br-3, MDA-MB-453, MDA-MB- 231, MDA-MB-436, BT549, MCF-7(AOR), Hs578T, MDA-MB-435, and LCC15-MB) and OPN expression was detected only in two of these (MDA-MB-435 and LCC15-MB). To examine the possibility that expression of these genes was down-regulated in cell culture, several cell lines were grown as nude mouse xenografts in vivo; however, these tumors also failed to express BSP. OPN expression was identified in all cell lines grown as nude mouse xenografts. Our data suggest that in human primary breast tumors, the origin of BSP and OPN mRNA is predominantly the breast cancer cells and that expression of these transcripts is influenced by the tumor environment.

Targeting cancer with a lupus autoantibody

Systemic lupus erythematosus (SLE) is distinct among autoimmune diseases because of its association with circulating autoantibodies reactive against host DNA. The precise role that anti-DNA antibodies play in SLE pathophysiology remains to be elucidated, and potential applications of lupus autoantibodies in cancer therapy have not previously been explored. We report the unexpected finding that a cell-penetrating lupus autoantibody, 3E10, has potential as a targeted therapy for DNA repair–deficient malignancies. We find that 3E10 preferentially binds DNA single-strand tails, inhibits key steps in DNA single-strand and double-strand break repair, and sensitizes cultured tumor cells and human tumor xenografts to DNA-damaging therapy, including doxorubicin and radiation. Moreover, we demonstrate that 3E10 alone is synthetically lethal to BRCA2-deficient human cancer cells and selectively sensitizes such cells to low-dose doxorubicin. Our results establish an approach to cancer therapy that we expect will be particularly applicable to BRCA2-related malignancies such as breast, ovarian, and prostate cancers. In addition, our findings raise the possibility that lupus autoantibodies may be partly responsible for the intrinsic deficiencies in DNA repair and the unexpectedly low rates of breast, ovarian, and prostate cancers observed in SLE patients. In summary, this study provides the basis for the potential use of a lupus anti-DNA antibody in cancer therapy and identifies lupus autoantibodies as a potentially rich source of therapeutic agents.

MicroRNAs targeting mutant K-ras by electrotransfer inhibit human colorectal adenocarcinoma cell growth in vitro and in vivo

Mutations of K-ras have been found in 30-60% of colorectal carcinomas and are believed to be associated with tumor initiation, tumor progression and metastasis formation. Therefore, silencing of mutant K-ras expression has become an attractive therapeutic strategy for colorectal cancer treatment. The aim of our study was to investigate the effect of microRNA (miRNA) molecules directed against K-ras (miRNA-K-ras) on K-ras expression level and the growth of colorectal carcinoma cell line LoVo in vitro and in vivo. In addition, we evaluated electroporation as a gene delivery method for transfection of LoVo cells and tumors with plasmid DNA encoding miRNA-K-ras (pmiRNA-K-ras). Results of our study indicated that miRNAs targeting K-ras efficiently reduced K-ras expression and cell survival after in vitro electrotransfection of LoVo cells with pmiRNA-K-ras. In vivo, electroporation has proven to be a simple and efficient delivery method for local administration of pmiRNA-K-ras molecules into LoVo tumors. This therapy shows pronounced antitumor effectiveness and has no side effects. The obtained results demonstrate that electrogene therapy with miRNA-K-ras molecules can be potential therapeutic strategy for treatment of colorectal cancers harboring K-ras mutations. © 2010 Nature Publishing Group All rights reserved.

Chemotherapeutic compounds targeting the DNA double-strand break repair pathways : the good, the bad, and the promising

The repair of DNA double-strand breaks (DSBs) is a critical cellular mechanism that exists to ensure genomic stability. DNA DSBs are the most deleterious type of insult to a cell’s genetic material and can lead to genomic instability, apoptosis, or senescence. Incorrectly repaired DNA DSBs have the potential to produce chromosomal translocations and genomic instability, potentially leading to cancer. The prevalence of DNA DSBs in cancer due to unregulated growth and errors in repair opens up a potential therapeutic window in the treatment of cancers. The cellular response to DNA DSBs is comprised of two pathways to ensure DNA breaks are repaired: homologous recombination and non-homologous end joining. Identifying chemotherapeutic compounds targeting proteins involved in these DNA repair pathways has shown promise as a cancer therapy for patients, either as a monotherapy or in combination with genotoxic drugs. From the beginning, there have been a number of chemotherapeutic compounds that have yielded successful responses in the clinic, a number that have failed (CGK-733 and iniparib), and a number of promising targets for future studies identified. This review looks in detail at how the cell responds to these DNA DSBs and investigates the chemotherapeutic avenues that have been and are currently being explored to target this repair process.

