Allelic loss at chromosome 11q13 alters FGF3 gene expression in a human breast cancer progression model

Identification of markers with the potential to predict tumorigenic behavior is important in breast cancer, due to the variability in clinical disease progression. Genetic alterations during neoplastic progression may appear as changes in total DNA content, single genes, or gene expression. Oncogenic alterations are thought to be prognostic indices for patients with breast cancer. Breast cancer deregulation can occur in the normal cellular process and can be measured by microsatellite instability (MSI)/loss of heterozygosity (LOH). Chromosome 11 is unique in this respect, as three regions of MSI/LOH have been identified (11p15-p15.5, 11q13-q13.3 and 11q23-q24). There are many important families of genes, such as FGF, CCND1, FADD, BAD and GAD2, that are located on chromosome 11 and these play a crucial role in breast cancer progression. Among them, different members of the fibroblast growth factor (FGF) family of genes are clustered around human chromosome 11q13 amplicon, which are constantly altering during breast cancer progression. Therefore, in this study, locus 11q13 and FGF3 gene (11q13) function were investigated in a radiation and estrogen breast cancer model induced by high-LET (α-particle) radiation and estrogen exposure. To assess the effect of ionizing radiation and estrogen at chromosome 11q13 loci and the subsequent role of FGF3 gene expression, various microsatellite markers were chosen in this region, and allelic loses (~20-45%) were identified by PCR-SSCP analysis. Results showed an increase in FGF3 protein expression and a 6- to 8-fold change in gene expression of FGF3 and associated genes. These deregulations could be utilized as an appropriate target for therapeutic intervention in breast cancer.

Vimentin and Notch as biomarkers for breast cancer progression

Breast cancer, the most common spontaneous malignancy diagnosed in women, is a classical model of hormone dependency as it is associated with prolonged exposure to female hormones. Different cytoplasmic proteins are important in the transformation of a normal cell to an invasive tumor cell, and these include vimentin and Notch. To investigate the importance of these two genes and proteins in breast carcinogenesis, we used an in vitro breast cancer model system, in which an immortalized human breast epithelial cell line, MCF-10F, was malignantly transformed by exposure to low doses of high linear energy transfer α particle (150 keV/μm) radiation and subsequent growth in the presence or absence of 17β-estradiol. This model consisted of human breast epithelial cells in different stages of transformation: i) a parental cell line (MCF-10F), ii) an Estrogen cell line (MCF-l0F continuously grown with estradiol at 10⁻⁸), iii) a malignant and non-tumorigenic cell line (Alpha3), iv) a malignant and tumorigenic cell line (Alpha5) and v) a Tumor2 cell line derived from a xenograft of the Alpha5 cell line injected into nude mice. Vimentin and Notch showed greater expression in the Alpha5 and Tumor2 cell lines compared with that in the non-tumorigenic cell lines, MCF-10F, Estrogen and Alpha3. In the present study, positive staining for vimentin was found in 21% of cases. Vimentin and Notch protein expression was negative in noninvasive ductal carcinoma biopsies from breast cancer patients. However, positive cell expression was observed in invasive ductal carcinoma biopsies. These biomarkers can be considered important indicators of breast cancer progression and can be added to the diagnostic panel when overall survival is a primary end-point.

Skin cancer risk affected by ultraviolet solar irradiance in Arica, Chile

The present study analyzed the risk of skin cancer due to ultraviolet erythemal irradiance (UV_ery) in Arica, Chile, using measurements of the solar ultraviolet index (UVI) between 2006 and 2011. The daily maximum value by biometer Yankee Environmental Systems (YES) solar ultraviolet B (UVB)-1 was measured between 2007 and 2012, and seasonal variations were clearly observed, with higher UVI levels during the summer when UVI usually reached extreme values of >11. The maximum UVI value was 15.6 in the summer of 2008 and the minimum was 2.2 in the winter of 2008. The UVI mean values that were collected monthly at noon between 2006 and 2010 fluctuated between 13 and 6, and reached higher values in January and lower values in June and July. Thus, a seasonal UVI response was observed during the two seasons. The accumulated UV_ery/day was calculated between September 2006 and 2007, the time when Arica normally receives the highest UVI levels. It was also noted that 60% of the days in September demonstrated values of >3.41 kJ/m²/day, while 3.3% of cloudy days had values of <2.0 kJ/m²/day. The mean value of UV_ery during 2007 was 3.23 kJ/m²/day and the variation was 1.9-4.6 kJ/m²/day. These UV_ery values were several times higher than the minimal erythemal doses (MEDs) corresponding to the skin types most frequently observed in Chile, skin types III and IV. The MED for skin type IV was 0.60 kJ/m². The results demonstrated that the skin cancer rate was increased due to the fact that individuals from Arica are exposed to several times more UV_ery than the MED for their skin type during the spring and summer seasons.

