Role of specific DNA mutations in the peripheral blood of colorectal cancer patients for the assessment of tumor stage and residual disease following tumor resection

In the present study, the detection of tumor-specific KRAS proto-oncogene, GTPase (KRAS) and B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations in the peripheral blood of colorectal cancer (CRC) patients at all stages and adenomas was used for the estimation of disease stage prior to surgery and for residual disease following surgery. A total of 65 CRC patients were enrolled. The primary tumor tested positive for the specific mutations (KRAS mutations in codons 12, 13, 61, 117 or 146 and BRAF mutations in codon 600) in 35 patients. In all these patients, the specimen of normal bowel resected with the tumor was also tested for the presence of the same mutations in order to exclude the germ-line mutations. Only patients who tested positive for the specific mutation in the primary tumor were included in further analysis for the presence of tumor-specific mutation in the peripheral blood. No statistically significant differences were found between the detection rates of tumor mutations in the blood and different tumor stages (P=0.491). However, statistically significant differences in the proportions of patients with detected tumor-specific DNA mutations in the peripheral blood were found when comparing the groups of patients with R0 and R2 resections (P=0.038). Tumor-specific DNA mutations in the peripheral blood were more frequently detected in the patients with an incomplete surgical clearance of the tumor due to macroscopic residual disease (R2 resections). Therefore, the study concludes that the follow-up of somatic KRAS- and BRAF-mutated DNA in the peripheral blood of CRC patients may be useful in assessing the surgical clearance of the disease.

The impact of FcγRIIa and FcγRIIIa gene polymorphisms on responses to RCHOP chemotherapy in diffuse large B-cell lymphoma patients

Rituximab is a monoclonal antibody routinely used in the treatment of B-cell non-Hodgkin lymphomas. It mediates antibody-dependent cellular cytotoxicity of B lymphocytes by bridging them with Fcγ receptors (FcγR) on effector cells. Several polymorphisms in the FcγR genes have been identified to influence rituximab binding to FcγR, thus altering its antitumor effect in indolent lymphomas. In the present study, the impact of FcγRIIa and FcγRIIIa polymorphisms on the survival and response to immunochemotherapy consisting of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone was evaluated in diffuse large B-cell lymphoma (DLBCL) patients. A total of 29 Slovenian DLBCL patients were studied. Genotyping was conducted for FcγRIIa-27, FcγRIIa-131, FcγRIIIa-48 and FcγRIIIa-158 polymorphisms. The median follow-up time was 29.7 months (range, 9.7–45.4 months). No significant impact of the genotypes was observed on the treatment response, progression-free or overall survival of DLBCL patients. There was a non-significant trend of an improved response to chemotherapy without additional irradiation in patients homozygous for Val at FCγIIIa-158 compared to Phe carriers. The findings of the present study indicate that FcγR polymorphisms have no influence on the survival of DLBCL patients.

Low-Dose Fluvastatin and Valsartan Rejuvenate the Arterial Wall Through Telomerase Activity Increase in Middle-Aged Men

BACKGROUND AND AIM

Previously, we have shown that slightly to moderately aged arteries in middle-aged males can be rejuvenated functionally by sub-therapeutic, low-dose fluvastatin and valsartan treatment. Here, we explore whether this treatment could also increase telomerase activity. We hypothesized that telomerase activity might be associated with (1) an improvement of arterial wall properties and (2) a reduction of inflammatory/oxidative stress parameters (both observed in our previous studies).

METHODS

The stored blood samples from 130 apparently healthy middle-aged males treated with fluvastatin (10 mg daily), valsartan (20 mg daily), fluvastatin and valsartan combination (10 and 20 mg), respectively, and placebo (control), were analyzed. The samples were taken before and after treatment lasting 30 days, and 5 months after treatment discontinuation. Telomerase activity was measured in blood leukocytes by a TaqMan Gene Expression Assay.

