Maria Grazia Tibiletti

Genomic and expression profiling identifies the B‐cell associated tyrosine kinase Syk as a possible therapeutic target in mantle cell lymphoma

Among B‐cell lymphomas mantle cell lymphoma (MCL) has the worst prognosis. By using a combination of genomic and expression profiling (Affymetrix GeneChip Mapping 10k Xba131 and U133 set), we analysed 26 MCL samples to identify genes relevant to MCL pathogenesis and that could represent new therapeutic targets. Recurrent genomic deletions and gains were detected. Genes were identified as overexpressed in regions of DNA gain on 3q, 6p, 8q, 9q, 16p and 18q, including the cancer genes BCL2 and MYC. Among the transcripts with high correlation between DNA and RNA, we identified SYK, a tyrosine kinase involved in B‐cell receptor signalling. SYK was amplified at DNA level, as validated by fluorescence in situ hybridisation (FISH) analysis, and overexpressed at both RNA and protein levels in the JeKo‐1 cell line. Low‐level amplification, with protein overexpression of Syk was demonstrated by FISH in a small subset of clinical samples. After treatment with low doses of the Syk inhibitor piceatannol, cell proliferation arrest and apoptosis were induced in the cell line overexpressing Syk, while cells expressing low levels of Syk were much less sensitive. A combination of genomic and expression profiling suggested Syk inhibition as a new therapeutic strategy to be explored in lymphomas.

Genome wide DNA-profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome

Marginal zone B-cell lymphomas (MZLs) have been divided into 3 distinct subtypes (extranodal MZLs of mucosa-associated lymphoid tissue [MALT] type, nodal MZLs, and splenic MZLs). Nevertheless, the relationship between the subtypes is still unclear. We performed a comprehensive analysis of genomic DNA copy number changes in a very large series of MZL cases with the aim of addressing this question. Samples from 218 MZL patients (25 nodal, 57 MALT, 134 splenic, and 2 not better specified MZLs) were analyzed with the Affymetrix Human Mapping 250K SNP arrays, and the data combined with matched gene expression in 33 of 218 cases. MALT lymphoma presented significantly more frequently gains at 3p, 6p, 18p, and del(6q23) (TNFAIP3/A20), whereas splenic MZLs was associated with del(7q31), del(8p). Nodal MZLs did not show statistically significant differences compared with MALT lymphoma while lacking the splenic MZLs-related 7q losses. Gains of 3q and 18q were common to all 3 subtypes. del(8p) was often present together with del(17p) (TP53). Although del(17p) did not determine a worse outcome and del(8p) was only of borderline significance, the presence of both deletions had a highly significant negative impact on the outcome of splenic MZLs.

CHK1 frameshift mutations in genetically unstable colorectal and endometrial cancers.

The protein encoded by the CHK1 gene plays an important role in the G2 checkpoint in mammalian cells. In its coding region it presents a sequence of nine consecutive adenines that are a potential site of mutations in tumors with microsatellite instability (MSI). We analyzed the presence of frameshift mutations in the CHK1 gene in human colon and endometrial cancer samples. In the same cancer samples genes known to be altered in these tumors (BAX, TGFBRII, and IGFIIR) were also analyzed. CHK1 frameshfit mutations were found in 1 out 10 colon cancers and 2 out of 7 endometrial cancers showing MSI. CHK1 alterations were associated with the presence of a high degree of MSI. No alterations were found in patients with tumors showing low frequency or lacking instability (microsatellite stable). The same was true for the other four genes analyzed. The insertion or deletion of one A in the poly A tract resulted in a truncated protein. Alterations of the CHK1 gene could represent an alternative way of cancer cells to escape from cell cycle control. Genes Chromosomes Cancer 26:176–180, 1999.

Genetic progression in microsatellite instability high (MSI-H) colon cancers correlates with clinico-pathological parameters: A study of the TGFβRII, BAX, HMSH3, HMSH6, IGFIIR and BLM genes