Melatonin protects the heart, lungs and kidneys from oxidative stress under intermittent hypobaric hypoxia in rats

Melatonin (N-acetyl-5-methoxytryptamine) is the main secretory product of the pineal gland in all mammals including humans, but it is also produced in other organs. It has been previously demonstrated to be a powerful organ-protective substance under oxidative stress conditions. The aim of this study was to evaluate the protective effect of melatonin in several organs such as heart, lung, kidney, and of the reproductive system, such as testis and epididymis in animals exposed to intermittent hypobaric hypoxia and therefore exposed to oxidative stress and analyzed by lipid peroxidation. Ten-week-old male Wistar rats were divided into 6 groups for 96 hours during 32 days under: 1) Normobaric conditions, 2) plus physiologic solution, 3) plus melatonin, 4) intermittent hypobaric hypoxia, 5 plus physiologic solution and 6) plus melatonin. The animals were injected with melatonin (10 mg/kg body weight) at an interval of 96 hours during 32 days. Results indicated that melatonin decreased lipid peroxidation in heart, kidneys and lung under intermittent hypobaric hypoxia conditions. However, it did not exhibit any protective effect in liver, testis, epididymis and sperm count.

Differential expression of cell adhesion molecules in an ionizing radiation-induced breast cancer model system

Cell-cell adhesion is mediated by members of the cadherin-catenin system and among them E-cadherin and β-catenin are important adhesion molecules for epithelial cell function and preservation of tissue integrity. To investigate the importance of cell adhesion molecules in breast carcinogenesis, we developed an in vitro breast cancer model system wherein immortalized human breast epithelial cell line, MCF-10F, was malignantly transformed by exposure to low doses of high linear energy transfer (LET) α particle radiation (150 keV/µm) and subsequent growth in the presence or absence of 17β-estradiol. This model consisted of human breast epithelial cells in different stages of transformation: i) parental cell line MCF-10F; ii) MCF-l0F continuously grown with estradiol at 10(-8) (Estrogen); iii) a non-malignant cell line (Alpha3); and iv) a malignant and tumorigenic cell line (Alpha5) and the Tumor2 cell line derived from the nude mouse xenograft of the Alpha5 cell line. Expression levels of important cell adhesion molecules such as α-catenin, β-catenin, γ-catenin, E-cadherin and integrin were found to be higher at the protein level in the Alpha5 and Tumor2 cell lines relative to these levels in the non-tumorigenic MCF-10F, Estrogen and Alpha3 cell lines. In corroboration, cDNA expression analysis revealed elevated levels of genes involved in the cell adhesion function [E-cadherin, integrin β6 and desmocollin3 (DSc3)] in the Alpha5 and Tumor2 cell lines relative to the levels in the MCF-10F, Estrogen and Alpha3 cell lines. Collectively, our results suggest that cell adhesion molecules are expressed at higher levels in malignantly transformed breast epithelial cells relative to levels in non-malignant cells. However, reduced levels of adhesion molecules observed in the mouse xenograft-derived Tumor 2 cell line compared to the pre-tumorigenic Alpha5 cell line suggests that the altered expression levels of adhesion molecules depend on the tumor tissue microenvironment.

Radiation-induced non-targeted response in vivo: role of the TGFβ-TGFBR1-COX-2 signalling pathway

Background:

Previous studies from our group and others have shown that cyclooxygenase-2 (COX-2) has an essential role in radiation-induced non-targeted responses and genomic instability in vivo. However, the signalling pathways involved in such effects remain unclear.

Methods:

A 1 cm² area (1 cm × 1 cm) in the lower abdominal region of gpt delta transgenic mice was irradiated with 5 Gy of 300 keV X-rays. Nimesulide, a selective COX-2 inhibitor, was given to mice for five consecutive days before irradiation. Changes in transforming growth factor-beta (TGF-β) and TGF-β receptor type-1 (TGFBR1) mediated signalling pathways, in the out of radiation field lung and liver tissues were examined.