Transforming the future of treatment for ovarian cancer

As for many other cancers, metastasis is the leading cause of death of patients with ovarian cancer. Vigorous basic and clinical research is being performed to initiate more efficacious treatment strategies to improve the poor outcome of women with this cancer. Current treatment for ovarian cancer includes advanced cyto-reductive surgery and traditional platinum and taxane combined chemotherapy. Clinical trials using novel cytotoxic reagents and tyrosine kinase inhibitors have also been progressing. In parallel, the application of robust unbiased high throughput research platforms using transcriptomic and proteomic approaches has identified that not only individual cell signalling pathways, but a network of molecular pathways, play an important role in the biology of ovarian cancer. Furthermore, intensive genomic and epigenetic analyses have also revealed single nucleotide polymorphisms associated with risk and/or aetiology of this cancer including patient response to treatment. Taken together, these approaches, that are advancing our understanding, will have an impact on the generation of new therapeutic approaches and strategies for improving the outcome and quality of life of patients with ovarian cancer in the near future.

The expression profiles of the galectin gene family in primary and metastatic papillary thyroid carcinoma with particular emphasis on galectin-1 and galectin-3 expression

INTRODUCTION: Galectin family members have been demonstrated to be abnormally expressed in cancer at the protein and mRNA level. This study investigated the levels of galectin proteins and mRNA expression in a large cohort of patients with papillary thyroid carcinoma and matched lymph node metastases with particular emphasis on galectin-1 and galectin-3. METHODS: mRNA expression of galectin family members (1, 2, 3, 4, 7, 8, 9, 10 and 12) were analysed by real-time polymerase chain reaction in 65 papillary thyroid carcinomas, 30 matched lymph nodes with metastatic papillary thyroid carcinoma and 5 non-cancer thyroid tissues. Galectin-1 and 3 protein expression was determined by immunohistochemistry in these samples. RESULTS: Significant expression differences in all tested galectin family members (1, 2, 3, 4, 7, 8, 9, 10 and 12) were noted for mRNA in papillary thyroid carcinomas, with and without lymph node metastasis. Galectin-1 protein was more strongly expressed than galectin-3 protein in papillary thyroid carcinoma. Galectin-1 protein was found to be overexpressed in 32% of primary papillary thyroid carcinomas. A majority of lymph nodes with metastatic papillary thyroid carcinoma (53%) had significantly increased expression of galectin-1 protein, as did 47% of primaries with metastases. Galectin-1 mRNA levels were decreased in the vast majority (94%) of primary thyroid carcinomas that did not have metastases present. Galectin-3 protein levels were noted to be overexpressed in 15% of primary papillary thyroid carcinomas. In primary papillary thyroid carcinoma with lymph node metastases, 32% had over expression of galectin-3 protein. Overexpression of galectin-3 mRNA was noted in 58% of papillary thyroid carcinomas and 64% of lymph nodes bearing metastatic papillary thyroid carcinoma. Also, primary papillary thyroid carcinoma with lymph node metastases had significantly higher expression of galectin-3 mRNA compared to those without lymph node metastases. CONCLUSION: Galectin family members show altered expression at the mRNA level in papillary thyroid cancers. Overexpression of galectin-1 and 3 proteins were noted in papillary thyroid carcinoma with lymph node metastases. The results presented here demonstrated that galectin-1 and galectin-3 expression have important roles in clinical progression of papillary thyroid carcinoma.

