Genetic predisposition to cancer in man: in vitro studies

Stem cell properties in cell cultures from different stage of melanoma progression

Cutaneous melanoma is an extremely heterogenous human cancer. The most aggressive melanoma may contain deregulated cells with undifferentiated/stem cell-like phenotype. A critical mechanism by which melanoma cells enhance their invasive capacity is the dissolution of the intercellular adhesion and the acquisition of mesenchymal features as a part of an epithelial-to-mesenchymal transition. The aim of this study was to clarify the role of a stem cell-like population in human melanomas by means of melanocytic cell culture analysis obtained from distinct histotypes of primary and metastatic malignant melanoma. Patients with advanced melanoma >2 cm in diameter and/or >300 mm surface were enrolled. The melanoma cells were isolated from skin biopsies of lentigo maligna melanoma, superficial spreading melanoma, nodular melanoma, and metastatic melanoma. The colony forming unit assay and alkaline phosphatase stain were evaluated. Cells were subsequently cultured and maintained in different media to evaluate their ability to differentiate into osteogenic and adipogenic lineages. Immunohistochemistry and flow cytometry analysis were performed to evaluate antigenic markers CD90, CD73, CD105, CD146, CD20, CD166, and Nestin. This study confirms that melanoma can include heterogenous cell populations with the ability both to self-renew and to a give rise to differentiated progeny. Melanoma cells displayed intratumoral heterogeneity and dynamic antigen phenotypes. Histologically, transitions from normal skin to melanoma were associated with a gradual increase in the expression of CD146, CD20, CD133, Nestin, and CD73. These molecular profiles could be further analyzed and, in the future, used for the development of novel biomolecular targeted-therapy approaches.

The role of the tumor microenvironment in regulating angiogenesis

The tumor-associated stroma has been shown to play a significant role in cancer formation. Paracrine signaling interactions between epithelial tumor cells and stromal cells are a key component in the transformation and proliferation of tumors in several organs. Whereas the intracellular signaling pathways regulating the expression of several pro- and antiangiogenic proteins have been well characterized in human cancer cells, the intercellular signaling that takes place between tumor cells and the surrounding tumor-associated stroma has not been as extensively studied with regard to the regulation of angiogenesis. In this chapter we define the key players in the regulation of angiogenesis and examine how their expression is regulated in the tumor-associated stroma. The resulting analysis is often seemingly paradoxical, underscoring the complexity of intercellular signaling within tumors and the need to better understand the environmental context underlying these signaling mechanisms.

APC +/- alters colonic fibroblast proteome in FAP

Here we compared the proteomes of primary fibroblast cultures derived from morphologically normal colonic mucosa of familial adenomatous polyposis (FAP) patients with those obtained from unaffected controls. The expression signature of about 19% of total fibroblast proteins separates FAP mutation carriers from unaffected controls (P < 0.01). More than 4,000 protein spots were quantified by 2D PAGE analysis, identifying 368 non-redundant proteins and 400 of their isoforms. Specifically, all three classes of cytoskeletal filaments and their regulatory proteins were altered as were oxidative stress response proteins. Given that FAP fibroblasts showed heightened sensitivity to transformation by KiMSV and SV40 including elevated levels of the p53 protein, events controlled in large measure by the Ras suppressor protein-1 (RSU-1) and oncogenic DJ-1, here we show decreased RSU1 and augmented DJ-1 expression in both fibroblasts and crypt-derived epithelial cells from morphologically normal colonic mucosa of FAP gene-carriers. The results indicate that heterozygosity for a mutant APC tumor suppressor gene alters the proteomes of both colon-derived normal fibroblasts in a gene-specific manner, consistent with a "one-hit" effect.

Altered gene expression in morphologically normal epithelial cells from heterozygous carriers of BRCA1 or BRCA2 mutations

We hypothesized that cells bearing a single inherited "hit" in a tumor suppressor gene express an altered mRNA repertoire that may identify targets for measures that could delay or even prevent progression to carcinoma. We report here on the transcriptomes of primary breast and ovarian epithelial cells cultured from BRCA1 and BRCA2 mutation carriers and controls. Our comparison analyses identified multiple changes in gene expression, in both tissues for both mutations, which were validated independently by real-time reverse transcription-PCR analysis. Several of the differentially expressed genes had been previously proposed as cancer markers, including mammaglobin in breast cancer and serum amyloid in ovarian cancer. These findings show that heterozygosity for a mutant tumor suppressor gene can alter the expression profiles of phenotypically normal epithelial cells in a gene-specific manner; these detectable effects of "one hit" represent early molecular changes in tumorigenesis that may serve as novel biomarkers of cancer risk and as targets for chemoprevention.

