Long-chain n-3 PUFA against breast and prostate cancer: Which are the appropriate doses for intervention studies in animals and humans?

The potential antineoplastic effect of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) remains a highly controversial issue. Numerous animal studies have supported the anticancer role of these dietary fatty acids, whereas conflicting results have been obtained in population studies, and only a few intervention human trials have been so far performed. In view of the possibility that the anticancer effects may be maximally observed within a defined range of EPA and DHA doses, herein we critically review the results and doses used in both animal studies and human clinical trials focusing on the possible n-3 PUFA protective effects against breast and prostate cancer. Our main aim is to identify the EPA and/or DHA ranges of doses needed to obtain clear anticancer effects. This may be of great help in designing future animal studies, and also in understanding the most appropriate dose for further human intervention studies. Moreover, since the healthy effects of these fatty acids have been strictly related to their increased incorporation in plasma and tissue lipids, we also examine and discuss the incorporation changes following the administration of the effective anticancer EPA and/or DHA doses in animals and humans.

DHA induces apoptosis by altering the expression and cellular location of GRP78 in colon cancer cell lines.

n-3 polyunsaturated fatty acids exert growth-inhibitory and pro-apoptotic effects in colon cancer cells. We hypothesized that the anti-apoptotic glucose related protein of 78kDa (GRP78), originally described as a component of the unfolded protein response in endoplasmic reticulum (ER), could be a molecular target for docosahexaenoic acid (DHA) in these cells. GRP78 total and surface overexpression was previously associated with a poor prognosis in several cancers, whereas its down-regulation with decreased cancer growth in animal models. DHA treatment induced apoptosis in three colon cancer cell lines (HT-29, HCT116 and SW480), and inhibited their total and surface GRP78 expression. The cell ability to undergo DHA-induced apoptosis was inversely related to their level of GRP78 expression. The transfection of the low GRP78-expressing SW480 cells with GRP78-GFP cDNA significantly induced cell growth and inhibited the DHA-driven apoptosis, thus supporting the essential role of GRP78 in DHA pro-apoptotic effect. We suggest that pERK1/2 could be the first upstream target for DHA, and demonstrate that, downstream of GRP78, DHA may exert its proapoptotic role by augmenting the expression of the ER resident factors ERdj5 and inhibiting the phosphorylation of PKR-like ER kinase (PERK), known to be both physically associated with GRP78, and by activating caspase-4. Overall, the regulation of cellular GRP78 expression and location is suggested as a possible route through which DHA can exert pro-apoptotic and antitumoral effects in colon cancer cells.

New Insights into the CD133 (Prominin-1) Expression in Mouse and Human Colon Cancer Cells.

Following its discovery as a cancer stem cell marker, CD133 has been widely studied for its role in colorectal tumorigenesis. Indeed, colon cancer remains one of the major causes of cancer-related disease and death worldwide, and there is a strong need for an improvement of current diagnostic, prognostic, and therapeutic strategies. Thus, efforts have been devoted to try to understand whether CD133 might play a role in human colorectal tumorigenesis and might contribute to a better management of colon cancer patients. This chapter reviews the current knowledge on CD133 expression in normal and cancer colon tissues, both in humans and mice, discussing apparently conflicting data reported in the two species. Moreover, a great attention is devoted to the available information regarding the functional role of CD133 in colon cancer cells. Finally, the proposed clinical applications of CD133, as a prognostic and/or predictive marker as well as a target for novel antineoplastic strategies in colorectal cancer, are discussed. Overall, the available data support a potential important role of CD133 as cancer stem cell marker in colon cancer cells and warrant future studies to verify its potential use in the routine clinical management of colon cancer patients.

DHA induces apoptosis and differentiation in human melanoma cells in vitro: involvement of HuR-mediated COX-2 mRNA stabilization and ß-catenin nuclear translocation.