BRAF inhibitors : from the laboratory to clinical trials

BRAF is one of the most commonly mutated proto-oncogenes and plays a significant role in the development of numerous cancers of high clinical impact. Due to the commonality of BRAF mutations, a number of BRAF inhibitors have been developed as tools in the management of patients with cancers dependent on the action of mutant BRAF to drive cellular proliferation. In this review, we examine the current state of clinical trials and laboratory research concerning BRAF inhibitors in development and available for clinical use. We contrast the effectiveness of type-I and type-II BRAF inhibitors, the former typically showing much more restricted inhibitory selectivity and greater patient response rates.

Expression profile of endothelin 1 and its receptor endothelin receptor A in papillary thyroid carcinoma and their correlations with clinicopathologic characteristics

The endothelin axis is a group of signaling molecules and their receptors that have been implicated in vascularization of cancers, with their expression being observed to change in different cancer types. In this research, we examined the expression of endothelin 1 and endothelin receptor A at the protein and messenger RNA (mRNA) levels in 123 papillary thyroid carcinomas and 40 matched lymph nodes with metastatic papillary thyroid carcinomas. We found altered endothelin axis mRNA expression in several clinicopathologic parameters with increased endothelin 1 expression in thyroid papillary carcinoma showing stromal calcification, cancers in men, and primary cancers with lymph node metastases. Increased endothelin receptor A mRNA expression was noted in the larger cancers. There is a significant correlation between expression of endothelin receptor A and endothelin 1 in papillary thyroid carcinoma. Both endothelin receptor A and endothelin 1 mRNA expressions were significantly higher in metastatic carcinoma in the lymph node than in primary thyroid cancer. The metastatic carcinoma in the lymph node had increased expression compared with matched primary thyroid carcinoma. Expressions of endothelin 1 and endothelin receptor A were also documented as being high at the protein level. Our results indicate that in thyroid cancer, endothelin 1 and endothelin receptor A are associated with growth in advanced stages and lymph node metastases, likely through known angiogenic linkages. Targeting the endothelin axis may be useful in planning angiogenesis therapy for thyroid cancer.

Regulation of microRNA-1288 in colorectal cancer : altered expression and its clinicopathological significance

We aim to examine the miR-1288 expression in cancer cell lines and a large cohort of patients with colorectal cancer. Two colon cancer cell lines (SW480 and SW48) and one normal colonic epithelial cell line (FHC) were recruited. The miRNA expressions of miR-1288 were tested on these cell lines by using quantitative real-time polymerase chain reaction (qRT-PCR). An exogenous miR-1288 (mimic) was used to detect cell proliferation and cell cycle changes in SW480 using MTT calorimetric assay and flow cytometry, respectively. In addition, tissues from 122 patients with surgical resection of colorectum (82 adenocarcinomas, 20 adenomas, and 20 non-neoplastic tissues) were tested for miR-1288 expression by qRT-PCR. The colon cancer cell lines showed reduced expression of miR-1288 compared to normal colonic epithelial cell line. Over expression of miR-1288 in SW480 cell line showed increased cell proliferation and increased G2-M phase cells. In tissues, reduced miR-1288 expression was noted in majority of colorectal adenocarcinoma compared to colorectal adenoma and non-neoplastic tissues. Reduced or absent expression of miR-1288 was noted in 76% (n = 62/82) of the cancers. The expression levels of miR-1288 were higher in distal colorectal adenocarcinomas (P = 0.013) and in cancers of lower T staging (P = 0.033). To conclude, alternation of miR-1288 expression is important in the progression of colorectal cancer. The differential regulation of miR-1288 was found to be related to cancer location and pathological staging in colorectal cancers.

Co-regulatory potential of vascular endothelial growth factor–A and vascular endothelial growth factor–C in thyroid carcinoma