Tumor microenvironment: the role of the tumor stroma in cancer

The tumor microenvironment, composed of non-cancer cells and their stroma, has become recognized as a major factor influencing the growth of cancer. The microenvironment has been implicated in the regulation of cell growth, determining metastatic potential and possibly determining location of metastatic disease, and impacting the outcome of therapy. While the stromal cells are not malignant per se, their role in supporting cancer growth is so vital to the survival of the tumor that they have become an attractive target for chemotherapeutic agents. In this review, we will discuss the various cellular and molecular components of the stromal environment, their effects on cancer cell dynamics, and the rationale and implications of targeting this environment for control of cancer. Additionally, we will emphasize the role of the bone marrow-derived cell in providing cells for the stroma.

Fibroblasts in cancer

Tumours are known as wounds that do not heal - this implies that cells that are involved in angiogenesis and the response to injury, such as endothelial cells and fibroblasts, have a prominent role in the progression, growth and spread of cancers. Fibroblasts are associated with cancer cells at all stages of cancer progression, and their structural and functional contributions to this process are beginning to emerge. Their production of growth factors, chemokines and extracellular matrix facilitates the angiogenic recruitment of endothelial cells and pericytes. Fibroblasts are therefore a key determinant in the malignant progression of cancer and represent an important target for cancer therapies.

Cancer in Jews: introduction and overview

This article is based upon a literature overview of cancer in Jews. It involves a comparison of variation in incidence and prevalence rates between Jews and non-Jews. However, the reader must exercise a certain amount of skepticism when considering secular changes in cancer incidence and prevalence and the public health implications of such cancer variation. Ashkenazi Jews have a lifetime CRC risk of 9--15%. This elevated CRC risk is similar to that of individuals in the "familial risk'' category, and differs strikingly from the 5-6% CRC risk for non-Ashkenazi members of general Western populations. A MedLine search tested the hypothesis that site-specific and/or all-cancer incidence and mortality rates are either higher or lower than expected in Ashkenazi Jews worldwide, when compared with reference populations. Results showed that all cancer incidence and mortality is not higher in Ashkenazi Jews when compared to North American non-Hispanic whites. Indeed, rates for some cancers, such as carcinoma of the lung in Ashkenazi males, are low; this example is likely attributable in large part to decreased tobacco use. Carcinoma of the ovary, pancreas, stomach, and non-Hodgkin's lymphoma have a higher incidence rate in Ashkenazi. Even though BRCA1 and BRCA2 founder mutations which predispose to carcinoma of the breast and ovary appear increased in Ashkenazi breast cancer affected women, there was no evidence supporting an elevated risk of breast cancer among Ashkenazi women. Our primary concern, however, is that Ashkenazi Jews may have one of the highest lifetime CRC risks of any ethnic group in the world, a risk that diverges significantly from that of the general population; therein, it logically calls for more intensive CRC screening guidelines. We have emphasized that the reader use caution in the interpretation of statistics which portray variation in incidence and prevalence figures for cancer in any racial, ethnic, or religious group, inclusive, of course, of Jews. Clearly, more research will be required in the interest of accuracy in the understanding of these cancer variations, since they portend the need for special cancer control strategies. A lesser degree of attention can then be given to carcinoma of the penis and uterine cervix, which occur very infrequently in Jews. We urge our colleagues to continue to probe further into these statistical differences in cancer's incidence and prevalence in order to garner a better understanding of cancer's etiology and pathogenesis.

New insights into the role of extracellular matrix during tumor onset and progression

Recently, a view of the tumor as a functional tissue interconnected with the microenvironment has recently been described. For many years, the stroma has been studied in the context of the malignant lesion, and only rarely has its role been considered before carcinogenic lesions appear. Recent studies have provided evidence that stromal cells and their products can cause the transformation of adjacent cells through transient signaling that leads to the disruption of homeostatic regulation, including control of tissue architecture, adhesion, cell death, and proliferation. It is now well established that tumor progression requires a continually evolving network of interactions between neoplastic cells and extracellular matrix. A relevant step of this process is the remodeling of microenvironment which surrounds tumors leading to the release of ECM-associated growth factors which can then stimulate tumor and/or endothelial cells. Finally, tumor cells reorganizing the extracellular matrix to facilitate communications and escape the homeostatic control exerted by the microenvironment modify response to cytotoxic treatments.

