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Nucleic acid for the treatment of cancer: genetic vaccines and DNA adjuvants.

Despite some interesting pilot experiments more than a century ago, nucleic acid has only recently been added to the list of agents used for the prevention and therapy of cancer. Two distinct features of nucleic acids are used for this purpose: in DNA and RNA vaccines, genetic information for pathogen- or tumor-derived antigens is delivered to the host who then produces the encoded antigen and initiates an immune response. In DNA adjuvants, immunostimulatory sequences (CpG motifs) present in DNA of bacterial origin are used. Such sequences are delivered in the form of oligonucleotides or within the sequence of DNA vaccine. In addition, CpG oligonucleotides by themselves have successfully been used to stimulate the immune system in an antigen-independent manner for the treatment of experimental tumors. DNA and RNA vaccines for the treatment and prevention of cancer and other diseases suffer from two some shortcomings: insufficient immunogenicity and--in the case of RNA--low stability. A variety of strategies are being explored to improve the efficacy of nucleic acid vaccines (genetic vaccines) especially for self-antigens in the case of cancer. Among the most recent improvements are self-replicating RNA vaccines and replicase-based DNA-vaccines in which antigen expression is under the control of an alphaviral replicase. Despite highly promising results in many animal tumor models the efficacy of nucleic acid vaccines and adjuvants in the clinic remains to be seen.

Adjuvants, Immunologic↗

Genome imprinting and cancer genetics.

Parent-of-origin-dependent modification of the genome (genome imprinting) is thought to be involved in the formation of several types of human cancer. Simple modifications of Knudson's two-hit model give rise to two types of predictions with respect to the genetic behavior of such diseases. In the first, rare alleles of modifier genes will give rise to the retention of the same parent's tumor suppressor alleles in sporadic cases. In the second, other variants of the modifier genes will result in failure to establish linkage between tumor suppressor genes and disease predisposition in familial cases. Both of these predictions are fulfilled by experiment. Additional modifications of existing models are predicted to result in more complex patterns of inheritance. The demonstration of such patterns in human pedigrees will require an extremely sophisticated level of genetic analysis.

Genome, Human↗

Cancer genetics: tumor suppressor meets oncogene.

The adenomatous polyposis coli (APC) tumor suppressor protein is inactivated by mutations in the majority of colorectal cancers. A recent study has revealed that alterations in the APC signaling pathway can result in the transcriptional activation of the c-MYC gene.

Genes, APC↗

[Cancer genetics. A review of oncological molecular biology seen in relation to the human genome].

Genetic changes are associated with the neoplastic process, when a normal cell is transformed into a cancer cell. Cell growth and differentiation are regulated by complicated interactions between growth promoting and inhibiting signals. Oncogenes are examples of growth promoting genes and tumour suppressor genes (gatekeepers and caretakers) are examples of growth inhibiting genes. Binding of a growth factor to its membrane receptor induces a cascade of intracellular signals resulting in proliferation. Regulation of proliferation is tightly correlated to the regulation of cell cycle, and many of the growth regulating genes also regulate cell cycle, and vice versa. The malignant transformation also includes evasion of programmed cell death (apoptosis), limitless replicative potential (evasion of senescence), sustained angiogenesis, and tissue invasion and metastasis. A rough sketch of the human genome has recently been published, and it brings hope of new potentials in cancer diagnostics, treatment, and choice of treatment, but also in revealing the molecular mechanisms behind cancer predisposition and environmental interactions. It is to be hoped that this will result in possibilities of cancer prophylaxis.

Apoptosis↗

Lung cancer genetics and pharmacogenomics.

Epidermal growth factor receptor (EGFR)-targeted therapies have demonstrated remarkable success in a small subset of non-small cell lung cancer patients. The mechanism of response has been an area of active research, with somatic mutation in a number of genes in the EGFR signal transduction pathway and copy number alterations of genes of the EGFR family as candidates contributing towards response. Continuing studies should help determine an appropriate biomarker or combination of biomarkers that can be used to predict response to this class of therapy.

Antineoplastic Agents↗

Breast cancer genetics in an oncology clinic: 328 consecutive patients.