The pro-inflammatory phenotype accompanying melanoma progression includes an enhanced expression of cyclooxygenase-2 (COX-2), which plays an important role in the acquisition of apoptosis resistance, and is a suitable target for melanoma prevention and therapy. We observed that the WM266-4 metastatic melanoma cell line showed a constitutive COX-2 expression higher than that of the primary WM115 cells, an increased cytosolic level of the COX-2 messenger RNA (mRNA)-stabilizer human antigen R (HuR) and a lower susceptibility to basal apoptosis. The transfection of HuR siRNA induced apoptosis and reduced COX-2 protein abundance in both the cells. The same effects were observed treating the cells with the n-3 polyunsaturated fatty acid docosahexaenoic acid (DHA), which reduced the cytoplasmic location and expression of HuR and, correspondently, decreased COX-2 protein expression and induced apoptosis. DHA also decreased the expression and stability of COX-2 mRNA, increased the ß-catenin expression in the nuclei and reduced it in the cytosol, where it forms a complex with HuR and COX-2 mRNA. DHA had also a pro-differentiating effect, which is compatible with the nuclear translocation of ß-catenin. These findings allow us to associate for the first time the constitutive expression of COX-2 in melanoma cells to the HuR-mediated stabilization of its mRNA and suggest that also ß-catenin may play a role in HuR-mediated COX-2 stabilization in these cells. The data demonstrate that the HuR-mediated stabilization of COX-2 may represent a target of DHA action in melanoma cells and suggest the application of DHA in the prevention and therapy of melanoma.

Increased expression of CD133 is a strong predictor of poor outcome in stage I colorectal cancer patients.

OBJECTIVE: Stage I colorectal carcinomas display a highly variable behavior which is not accurately predicted by the available prognostic markers. CD133 is considered a useful marker to identify the so-called cancer stem cells in colorectal cancers (CRCs) and its expression has been shown to have prognostic significance in CRC patients. This study aimed to verify whether immunohistochemical evaluation of CD133 might correlate with the progression risk of stage I CRC patients. MATERIAL AND METHODS: Expression levels of the CD133 molecule were analyzed and compared in two series of stage I surgically resected CRC patients showing disease progression and death for the disease and patients with no evidence of disease progression after at least 6 years after surgery. RESULTS: A positive staining for CD133 was detected in 52% of the cases with poor prognosis and only in 9% of the group with good prognosis, and this difference was highly significant (p < 0.001). A significant correlation was detected between CD133 expression and histological parameters, such as tumor budding, vascular invasion, and presence of lymph node micrometastases but not tumor grading, gender, and age. Disease-free survival and cancer-specific survival of CD133 negative tumors were significantly longer compared to positive cases. In multivariate analyses, CD133 staining confirmed to be a predictor of shorter survival independent from vascular invasion but not from lymph nodes micrometastases. CONCLUSIONS: These findings demonstrate that CD133 immunostaining is a useful predictor of high risk progression in stage I CRC patients and might help to identify patients eligible for adjuvant chemotherapy.

Identification of Endothelin-1 and NR4A2 as CD133-regulated genes in colon cancer cells.

Several in vitro assays have been proposed to identify cancer stem cells (CSCs), including immunophenotyping, sphere assay and side population (SP) assay. CD133 antigen has been proposed as a CSC marker in colon cancer (CC). However, no functional data are available to date and conflicting results have been reported regarding its role as true CSC marker. Here we set out to identify a molecular signature associated with potential CSC. CD133(+) cells isolated from the CaCo-2 CC cell line were analysed by microarray molecular profiling compared to CD133(-) counterparts. Various differentially expressed genes were identified and the most relevant transcripts found to be over-expressed in CD133(+) cells were evaluated by quantitative RT-PCR in the CD133(+) fractions isolated from several CC cell lines. In the attempt to find a correlation between putative CSCs, isolated by means of CD133 immunophenotyping and the SP approach, we demonstrated a significant enrichment of CD133(+) cells within the SP fraction of CC cells, and comparison of the gene expression profiles revealed that Endothelin-1 (END-1) and nuclear receptor subfamily 4, group A, member 2 (NR4A2) transcripts are highly expressed in both CD133(+) and SP fractions of CC cells. Moreover, depletion of CD133 by siRNA induced a significant attenuation of END-1 and NR4A2 expression levels in CaCo-2 cells, while expression of all three molecules decreased during sodium butyrate-induced differentiation. In conclusion, we have identified a molecular signature associated with potential CSCs and showed for the first time the existence of a functional relationship between CD133, END-1 and NR4A2 expression in colon cancer cells.

