Daniele Calistri

Fecal multiple molecular tests to detect colorectal cancer in stool.

BACKGROUND & AIMS Evaluation of molecular alterations in fecal DNA is a potential, noninvasive, alternative tool for the detection of colorectal cancer. We analyzed a large panel of molecular alterations involved in tumor transformation and progression to define their single diagnostic contribution in terms of sensitivity, cost, and time required to carry out the different tests. METHODS DNA was analyzed in stool from 38 healthy individuals and in paired stools and primary lesions from 56 patients with colorectal cancer. p53 exons 5-8, K-ras exons 1-2, four fragments of adenomatous polyposis coli (APC) exon 15, and 5 microsatellite loci were analyzed. Moreover, DNA amplification was evaluated for 4 exons of both p53 and APC. RESULTS K-ras (34%) and p53 (34%) mutations were the most frequent alterations in tumors, followed by microsatellite instability (13%) and APC mutations (13%). The most frequent event in stool was DNA amplification (51%), followed by alterations of K-ras (11%), p53 and microsatellite instability (6%), and APC (2%). K-ras and p53 gene mutations increased the capacity of DNA amplification to detect tumor cells by 8%. CONCLUSIONS K-ras and p53 gene mutations were the most frequent alterations observed in stool from patients with colorectal cancer, but DNA amplification was even more frequent, being present in more than half of patients. If these preliminary results are confirmed in a prospective study on a larger case series, this approach could be used for noninvasive colon cancer diagnosis in screening programs.

Microsatellite instability and mutations of p53 and TGF-β RII genes in gastric cancer

To investigate the molecular mechanism of gastric carcinogenesis, we analyzed genetic instability and p53 gene mutations in 40 primary gastric carcinomas. Tumor samples were from untreated patients with no family history suggestive of genetic predisposition to cancer. We screened six microsatellite loci by the polymerase chain reaction (PCR) method, and exons 5–8 of the p53 gene by the PCR-based denaturing gradient gel electrophoresis and sequencing techniques. Microsatellite instability was detected in 32.5% (13/40), and gene mutations in 40% (16/40), of the tumors analyzed. No statistically significant associations were found between genetic alterations and clinico-pathological variables (with the exception of diffusion of lymph node metastases, which was inversely associated with the presence of microsatellite alterations; P < 0.01). Interestingly, a negative association was found between genetic instability and p53 gene mutations: 11 out of 13 tumors showing instability proved to carry a nonmutated p53 gene versus 2/13 carrying a mutated gene (P = 0.03). These observations suggest that genetic instability and p53 gene mutations play a crucial role in the gastric carcinogenic process, but likely act through distinct pathways during cancer development. However, genetic instability is not in and of itself neoplastic. Therefore, we investigated whether insertion/deletion mutations of the polyadenine tract within the transforming growth factor-β type II receptor gene (TGF-βRII) were frequently present in gastric tumors with an RER+ (replication error) phenotype. We found RII mutations in 8/40 (20%) samples: mutations were present in 7/13 (54%) RER+ tumors versus 1/27 (4%) RER– cases (P < 0.001).

p16INK4A and CDH13 hypermethylation in tumor and serum of non-small cell lung cancer patients

Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the etiopathogenesis of lung cancer and is a promising tool for cancer detection. In the present study, promoter hypermethylation of p16INK4A and CDH13 genes was investigated in tumor tissue and in matched serum from 61 patients with histologically confirmed non‐small cell lung cancer. Using a fluorescence‐based method of methylation‐specific PCR (F‐MSP), methylation of p16INK4A and CDH13 was detected in 79% and 66% of tumors, respectively, and was not significantly related to conventional clinicopathological characteristics of patients or tumors. Methylation of both genes was observed in 52% of tumors and of at least one gene in 92% of lesions. In matched serum, hypermethylation of p16INK4A and CDH13 was observed in 26% and 23% of patients, respectively, but as they were not associated, the methylation of at least one gene was detected in 39% of patients. In conclusion, the frequency of p16INK4A or CDH13 hypermethylation in patient serum, together with evidence of their early occurrence in lung cancerogenesis and the total lack of methylation in serum from healthy individuals, offer a promising tool for non invasive early detection of lung cancer.