We have provided intensive medical-genetic follow-up on a previously published cohort of 225 consecutively ascertained patients with verified breast cancer evaluated in our oncology clinic. Similar evaluation was performed on 103 newly ascertained breast cancer patients, giving a total of 328 consecutive patients with verified breast cancer. We believe that this represents one of the most intensive efforts of its type for meticulous documentation of genealogy and cancer of all anatomic sites on a series of breast cancer patients. The results showed that the familial and putative hereditary categories almost doubled among our original 225 breast cancer probands. We conclude that the impact of the host factor component in breast cancer etiology, as reflected in most reports in the literature, suffers from severe underestimation.

Breast Neoplasms↗

A large kindred with 17q-linked breast and ovarian cancer: genetic, phenotypic, and genealogical analysis.

BACKGROUND: Mutation of a specific, but as yet unidentified, gene BRCA1 on chromosome 17q results in increased susceptibility to breast and ovarian cancer. It is important to know the effects of this gene in terms of the age-specific risks of these cancers and the potential interaction of this gene with other known risk factors. PURPOSE: We performed detailed studies on a large multigenerational family, in which there is known 17q-linked breast and ovarian cancer, in order to characterize the effects of the BRCA1 mutation on development of breast and ovarian cancer. METHODS: Data from the Utah Population Database were used to identify a family (identified as K2082) with a cluster of premenopausal breast cancer and ovarian cancer at any age. Blood samples from 195 members of the family were obtained and these individuals were genotyped for a series of four chromosome 17q polymorphic markers. Information on reproductive history, cancer incidence and treatment, and lifestyle factors was collected on 72 women in the family by questionnaire or through contact with living relatives. RESULTS: Odds in favor of linkage of breast and ovarian cancer in this family to the BRCA1 region of chromosome 17q are greater than 10(8) to 1. The estimated risks for breast or ovarian cancer because of the BRCA1 mutation in this family are 40% by age 50 years and 90% by age 70. No differences between affected and unaffected older BRCA1 gene carriers were observed for a number of known epidemiologic risk factors for these cancers. The gender of the parent from whom the mutant BRCA1 allele was inherited was significantly associated with phenotypic expression (P = .04). A recombinant which places BRCA1 distal to the marker Mfd191 was observed. CONCLUSIONS: Women with the BRCA1 mutation are at increased risk of developing breast and ovarian cancer. In our study population, the mutation appears to confer a lower risk of cancer at younger ages than found in previous studies. Continued interaction with family K2082 will be useful in longitudinal follow-up studies and in studies of the psychosocial implications of providing DNA diagnosis of BRCA1.

Adult↗

Experimental pathology and breast cancer genetics: new technologies.

The goal is to understand the critical events in tumour development and to apply this understanding to new approaches to diagnosis, prevention and treatment. It is clear that breast cancer is a heterogeneous disease at the molecular level, raising the possibility of a future functional classification based on mechanisms rather than morphology. These molecular phenotypes will also confer predictive value on the potential of the tumour to invade, metastasise and respond to or resist new therapeutic strategies. Studies of the genome in individuals are predicted also to enable the identification of polymorphisms that are associated with increased susceptibility to environmental factors, in addition to possibly explaining de novo variations in responses to drugs and radiation. The difficulty is how to identify which, of the approximately 30,000 genes expressed by a typical cancer cell alone or in combination, are the ones involved in these processes. The majority of breast cancers have such a multitude of molecular changes that it is difficult to distinguish between those that are critical to tumour progression and those that are epiphenomena of genetic instability and abnormalities in DNA repair. The identification of the earliest events in carcinogenesis must be the best hope, as it will then be possible to target the events that predispose to other secondary changes before they occur. Genomics and proteomics is the current hope to take us forward. This involves the application of a number of new technologies to facilitate the profiling of individual tumours, including laser-guided microdissection of microscopic lesions, comparative genomic hybridisation and loss of heterozygosity analysis of DNA using microarray technology to study DNA and expressed RNAs and protein profiling using 2D gel mass spectroscopy. With over 100,000 mRNAs and proteins to examine in complex tissues and in various combinations, there is obviously going to be a requirement for a large investment in computing power (bioinformatics) to facilitate the analysis of these data in relation to the clinical characteristics of the individual tumour and the patient.