Urotensin II receptor predicts the clinical outcome of prostate cancer patients and is involved in the regulation of motility of prostate adenocarcinoma cells.

Urotensin II (UT-II) is a potent vasoconstrictor peptide and its receptor (UTR) was correlated with human cortico-adrenal carcinoma proliferation. In this study, we have evaluated the correlation between UTR expression and prognosis of human prostate adenocarcinoma and the involvement of this receptor in the regulation of biological properties on both in vivo and in vitro models. UTR mRNA and protein, evaluated by real-time PCR and Western blotting, respectively, were expressed at high levels only in androgen-dependent LNCaP cells. In order to investigate UTR changes occurring in human prostate tumorigenesis, we have also evaluated the expression of UTR in vivo in 195 human prostate tissue samples. UTR was always expressed at low intensity in hyperplastic tissues and at high intensity in well-differentiated carcinomas (Gleason 2-3). Moreover, we have evaluated the effects of an antagonist of UTR, urantide on migration and invasion of LNCaP cells. Urantide induced a dose-dependent decrease of motility and invasion of LNCaP cells whose characteristic ameboid movement seems to be advantageous for their malignancy. These effects were paralleled by down-regulating the autophosphorylation of focal adhesion kinase and the integrin surface expression on LNCaP cells. The effects on cell motility and invasion were likely due to the inhibition of RhoA activity induced by both urantide and shRNA UTR. These data suggest that UTR can be considered a prognostic marker in human prostate adenocarcinoma patients.

Dietary n-3 polyunsaturated fatty acids and the paradox of their health benefits and potential harmful effects.

There is some evidence to support the toxicity of polyunsaturated fatty acids (PUFAs) and their oxidative products, suggesting their involvement in the pathogenesis of different chronic diseases, including cancer. It has been shown that products of PUFA oxidation may exert a carcinogenic action by forming mutagenic adducts with DNA. However, a large amount of evidence accumulated over several decades has indicated the beneficial effects of administration of n-3 PUFAs in the prevention and therapy of a series of diseases. In particular, there is much evidence that n-3 PUFAs exert anti-inflammatory and antineoplastic effects, whereas n-6 PUFAs promote inflammation and carcinogenesis. In our tissues, both of the two classes of PUFAs can be converted into bioactive products, incorporated into membrane phospholipids or bound to membrane receptors, where they may alter, often in opposite ways, transduction pathways and affect important biological processes, such as cell death and survival, inflammation, and neo-angiogenesis. In the present review, we intend to shed light on the paradox of the coexisting healthy and toxic effects of n-3 PUFAs, focusing on their possible pro-oxidant cytotoxic and carcinogenic effect, in order to understand if their increased intake, recommended by a number of health agencies worldwide and promoted by nutraceutical producers, may or may not represent a hazard to human health.

Modulation of TRPM6 and Na(+)/Mg(2+) exchange in mammary epithelial cells in response to variations of magnesium availability.

Mammary epithelial cells (HC11) chronically adapted to grow in a low-magnesium (0.05 mM vs. 0.5 mM) or in a high-magnesium (40 mM) medium were used to investigate on the mechanisms of cell magnesium transport under conditions of non-physiological magnesium availability. Magnesium influx was higher in low-magnesium cells compared to control or high-magnesium cells, whereas magnesium efflux was higher in high-magnesium cells compared to control and low-magnesium cells. Magnesium efflux was partially inhibited by imipramine, inhibitor of the Na(+)/Mg(2+) exchange. Using a monoclonal antibody detecting a approximately 70 kDa protein associated with Na(+)/Mg(2+) exchange activity, we found that the expression levels of this protein were proportional to magnesium efflux capacity, that is, high-magnesium cells > control cells > low-magnesium cells. As for magnesium influx, this was abolished by Co(III)hexaammine, inhibitor of magnesium channels. Surprisingly, we found that cells grown in low magnesium upregulated mRNA for the magnesium channel TRPM6, but not for other channels like TRPM7 or MagT1. TRPM6 mRNA was also rapidly upregulated or downregulated in HC11 cells deprived of magnesium or in low-magnesium cells re-added with magnesium, respectively. TRPM6 protein levels, as assessed by Western blot and immunofluorescence, underwent similar changes under comparable conditions. We propose that mammary epithelial cells adapt to decreased magnesium availability by upregulating magnesium influx via TRPM6, and counteract increased magnesium availability by increasing magnesium efflux primarily via Na(+)/Mg(2+) exchange. These results show, for the first time, that TRPM6 contributes to regulating magnesium influx in mammary epithelial cells, similar to what is known for intestine and kidney.

