Sanja Kapitanović

Natural zeolite clinoptilolite: new adjuvant in anticancer therapy

Natural silicate materials, including zeolite clinoptilolite, have been shown to exhibit diverse biological activities and have been used successfully as a vaccine adjuvant and for the treatment of diarrhea. We report a novel use of finely ground clinoptilolite as a potential adjuvant in anticancer therapy. Clinoptilolite treatment of mice and dogs suffering from a variety of tumor types led to improvement in the overall health status, prolongation of life-span, and decrease in tumors size. Local application of clinoptilolite to skin cancers of dogs effectively reduced tumor formation and growth. In addition, toxicology studies on mice and rats demonstrated that the treatment does not have negative effects. In vitro tissue culture studies showed that finely ground clinoptilolite inhibits protein kinase B (c-Akt), induces expression of p21WAF1/CIP1 and p27KIP1 tumor suppressor proteins, and blocks cell growth in several cancer cell lines. These data indicate that clinoptilolite treatment might affect cancer growth by attenuating survival signals and inducing tumor suppressor genes in treated cells.

Gastric cancer: the role of insulin-like growth factor 2 (IGF 2) and its receptors (IGF 1R and M6-P/IGF 2R).

Insulin‐like growth factor 2 (IGF 2) appears to be involved in the progression of many tumours. It binds to at least two different types of receptor: IGF type 1 (IGF 1R) and mannose 6‐phosphate/IGF type 2 (M6‐P/IGF 2R). Ligand binding to IGF 1R provokes mitogenic and anti‐apoptotic effects. M6‐P/IGF 2R has a tumour suppressor function—it mediates IGF 2 degradation. Mutation of M6‐P/IGF 2R causes both diminished growth suppression and augmented growth stimulation. The aim of this study was to investigate the role of IGF 2 and its receptors (IGF 1R and IGF 2R) in human gastric cancer. The expression of IGF 2 and its receptors was measured in order to analyse the possible correlation between the activity of these genes and cell proliferation in two different gastric tumour types: diffuse and intestinal. The effect of IGF 1 receptor blockage on cell proliferation and anchorage‐independent cell growth was also examined. Increased expression of IGF 2 and IGF 1R genes (at the mRNA and protein level) was found in gastric cancer when compared with non‐tumour tissue. Furthermore, there was a significant difference between IGF 2 expression in the more aggressive diffuse type and that in the intestinal type of gastric cancer. Moreover, the IGF 2 peptide level in the culture media obtained from the diffuse type of cancer cells was significantly higher when compared with the intestinal type. The level of IGF 2 peptide in the conditioned media strongly correlated with [3H]thymidine incorporation and cell proliferation. On the contrary, IGF 2R mRNA expression was much higher in the intestinal type of cancer than in the diffuse type. In addition, IGF 2R protein expression was substantially lower with progression of the diffuse cancer type to a higher stage. The αIR3 monoclonal antibody strongly inhibited [3H]thymidine incorporation and decreased the number of colonies in soft agar of cells overexpressing IGF 2. These findings suggest that members of the IGF family are involved in the pathogenesis of gastric cancer, probably by autocrine/paracrine stimulation of cell growth. Such tumours might be excellent candidates for therapeutic strategies aimed at interference with this pathway. Copyright

Allele-specific reprogramming of cancer metabolism by the long non-coding RNA, CCAT2

Altered energy metabolism is a cancer hallmark as malignant cells tailor their metabolic pathways to meet their energy requirements. Glucose and glutamine are the major nutrients that fuel cellular metabolism, and the pathways utilizing these nutrients are often altered in cancer. Here, we show that the long ncRNA CCAT2, located at the 8q24 amplicon on cancer risk-associated rs6983267 SNP, regulates cancer metabolism in vitro and in vivo in an allele-specific manner by binding the Cleavage Factor I (CFIm) complex with distinct affinities for the two subunits (CFIm25 and CFIm68). The CCAT2 interaction with the CFIm complex fine-tunes the alternative splicing of Glutaminase (GLS) by selecting the poly(A) site in intron 14 of the precursor mRNA. These findings uncover a complex, allele-specific regulatory mechanism of cancer metabolism orchestrated by the two alleles of a long ncRNA.

Expression of erbB-3 protein in colorectal adenocarcinoma: correlation with poor survival