Results:

While the plasma level of cytokines remained unchanged, the expression of TGF-β and its receptors was elevated in non-targeted lung tissues after partial body irradiation. In contrast to the predominant expression of TGF-β in stromal and alveolar cells, but not in bronchial epithelial cells, TGF-β receptors, especially TGFBR1 were significantly elevated in non-targeted bronchial epithelial cells, which is consistent with the induction of COX-2. The different expression levels of TGFBR1 between liver and lung resulted in a tissue specific induction of COX-2 in these two non-targeted tissues. Multiple TGF-β induced signalling pathways were activated in the non-targeted lung tissues.

Conclusion:

The TGFβ-TGFBR1-COX-2 Signalling Pathway has a critical role in radiation-induced non-targeted response in vivo.

Male reproductive system and antioxidants in oxidative stress induced by hypobaric hypoxia

In Chile, due to the intensive activity developed in confining areas of the Andes Mountains ranging in altitude over 4000 asl, there has been an increasing intermittent movement of human resources to high altitude conditions. This unusual condition, defined as hypobaric hypoxia, affects notoriously in any living organism and there shows a series of physiological responses. Studies performed in rats under chronic hypobaric hypoxia and intermittent hypobaric hypoxia have registered changes in testicular morphology together with loss of spermatogenic cells in all stages of spermatogenic cycle. Furthermore, recent tests reinforced the existence of an oxidative metabolism in epididymis of rats subjected to hypobaric hypoxia due to the increase in the regulator enzyme expression of reactive oxygen species (ROS), This increase in the production of ROS induced a rise in apoptosis at germinal cell level, leading to a state of hypo-spermatogenesis that may jeopardise masculine fertility. Therefore, the eventual development of oxidative stress in spermatogenic cells and consequently the spermatozoids of workers subjected to high altitude, either chronic or intermittent, turns out to be critical when it poses as an imminent risk to the viability and quality of the reproductive cells of workers subjected to intermittent hypobaric hypoxia.

Ultraviolet light exposure and skin cancer in the city of Arica, Chile

An increase in the amount of solar ultraviolet light that reaches the Earth is considered to be responsible for the worldwide increase in skin cancer. Solar ultraviolet B (UVB) light (290-320 nm) has multiple effects that can be harmful to human beings. The city of Arica in Chile receives high UV levels. This can explain the high prevalence of skin cancer in the Arica population. In the present study, pathological reports of skin cancer were collected from an Arica hospital and retrospectively examined to investigate the possible effects of UV radiation. Among the malignant skin tumor types, basocellular and spinocellular carcinomas were more common in men (44.4 and 16.6%, respectively) than in women (24.9 and 10.7%, respectively). Basocellular carcinoma was observed in individuals 40-79 years of age. The incidence of skin cancer significantly increased (P<0.05) between 2000 and 2006 per 100,000 population. The factor of incidence of skin cancer per 100,000 population significantly increased (P<0.05) between 1980 and 2000 in both genders, but was higher in men (0.79-1.99) than in women (0.63-1.56). The results of the study indicate a steady increase in the incidence of skin cancer in Arica, Chile, most probably due to the high levels of ultraviolet light to which individuals are exposed throughout the year, and the cumulative effect of this type of radiation on the skin.

The stemness phenotype model

The identification of a fraction of cancer stem cells (CSCs) associated with resistance to chemotherapy in most solid tumors leads to the dogma that eliminating this fraction will cure cancer. Experimental data has challenged this simplistic and optimistic model. Opposite to the classical cancer stem cell model, we introduced the stemness phenotype model (SPM), which proposed that all glioma cells possess stem cell properties and that the stemness is modulated by the microenvironment. A key prediction of the SPM is that to cure gliomas all gliomas cells (CSCs and non-CSCs) should be eliminated at once. Other theories closely resembling the SPM and its predictions have recently been proposed, suggesting that the SPM may be a useful model for other type of tumors. Here, we review data from other tumors that strongly support the concepts of the SPM applied to gliomas. We include data related to: (1) the presence of a rare but constant fraction of CSCs in established cancer cell lines, (2) the clonal origin of cancer, (3) the symmetrical division, (4) the ability of “non-CSCs” to generate “CSCs,” and (5) the effect of the microenvironment on cancer stemness. The aforenamed issues that decisively supported the SPM proposed for gliomas can also be applied to breast, lung, prostate cancer, and melanoma and perhaps other tumors in general. If the glioma SPM is correct and can be extrapolated to other types of cancer, it will have profound implications in the development of novel modalities for cancer treatment.