Loss of nuclear p27(kip1) and α-dystroglycan is a frequent event and is a strong predictor of poor outcome in renal cell carcinoma.

Expression levels of p27(kip1) , a negative regulator of the G1 phase of the cell cycle, and 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were assessed by immunostaining in a series of renal cell carcinomas (RCCs) and their prognostic significance was evaluated. Expression of p27(kip1) as well as of the α-subunit of the dystroglycan (DG) complex, previously reported to be altered in RCC, was also evaluated by western blot analysis. Nuclear expression of p27(kip1) was reduced in a significant fraction of tumors and low p27(kip1) staining correlated with higher tumor grade (P < 0.01). Recurrence and death from clear cell RCCs were significantly more frequent in p27(kip1) -low expressing tumors and Kaplan-Meier curves showed a significant separation between high vs low expressor groups for both disease-free (P = 0.011) and overall (P = 0.002) survival. Low nuclear expression of p27(kip1) as well as loss of α-DG were confirmed to be independent prognostic parameters at a multivariate analysis and the simultaneous loss of both molecules defined a "high-risk" group of patients with increased risk of recurrence (RR = 28.7; P = 0.01) and death (RR = 12.9; P = 0.03). No significant correlation with clinical or pathological parameters was found for 8-OHdG staining. Western blot analyses suggested a post-translational mechanism for the loss of α-DG expression and demonstrated that cytoplasmic dislocation of the protein contributes to the loss of active nuclear p27(kip1) . Loss of nuclear p27(kip1) is a frequent event in human RCCs and is a powerful predictor of poor outcome which, in combination with low DG expression, could help to identify high-risk patients with clear cell RCC.

Intracellular magnesium detection: imaging a brighter future.

A wide variety of biochemical reactions and physiological functions are known to require magnesium; nonetheless, its regulatory mechanisms (both at the cellular and systemic level) are still poorly characterised. Derangement of magnesium homeostasis is associated with several relevant human pathologies, e.g. diabetes, neuromuscular disorders, hypertension and other cardiovascular diseases. The study of the regulation of magnesium has gained particular interest in the last decades thanks to the molecular characterisation of specific magnesium transporters and the exploitation of molecular biology techniques to clarify their cellular and physiological function(s). In contrast, experimental tools to trace cellular magnesium and to define its homeostasis in living cells have not witnessed a corresponding progress. It was not until recently that efforts were paid to design more appropriate fluorescent indicators that could translate the advances of live imaging techniques into the field of magnesium research. Herein we critically summarise the state of the art in intracellular magnesium detection by fluorescent probes and focus on the need for improving methods and techniques in this area. We highlight the advantages of last-generation fluorescent indicators and discuss a number of challenges and opportunities that the development of novel and better sensors for magnesium still faces.

Effect of dihydrotestosterone on cultured human tenocytes from intact supraspinatus tendon.