RESULTS

Low-dose fluvastatin or valsartan increased telomerase activity (106.9% and 59.5% respectively; both p < 0.05, vs. control), whereas their combination was even more effective (an increase of 228.0%; p < 0.001, vs. control). No change was noted in the control group. Importantly, increased telomerase activity obtained in the combination group significantly correlated with arterial function, measured by flow-mediated dilation (FMD) (r = 0.79; p < 0.001) and C-reactive protein concentration (r = -0.54; p = 0.02) and total anti-oxidative status (r = 0.50; p = 0.03).

CONCLUSION

We found that a low-dose combination of fluvastatin and valsartan substantially increased telomerase activity, which significantly correlated with an improvement of endothelial function and a decrease of inflammation/oxidative stress. These findings could lead to a new innovative approach to arterial rejuvenation.

Putative mesenchymal stem cells isolated from adult human ovaries

PURPOSE

The purpose of this study was to show that healthy adult human ovaries can be a source of cells showing typical MSCs characteristics under in vitro conditions.

METHODS AND RESULTS

The cells, which were isolated from ovarian cortex tissue and named putative ovarian mesenchymal stem cells (PO-MSCs), were compared to bone marrow-derived MSCs (BM-MSCs) and to adult human dermal fibroblasts (HDFs). The results of a gene expression analysis using the Human Mesenchymal Stem Cell RT² Profiler™ PCR Array revealed that PO-MSCs were different than fibroblasts. They expressed most of the analyzed genes as BM-MSCs, although some genes were differentially expressed. However, the heterogeneity of PO-MSCs samples was revealed. The PO-MSCs expressed the characteristic genes related to MSCs, such as CD105, CD44, CD90, M-CAM, CD73 and VCAM1. In addition, the expression of markers CD44, CD90, M-CAM and STRO-1 was confirmed in PO-MSCs using immunocytochemistry. The PO-MSCs showed multipotent character, since they were able to differentiate into the cells of adipogenic, osteogenic, neural and pancreatic lineage.

CONCLUSIONS

Healthy adult human ovaries can harbour an interesting population of cells showing typical MSCs characteristics under in vitro conditions and for this reason we named these cells putative MSCs. These cells express genes encoding main MSCs markers and have an interesting differential potential. Based on these results, we propose PO-MSCs as a novel type of MSCs which share some similarities with BM-MSCs. Nevertheless they show distinct and specific characteristics and are not fibroblasts.

Isolation, characterization and differentiation of cells expressing pluripotent/multipotent markers from adult human ovaries

Pluripotent stem cells are still generally accepted not to exist in adult human ovaries, although increasing studies confirm the presence of pluripotent/multipotent stem cells in adult mammalian ovaries, including those of humans. The aim of this study is to isolate, characterize and differentiate in vitro stem cells that originate from the adult human ovarian cortex and that express markers of pluripotency/multipotency. After enzymatic degradation of small ovarian cortex biopsies retrieved from 18 women, ovarian cell cultures were successfully established from 17 and the formation of cell colonies was observed. The presence of cells/colonies expressing some markers of pluripotency (alkaline phosphatase, surface antigen SSEA-4, OCT4, SOX-2, NANOG, LIN28, STELLA), germinal lineage (DDX4/VASA) and multipotency (M-CAM/CD146, Thy-1/CD90, STRO-1) was confirmed by various methods. Stem cells from the cultures, including small round SSEA-4-positive cells with diameters of up to 4 μm, showed a relatively high degree of plasticity. We were able to differentiate them in vitro into various types of somatic cells of all three germ layers. However, these cells did not form teratoma when injected into immunodeficient mice. Our results thus show that ovarian tissue is a potential source of stem cells with a pluripotent/multipotent character for safe application in regenerative medicine.