Free DNA and Carcinoembryonic Antigen Serum Levels: An Important Combination for Diagnosis of Colorectal Cancer

Purpose: The identification of new molecular markers for the early detection of colorectal cancer has become an important objective. We compared the sensitivity and specificity of free circulating DNA with that of the more conventional carcinoembryonic antigen (CEA) and evaluated the two markers in combination. Experimental Design: The study was carried out on 75 healthy donors and 75 colorectal cancer patients. Free DNA was determined in serum with quantitative PCR analysis. The diagnostic accuracy of each assay was calculated using receiver operating characteristic (ROC) curves. The diagnostic relevance of the two-marker combination was analyzed by the logistic regression model. Results: Median free DNA concentration was ∼5-fold higher in patients than in healthy donors (P < 0.001). The area under the ROC curve was 0.86, and when 12.5 ng/mL was used as cutoff, 81.3% sensitivity and 73.3% specificity were observed for the overall series. As CEA and free DNA provided independent diagnostic information, they were also considered in combination. ROC curve analysis of the combined CEA and free DNA algorithms showed a higher diagnostic capacity (area under the ROC curve, 0.92) than that of markers considered singly, with 84% sensitivity and 88% specificity. Conclusions: Free circulating DNA, especially when used in combination with CEA, represents a potentially useful tool for the diagnosis of early-stage colorectal cancer.

c-kit and SCF Expression in Normal and Tumor Breast Tissue

Several studies have shown a role of the tyrosine kinase receptor, c-kit, and its ligand, SCF, during organogenesis, normal cell development and growth of some tumor histotypes. In breast cancer, studies using different methodologies have shown conflicting results. In the present study we analyzed c-kit and SCF in 14 normal mammary epithelia samples, in 16 in situ and in 75 invasive breast cancers. The expression of c-kit and SCF protein was analyzed by immunohistochemistry and mRNA expression was evaluated by in situ hybridization and reverse-transcriptase polymerase chain reaction (RT-PCR). The different methodologies gave somewhat different results.Using immunohistochemistry and in situ hybridization, protein and mRNA expression of c-kit and SCF were high in normal mammary gland, significantly lower in in situ and almost completely undetectable in invasive breast cancer. Conversely, using RT-PCR, mRNA expression was observed in normal tissue and in all pathologic lesions of mammary gland, probably due to the high sensitivity of the methodology or to the positivity of elements other than tumor cells expressing the receptor and/or its ligand.These results suggest that the c-kit/SCF pathway plays an important role in the maintenance of normal growth of mammary epithelium and that the process of malignant transformation is accompanied by their progressive loss. Furthermore, we demonstrated that different results are attributable to different methodologies and that morphologic approaches are the most reliable for defining the cellular source of c-kit or SCF expression.

Circulating cell-free AR and CYP17A1 copy number variations may associate with outcome of metastatic castration-resistant prostate cancer patients treated with abiraterone

Background:This study aimed to investigate copy number variations (CNVs) of CYP17A1 and androgen receptor (AR) genes in serum cell-free DNA collected before starting abiraterone in 53 consecutive patients with castration-resistant prostate cancer (CRPC).Methods:Serum DNA was isolated and CNVs were analysed for AR and CYP17A1 genes using Taqman copy number assays. The association between CNVs and progression-free/overall survival (PFS/OS) was evaluated by the Kaplan–Meier method and log-rank test.Results:Median PFS of patients with AR gene gain was 2.8 vs 9.5 months of non-gained cases (P<0.0001). Patients with CYP17A1 gene gain had a median PFS of 2.8 months vs 9.2 months in the non-gained patients (P=0.0014). A lower OS was reported in both cases (AR: P<0.0001; CYP17A1: P=0.0085). Multivariate analysis revealed that PSA decline ⩾50%, AR and CYP17A1 CNVs were associated with shorter PFS (P<0.0001, P=0.0004 and P=0.0450, respectively), while performance status, PSA decline ⩾50%, AR CNV and DNA concentration were associated with OS (P=0.0021, P=0.0014, P=0.0026 and P=0.0129, respectively).Conclusions:CNVs of AR and CYP17A1 genes would appear to be associated with outcome of CRPC patients treated with abiraterone.

MICROSATELLITE INSTABILITY IN INTESTINAL‐ AND DIFFUSE‐TYPE GASTRIC CARCINOMA

To investigate the role of genetic instability in the development of intestinal‐ and diffuse‐type gastric cancers, six microsatellite loci were analysed in 98 carcinomas of the two main histotypes, at both early and advanced stages of progression, and in five preneoplastic lesions. RER+ phenotype frequency proved to be significantly higher (P=0·013) in intestinal (23 per cent) than in diffuse cancers (5 per cent) and slightly higher in advanced (19 per cent) than in early (12 per cent) tumours. When comparing early and advanced tumours of the same histotype, a similar frequency was found for diffuse tumours (4 per cent vs. 6 per cent), and an increase from 19 to 30 per cent for intestinal cancers. Instability at more than one locus was limited to intestinal tumours and replication errors were also detected in an intestinal dysplasia. On the whole, these data suggest that genetic instability has an important and early role in gastric carcinogenesis of the intestinal type and a less important role in gastric carcinogenesis of the diffuse type. Most tumours of this panel had previously been characterized for p53 gene mutations. p53 screening was extended to all samples, to investigate the possible association between gene mutations and microsatellite instability. Analysis showed a trend (P=0·07, Fishers exact test) towards a negative association between these two genetic lesions in tumours of the intestinal type.

