Alex Galanis

Reactive oxygen species and HIF-1 signalling in cancer.

The heterodimeric transcription factor HIF-1 (hypoxia-inducible factor 1) represents the key mediator of hypoxia response. HIF-1 controls numerous genes of pivotal importance for cellular metabolism, angiogenesis, cell cycle regulation and inhibition of apoptosis. HIF-1 overexpression and enhanced transcriptional activity are linked to tumour initiation and progression. Malfunction of the HIF-1 signalling network has been associated with breast, ovarian and prostate cancers. Elevated reactive oxygen species (ROS), also observed in such tumours, have been implicated in HIF-1 signalling. Deciphering the role of ROS in cancer onset and their involvement in signalling networks should prove invaluable for the design of novel anticancer therapeutics.

Environmental factors and genetic susceptibility promote urinary bladder cancer.

Cancer of the urinary bladder is the second most common malignancy of the genitourinary tract, currently accounting for up to 5% of all newly diagnosed tumours in the western world. Urinary bladder carcinogenesis seems to develop from the interaction of environmental exposure and genetic susceptibility. Smoking, specific industrial chemicals, dietary nitrates and arsenic represent the most important exogenous risk factors. Chromosomal abnormalities, silencing of certain genes by abnormal methylation of their promoter region, alterations in tumour suppressor genes and proto-oncogenes that induce uncontrolled cell proliferation and reduced apoptosis, are molecular mechanisms that have been reported in bladder carcinogenesis. In this article, we discuss the environmental risk factors of bladder cancer and we review the genetic and epigenetic alterations, including aberrant DNA methylation and deregulation of microRNAs expression. We also discuss the role of p53 and retinoblastoma suppressor genes in disease progression. Finally, we present recent reports on the use of molecular profiling to predict disease stage and grade and direct targeted therapy.

Metal-induced carcinogenesis, oxidative stress and hypoxia signalling

Heavy metal-induced carcinogenesis is well documented by epidemiological studies. Several diverse mechanisms of cancer induction may be involved, depending on the form of every metal and the tissue that is exposed. Over the recent years, induction of signalling pathways that regulate key cellular responses related to cancer growth and progression by metals has been the focus of many studies. The unravelling of these pathways and the deciphering of their interplay with metals should allow a better understanding of metal toxicity and hopefully will enable development of prophylactic strategies and therapeutic approaches. In this work, we review the mechanisms of carcinogenesis caused by heavy metals emphasizing on the involvement of the hypoxia signalling pathway by metal-induced generation of reactive oxygen species and oxidative stress generation in cancer progression.

Effect of probiotic-fermented milk administration on gastrointestinal survival of Lactobacillus casei ATCC 393 and modulation of intestinal microbial flora.

The aim of the present study was to assess the survival of free and immobilized Lactobacillus casei ATCC 393 on apple pieces, contained in probiotic-fermented milk, after gastrointestinal (GI) transit and to investigate the potential regulation of intestinal microbial flora in a rat model. In in vitro GI stress tolerance tests, immobilized L. casei ATCC 393 exhibited significantly higher survival rates compared to free cells. At a second stage, probiotic-fermented milk produced by either free or immobilized cells was administered orally at a single dose or daily for 9 days in Wistar rats. By 12 h after single-dose administration, both free and immobilized cells were detected by microbiological and molecular analysis at levels ≧6 logCFU/g of feces. Moreover, daily administration led to significant reduction of staphylococci, enterobacteria, coliforms and streptococci counts. In conclusion, L. casei ATCC 393 contained in fermented milk survived GI transit and modulated intestinal microbiota.

Distinct adhesion of probiotic strain Lactobacillus casei ATCC 393 to rat intestinal mucosa.

Adhesion to the intestine represents a critical parameter for probiotic action. In this study, the adhesion ability of Lactobacillus casei ATCC 393 to the gastrointestinal tract of Wistar rats was examined after single and daily administration of fermented milk containing either free or immobilized cells on apple pieces. The adhesion of the probiotic cells at the large intestine (cecum and colon) was recorded at levels ≥6 logCFU/g (suggested minimum levels for conferring a probiotic effect) following daily administration for 7 days by combining microbiological and strain-specific multiplex PCR analysis. Single dose administration resulted in slightly reduced counts (5 logCFU/g), while they were lower at the small intestine (duodenum, jejunum, ileum) (≤3 logCFU/g), indicating that adhesion was a targeted process. Of note, the levels of L. casei ATCC 393 were enhanced in the cecal and colon fluids both at single and daily administration of immobilized cells (6 and 7 logCFU/g, respectively). The adhesion of the GI tract was transient and thus daily consumption of probiotic products containing the specific strain is suggested as an important prerequisite for retaining its levels at an effective concentration.