Novel BRCA1 and BRCA2 pathogenic mutations in Slovene hereditary breast and ovarian cancer families

The estimated proportion of hereditary breast and ovarian cancers among all breast and ovarian cancer cases is 5–10%. According to the literature, inherited mutations in the BRCA1 and BRCA2 tumour-suppressor genes, account for the majority of hereditary breast and ovarian cancer cases. The aim of this report is to present novel mutations that have not yet been described in the literature and pathogenic BRCA1 and BRCA2 mutations which have been detected in HBOC families for the first time in the last three years. In the period between January 2009 and December 2011, 559 individuals from 379 families affected with breast and/or ovarian cancer were screened for mutations in the BRCA1 and BRCA2 genes. Three novel mutations were detected: one in BRCA1 - c.1193C>A (p.Ser398^*) and two in BRCA2 - c.5101C>T (p.Gln1701*) and c.5433_5436delGGAA (p.Glu1811Aspfs^*3). These novel mutations are located in the exons 11 of BRCA1 or BRCA2 and encode truncated proteins. Two of them are nonsense while one is a frameshift mutation. Also, 11 previously known pathogenic mutations were detected for the first time in the HBOC families studied here (three in BRCA1 and eight in BRCA2). All, except one cause premature formation of stop codons leading to truncation of the respective BRCA1 or BRCA2 proteins.

Efficacy of first-line systemic treatment in correlation with BRAF V600E and different KRAS mutations in metastatic colorectal cancer - a single institution retrospective analysis

BACKGROUND

KRAS mutation status in codons 12 and 13 is recognized as a predictive factor for resistance to anti-EGFR monoclonal antibodies. Despite having a wild type KRAS (wt-KRAS), not all patients with wt-KRAS respond to anti-EGFR antibody treatment. Additional mechanisms of resistance may activate mutations of the other main EGFR effectors pathway. Consequently, other molecular markers in colorectal cancer are needed to be evaluated to predict the response to therapy.

PATIENTS AND METHODS

In this retrospective study, objective responses (OR), time to progression (TTP), overall survival (OS) were analyzed in 176 metastatic colorectal cancer (mCRC) patients treated with first-line chemotherapy in combination with monoclonal antibodies in respect of KRAS status in codons 12 and 13 and BRAF mutational status.

RESULTS

The KRAS mutations were found in 63 patients (35.8 %), the KRAS mutation in codon 12 in 53 patients (30.1%) and the KRAS mutation in codon 13 in 10 patients (5.7%). The BRAF V600E mutation was detected in 13 of 176 patients (7.4%). In the subgroup of mCRC patients having wt-KRAS and wild type BRAF (wt-BRAF), the objective response rates were higher (OR 54.0% ,CR 14.7%, PR 39.3%) than in the patients with wt-KRAS and mt-BRAF (OR 38.5%,CR 15.4%, PR 23.1%), the difference was not statistically significant (p= 0.378). Median OS in patients with wt-KRAS wt-BRAF, and in patients with wt-KRAS mt-BRAF, was 107.4 months and 45 months, respectively. The difference was statistically significant (p= 0.042). TTP in patients with wt-KRAS wt-BRAF, and in patients with wt-KRAS mt-BRAF, was 16 months and 12 months, respectively. The difference was not statistically significant (p= 0.558).

CONCLUSIONS

Patients with BRAF V600E mutation have statistically significantly worse prognosis than the patients with wt-BRAF and progress earlier during treatment. The definitive role of the BRAF V600E mutation as a prognostic and predictive factor for the response to anti-EGFR monoclonal antibodies needs to be analyzed in large prospective clinical studies.

Age at menarche and menopause is not associated with two common genetic variants in the methylenetetrahydrofolate reductase (MTHFR) gene

OBJECTIVES

The study aimed at investigating the independent and the combined effects of the two common genetic variants in the methylenetetrahydrofolate reductase (MTHFR) gene, 677C > T and 1298A > C, and their interaction with lifestyle factors on timing of menarche and natural menopause.

METHODS

Postmenopausal women (N = 792) were assessed for the association of the two genetic variants with age at menarche (AM). A subsample of 578 of them who had a natural menopause were further investigated for the association of the two genetic variants with age at natural menopause (ANM). Genotyping was done by means of the TaqMan(®) allelic discrimination method. The effect of genetic variants and of lifestyle factors on AM and ANM were calculated by linear regression models.

RESULTS

The study revealed no association between the individual or combined effects of the two genetic variants and AM or ANM. The genetic variant 677C > T showed a significant interaction effect with duration of breastfeeding on ANM (p = 0.047).