Prevalence of human papillomavirus in university young women

Cervical cancer is the second most prevalent female cancer worldwide. The majority of cases appear between the age of 30 and 50. Human papillomavirus (HPV) plays a central role in cervical cancer with 99.7% of HPV DNA identified in invasive cervical carcinomas. The prevalence of the HPV infection varies substantially among countries and according to age and lifestyle. HPV is a common sexually transmitted infection among males and females with a 70% higher incidence in sexually active females. This study aimed to determine the prevalence of human papillomavirus in young university women by analyzing the correlation between Papanicolaou (PAP)-stained cervical tests and HPV detection by genotyping, as well as other risk factors. A total of 200 women aged between 18 and 25 years were enrolled in this study, which took place between September 2008 and May 2009 at the Universidad de Tarapacá, Arica, Chile. Results of the PAP smears showed that 97.5% of cells had normal characteristics, although an inflammatory pattern was noted. The prevalence of generic HPV infection was 3.5% when testing for HPV DNA using the polymerase chain reaction (PCR) method. An analysis of the genotype of infected female individuals indicated that high-risk HPV types, such as HPV 16 and 31 were present in 42.84 and 14.29% of females, respectively, and low-risk types such as HPV 6, in 14.29%. Only one sample with differentiated non-HPV (14.29%) was found. A 95% correlation between PAP-stained cervical tests and the method of testing for HPV was observed. Using the PCR method, it was found that of the 195 negative PAP smears, 5 were positive for HPV and two of the samples that were positive for ASC-US were also positive. A significantly increased (P<0.05) HPV infection risk was observed in the 18-21 age group with a higher prevalence (71.40%) when compared to the 22-25 age group (28.6%). A significant (P<0.042) difference was found between smoking and HPV infection. In conclusion, a significant (P<0.05) correlation was found between PAP and PCR methods for HPV testing in young university women. A significant correlation between smoking and HPV was detected, whereas no difference was noted with other parameters.

Synergistic effect of malathion and estrogen on mammary gland carcinogenesis

Breast cancer is the most frequent malignancy diagnosed in women and is a classical model of hormone-dependent malignancy. Over the past 15-20 years, epidemiological studies have pointed to an increased breast cancer risk associated with prolonged exposure to female hormones. On the other hand, environmental chemicals such as malathion, an organophosphorous pesticide used to control a wide range of sucking and chewing pests of field crops, may be involved in the etiology of breast cancers. Results indicated that estrogen alone increased average number of lobules per mm2 of rat mammary glands in comparison to control and malathion alone at 30, 124, 240 and 400 days after 5-day treatments. On the other hand, malathion alone significantly increased the number of ducts in stage of proliferation at 10-240 days after 5-day treatments. Furthermore, markers for cancer detection such as mutant p53, c-myc, c-fos and CYPs proteins were overexpressed after treatments. Atropine, an anticholinergic drug, counteracted these effects when it was combined with malathion under similar conditions. The combination of malathion and estrogen synergistically increased number of lobules and ducts per mm2 of rat mammary glands after treatments and inducing mammary cancer. It can be concluded that combination of an environmental substance such as the pesticide malathion and an endogenous substance such as estrogen can enhance the deleterious effects in human mammary glands inducing cancer and atropine is able to diminish these effects.

Malignant transformation of rat kidney induced by environmental substances and estrogen

The use of organophosphorous insecticides in agricultural environments and in urban settings has increased significantly. The aim of the present study was to analyze morphological alterations induced by malathion and 17β-estradiol (estrogen) in rat kidney tissues. There were four groups of animals: control, malathion, estrogen and combination of both substances. The animals were injected for five days and sacrificed 30, 124 and 240 days after treatments. Kidney tissues were analyzed for histomorphological and immunocytochemical alterations. Morphometric analysis indicated that malathion plus estrogen-treated animals showed a significantly (p < 0.05) higher grade of glomerular hypertrophy, signs of tubular damage, atypical proliferation in cortical and hilium zone than malathion or estrogen alone-treated and control animals after 240 days. Results indicated that MFG, ER-α, ER-β, PgR, CYP1A1, Neu/ErbB2, PCNA, vimentin and Thrombospondin 1 (THB) protein expression was increased in convoluted tubules of animals treated with combination of malathion and estrogen after 240 days of 5 day treatment. Malignant proliferation was observed in the hilium zone. In summary, the combination of malathion and estrogen induced pathological lesions in glomeruli, convoluted tubules, atypical cell proliferation and malignant proliferation in hilium zone and immunocytochemical alterations in comparison to control animals or animals treated with either substance alone. It can be concluded that an increased risk of kidney malignant transformation can be induced by exposure to environmental and endogenous substances.