Stromal cells can contribute oncogenic signals

The majority of studies of neoplastic transformation have focused attention on events that occur within transformed cells. These cell autonomous events result in the disruption of molecular pathways that regulate basic activities of the cells such as proliferation, death, movement and genomic integrity. Other studies have addressed the microenvironment of tumor cells and documented its importance in supporting tumor progression. Recent work has begun to expand on these initial studies of tumor microenvironment and now provide novel insights into the possible initiation and progression of malignant cells. This review will address the transforming effect of stromal cells on epithelial components.

Know thy neighbor: stromal cells can contribute oncogenic signals

Although the stroma within carcinogenic lesions is known to be supportive and responsive to tumors, new data increasingly show that the stroma also has a more active, oncogenic role in tumorigenesis. Stromal cells and their products can transform adjacent tissues in the absence of pre-existing tumor cells by inciting phenotypic and genomic changes in the epithelial cells. The oncogenic action of distinctive stromal components has been demonstrated through a variety of approaches, which provide clues about the cellular pathways involved.

Partial trisomies in two spontaneously arising long-lived human keratinocyte lines

During experiments concerning the introduction of oncogenes into normal human keratinocytes, we observed long-lived colonies arising spontaneously at the same low frequency in control cultures as in those transfected with Ha-rasEJ or activated c-myc or both. Two of these were karyotyped early in their life span and showed additional chromosomal material on the short arm of chromosome 9 in one case and of chromosome 18 in the other, whereas the parental cells had a normal karyotype. This indicates the presence of a partial trisomy in each line, although the origin of the extra chromosomal material is not known. A similarly long-lived human keratinocyte line containing an isochromosome of the long arm of chromosome 8 has been described elsewhere. Together these results suggest that the spontaneous occurrence of long-lived lines is more common in human keratinocytes than in fibroblasts and that a triple dose of one or more genes may be the initial event in this process.

Detection of 6-thioguanine resistance in human peripheral blood lymphocytes (PBL) of industrial workers and lung cancer patients

Human peripheral blood lymphocytes (PBL) were selected for 6-thioguanine (6-TG) resistance in short-term (42-h) cultures in 110 high-cancer-risk industrial workers, 131 primary lung cancer patients and 96 low-risk controls. The lymphocytes were cultured and stimulated by phytohemagglutinin (PHA). A labeling index (LI) was scored using light microscope autoradiography, based on the lymphocyte's ability to incorporate tritiated thymidine with or without selective agent 6-TG. The number of 6-TG-resistant cells increased in the high-occupational-cancer-risk group of vinyl chloride- and mixed organic industrial dust (MOID)-exposed workers as well as in the primary lung cancer patients. The results were compared with the low-occupational-cancer-risk groups and with samples taken from the 70 healthy individuals and 26 hospitalized, non-cancerous controls. In both risk-exposed groups the frequency of 6-TG-resistant lymphocytes was significantly higher (p less than 0.01) than in the controls. These results suggest that the original Strauss and Albertini (1977, 1979) method can be used to study qualitative risk assessment in carcinogen- or mutagen-exposed occupational groups.

Familial colon cancer in the Tel-Aviv area and the influence of ethnic origin

The family history of colon cancer was investigated in 38,823 individuals (2,129 families) who comprised a control and an oncology patient series from Tel-Aviv and nearby areas. A significant increased risk for colon cancer was observed among first-degree relatives of colon cancer patients when compared to controls. When the patient sample was divided into two groups based on country and continent of birth--European (Ashkenazim) and other (nonAshkenazim)--the relatives of the nonAshkenazi subjects showed a greater relative risk for colon cancer (P less than 0.05). Colon cancer was found to be less frequent in nonAshkenazim than in Ashkenazim controls. These findings suggest that although the colon cancer frequency in the nonAshkenazi group is lower, the genetic component may be more important than for the Ashkenazi sample. The nonAshkenazi Jews may represent distinct subgroups that differ with respect to either primary genetic susceptibility to colorectal cancer and/or they may have been subjected to peculiar, environmental carcinogenic exposures when compared to their Ashkenazim brethren.