CONCLUSION

We were unable to replicate previous findings suggesting that the MTHFR gene influences the onset of menarche and natural menopause. The interaction effect between the 677C >T genetic variant and duration of breastfeeding on the timing of natural menopause requires further investigation.

Tumor vaccine composed of CpG ODN class C and irradiated tumor cells up-regulates the expression of genes characteristic of mature dendritic cells and of memory cells

Only properly mature dendritic cells (DCs) in the presence of tumor antigens accomplish to activate all of the elements of the immune network and have the potential to induce tumor-specific effectors and memory T cells. In the current study, we firstly aimed to investigate the in vivo maturation of antigen presenting cells (APCs) at the molecular level by following the expression of CD11c, CD86 and MyD88 genes in the mixture of mononuclear cells after treatment of mice with a tumor vaccine composed of C-class CpG oligodeoxynucletides (CpG ODN) and irradiated melanoma B16F1 tumor cells. The second objective was to define whether the tumor vaccine induces generation of memory T cells (CD44hiCD62Llo/hiCD27hi). Finally, based on gene expression pattern we aimed to determine the tissue distribution and homing of the (mature) APCs and memory cells after vaccination. We demonstrated that by tumor vaccine the APCs (including DCs) are manipulated in vivo. By this kind of vaccine, the differentiation and maturation of APCs is triggered primarily in the spleen and is subsequently followed by the migration of these APCs to the bone marrow. Once in the bone marrow, these APCs play a crucial role in the development and maintenance of long-lived memory T cells capable of preventing a relapse of malignant disease. In conclusion, our results provide insight into the nature and scope of the antitumor immune response elicited by this kind of tumor vaccine in vivo. We showed that the maturation of APCs is a prerequisite for the generation of effective long-term antitumor immunity.

KRAS mutations in Slovene patients with colorectal cancer: frequency, distribution and correlation with the response to treatment

KRAS mutations are proved as a predictor of response to EGFR-targeted therapies for patients with metastatic colorectal cancer. For identifying the wild-type KRAS (wt-KRAS) responder subset of patients who will benefit from novel agents our laboratory has introduced the TheraSreen K-RAS Mutation Kit(R) an allele-specific RT-PCR based assay. Our aim is to describe the validation procedure of this method in our laboratory, determine the portion of colorectal cancer patients with wt-KRAS status, and assess the prognostic power of mutational status for the anti-EGFR therapy outcome in colorectal cancer patients. In this study 302 samples from 273 patients with metastatic colorectal cancer were tested for 7 most common mutations on codon 12 and 13 of the KRAS gene. We used HT-29 and CCL-247 cell lines to determine the sensitivity of the method for different proportions of tumor cells in the sample. We determined that 2% of cells carrying a KRAS mutation must be present in the sample for an undisputable detection of mutated signal using the LightCycler Adapt Software. Among the tested patients 54.5% had a wt-KRAS genotype and 45.5% had a mutated KRAS genotype. The p.Gly12Asp was the most common detected mutation (38.5%). Among the cetuximab therapy responders, 85.7% had a wt-KRAS genotype. We have shown that the RT-PCR method introduced to discriminate between anti-EGFR therapy responders and non-responders is efficient, reliable and quickly applicable. The ratio of mutated versus wt-KRAS patients in our study is similar to ratios reported by other authors, as is the high correlation between wt-KRAS genotype and response to cetuximab therapy. Nevertheless the selection of patients for treatment solely on the basis of KRAS status is not perfect due to the fact that some responders are among the patients with mutated KRAS and some non-responders among the wt-KRAS patients.

Tumor vaccine composed of C-class CpG oligodeoxynucleotides and irradiated tumor cells induces long-term antitumor immunity

Background

An ideal tumor vaccine should activate both effector and memory immune response against tumor-specific antigens. Beside the CD8+ T cells that play a central role in the generation of a protective immune response and of long-term memory, dendritic cells (DCs) are important for the induction, coordination and regulation of the adaptive immune response. The DCs can conduct all of the elements of the immune orchestra and are therefore a fundamental target and tool for vaccination. The present study was aimed at assessing the ability of tumor vaccine composed of C-class CpG ODNs and irradiated melanoma tumor cells B16F1 followed by two additional injections of CpG ODNs to induce the generation of a functional long-term memory response in experimental tumor model in mice (i.p. B16F1).