Prediction of skin cancer occurrence by ultraviolet solar index

An increase in the amount of solar ultraviolet light that reaches the Earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that exposure to excessive levels of solar ultraviolet light has multiple effects, which can be harmful to humans. Experimental ultraviolet light measurements were obtained in several locations in Chile between 2006 and 2009 using wide-band solar light Biometer YES, calibrated according to World Meteorological Organization (WMO) criteria and integrated into the National Meteorological Center of Chile ultraviolet network (DMC). The aim of this study was to determine skin cancer rates in relation to experimental data accumulated during one year of studying the solar ultraviolet index in Chile, in order to explain the possible effect of radiation on skin cancer. The rate of skin cancer per 100,000 persons was considered in Arica, Santiago, Concepción and Valdivia and extrapolated to other cities. Results of the present study showed that the incidence of skin cancer was markedly correlated with accumulative ultraviolet radiation, and rates of skin cancer could be extrapolated to other locations in Chile. There is a steady increase in the rate of skin cancer in cities located nearest to the equator (low latitude) that receive greater accumulated solar ultraviolet radiation, due to the accumulative effects of this type of radiation on the skin. It can be concluded that Arica is a city at sea level that receives higher levels of ultraviolet solar radiation than other locations, which may explain the higher prevalence of skin cancer in the population of this location, compared with other cities in Chile.

Protective role of curcumin in oxidative stress of breast cells

Curcumin (diferuloylmethane) is a well known antioxidant that exerts anti-proliferative and apoptotic effects. The effects of curcumin were evaluated in a breast cancer model that was developed with the immortalized breast epithelial cell line, MCF-10F after exposure to low doses of high LET (linear energy transfer) α particles (150 keV/µm) of radiation, and subsequently cultured in the presence of 17β-estradiol (estrogen). This model consisted of human breast epithelial cells in different stages of transformation: i) a control cell line, MCF-10F, ii) an estrogen-treated cell line, named Estrogen, iii) a malignant cell line, named Alpha3 and iv) a malignant and tumorigenic, cell line named Alpha5. Curcumin decreased the formation of hydrogen peroxide in the control MCF-10F, Estrogen and Alpha5 cell lines in comparison to their counterparts. Curcumin had little effect on NFκB (50 kDa) but decreased the protein expression in the Estrogen cell line in comparison to their counterparts. Curcumin enhanced manganese superoxide dismutase (MnSOD) protein expression in the MCF-10F and Alpha3 cell lines. Results indicated that catalase protein expression increased in curcumin treated-Alpha3 and Alpha5 cell lines. Curcumin slightly decreased lipid peroxidation in the MCF-10F cell lines, but significantly (P<0.05) decreased it in the Alpha5 cell line treated with curcumin in comparison to their counterparts as demonstrated by the 8-iso-prostaglandin F2α (8-iso-PGF2α) levels. It can be concluded that curcumin acted upon oxidative stress in human breast epithelial cells transformed by the effect of radiation in the presence of estrogen.

Transforming growth factor-β-induced protein (TGFBI) suppresses mesothelioma progression through the Akt/mTOR pathway

As an uncommon cancer, mesothelioma is very hard to treat with a low average survival rate owing to its usual late detection and being highly invasive. The link between asbestos exposure and the development of mesothelioma in humans is unequivocal. TGFBI, a secreted protein that is induced by transforming growth factor-β in various human cell types, has been shown to be associated with tumorigenesis in various types of tumors. It has been demonstrated that TGFBI expression is markedly suppressed in asbestos-induced tumorigenic cells, while an ectopic expression of TGFBI significantly suppresses tumorigenicity and progression in human bronchial epithelial cells. In order to delineate a potential role of TGFBI in mediating the molecular events that occur in mesothelioma tumorigenesis, we generated stable TGFBI knockdown mutants from the mesothelium cell line Met-5A by using an shRNA approach, and secondly created ectopic TGFBI overexpression mutants from the mesothelioma cell line H28 in which TGFBI is absent. We observed that in the absence of TGFBI, the knockdown mesothelial and mesothelioma cell lines exhibited an elevated proliferation rate, enhanced plating efficiency, increased anchorage-independent growth, as well as an increased cellular protein synthesis rate as compared with their respective controls. Furthermore, cell cycle regulatory proteins c-myc/cyclin D1/phosphor-Rb were upregulated; a more active PI3K/Akt/mTOR signaling pathway was also detected in TGFBI-depleted cell lines. These findings suggest that TGFBI may repress mesothelioma tumorigenesis and progression via the PI3K/Akt signaling pathway.