Vascular endothelial growth factor (VEGF) promotes growth of blood or lymphatic vessels. The aim of the current study is to identify relationships between VEGF-A and VEGF-C, and their impact in angiogenesis and metastases in thyroid cancers. VEGF-A and VEGF-C mRNA and protein expression was investigated in 136 thyroid cancers (123 papillary thyroid carcinomas and 13 undifferentiated thyroid carcinomas) and 40 matched lymph node metastases with papillary thyroid carcinoma using reverse transcription polymerase chain reaction and immunohistochemistry. VEGF-A and VEGF-C mRNA expression was significantly different between conventional papillary thyroid carcinoma, follicular variant of papillary thyroid carcinoma, and undifferentiated thyroid carcinomas (P = 1 x 10(-6) and 1 x 10(-5), respectively). In undifferentiated carcinoma, VEGF-A and VEGF-C protein overexpression was noted in all cases. VEGF-A and VEGF-C mRNA overexpression was noted in 51% (n = 62) and 27% (n = 33) of the papillary thyroid carcinomas, whereas VEGF-A and VEGF-C protein overexpression was also identified in 70% (n = 86) and 62% (n = 76) of the carcinomas. VEGF-A mRNA was significantly higher in cancers with lymph node metastases compared with nonmetastatic cancers (P = .001), whereas most metastatic cancers underexpressed VEGF-C (P = .0002), with a similar trend for protein. The expression of VEGF-A and VEGF-C correlated with each other at both mRNA and protein levels (P = .00004 and .003, respectively). In summary, VEGF-A and -C expressions correlate with the pathological parameters and metastatic status of thyroid carcinomas. The significant correlations between the expressions of these genes add weight to hypotheses concerning VEGF-A and -C interaction in cancer progression.

B-Raf mutation : a key player in molecular biology of cancer

B-Raf is one of the more commonly mutated proto-oncogenes implicated in the development of cancers. In this review, we consider the mechanisms and clinical impacts of B-Raf mutations in cancer and discuss the implications for the patient in melanoma, thyroid cancer and colorectal cancer, where B-Raf mutations are particularly common.

Clinicopathological relevance of BRAF mutations in human cancer

BRAF represents one of the most frequently mutated protein kinase genes in human tumours. The mutation is commonly tested in pathology practice. BRAF mutation is seen in melanoma, papillary thyroid carcinoma (including papillary thyroid carcinoma arising from ovarian teratoma), ovarian serous tumours, colorectal carcinoma, gliomas, hepatobiliary carcinomas and hairy cell leukaemia. In these cancers, various genetic aberrations of the BRAF proto-oncogene, such as different point mutations and chromosomal rearrangements, have been reported. The most common mutation, BRAF V600E, can be detected by DNA sequencing and immunohistochemistry on formalin fixed, paraffin embedded tumour tissue. Detection of BRAF V600E mutation has the potential for clinical use as a diagnostic and prognostic marker. In addition, a great deal of research effort has been spent in strategies inhibiting its activity. Indeed, recent clinical trials involving BRAF selective inhibitors exhibited promising response rates in metastatic melanoma patients. Clinical trials are underway for other cancers. However, cutaneous side effects of treatment have been reported and therapeutic response to cancer is short-lived due to the emergence of several resistance mechanisms. In this review, we give an update on the clinical pathological relevance of BRAF mutation in cancer. It is hoped that the review will enhance the direction of future research and assist in more effective use of the knowledge of BRAF mutation in clinical practice.

Metachronous carcinomas in colorectum and its clinicopathological significance

PURPOSE The study was designed to examine the significance of colorectal metachronous carcinoma in a large cohort of patients. METHODS Over a mean follow-up period of 10 years, the clinicopathological features, microsatellite instability (MSI) and clinical follow-up of 56 patients with metachronous colorectal carcinoma were analysed. RESULTS The prevalence of metachronous colorectal carcinoma was 2.1 %. The metachronous colorectal carcinomas appeared between 7 and 246 months (mean = 66 months) after surgical resection of the index colorectal carcinomas. Thirty-six per cent (n = 20) of the metachronous carcinoma occurred more than 5 years after the operation of the index carcinoma. Of the 56 patients, 20 % (n = 11) of the metachronous colorectal carcinomas were mucinous adenocarcinoma. Cancers detected in the secondary operations (metachronous colorectal carcinomas), when compared with the primary index cancers, were smaller, showed higher proportions of mucinous adenocarcinoma and more often located in the proximal colon. Patients with metachronous colorectal cancers had higher prevalence of mucinous adenocarcinoma, loss of staining for MSI markers and better survival rates than other patients with colorectal cancers. CONCLUSIONS Patients with metachronous colorectal carcinomas have characteristic features, and attention to these features is important for better management of this group of cancer.