Tissue culture assays in familial polyposis coli: observations and considerations

The present studies illustrate the utility of biomarkers that occur systemically in two of the relatively frequent, dominantly inherited, precancer disorders: adenomatosis of the colon and rectum (ACR) and neurofibromatosis (NF). These biomarkers provide insight about the initiated cell phenotype, systemic abnormalities and cancer progression, genetic determinants of cancer predisposition, and clinical-genetic considerations. In conjunction with clinical signs, these biomarkers can be used to determine gene expression and gene penetrance. Biomarkers are currently being used in a study of a kindred in which, remarkably, a patient manifested both ACR and NF. Extension of these studies may permit the early detection of cancer in the general population, including "cancer-cured" individuals.

Enhanced sensitivity of skin fibroblasts from neurofibromatosis patients to transformation by the Kirsten murine sarcoma virus. A potential laboratory assay for individuals at risk of cancer

The present work describes a laboratory assay for individuals predisposed to cancer within NF pedigrees. The assay is based on the association between the increased sensitivity of human skin fibroblasts to transformation by the Kirsten murine sarcoma virus and predisposition to cancer in clinically affected patients and in otherwise apparently healthy individuals within NF pedigrees. The more sensitive the cells are to transformation by KiMSV, the greater the probability that a person from whom such cells have been derived will develop cancer. The results show a strong correlation with the NF trait. Together with the clinical data this laboratory assay could, therefore, be used to ascertain the NF genotype.

Enhanced radiotolerance to ionizing radiation is correlated with increased cancer proneness of cultured fibroblasts from precursor states in neurofibromatosis patients

We have determined the sensitivity to gamma rays of cultured fibroblasts derived from clinically defined areas on the skin of neurofibromatosis patients. Fibroblasts from skin of normal appearance were normally sensitive to gamma irradiation. Significantly, however, fibroblasts from café-au-lait lesions and from neurofibromas were abnormally radiotolerant (about twofold) to treatment with gamma rays. This was seen in specimens taken from the same patient, as well as from different patients, within four different neurofibromatosis pedigrees. In contrast, no differences in radiosensitivity have been observed between fibroblasts derived from skin of normal appearance and those obtained from melanotic freckles of individuals with no family history of cancer. The results suggest that increased propensity to cancer in this cell system is associated with increased radiotolerance to ionizing radiation.

An imbalance in sex chromosomes alters cell survival of human skin fibroblasts exposed to ionizing radiation in vitro

We report that a cell clone with a 45,X(-Y) karyotype, obtained from a male individual who is a gene carrier for hereditary adenomatosis of the colon and rectum (ACR), was considerably more resistent to gamma-ray irradiation (D0 range 184-240) than were diploid ACR skin fibroblasts (SF) obtained from sister biopsies of the same individual or of normal controls (D0 range 90-125). In addition, cell clones obtained from a Turner's syndrome female patient and from a female patient with focal endometrial hyperplasia, each with a 45,X(-X) karyotype, were abnormally resistent to gamma-ray irradiation (D0 range 168-195). These results may suggest an association between the status of the sex chromosomes and an altered response to gamma-ray-induced cytotoxicity of human SF.

Actin distribution patterns in patients with adenomatosis of colon and rectum

The actin cytoskeleton was examined in cultured skin fibroblasts of control individuals and patients with adenomatosis of colon and rectum using a fluorescent dye specific for F-actin, NBD-phallacidin. We confirmed that the actin distribution pattern differs significantly between the group of controls and the group of patients. However, the method is not practicable for the diagnosis of individual patients due to the number of false positives and negatives to be expected.

Cytogenetic study of patients with carcinoma of the colon and rectum: particular C-band variants as possible markers for cancer proneness

A possible involvement of chromosomal heterochromatic polymorphisms in propensity to cancer has been considered and discussed by several investigators who studied groups of patients presenting with different forms of malignancy. We report a cytogenetic study on the circulating lymphocytes of patients suffering from colorectal carcinoma, most of whom were of European origin. Significantly increased incidence of polymorphisms of chromosomes #1 and #9 was found, especially partial inversions (PI). Emphasis is given to the problem of selecting adequate controls, which must be as homogeneous as possible.