TGFBI expression reduces in vitro and in vivo metastatic potential of lung and breast tumor cells

Controversy has arisen as to the role of transforming growth factor-β-induced protein (TGFBI) in the regulation of tumor metastasis. Using lung and breast cancer cell lines (H522 and MCF-7, respectively), we established that TGFBI induced cell adhesion to extracellular matrix proteins by activating adhesion-associated signaling and subsequent structure reformation, ultimately leading to cells less motile; whereas TGFBI reduced abilities of colony formation in soft agar, penetration through matrix gel, and activation of matrix metalloproteinases 2 and 9. Furthermore, injection of TGFBI-expressing cells into immuno-deficient mice resulted in a significant reduction in tumor metastasis in vivo. Taken together, these data suggest that TGFBI moderates the metastatic potential of cancer cells.

Catechol estrogens as biomarkers for mammary gland cancer

The origin of human tumors has been attributed to the exposure to several environmental chemicals and implicated in the increase of incidence in breast cancer. Progression of breast cancer follows a complex multistep process that seems to depend on various exogenous and endogenous factors. The aim of this study was to examine the effects of the organo-phosphorous pesticide malathion in the presence of estrogen on neoplastic transformation of rat mammary glands. Virgin female rats were sacrificed after 30, 124 and 240 days of 5-day injections twice a day. There were four groups: i) control, ii) malathion (22 mg/100 g body weight, BW), iii) 17β-estradiol (30 µg/100 g BW) and iv) combination of both. Progressive alterations in ducts were observed by the effect of malathion in comparison to control after 240 days. Ducts markedly increased in size and number of cells per square millimeter and tumors similar to ductal carcinoma were originated. The increase in number of proliferative ducts per square millimeter was significantly (P<0.05) higher in malathion-treated animals compared to the other groups. Progressive alterations in lobules with estrogen treatment were found after 240 days. Lobules became markedly abnormal, referred to as secretory lobules, increased in number and size and the tumors originated were similar to lobular carcinoma. The increase in number of secretory lobules was significantly (P<0.05) higher in estrogen- treated animals compared to the other groups. Treatment with the combination of malathion and estrogen gave rise to tumors constituted of both proliferative ducts and secretory lobules as well as formation of estrogen metabolites such as 2 and 4 catechol estrogens in the blood of the animals after 240 days. We concluded that morphological changes and alterations in the blood of the animals can be used as biomarkers for mammary gland cancer.

Deleterious MnSOD signals lead to abnormal breast cell proliferation by radiation and estrogen exposure

Manganese superoxide dismutase (MnSOD) seems to have a pivotal role in maintaining the normal phenotype by suppressing cell growth through blocking the entrance of quiescent cells into the cell cycle. MnSOD protein expression has been shown to be dysregulated in malignant cells. A well-established experimental breast epithelial cell cancer model was used to observe the relationship in the presence or absence of such protein and the phenotype of the cells. This model was derived from the spontaneously immortalized breast epithelial cell line MCF-10F, which was transformed with estrogen and radiation. The results of this study showed that deleterious expression of MnSOD enhanced the malignant phenotype demonstrated by cell cycle protein expression changes. Thus, the malignant cell line, called Alpha5, which had high levels of MnSOD protein expression, maintained a similar phenotype to the normal cell line MCF-10F. The cell cycle arrest observed in G1 phase of the Alpha5 cell line was induced by p16 protein expression which has been shown to inhibit the Cyclin D1/CdK4 complex explaining such arrest. It can be concluded from these studies that SOD expression, played a critical role in free radical detoxification and it is directly correlated with the cell cycle, defining one of the most important characteristics of tumor cells, namely cell growth and proliferation. These findings are in agreement with the hypothesis that MnSOD plays a role as a possible tumor suppressor gene. Furthermore, this work is a contribution to understanding the possible changes that occur in α-particle irradiated cells, sensitized with estrogen, due to the presence of superoxide dismutase scavenger that could have significant implications in the design of clinical radiotherapeutic protocols.