Colon carcinomas with microsatellite mutator phenotype exhibit specific genetic and clinico‐pathological features. This report describes the analysis of 63 “microsatellite instability‐high” (MSI‐H) tumors for the presence of mutations in microsatellites located in the coding regions (CDRs) of 6 genes: TGFβRII, BAX, hMSH3, hMSH6, IGFIIR, and BLM. The following frequencies of mutations were detected: TGFβRII (70%), BAX (54%), hMSH3 (36.5%), IGFIIR (22%), hMSH6 (17.5%), and BLM (16%). The overall picture revealed combinations of mutations suggestive of a progressive order of accumulation, with mutations of TGFβRII and BAX first, followed by frameshifts in hMSH3, hMSH6, IGFIIR, and BLM. Correlations with 12 clinico‐pathological parameters revealed that tumors with frameshifts in 1 or 2 CDRs were significantly better differentiated than tumors with frameshifts in more than 2 CDRs. We also found that mutations in the hMSH3 gene were significantly associated with decreased wall invasiveness and aneuploidy, and frameshifts in the BLM gene were significantly associated with the mucinous histotype. A trend toward an association between hMSH3 and IGFIIR with the medullary and conventional adenocarcinoma histotypes, respectively, was seen. Our results strengthen the concept that mutations in target genes have a role in the tumorigenic process of MSI‐H tumors, and indicate that frameshifts in microsatellites located in CDRs occur in a limited number of combinations that could determine distinct clinico‐pathological traits. Int. J. Cancer 89:230–235, 2000.

Immunohistochemical pattern of hMSH2/hMLH1 in familial and sporadic colorectal, gastric, endometrial and ovarian carcinomas with instability in microsatellite sequences

Abstract. Alterations of DNA mismatch repair (MMR) genes are involved in carcinogenesis of sporadic and inherited human cancers characterised by instability of DNA microsatellite sequences (MSI). MSI tumours are usually identified using molecular analysis. In the present investigation, hMLH1 and hMSH2 immunohistochemistry was tested in order to evaluate the utility of this method in predicting MMR deficiency. Colorectal (72), gastric (68), endometrial (44) and ovarian (17) carcinomas were independently evaluated for familial history, histological type of tumour, MSI status and immunohistochemical results. Loss of expression of either hMLH1 or hMSH2 was observed in 51 of 55 (92.8%) MSI tumours, while 145 of 146 microsatellite stable (MSS) tumours expressed both the hMLH1 and hMSH2 gene products. Independently of tumour site, an overall agreement between immunohistochemical and molecular results was observed in 15 hereditary non-polyposis colorectal cancer-related tumours. Among sporadic tumours, only 2 of 60 colorectal and 2 of 66 gastric carcinomas, displaying MSI, expressed both hMLH1 and hMSH2 gene products. All 39 endometrial and 16 ovarian tumours presented a concordant molecular and immunohistochemical profile. These data show that immunohistochemistry is an accurate and rapid method to predict the presence of defective DNA MMR genes and to identify both sporadic and familial MSI tumours.

Development of sarcomas in mice implanted with mesenchymal stem cells seeded onto bioscaffolds

Bone marrow-derived mesenchymal stem cells (MSCs) are precursors of bone, cartilage and fat tissue. MSC can also regulate the immune response. For these properties, they are tested in clinical trials for tissue repair in combination with bioscaffolds or injected as cell suspension for immunosuppressant therapy. Experimental data, however, indicate that MSC can undergo or induce a tumorigenic process in determined circumstances. We used a modified model of ectopic bone formation in mice by subcutaneously implanting porous ceramic seeded with murine MSC. In this new model, host-derived sarcomas developed when we implanted MSC/bioscaffold constructs into syngeneic and immunodeficient recipients, but not in allogeneic hosts or when MSCs were injected as cell suspensions. The bioscaffold provided a tridimensional support for MSC to aggregate, thus producing the stimulus for triggering the process eventually leading to the transformation of surrounding cells and creating a surrogate tumor stroma. The chemical and physical characteristics of the bioscaffold did not affect tumor formation; sarcomas developed either when a stiff porous ceramic was used or when the scaffold was a smooth collagen sponge. The immunoregulatory function of MSC contributed to tumor development. Implanted MSC expanded clones of CD4+CD25+ T regulatory lymphocytes that suppressed hosts antitumor immune response.

Concomitant MYC and microRNA cluster miR-17-92 (C13orf25) amplification in human mantle cell lymphoma.

Chromosome 13q31 amplification frequently occurs in solid tumours and in lymphomas and it targets miR-17-92 cluster [1],[2]. The mir-17-92 cluster is amplified and over-expressed in lymphomas [2],[...