Bacteriophages↗

Effects of risk counseling on interest in breast cancer genetic testing for lower risk women.

PURPOSE: A randomized trial was conducted to test the effects of two counseling methods (genetic counseling and group counseling) against a control no-intervention condition on interest in genetic testing in lower risk women. METHODS: After completing baseline surveys, women (N = 357) were randomized to one of three conditions: to receive individual genetic risk counseling, to receive a group psychosocial group counseling, or to serve as a control group. Participants completed follow-up questionnaires 6 months after randomization. RESULTS: All participants had some familial history of breast cancer, but none had a family history indicative of autosomal dominant genetic mutation. At baseline over three fourths of the sample judged themselves to be appropriate candidates for testing. By the end of the survey, two thirds (70%) of the women in the counseling group still judged themselves to be appropriate candidates for testing. Findings were similar for interest in genetic testing. Changes in beliefs about genetic testing (e.g., beliefs about potential stigma associated with testing) altered the effects of counseling. CONCLUSION: These results indicate that counseling can change interest in genetic testing only slightly and that changing women's beliefs about the properties of testing might be one mechanism of doing so.

Adolescent↗

Cancer genetics and the human genome.

We can fully expect that the information from the genome project, combined with epidemiologic and other genetic studies, will pinpoint the series of events, in germ cells and somatic cells, that result in the initiation and progression of the various cancers. Within 10 years, the treatment and prevention of at least one of the major common cancers should be within reach.

Chromosome Aberrations↗

Founder populations and their uses for breast cancer genetics.

Numerous founder mutations have been reported in BRCA1 and BRCA2. For genetic screening of a population with a founder mutation, testing can be targeted to the mutation, allowing for a more rapid and less expensive test. In addition, more precise estimates of the prior probability of carrying a mutation and of the likelihood of a mutation carrier developing cancer should be possible. For a given founder mutation a large number of carriers are available, so that focused scientific studies of penetrance, expression, and genetic and environmental modifiers of risk can be performed. Finally, founder populations may be a powerful resource to localize additional breast cancer susceptibility loci, because of the reduction in locus heterogeneity.

Adult↗

MAP2K4/MKK4 expression in pancreatic cancer: genetic validation of immunohistochemistry and relationship to disease course.

MKK4 (MAP2K4/SEK1) is a member of the mitogen-activated protein kinase family, originally identified as a kinase involved in the stress-activated protein kinase pathway by directly phosphorylating c-Jun NH2-terminal kinase. MKK4 genetic inactivation has been observed in a subset of pancreatic carcinomas, implicating deregulation of the stress-activated protein kinase pathway in pancreatic carcinogenesis. We evaluated Mkk4 protein expression patterns by immunohistochemical labeling in a series of 60 resected primary infiltrating pancreatic adenocarcinomas (24 cases with known MKK4 genetic status), and 14 different tissue arrays representing the primary carcinoma and all of the gross metastases from 26 patients that died of metastatic pancreatic cancer. Among the surgically resected carcinomas, focal or diffuse-positive immunolabeling for Mkk4 protein was found in 52 of 60 cases (86.7%). Among the eight carcinomas with negative Mkk4 immunolabeling, three harbored a homozygous deletion or intragenic mutation of the MKK4 gene, in contrast to none of the 52 cases with positive Mkk4 immunolabeling (P < 0.01). Loss of Mkk4 immunolabeling showed a trend toward shorter survival, with Mkk4-positive carcinomas having half the risk of death than Mkk4-negative carcinomas (P = 0.09). Mkk4 immunolabeling patterns were also evaluated among unresectable primary and metastatic cancer tissues from autopsy specimens, indicating intact Mkk4 immunolabeling in 88.8% of the unresectable primary carcinomas as compared with 63.3% of distant metastases (P < 0.001). Our data indicate that the loss of Mkk4 protein expression in pancreatic carcinomas may be more frequent than suggested by the rates of genetic inactivation alone and that MKK4 loss may contribute to disease progression. The correlation of MKK4 genetic status with immunolabeling patterns validate this approach for the evaluation of MKK4 status in routine histologic sections and may provide useful information regarding patient prognosis.

Adenocarcinoma↗