Background/aims: The family of erbB receptors includes four transmembrane glycoproteins with tyrosine kinase activity. These receptors are widely expressed in normal tissues, but they also have been implicated in the development of several human adenocarcinomas. c-erbB-3/HER-3 has been detected to a greater or lesser extent in many tissues from the digestive, urinary, reproductive and respiratory tracts. The overexpression of c-erbB-3/HER-3 protein has also been shown in 53%–88% of colorectal adenocarcinomas. In this study we investigated the expression of the c-erbB-3/HER-3 gene product in colorectal tumour samples, and compared the results obtained with several clinicopathological parameters, including the survival of patients. Methods: Paraffin-embedded tissue sections were analysed immunohistochemically, using monoclonal antibody RTJ1 to human erbB-3 protein. Antibody RTJ1 specificity was confirmed by immunoprecipitation followed by Western blotting analysis. Amplification of the erbB-3 oncogene was tested by dot-blot hybridization. Results: Adenocarcinomas of the colon were positive for erbB-3 protein in 78% of samples examined. Dot-blot analysis showed no amplification of the erbB-3 gene in colon adenocarcinomas. Statistical analysis showed that patients with tumours that could not be stained for erbB-3 protein survived significantly longer (P < 0.05) than patients with tumours staining positive for the erbB-3 protein. A Cox proportional-hazards model with stepwise variable selection identified age, sex and erbB-3 expression as important prognostic factors. Conclusion: These findings demonstrate that erbB-3 protein expression could serve as a prognostic factor in colorectal malignancies.

NF1 gene loss of heterozygosity and expression analysis in sporadic colon cancer

Background and aim: Colon cancer tumorigenesis is a multistep process of mutation accumulation in a number of oncogenes and tumour suppressor genes. NF1 gene protein, neurofibromin, acts as a tumour suppressor by turning the active form of Ras into an inactive form. This molecular switch has an important role in the control of the cell cycle and differentiation, and changes in Ras activity are present in many different cancers. This is the first study to investigate the role of NF1 in sporadic colon cancer. Methods: We investigated loss of heterozygosity (LOH) at the NF1 locus. Real time reverse transcription-polymerase chain reaction was used to determine NF1 mRNA expression in tumours and corresponding normal tissue. Expression of neurofibromin was analysed by immunohistochemistry. Relative ratio of NF1 mRNA type I and II isoform expression was also examined. Results: LOH of the NF1 gene was detected in 20.7% of heterozygous samples. NF1 mRNA expression was significantly increased in tumour tissue compared with corresponding normal tissue (p = 0.04291). There was a statistically significant increase in NF1 type I isoform expression (p = 0.0005) in tumour tissue compared with corresponding normal colon tissue. NF1 isoform type II was predominantly expressed in normal tissue while the NF1 isoform type I prevailed in tumour samples. The transition from dominant expression of isoform type II in normal mucous tissue 15 cm away from the tumour to dominant expression of isoform type I in tumour tissue itself was detected. Total neurofibromin expression increased as tumours were more advanced but expression of wild-type neurofibromin remained the same. Conclusions: Our findings suggest that the NF1 gene may play a role in the development and progression of colon cancer and the NF1 gene may be a potential tumour marker and a new potential target for colon cancer therapy.

nm23-H1 expression and loss of heterozygosity in colon adenocarcinoma

Background: The discovery that genetic alterations in oncogenes and tumour suppressor genes accompany tumour formation in many human tumours has encouraged the search for genes that promote or suppress tumour spread and metastasis; nm23 is a promising candidate for a metastasis suppressing gene. Aims: To evaluate whether expression of nm23-H1 protein or loss of heterozygosity (LOH) of the nm23-H1 gene is associated with colon cancer progression. Materials/Methods: Paraffin wax embedded tissue sections were analysed immunohistochemically. DNA isolated from normal and tumour tissue was used for LOH analysis using a variable nucleotide tandem repeat (VNTR) marker located in the untranslated 5′ region of the nm23-H1 gene. RNA isolated from tumour and normal tissue was used for “real time” RT-PCR. Results: Of 102 adenocarcinomas examined, 58.8% stained weakly for nm23-H1 protein. There was a negative correlation between nm23-H1 positivity and tumour histological grade. In VNTR analysis, 70.2% of patients were informative and 27.4% of tumours had nm23-H1 LOH. There was a positive correlation between nm23-H1 LOH and both tumour histological grade and Dukes’s stage. Expression of nm23-H1 mRNA was increased in 22 of 30 colon tumours compared with normal tissue. No significant correlation was found between nm23-H1 mRNA expression and histological grade or Dukes’s stage of tumours. Conclusions: These findings suggest that nm23-H1 protein expression in early stages may have a role in suppressing metastasis in sporadic colon cancer, whereas at a later stage both reduced nm23-H1 protein expression and LOH of the nm23-H1 gene may play role in colon cancer progression and metastasis.

Vascular endothelial growth factor polymorphisms -1154 G/A and -460 C/T are not associated with VEGF mRNA expression and susceptibility to sporadic colon cancer

Vascular endothelial growth factor (VEGF) is important mediator of angiogenesis, and its expression in colorectal tumors is related to tumor progression. VEGF expression has been detected in normal mucosa, primary colon cancers, and metastatic tumors, and patients with low VEGF expression have a better survival rate. In addition, anti-VEGF monoclonal antibody improves overall survival when used in combination with existing metastatic colorectal cancer therapy. Therefore, prediction of VEGF production based on individual genetic background might be important for predicting the course of the disease and the efficacy of anticancer treatment. The number of studies evaluating the influence of VEGF polymorphisms on cancer susceptibility is growing; however, their results are often conflicting. In addition, these studies are rarely accompanied with the expression analysis examining the influence of these polymorphisms on mRNA expression in tumor tissue. In this study, we have examined the influence of VEGF polymorphisms -1154 G/A and -460 C/T on VEGF mRNA expression and susceptibility to sporadic colon cancer by real-time PCR-SNP and mRNA expression analysis. The study included population control group consisting of 160 unrelated volunteers and a group of 160 patients with sporadic colon cancer. According to our results, -1154 G/A and -460 C/T do not influence VEGF mRNA expression in colorectal tumors and susceptibility to sporadic colon cancer, although the role of other polymorphisms cannot be excluded.

