Key Molecular Alterations Research Articles

The Role of SPINK1 in ETS Rearrangement-Negative Prostate Cancers

ETS gene fusions have been characterized in a majority of prostate cancers; however, the key molecular alterations in ETS-negative cancers are unclear. Here we used an outlier meta-analysis (meta-COPA) to identify SPINK1 outlier expression exclusively in a subset of ETS rearrangement-negative cancers ( approximately 10% of total cases). We validated the mutual exclusivity of SPINK1 expression and ETS fusion status, demonstrated that SPINK1 outlier expression can be detected noninvasively in urine, and observed that SPINK1 outlier expression is an independent predictor of biochemical recurrence after resection. We identified the aggressive 22RV1 cell line as a SPINK1 outlier expression model and demonstrate that SPINK1 knockdown in 22RV1 attenuates invasion, suggesting a functional role in ETS rearrangement-negative prostate cancers.

Angiogenesis as a therapeutic target in advanced breast cancer

Therapy of metastatic breast cancer is still palliative with a very low probability to induce complete remission and definitive cure of disease. The relevant efforts of basic research to identify the key and selective molecular alterations, which sustain breast cancer growth and progression allowed developing specific molecular target treatments. Angiogenesis, the process of new blood vessel formation, is required for tumour growth and metastasis. There is substantial preclinical and clinical evidence supporting the central role of angiogenesis in tumour formation and metastasis. Thus, the inhibition of angiogenesis may provide an effective treatment for patients with advanced breast cancer. Several chemotherapeutic and hormonal agents routinely used in cancer treatment have antiangiogenic properties. Novel antiangiogenic agents targeting the vascular endothelial growth factor ligand and receptor tyrosine kinase inhibitors are being developed. Recently, a large phase III clinical trial demonstrated a significant benefit in progression-free survival with the addition of anti-VEGF monoclonal antibody bevacizumab to paclitaxel for first-line treatment of advanced breast cancer. This study established that antiangiogenic therapy is effective in advanced breast cancer, and additional studies of antiangiogenic agents are under way. This review provides an updated overview of the role of angiogenesis in breast cancer pathogenesis, the challenges of developing antiangiogenic agents, and current agents in clinical trials.

Targeted Therapy of Breast Cancer

Breast cancer is the most frequent tumor of women. The development of effective adjuvant therapy based on postoperative administration of short-term chemotherapy (4-6 months) or long-term hormone therapy (5 years) or both, significantly improved survival of patients. However, therapy of adjuvant/metastatic disease is still palliative with a very low probability to induce complete remission and definitive cure of disease. The relevant efforts of basic research to identify the key and selective molecular alterations, which sustain breast cancer growth and progression allowed the possibility to develop specific molecular target treatments. Trastuzumab, a humanized monoclonal antibody to HER-2, is the first molecular targeting agent approved for therapy of metastatic breast cancer, capable to significantly improve clinical outcome in combination with cytotoxic therapy. Recent preliminary data from randomized, prospective, clinical trials suggest that trastuzumab decreases the risk of early recurrence by 50% in patients with HER-2-positive disease. Other novel targeted treatments are in clinical evaluation, including antiangiogenic compounds (Bevacizumab, sunitinib, vatalanib, and others) and bi-functional drugs such as lapatinib (anti Her-2 and EGFR agent) showing promising activity. This review provides an updated overview of the status of development of targeted therapy in breast cancer, as well as the challenges related to the rational use of molecular targeting agents.

Genomics Identifies Medulloblastoma Subgroups That Are Enriched for Specific Genetic Alterations

Traditional genetic approaches to identify gene mutations in cancer are expensive and laborious. Nonetheless, if we are to avoid rejecting effective molecular targeted therapies, we must test these drugs in patients whose tumors harbor mutations in the drug target. We hypothesized that gene expression profiling might be a more rapid and cost-effective method of identifying tumors that contain specific genetic abnormalities. Gene expression profiles of 46 samples of medulloblastoma were generated using the U133av2 Affymetrix oligonucleotide array and validated using real-time reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Genetic abnormalities were confirmed using fluorescence in situ hybridization (FISH) and direct sequencing. Unsupervised analysis of gene expression profiles partitioned medulloblastomas into five distinct subgroups (subgroups A to E). Gene expression signatures that distinguished these subgroups predicted the presence of key molecular alterations that we subsequently confirmed by gene sequence analysis and FISH. Subgroup-specific abnormalities included mutations in the Wingless (WNT) pathway and deletion of chromosome 6 (subgroup B) and mutations in the Sonic Hedgehog (SHH) pathway (subgroup D). Real-time RT-PCR analysis of gene expression profiles was then used to predict accurately the presence of mutations in the WNT and SHH pathways in a separate group of 31 medulloblastomas. Genome-wide expression profiles can partition large tumor cohorts into subgroups that are enriched for specific genetic alterations. This approach may assist ultimately in the selection of patients for future clinical trials of molecular targeted therapies.