BCL2, BCL6, MYC, MALT 1, and BCL10 rearrangements in nodal diffuse large B-cell lymphomas: a multicenter evaluation of a new set of fluorescent in situ hybridization probes and correlation with clinical outcome ☆

Diffuse large B-cell lymphoma is the most common type of non-Hodgkin lymphoma. Although it is a curable disease, fewer than half of patients are cured with conventional chemotherapy. The highly variable outcome reflects a heterogeneous group of tumors, with different genetic abnormalities and responses to therapy. We analyzed 74 cases of diffuse large B-cell lymphoma using interphase fluorescent in situ hybridization with commercially available probes for split-signal targeting BCL-2, BCL-6, MYC, BCL-10, and MALT-1. Gene rearrangements were identified in 48 (65%) of 74 cases. BCL-6 was the most rearranged gene (45%), followed by BCL-2 (21%), BCL-10 (18%), and MYC (16%). No MALT-1 rearrangements were found. When diffuse large B-cell lymphoma cases were subdivided into germinal-center B-cell-like and activated B-cell-like groups, an inverse pattern of BCL-2 and BCL-6 rearrangements was observed. Of interest, the presence of chromosome rearrangements was associated with a worse prognosis. The pattern of cytogenetic abnormalities highlighted the fact not only that diffuse large B-cell lymphoma is a heterogeneous entity but also that even individual cases may contain subclones bearing different chromosomal rearrangements. The relevance and the clinical implication of minor clones showing gene rearrangements are poorly understood; however, this first observation suggests that different rearrangements may be involved in the progression of the disease. The fluorescent in situ hybridization analysis with the panel used in this study is useful to detect the heterogeneity of diffuse large B-cell lymphomas and identify alterations with prognostic implications.

PREMATURE OVARIAN FAILURE

Secondary amenorrhoea with elevated gonadotrophins occurring under the age of 40 (premature ovarian failure (POF)), and at the age between 41 and 44 years (early menopause (EM)), respectively, affects 1-2% and 5% of women in the general population. Objective of this study was to evaluate the prevalence of familial cases of POF and EM and to assess the clinical and genetic characteristics of these patients. One hundred and sixty women with idiopathic secondary amenorrhoea before the age of 45 and serum follicle-stimulating hormone (FSH) levels greater than or equal to 40 IU/l were included in the study. Tests performed on patients included complete medical history, pedigrees analysis, clinical pelvic examination, gonadotrophins and thyroid assessment, chromosomal analysis. The 160 patients included in the study showed idiopathic POF (n=130) or EM (n=30). Following pedigree assessment, we were able to identify an incidence of familial cases of 28.5% in the POF group (n=37) and of 50% in the EM group (n=15). POF and EM condition were often present in the same family. There were no differences between POF and EM patients and between familial and sporadic cases regarding age at menarche, personal history, gynaecological history, weight, height and diet habits. There was a statistically significant difference between sporadic and familial cases in age at POF onset: 32.0+/-7.3 years (12-40) compared to 35. 0+/-5.8 (18-40), respectively (P<0.05). The POF and EM families identified showed two or more affected females and transmission through either maternal or paternal relatives; in four families both maternal and paternal transmission was observed. This study suggests that idiopathic POF and EM conditions, differing only in age of menopause onset, may represent a variable expression of the same genetic disease. The different age of menopause onset in these patients may be explained by genetic heterogeneity and/or by different environmental factors. Our results indicate a high rate of familial transmission of the condition. Pedigrees analysis suggests an autosomal or an X-linked dominant sex-limited pattern of inheritance for POF and EM.

Cloning and characterization of a senescence inducing and class II tumor suppressor gene in ovarian carcinoma at chromosome region 6q27.

Cytogenetic, molecular and functional analysis has shown that chromosome region 6q27 harbors a senescence inducing gene and a tumor suppressor gene involved in several solid and hematologic malignancies. We have cloned at 6q27 and characterized the RNASE6PL gene which belongs to a family of cytoplasmic RNases highly conserved from plants, to man. Analysis of 55 primary ovarian tumors and several ovarian tumor cell lines indicated that the RNASE6PL gene is not mutated in tumor tissues, but its expression is significantly reduced in 30% of primary ovarian tumors and in 75% of ovarian tumor cell lines. The promoter region of the gene was unaffected in tumors cell lines. Transfection of RNASE6PL cDNA into HEY4 and SG10G ovarian tumor cell lines suppressed tumorigenicity in nude mice. When tumors were induced by RNASE6PL-transfected cells, they completely lacked expression of RNASE6PL cDNA. Tumorigenicity was suppressed also in RNASE6PL-transfected pRPcT1/H6cl2T cells, derived from a human/mouse monochromosomic hybrid carrying a human chromosome 6 deleted at 6q27. Moreover, 63.6% of HEY4 clones and 42.8% of the clones of XP12ROSV, a Xeroderma pigmentosum SV40-immortalized cell line, transfected with RNASE6PL cDNA, developed a marked senescence process during in vitro growth. We therefore propose that RNASE6PL may be a candidate for the 6q27 senescence inducing and class II tumor suppressor gene in ovarian cancer.