The role of hormones in the pathogenesis of tendinopathy is not well recognised, even though the use of anabolic steroids is correlated with a higher incidence of spontaneous tendon ruptures. The aim of this study was to investigate the effects of dihydrotestosterone (DHT) on human tenocyte cultures from the intact supraspinatus tendon of male subjects. Cultured human tenocytes were seeded into culture plates at a density of 5 x 10(4) cells per well and incubated for 24 h. Then, 10(-9) M-10(-7) M DHT or Dulbecco's modified Eagle's medium (DMEM) only (control) was added to the culture plate wells. Cell morphology assessment and cell proliferation tests were performed 48, 72 and 96 h after DHT treatment. DHT-treated tenocytes showed an increased proliferation rate at DHT concentration higher than 10(-8) M. Differences in cell numbers between control and DHT-treated cells were statistically significant (P < 0.05) after 48 and 72 h of treatment with DHT concentrations of 10(-8) and 10(-7) M. The tenocytes treated with DHT (10(-8) and 10(-7) M) became more flattened and polygonal compared to control cells that maintained their fibroblast-like appearance during the experiment at each observation time. In conclusion, in vitro, progressive increasing concentration of DHT at doses greater than 10(-8) M had direct effects on male human tenocytes, increasing cell number after 48 and 72 h of treatment, and leading to a dedifferentiated phenotype after 48 h of treatment. This effect can be important during tendon-healing and repair, when active proliferation is required. Our results represent preliminary evidence for a possible correlation between testosterone abuse and shoulder tendinopathy.

Evaluation of in vitro toxic effects of cement dusts: a preliminary study.

Cement is widely used for construction and several reports have suggested a potential toxicity of cement dusts although it has never been definitively assessed. To determine the cytotoxic and bioactive effects of cement dusts, cultures of normal rat fibroblasts were exposed to different types of cements and cell growth parameters, apoptosis and the occurrence of DNA damage (both in terms of DNA breaks and oxidative damage) were analyzed. Cells were exposed to cement extracts or cultured in direct contact with cement dusts and the results obtained were compared to cells cultured in fresh medium. A dose-dependent decrease in viable cells was observed with all tested cements. Different results were obtained in the cell-cement direct contact tests compared to the indirect contact tests performed using extracts. Inhibition of cell growth was associated in most cases with an accumulation of cells in the S-phase of the cell-cycle and the appearance of an apoptotic peak. DNA strand breaks, assessed by comet test, and increase in the levels of 8-OHdG, an important marker of DNA oxidative damage, always occurred by incubating cells in the presence of cement extracts or dusts. However, after removal of cement, a rapid damage repair was generally observed with an almost complete recovery within 12 hours. In conclusion, all cements analyzed in this study displayed a limited toxicity in vitro without significant differences amongst them. Overall, the results obtained indicate that cements should be treated as hazardous materials but they do not allow to make accurate predictions regarding the in vivo effects. Further studies are warranted to reach a better understanding of the potential toxic effects of cements, to identify the responsible mechanisms and to evaluate the possibility of modulating and/ or preventing them.

[Evaluation of gastric emptying and gastrointestinal symptoms in dyspeptic patients before and after hydropinic therapy]. / Valutazione dello svuotamento gastrico e di sintomi gastrointestinali in soggetti dispeptici prima e dopo terapia idropinica con acqua minerale.

Dispepsy is one of the most diffuse syndromes in general population. The high number of subjects affected from this pathology and the very annoying symptomatology does so as that the pharmaceutical costs of antacids and of prokinetics are very high. Aim of the study is to assess if a hydropinic therapy is able to facilitate digestive processes of the dispeptic patients accelerating gastric emptying. The 30 recruited subjects, 20 patients and 10 healthy volunteers, have answered to test about their symptoms and have executed a 13C octanoic acid breath test in order to estimate the gastric emptying to a basal time, and 30 days after supplementation of mineral water, 1.5 liters/day, for 21 days. At the end of the study, both the time of gastric emptying and the gastrointestinal symptoms improved after the hydropinic therapy, demonstrating that a supplementazione with mineral water can induce a benefit in the dispeptics subjects.

Identification of Sp1 and GC-boxes as transcriptional regulators of mouse Dag1 gene promoter.