Ultraviolet light exposure influences skin cancer in association with latitude

The increase in the amount of solar ultraviolet (UV) light that reaches the earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that excessive levels of UVA and UVB light have multiple effects, which can be harmful to humans. Experimental measurements were obtained using wide-band solar light YES biometers from 2006 to 2009 in Arica, Chile and from 2003 to 2006 in Valdivia, Chile, both instruments having been calibrated according to the World Health Organization (WHO) criteria and integrated into the Chilean Meteorological Organization network. To explain the possible effect of radiation on skin cancer, revised pathological reports in Arica and Valdivia were analyzed. In Arica, data on men and women were collected between 1997 and 1998-2002, and in Valdivia, between 1997-2000 and 2001-2007. In this study, comparative values of ultraviolet index (UVI) from the above datasets, were analyzed. Arica is a city located in the subtropical zone of northern Chile, 25 meters above sea level, with a latitude of 18˚49'S and a longitude of 70˚19'W. It has a microclimate characterized by stable meteorological conditions throughout the year, including low precipitation (<5 mm per decade), predictable winds, a high percentage of clear sky days and high ground reflectivity due to the presence of light sand. Due to its location near sea level, the population performs a great number of outdoor activities. Valdivia is a city located in the southern part of Chile, 19 meters above sea level with a latitude of 39˚38'S and a longitude of 73˚5'W. The aim of the present study was to determine the relationship between latitude and the risk of skin cancer in two cities with different latitudes. The incidence of skin cancer per 100,000 persons significantly (P<0.05) increased in both genders between the periods 1997-2000 and 2001-2007 in Arica. However, it decreased in men between the periods 1993-1997 and 1998-2002 in Valdivia. The results of this study indicate a steady increase in the incidence of skin cancer in Arica, most probably due to the high levels of UV light and the latitude to which individuals are exposed throughout the year, as well as the accumulative effect of this type of radiation on the skin. It can be concluded that Arica presented a greater UVI than Valdivia, which can explain the high prevalence of skin cancer in this population according to the pathological reports.

P504S expressing circulating prostate cells as a marker for prostate cancer

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of cancer deaths. The serum prostate specific antigen (PSA) is the only biomarker routinely used in screening. The aim of this study was to develop a system to test the presence of circulating prostate cells in men without a diagnosis of prostate cancer in relation with age, serum PSA levels and prostate biopsy by determining the co-expression of several markers such as CD82, HER-2 and matrix metalloproteinase 2 (MMP-2). For this purpose mononuclear cells were separated from blood using differential centrifugation and then prostate cells were identified by using standard immunocytochemical method. Results indicated that among 409 men screened for prostate cancer 16.6% were positive for circulating prostate cells. Cells were positive for MMP-2 and HER-2 in 100 and 14.3% of cases, respectively, without an association with age or PSA levels. However, CD82 protein expression was associated with older age and low grade tumors. It can be concluded that the study of circulating prostate cells with various markers could be a useful complementary screening test for prostate cancer in men with increased PSA level.

Human RecQL4 helicase plays critical roles in prostate carcinogenesis

Prostate cancer is the second leading cause of cancer-associated deaths among men in the western countries. Here, we report that human RecQL4 helicase, which is implicated in the pathogenesis of a subset of cancer-prone Rothmund-Thomson syndrome, is highly elevated in metastatic prostate cancer cell lines. Increased RecQL4 expression was also detected in human prostate tumor tissues as a function of tumor grade with the highest expression level in metastatic tumor samples, suggesting that RecQL4 may be a potential prognostic factor for advanced stage of prostate cancer. Transient and stable suppression of RecQL4 by small interfering RNA and short hairpin RNA vectors drastically reduced the growth and survival of metastatic prostate cancer cells, indicating that RecQL4 is a prosurvival factor for prostate cancer cells. RecQL4 suppression led to increased poly(ADP-ribose) polymerase (PARP) synthesis and RecQL4-suppressed prostate cancer cells underwent an extensive apoptotic death in a PARP-1-dependent manner. Most notably, RecQL4 knockdown in metastatic prostate cancer cells drastically reduced their cell invasiveness in vitro and tumorigenicity in vivo, showing that RecQL4 is essential for prostate cancer promotion. Observation of a direct interaction of retinoblastoma (Rb) and E2F1 proteins with RecQL4 promoter suggests that Rb-E2F1 pathway may regulate RecQL4 expression. Collectively, our study shows that RecQL4 is an essential factor for prostate carcinogenesis.

Factors that influence the incidence of breast cancer in Arica, Chile (Review)

Breast cancer is a common disease estimated to occur in 1 in 9 women over their lifetime. Epidemiological research has identified a number of risk factors for breast cancer. Racial and ethnic differences in breast cancer mortality rates have been difficult to ascertain. The present review reports that there was an increase in the incidence of breast cancer in Arica, Chile, from 1997 to 2007, particularly in 2005, reaching 55.1% per 100,000 women, while the percentage decreased in 2006 and 2007. A greater percentage of breast cancer was found in individuals between 46 and 65 years of age when the population was distributed by age. The Indian population, Aymara, had only a 13.9% incidence of the disease. The incidence for breast cancer for patients with no family background reached approximately 88%, with or without Indian ethnicity, and 98.4% of these women did not have prior hormonal therapy. When the stage of the disease and the number of pregnancies were considered, results showed that there was an increase in the progression of the disease from stage I to stage III in women that had 1-3 pregnancies. Results also showed that 20.9 and 33.2% who received prior tamoxifen treatment were in stages I and IIA, respectively. The breast cancer incidence reached 42.4% when patients had a sister with the disease. It can be concluded that important differences in the risk factors of breast cancer should be identified in the future for a comparison with other biological factors, such as genetic and molecular factors. This may provide greater insight into breast cancer aetiology in different populations.