Mean age of tumor onset in hereditary nonpolyposis colorectal cancer (HNPCC) families correlates with the presence of mutations in DNA mismatch repair genes.

Fourteen Italian families affected with hereditary nonpolyposis colorectal cancer (HNPCC) were screened for germline mutations at three DNA mismatch repair (MMR) genes, MSH2, MLH1, and GTBP, by using a combination of different methods that included an in vitro synthesized protein assay, single‐strand conformation polymorphism analysis, and direct sequencing. DNA alterations were observed in six instances, including a single base deletion in MSH2 exon 14, an A‐to‐G transition in the splice donor site of MLH1 exon 6, and two missense mutations in MLH1 exons 5 and 9. A previously reported common mutation affecting the splice donor site of MSH2 exon 5 was identified in two families. No mutations were detected in the GTBP gene. In total, eight of 16 Italian HNPCC families (50%), including two previously reported kindreds, were found to carry a mutation in MMR genes. We compared the mean age of colorectal cancer onset in the index cases (three patients for each family) between the two groups of kindreds, those with identified mutation vs. those without, and found that the first had a significantly lower value (43.0 vs. 53.7 years, P = 0.014). This finding suggests that HNPCC families with a more advanced age of tumor onset are less likely to be associated with known MMR genes. Genes Chromsom. Cancer 19:135–142, 1997.

Microsatellite instability in colorectal-cancer patients with suspected genetic predisposition

Hereditary non‐polyposis colorectal cancer (HNPCC) is a dominantly inherited syndrome linked to DNA‐mismatch‐repair (MMR) gene defects, which also account for microsatellite instability (MSI) in tumour tissues. Diagnosis is based mainly on family history, according to widely accepted criteria (Amsterdam Criteria: AC). Aim of this work was to assess MSI in colorectal‐cancer patients with suspected genetic predisposition, and to verify whether MSI represents a tool to manage MMR gene (hMSH2 and hMLH1) mutation analysis. We investigated 13 microsatellites (including the 5 NCI/ICG‐HNPCC markers) in 45 patients with suspected hereditary predisposition (including 16 subjects from HNPCC families fulfilling the AC). We found MSI‐H (high frequency of instability, i.e., in ≥30% of the markers) in 85% of the HNPCC patients and in 16% of the non‐HNPCC subjects. The 5 NCI/ICG‐HNPCC microsatellites proved to be the most effective in detecting MSI, being mononucleotide repeats the most unstable markers. We investigated the association between hMSH2‐ and hMLH1 gene mutations and MSI. Our results indicate that AC are highly predictive both of tumour instability and of MMR‐gene mutations. Therefore, as the most likely mutation carriers, HNPCC subjects might be directly analyzed for gene mutations, while to test for MSI in selected non‐HNPCC patients and to further investigate MMR genes in MSI‐H cases, appears to be a cost‐effective way to identify subjects, other than those from kindred fulfilling AC, who might benefit from genetic testing. Int. J. Cancer (Pred. Oncol.) 89:87–91, 2000.

DNA Methylation profiles as predictors of recurrence in non muscle invasive bladder cancer: An MS-MLPA approach

BackgroundAlthough non muscle invasive bladder cancer (NMIBC) generally has a good long-term prognosis, up to 80% of patients will nevertheless experience local recurrence after the primary tumor resection. The search for markers capable of accurately identifying patients at high risk of recurrence is ongoing. We retrospectively evaluated the methylation status of a panel of 24 tumor suppressor genes (TIMP3, APC, CDKN2A, MLH1, ATM, RARB, CDKN2B, HIC1, CHFR, BRCA1, CASP8, CDKN1B, PTEN, BRCA2, CD44, RASSF1, DAPK1, FHIT, VHL, ESR1, TP73, IGSF4, GSTP1 and CDH13) in primary lesions to obtain information about their role in predicting local recurrence in NMIBC.MethodsFormaldehyde-fixed paraffin-embedded (FFPE) samples from 74 patients operated on for bladder cancer were analyzed by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA): 36 patients had relapsed and 38 were disease-free at the 5-year follow up. Methylation status was considered as a dichotomous variable and genes showing methylation ≥20% were defined as “positive”.ResultsMethylation frequencies were higher in non recurring than recurring tumors. A statistically significant difference was observed for HIC1 (P = 0.03), GSTP1 (P = 0.02) and RASSF1 (P = 0.03). The combination of the three genes showed 78% sensitivity and 66% specificity in identifying recurrent patients, with an overall accuracy of 72%.ConclusionsOur preliminary data suggest a potential role of HIC1, GSTP1 and RASSF1 in predicting local recurrence in NMIBC. Such information could help clinicians to identify patients at high risk of recurrence who require close monitoring during follow up.