Association of MTHFR, MTR, MTRR, RFC1, and DHFR gene polymorphisms with susceptibility to sporadic colon cancer.

Altered folate levels may play an important role in colon carcinogenesis. The aim of this study was to investigate the association of polymorphisms in key folate-metabolizing genes with susceptibility to sporadic colon cancer. Six common polymorphisms (two in MTHFR and one each in MTR, MTRR, RFC1, and DHFR genes) were genotyped in 300 healthy subjects and 300 colon cancer patients from Croatia. Obtained results indicate possible protective role of MTRR 66 AA in sporadic colon cancer (OR=0.655; 95% CI=0.441-0.973; p=0.04). Maximum-likelihood analysis of haplotypes revealed a linkage disequilibrium (LD) between the two investigated polymorphisms of the MTHFR gene (C677T and A1298C), both in the control and patient groups (p<0.01 for both). LD was also detected between MTRR A66G and MTHFR A1298C polymorphisms but only in a group of patients (p<0.01). A haplotype of A66G and A1298C polymorphisms, A/A, proved to be protective (OR=0.775; 95% CI=0.603-0.996; p=0.04), whereas haplotype A/G was a risk factor for colon cancer (OR=1.270; 95% CI=1.007-1.602; p=0.04). Contrary to some previous studies, single-locus analyses identified no polymorphisms associated with risk for colon cancer, but demonstrated a possible protective effect of MTRR 66 AA genotype. The detected significant LD between two loci (MTHFR A1298C and MTRR A66G) located on different chromosomes indicates a strong selective force as a mechanism for the maintenance of their linkage. Specific combinations of alleles of these two polymorphisms showed a protective but also a risk effect on colon cancer susceptibility.

Alterations of FHIT and P53 genes in keratocystic odontogenic tumor, dentigerous and radicular cyst

BACKGROUND The purpose of this study was to determine fragile histidine triad (FHIT) and p53 protein expression, and to analyze FHIT and p53 gene status in keratocystic odontogenic tumor (KOT), dentigerous cysts (DC) and radicular cysts (RC). METHODS The methods used were immunohistochemistry and molecular genetic methods including loss of heterozygosity (LOH) and gene sequencing. RESULTS FHIT protein expression was different among groups. Aberrant expression was the highest in KOT, then in RC and DC. p53 protein expression was different among groups. LOH in paraffin-embedded specimens was detected in 22.6% and 12.9% for FHIT and p53 respectively. Mutation of p53 gene at codon 237 was observed in only two specimens (one KOT and one DC). Of the six frozen specimens, three exhibited FHIT gene LOH (two RC and one KOT). KOT showed loss of exons 6-7 at FHIT locus and mutation at codon 237 at p53 locus, but this could be a chance result. CONCLUSION Aberrations of FHIT and p53 genes/proteins could be considered markers responsible for the development of odontogenic lesions.

Effect of the nonsteroidal anti-inflammatory drug indomethacin on proliferation and apoptosis of colon carcinoma cells

Purpose: Nonsteroidal anti-inflammatory drugs lower the incidence of and mortality from colon cancer. In this paper, we present the effect of indomethacin on growth inhibition and alterations in the expression of several genes involved in cell cycle and apoptosis in CaCo-2 colon adenocarcinoma cells. Methods: We used the MTT test to evaluate the effect of indomethacin on the proliferation rate of colon cancer and normal fibroblast cells in vitro. The expression of c-myc oncoprotein and p53 and p27 suppressor proteins was examined using the immunocytochemical method. Results: We have shown that indomethacin reduces the proliferation rate of CaCo-2 colon cancer cells (up to 60% at the concentration of 4 × 10−4 M), alters their morphology, and induces cell death by apoptosis. The most pronounced inhibitory effect was observed at the concentration of 6 × 10−4 M where the growth was completely suppressed. However, the growth of normal fibroblasts (Hef 522) was much less inhibited (about 30% of inhibition at the concentration of 6 × 10−4 M). Indomethacin reduces the proliferation rate and induces apoptosis in CaCo-2 colon cancer cells through enhanced expression of c-myc, p53, and p27 proteins. Conclusions: This is the first report about p27-increased expression in colon carcinoma cells induced by indomethacin treatment. Increased expression of p27 represents a new mechanism of apoptosis in cells treated with NSAIDs (indomethacin). This effect probably contributes to the anti-proliferative effect on colon cancer cells in vitro.