Dystroglycan is a widely expressed adhesion complex that anchors cells to the basement membrane and is involved in embryonic development and differentiation. Dystroglycan expression is frequently reduced in human dystrophies and malignancies, and its molecular functions are not completely understood. Several posttranslational mechanisms have been identified that regulate dystroglycan expression and/or function, while little is known about how expression of the corresponding Dag1 gene is regulated. This study aimed to clone the Dag1 gene promoter and to characterize its regulatory elements. Analysis of the mouse Dag1 gene 5'-flanking region revealed a TATA and CAAT box-lacking promoter including a GC-rich region. Transfection studies with serially deleted promoter constructs allowed us to identify a minimal promoter region containing three Specificity protein 1 (Sp1) sites and an E-box. Sp1 binding was confirmed by chromatin immunoprecipitation assay, and Sp1 downregulation reduced dystroglycan expression in muscle cells. Treatment with 5-aza-2'-deoxycytidine and/or the histone deacetylase inhibitor trichostatin A increased Dag1 mRNA expression levels in myoblasts, and methylation decreased promoter activity in vitro. Furthermore, Dag1 gene promoter methylation was reduced while its expression increased during differentiation of C(2)C(12) myoblast cells in myotubes. In conclusion, for the first time we have characterized the activity of the mouse Dag1 gene promoter, confirming a complex regulation by Sp1 transcription factor, DNA methylation, and histone acetylation, which might be relevant for a better understanding of the physiopathology of the dystroglycan complex.

Cyclin E correlates with manganese superoxide dismutase expression and predicts survival in early breast cancer patients receiving adjuvant epirubicin-based chemotherapy.

Anthracycline-based chemotherapy represents a milestone in the treatment of breast cancer. We previously demonstrated in an in vitro model that cyclin E overexpression is associated with increased expression of manganese superoxide dismutase (MnSOD) and resistance to doxorubicin. In the present study, immunohistochemical expression of cyclin E and MnSOD was evaluated in 134 early breast cancer patients receiving adjuvant epirubicin-based chemotherapy regimens containing epirubicin. Both parameters were correlated with the available clinicopathological parameters and with the outcome of patients. Overexpression of cyclin E and MnSOD was detected in 46 (34.3%) and 56 (41.8%) patients, respectively, and expression levels of the two proteins were related. Disease-free and alive patients displayed a lower mean percentage of cyclin E-expressing cells than relapsed and dead patients, respectively. Kaplan-Meier survival analysis demonstrated a significant separation between high versus low cyclin E-expressing tumors in terms of overall survival (P = 0.038 by log-rank). Similar results were obtained considering the subset of node-negative patients separately. No significant relationship with patient outcome was observed for MnSOD expression levels. At multivariate analysis cyclin E failed to demonstrate an independent prognostic value. In conclusion, the results of the present study support previous evidence that increased cyclin E expression is associated with higher MnSOD expression levels and poorer outcome, at least as evaluated in terms of overall survival. Further studies are warranted to evaluate the usefulness of cyclin E as a prognostic marker to identify breast cancer patients at higher risk of death from the disease when treated with adjuvant anthracycline-based therapy.

GSTM1 and NAT2 polymorphisms and colon, lung and bladder cancer risk: a case-control study.

BACKGROUND: Glutathione S-transferase M1 (GSTM1) and N-acetyltransferase-2 (NAT2) are phase II enzymes involved in the metabolism of xenobiotics and whose polymorphisms have been related to individual cancer risks. PATIENTS AND METHODS: A case-control study was performed including 92 colon, 75 lung and 23 bladder cancer patients and 121 corresponding controls to verify the existence of an association between the main genetic polymorphisms of GSTM1 and NAT2 and the risk to develop cancer. Genomic DNA, isolated from 5 mL whole blood, was used to study GSTM1 and NAT2 polymorphisms using multiplex PCR and a PCR-RFLP technique, respectively. RESULTS: GSTM1 homozygous null genotype was associated with an increased risk of colon cancer, especially in females and in younger patients. For NAT2 gene, the results suggest a role for the low acetylator phenotype in the development of colon and lung cancer, especially in females. In bladder cancer patients two rare NAT2 genotypes were found at a higher frequency compared with all the other groups. CONCLUSION: The results do not suggest a different distribution of GSTM1 and NAT2 polymorphisms in the studied population compared to those reported for other Caucasian populations and warrant further studies in order to evaluate their potential relationship with individual cancer risks.

Hypomagnesaemia in oncologic patients: to treat or not to treat?