Effective survival of immobilized Lactobacillus casei during ripening and heat treatment of probiotic dry-fermented sausages and investigation of the microbial dynamics.

The aim was the assessment of immobilized Lactobacillus casei ATCC 393 on wheat in the production of probiotic dry-fermented sausages and the investigation of the microbial dynamics. For comparison, sausages containing either free L. casei ATCC 393 or no starter culture were also prepared. During ripening, the numbers of lactobacilli exceeded 7 log cfu/g, while a drastic decrease was observed in enterobacteria, staphylococci and pseudomonas counts. Microbial diversity was further studied applying a PCR-DGGE protocol. Members of Lactobacillus, Leuconostoc, Lactococcus, Carnobacterium, Brochothrix, Bacillus and Debaryomyces were the main microbial populations detected. Microbiological and strain-specific multiplex PCR analysis confirmed that the levels of L. casei ATCC 393 in the samples after 66 days of ripening were above the minimum concentration for conferring a probiotic effect (≥ 6 log cfu/g). However, after heat treatment, this strain was detected at the above levels, only in sausages containing immobilized cells.

Lactobacillus casei Exerts Anti-Proliferative Effects Accompanied by Apoptotic Cell Death and Up-Regulation of TRAIL in Colon Carcinoma Cells.

Probiotic microorganisms such as lactic acid bacteria (LAB) exert a number of strain-specific health-promoting activities attributed to their immunomodulatory, anti-inflammatory and anti-carcinogenic properties. Despite recent attention, our understanding of the biological processes involved in the beneficial effects of LAB strains is still limited. To this end, the present study investigated the growth-inhibitory effects of Lactobacillus casei ATCC 393 against experimental colon cancer. Administration of live Lactobacillus casei (as well as bacterial components thereof) on murine (CT26) and human (HT29) colon carcinoma cell lines raised a significant concentration- and time-dependent anti-proliferative effect, determined by cell viability assays. Specifically, a dramatic decrease in viability of colon cancer cells co-incubated with 109 CFU/mL L. casei for 24 hours was detected (78% for HT29 and 52% for CT26 cells). In addition, live L. casei induced apoptotic cell death in both cell lines as revealed by annexin V and propidium iodide staining. The significance of the in vitro anti-proliferative effects was further confirmed in an experimental tumor model. Oral daily administration of 109 CFU live L. casei for 13 days significantly inhibited in vivo growth of colon carcinoma cells, resulting in approximately 80% reduction in tumor volume of treated mice. Tumor growth inhibition was accompanied by L. casei-driven up-regulation of the TNF-related apoptosis-inducing ligand TRAIL and down-regulation of Survivin. Taken together, these findings provide evidence for beneficial tumor-inhibitory, anti-proliferative and pro-apoptotic effects driven by this probiotic LAB strain.

Monitoring survival of Lactobacillus casei ATCC 393 in probiotic yogurts using an efficient molecular tool

The aim of the present study was to monitor the survival of the probiotic strain Lactobacillus casei ATCC 393 during refrigerated storage of natural regular yogurts compared with Lactobacillus delbrueckii ssp. bulgaricus. Both free and immobilized cells on supports of high industrial interest, such as fruits and oat pieces, were tested. Microbiological and strain-specific multiplex PCR analysis showed that both free and immobilized Lb. casei ATCC 393 were detected in the novel products at levels required to confer a probiotic effect (at least 6 log cfu/g) for longer periods than required by the dairy industry (≥ 30 d) during storage at 4°C. In contrast, the viable bacterial density of Lb. delbrueckii ssp. bulgaricus decreased to levels <6 log cfu/g after 14 d of cold storage. Of note, the final pH of all products was 4.2 to 4.3. Acid resistance or cold tolerance of Lb. casei ATCC 393 apparently allows for increased survival compared with Lb. delbrueckii ssp. bulgaricus in these yogurt formulations.

Phytochemical Profile and Evaluation of the Biological Activities of Essential Oils Derived from the Greek Aromatic Plant Species Ocimum basilicum, Mentha spicata, Pimpinella anisum and Fortunella margarita

Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.

Rapid Detection and Identification of Probiotic Lactobacillus casei ATCC 393 by Multiplex PCR

Many functional foods containing probiotic strains have been developed recently. Lactobacillus casei ATCC 393 is one of the most frequently used cultures in probiotic products. The present study aimed to develop a method for the detection and identification of L. casei ATCC 393 based on genetic polymorphisms of the hsp60 gene. A multiplex polymerase chain reaction (PCR) assay was designed, utilizing two novel strain-specific primer sets that enable identification of L. casei ATCC 393.The accuracy of our method was further confirmed by successful identification of our strain in probiotic cheese. The method described is an easy to use, rapid, inexpensive and accurate tool that may be readily applied to food, fecal and intestinal samples.