Results

It has been shown that the functional memory response in vaccinated mice persists for at least 60 days after the last vaccination. Repeated vaccination also improves the survival of experimental animals compared to single vaccination, whereas the proportion of animals totally protected from the development of aggressive i.p. B16F1 tumors after vaccination repeated three times varies between 88.9%-100.0%. Additionally, the long-term immune memory and tumor protection is maintained over a prolonged period of time of at least 8 months. Finally, it has been demonstrated that following the vaccination the tumor-specific memory cells predominantly reside in bone marrow and peritoneal tissue and are in a more active state than their splenic counterparts.

Conclusions

In this study we demonstrated that tumor vaccine composed of C-class CpG ODNs and irradiated tumor cells followed by two additional injections of CpG ODNs induces a long-term immunity against aggressive B16F1 tumors.

Distribution of some activating KRAS and BRAF mutations in Slovene patients with colorectal cancer

Numerous clinical studies have shown that anti-EGFR therapies are effective only in a subset of patients with colorectal cancer. Even though mutations in the KRAS gene have been confirmed as negative predictors of the response to EGFR-targeted therapies, not all KRAS wild-type (wt-KRAS) patients will respond to treatment. Recent studies have demonstrated that additionally wild-type BRAF (wt-BRAF) genotype is required for response to panitumumab or cetuximab, suggesting that BRAF genotype criteria should be used together with KRAS genotype for selecting the patients who are about to benefit from the anti-EGFR therapy. In this study, 239 samples obtained from 215 patients with metastatic colorectal cancer were tested for the presence of the seven most common mutations in the KRAS gene and the V600E mutation in the BRAF gene. Among the tested patients, 53.8% of patients had wt-KRAS genotype and 46.2% were KRAS mutants. Around five percent (5.1%) of the tested patients bore the V600E mutation in BRAF gene. All the patients showing to have the V600E mutation in BRAF were wt-KRAS. The concordance of KRAS and BRAF mutational status between primary and metastatic tumor tissue samples was 100%. We have shown that the proportions of mutated and non-mutated KRAS in Slovene patients, as well as the proportion of V600E mutations in BRAF is similar to genotyping results reported by other authors. The tested seven KRAS mutations on codons 12 and 13 were mutually exclusive with the V600E mutation in the BRAF gene. Summing up the results about the KRAS and the BRAF mutation carriers from our study, the portion of potentially non-responsive patients for the anti-EGFR treatment is 51.3%.

Class C CpG oligodeoxynucleotides as a single agent and in combination with radiotherapy efficiently delayed growth of subcutaneous B16F1 tumors

Until now, the anti-tumor efficacy of synthetic oligodeoxynucleotides containing CpG motifs (CpG ODNs) has been reported in a number of preventive and therapeutic tumor models. Predominately class B CpG ODNs were used, relatively little has been reported regarding the class C CpG ODNs. The present study was, therefore, aimed at assessing the ability of CpG ODNs class C applied as a single agent and in combination with radiotherapy to induce the anti-tumor immunity in an experimental tumor model in mice (subcutaneous [s.c.] B16F1). Class C CpG ODNs applied three times as a single agent efficiently delayed the growth of s.c. B16F1 tumors. The combined therapy (CpG ODNs and tumor irradiation) remarkably enhanced the anti-tumor effect. The peritumoral (p.t.) application of CpG ODNs in combination with irradiation increased the number of dendritic cells (DCs) at the tumor site and improved the antigen loading and maturation of DCs. In conclusion, the combined therapy with CpG ODNs and irradiation creates a unique in situ DCs vaccine that could be easily applicable without prior knowledge of tumor antigens.

Prevalence of variations in melanoma susceptibility genes among Slovenian melanoma families

Background

Two high-risk genes have been implicated in the development of CM (cutaneous melanoma). Germline mutations of the CDKN2A gene are found in < 25% of melanoma-prone families and there are only seven families with mutation of the CDK4 gene reported to date. Beside those high penetrance genes, certain allelic variants of the MC1R gene modify the risk of developing the disease.