Regulation of a protein phosphatase cascade allows convergent dopamine and glutamate signals to activate ERK in the striatum

Many drugs of abuse exert their addictive effects by increasing extracellular dopamine in the nucleus accumbens, where they likely alter the plasticity of corticostriatal glutamatergic transmission. This mechanism implies key molecular alterations in neurons in which both dopamine and glutamate inputs are activated. Extracellular signal-regulated kinase (ERK), an enzyme important for long-term synaptic plasticity, is a good candidate for playing such a role. Here, we show in mouse that d-amphetamine activates ERK in a subset of medium-size spiny neurons of the dorsal striatum and nucleus accumbens, through the combined action of glutamate NMDA and D1-dopamine receptors. Activation of ERK by d-amphetamine or by widely abused drugs, including cocaine, nicotine, morphine, and Delta(9)-tetrahydrocannabinol was absent in mice lacking dopamine- and cAMP-regulated phosphoprotein of M(r) 32,000 (DARPP-32). The effects of d-amphetamine or cocaine on ERK activation in the striatum, but not in the prefrontal cortex, were prevented by point mutation of Thr-34, a DARPP-32 residue specifically involved in protein phosphatase-1 inhibition. Regulation by DARPP-32 occurred both upstream of ERK and at the level of striatal-enriched tyrosine phosphatase (STEP). Blockade of the ERK pathway or mutation of DARPP-32 altered locomotor sensitization induced by a single injection of psychostimulants, demonstrating the functional relevance of this regulation. Thus, activation of ERK, by a multilevel protein phosphatase-controlled mechanism, functions as a detector of coincidence of dopamine and glutamate signals converging on medium-size striatal neurons and is critical for long-lasting effects of drugs of abuse.

Carcinoma of the prostate: inherited susceptibility, somatic gene defects and androgen receptors.

Multiple factors contribute to the development of prostate carcinoma (PCa) and to its progression to an androgen-independent state. In addition to the expected role of androgens and their receptors in facilitating the development of PCa, mutations in a growing number of candidate hereditary prostate cancer loci and genes, such as RNASEL and MSR1, have been detected, suggesting that defects in critical pathways involving DNA damage response, apoptosis and innate immunity may have a particularly important role in the initiation of PCa. Many somatic mutations, gene deletions, gene amplifications, chromosomal rearrangements, and changes in DNA methylation are detectable in PCa cells at the time of diagnosis. The identification of key molecular alteration cells implicates carcinogen defenses, including GSTP1, growth factor signaling pathways (such as PTEN and p27) and androgens as critical determinants of the phenotype of PCa.

The molecular biology of mucosal field cancerization of the head and neck.

Field cancerization was first described in 1953 as histologically altered epithelium surrounding tumor samples taken from the upper aerodigestive tract. Since then, the term has been used to describe multiple patches of pre-malignant disease, a higher-than-expected prevalence of multiple local second primary tumors, and the presence of synchronous distant tumors within the upper aerodigestive tract. Molecular techniques such as karyotype analysis, microsatellite analysis, p53 mutation screening, and X-chromosome inactivation studies have further refined the relationship among these lesions. While there are differences in the techniques used to identify the clonal origins of the lesions, these studies indicate that there is often lateral clonal spread of pre-malignant or malignant disease, and a significant portion of local second primary tumors are in fact genetically related. Distant second primary tumors found in the esophagus are often not related to concurrent head and neck cancer, whereas synchronous squamous lung tumors with a head and neck primary are often, in fact, metastases, rather than independently arising malignancies. These observations help to explain the high incidence of recurrent disease, despite excision or other therapy--pre-malignant or malignant clones often have the ability to migrate and persist outside of the field of treatment. Therefore, alternative means of prevention or therapy that can affect the entire head and neck region may be of benefit to such patients. Future studies will further refine the relationship among these lesions and perhaps identify key molecular alterations to be used as targets for gene therapy.

Molecular pattern of ductal pancreatic cancer.

Our understanding of the molecular pathology underlying the development and progression of ductal pancreatic cancer has been revolutionised during the last 5 years due to the spectacular development of novel molecular biological techniques. In the present article, we describe key molecular alterations of sporadic and inherited ductal pancreatic cancer. Overexpression of growth factors and growth factor receptors are present in a significant proportion of this tumour type. Mutation of the K-ras oncogene, and disruption of p53 or p16 tumour suppressor gene abrogates the control of the cyclin-dependent kinases (cdk) and retinoblastoma (Rb) gene pathway, causing continuous growth of the pancreatic tumour. Inactivation of the SMAD4 tumour suppressor gene leads to loss of the inhibitory influence of the transforming growth factor beta signalling pathway. Lost or decreased expression of retinoid receptors and failure of telomerase activity may play a role in pancreatic carcinogenesis. Tumour-associated proteinases, matrix metalloproteinases and plasminogen activators are reported to be involved in pancreatic cancer invasion and metastasis. Furthermore, the cytogenetic changes in this cancer are summarised. This molecular pattern distinguishes pancreatic cancer from other epithelial tumours and represents a promising basis for the development of diagnostic and other clinical applications.