Abstract 3454: Molecular markers for breast carcinogenesis models induced by environmental substances and estrogen

Breast cancer is the most common cancer in women throughout the world. Exogenous and endogenous agents such as environmental carcinogens and female hormones seem to be involved in the etiology of breast cancer. It is a multistage process involving a series of genetic alterations, identification of potential genes responsible for breast carcinogenesis is critical for timely diagnosis and prevention of breast cancer. To gain insights into the mechanisms for breast cancer initiation and development processes by exogenous environmental agents, we have developed many experimental breast cancer model systems: In vitro model with the immortalized human breast epithelial cell line, MCF-10F exposed to (I) low doses of high LET (linear energy transfer) alpha particles (150 keV/μm) (Carcinogenesis 21: 769, 2000) and b), (II) organophosphorous pesticides, either with Parathion (P) or Malathion (M) and (III) combination of either P or M in the presence of estrogen (E). Results showed that MCF-10F cells treated either with double dose of 60 cGy alpha particles in the presence of E or pesticides induced malignant transformation of MCF-10F. The malignant transformation was determined by multiple biological assays: increased cell proliferation, anchorage independency, invasive capabilities and tumor formation in nude mice, microsatellite instability and loss of heterozygosity in chromosomes 17, 11, 6, 8. Gene expression analysis using cancer pathway specific and affymetrix arrays detected alterations in the expression levels of p53, ErbB2, BRCA1, c-Ha-ras, Rho-A, PTEN, RB, c-Ha-ras, transforming protein Rho-A, F, GDP, TGF alpha, beta receptor, integrin B6, Notch3 and cathepsin. In addition to the in vitro human model, in vivo rat mammary gland model was also generated: (I) control (II) either P or M (III) E and (IV) P or M and E. Animals were treated for 5 days. These combined treatments induced significant progressive morphological and molecular changes. Alterations in the expression levels of RNA and protein were observed for c-fos, c-myc, mutant p53, ErbB2, BRCA1, c-Ha-ras, Rho-A, CYP1A1 gene and protein expression in the rat mammary gland after 240 days of treatment in comparison to control. Such stimulation led to mammary tumor formation. Collectively, our study shows the molecular signature of oncogenic deregulation in breast cancer progression induced by the combination of environmental substances and estrogen. Thus, aberrant expression of multiple genes involved in key signaling pathways renders these models as important tools for monitoring carcinogenic progression and chemo-intervention. Grant FONDECYT # 1080482 (GMC).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3454.

Phosphoproteomic profiling of arsenite-treated human small airway epithelial cells

Arsenic is well documented as a chemotherapeutic agent capable of inducing cell death; however, it is also considered as a human carcinogen. Although it has recently been shown that arsenite exposure can potentiate genotoxicity, little is known about its global effects exerted in cells at the proteome level. Immortalized human small airway epithelial cells exposed to arsenite were used to identify phosphoproteins of two major signaling cascades, such as the human phospho-receptor tyrosine kinase (Phospho-RTK) and the mitogen-activated protein kinases (MAPKs). These two arrays included several phosphoproteins, such as EGFR, ErbB2, ErbB4, InsulinR, Flt-3, extracellular signal-regulated kinases (ERK1/2), intracellular kinases such as AKT, GSK-3, c-Jun N-terminal kinases (JNK1-3) and different p38 isoforms (alpha/beta/delta/gamma). In arsenite-treated cells, phosphorylation of EGFR, InsulinR and Flt3R showed an increase when compared to their non-arsenite treated counterparts. Inhibitors of these proteins further confirmed the involvement of such proteins in the neoplasm transformation of arsenite-treated human small airway epithelial cells as seen in changes in plating efficiency, anchorage-independent growth and proliferation rate. It can be concluded that analysis of phosphoprotein by using phosphoproteomic profiling can be very useful to understand the mechanism of arsenite-induced carcinogenesis.