The aims of our study were: to determine the prevalence of germline CDKN2A mutations and variants in members of families with familial CM and in patients with multiple primary CM; to search for possible CDK4 mutations, and to determine the frequency of variations in the MC1R gene.

Methods

From January 2001 until January 2007, 64 individuals were included in the study. The group included 28 patients and 7 healthy relatives belonging to 25 families, 26 patients with multiple primary tumors and 3 children with CM. Additionally 54 healthy individuals were included as a control group. Mutations and variants of the melanoma susceptibility genes were identified by direct sequencing.

Results

Seven families with CDKN2A mutations were discovered (7/25 or 28.0%). The L94Q mutation found in one family had not been previously reported in other populations. The D84N variant, with possible biological impact, was discovered in the case of patient without family history but with multiple primary CM. Only one mutation carrier was found in the control group. Further analysis revealed that c.540C>T heterozygous carriers were more common in the group of CM patients and their healthy relatives (11/64 vs. 2/54). One p14ARF variant was discovered in the control group and no mutations of the CDK4 gene were found.

Most frequently found variants of the MC1R gene were T314T, V60L, V92M, R151C, R160W and R163Q with frequencies slightly higher in the group of patients and their relatives than in the group of controls, but the difference was statistically insignificant.

Conclusion

The present study has shown high prevalence of p16INK4A mutations in Slovenian population of familial melanoma patients (37%) and an absence of p14ARF or CDK4 mutations.

The hTERT mRNA in plasma samples of early breast cancer patients, non-cancer patients and healthy individuals

One of the most important changes, which make cancer cells immortal, is reactivation of the telomerase enzyme. Human telomerase is composed of at least two subunits, hTERT and hTR. Many investigators have already detected telomerase mRNA in bodily fluids. The first aim of our study was to find out if there is a difference in the appearance frequency of detectable hTERT mRNA in plasma of early breast cancer patients, non-cancer patients and healthy individuals. The second aim was to determine whether surgical removal of the tumor affects the presence of hTERT mRNA in plasma of early breast cancer patients. 87 patients with early breast cancer, 22 non-cancer patients and 21 healthy individuals were included in the study. From early breast cancer patients, two blood samples were collected, the first prior and the second 24 hours after the surgical removal of the tumor. From other individuals one blood sample was collected. The presence or absence of hTERT mRNA was determined from all blood samples. 47% of early breast cancer patients, 32% of non-cancer patients and 5% of healthy individuals tested positive for the presence of hTERT mRNA in plasma. The difference between early breast cancer patients and healthy individuals was statistically significant (p<0,001). Among early breast cancer patients, 26% were positive for the presence of plasma hTERT mRNA before and after the surgical removal of the tumor, 21% were positive before and negative after, 36% were negative before and after and 17% were negative before and positive after the surgical removal of the tumor. In conclusion, we found statistically significant difference of hTERT mRNA presence in plasma of early breast cancer patients when compared to healthy individuals. Second, we found that hTERT mRNA in plasma of early breast cancer patients is affected by the surgical removal of the tumor.

Optimization of an RNA isolation procedure from plasma samples

In this study, we aimed to optimize the isolation procedure of circulating RNA from large volumes of plasma. Simultaneously, the stability and integrity of RNA from plasma samples were examined. To investigate the isolation of circulating RNA, reverse transcription-PCR analysis in combination with capillary electrophoresis was used. The presence of amplifiable RNA in plasma from healthy volunteers and from breast cancer patients was analyzed. We found that circulating RNA in plasma was highly fragmented and degraded. Plasma RNA was most efficiently isolated from large volumes of samples after introducing the step of plasma concentration by evaporation and by using TRIzol LS reagent. A single freeze/thaw process had no significant effect on RNA integrity and quantity of plasma RNA. The average amount of RNA in plasma from breast cancer patients was lower than in plasma from healthy volunteers. The concentrating of large volumes of plasma facilitates isolation of plasma RNA and yields amplifiable RNA for at least fragments that are up to 310 bp long.