Over recent decades there have been several papers that documented hypomagnesaemia*, in cancer patients treated, with cisplatin, with combined chemotherapies and more recently, with cetuximab an antibody against the epidermal growth factor receptor. Recently, however, the clinical read-out of cetuximab-induced hypomagnesaemia has received different interpretations. Some reports called the readers' attention to the importance of magnesium supplementation in relieving patient's discomfort or preventing the most severe complications of hypomagnesaemia. Other reports claimed that magnesium deficiency could contribute to the oncologic efficacy of cetuximab. This latter interpretation implies that the decision on magnesium supplementation should consider the pros and cons of returning magnesium to normal levels. Given that decreased magnesium availability inhibits cell proliferation, hypomagnesaemia may slow down tumor growth. Unfortunately, one view does not fit all. We think it important to recapitulate our knowledge on the effects of magnesium on tumor growth, angiogenesis, invasion and metastatization with the aim of providing clinical oncologists with an overview of available data of the potential effects of hypomagnesaemia in tumor growth. Translating these results into clinical settings may help in designing suitable studies to better evaluate the consequences of hypomagnesaemia in cancer patients.

Polymorphisms of the DNA repair genes XRCC1 and XRCC3 and risk of lung and colorectal cancer: a case-control study in a Southern Italian population.

BACKGROUND: Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with a higher risk of developing cancer. Studies on the association between DNA repair gene polymorphisms and lung and colorectal cancer risk appear to be very limited. This study was designed to examine the polymorphisms associated with two DNA repair genes, namely XRCC1 Arg194Trp, XRCC1 Arg399Gln and XRCC3 Thr241Met, and to investigate their role as susceptibility markers for lung and colorectal cancer. MATERIALS AND METHODS: A case-control study was conducted including 94 and 109 cases of lung and colorectal cancer, respectively, and 121 hospital-based age- and sex-matched healthy controls to examine the role of XRCC1 and XRCC3 genetic polymorphisms in the context of lung and colorectal cancer risk for a Southern Italian population. Genomic DNA isolated from 5 ml whole blood was used to genotype XRCC1 Arg194Trp, XRCC1 Arg399Gln and XRCC3 Thr241Met by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. RESULTS: No differences were observed among the studied groups with regard to the genotype distribution of XRCC1 codon 194 and 399, thus the risk for lung and colorectal cancer did not appear to be significantly influenced by polymorphisms of this gene. Significant differences were observed among the studied groups with regard to the genotype distribution of XRCC3 codon 241. In particular, the XRCC3 241Met allele was associated with an increased risk of lung and colorectal cancer. CONCLUSION: Our results showed no evidence of a relationship between the XRCC1 Arg194Trp and Arg399Gln polymorphisms and the risk of lung and colorectal cancer. On the other hand, they suggested an increased risk in individuals with the XRCC3 Thr241Met polymorphism thus warranting further study to definitively evaluate the role of DNA repair mechanisms in colorectal and lung cancer susceptibility.

Magnesium and the control of cell proliferation: looking for a needle in a haystack.

Experimental evidence supports the important role of magnesium in the process of cellular proliferation, even though cell magnesium homeostasis is not completely clarified. We were the first to describe some molecular characteristics of the magnesium-dependent regulation of the cell cycle, and others proposed a mechanism for the magnesium-dependent regulation of protein synthesis occurring in the early phases of cell proliferation. We will attempt to relate such mechanisms with pathologic conditions whereby cell proliferation is severely disregulated, as in the case of tumors. It is interesting to note that recently some efforts have been made to correlate magnesium transport systems with its functions within the cells. Few, but stimulating new data are emerging which relate molecularly defined ion channels with magnesium homeostasis and its functions. Old and new data are now being merged and corroborated by diverse experimental approaches including molecular genetics, proteomics, electrophysiology and biochemistry. This, together with the development of new techniques to measure cell magnesium content and distribution, will hopefully pave the way to unravel the intimate mechanisms of such an essential though undefined metabolic regulator. New and deeper appreciation of magnesium homeostasis will help in delineating the key role of this cation in the regulation of normal or pathologic cell proliferation.