Molecular detection of TP53, Ki-Ras and p16INK4A promoter methylation in plasma of patients with colorectal cancer and its association with prognosis. Results of a 3-year GOIM (Gruppo Oncologico dell'Italia Meridionale) prospective study

BACKGROUND

Despite the improvement in detection and surgical therapy in the last years, the outcome of patients affected by colorectal carcinoma (CRC) remains limited by metastatic relapse. The aim of this study was to investigate the presence of free tumor DNA in the plasma of CRC patients in order to understand its possible prognostic role.

PATIENTS AND METHODS

Ki-Ras, TP53 mutations and p16(INK4A) methylation status were prospectively evaluated in tumor tissues and plasma of 66 CRC patients.

RESULTS

In 50 of the 66 primitive tumor cases (76%) at least one significant alteration was identified in Ki-Ras and/or TP53 and/or p16(INK4A) genes. Eighteen of the 50 patients presented the same alteration both in the plasma and in the tumor tissue. At univariate analysis, Ki-Ras mutations proved to be significantly related to quicker relapse (P <0.01), whereas only a trend towards statistical significance (P = 0.083) was observed for the TP53 mutations

CONCLUSIONS

Detection of Ki-Ras and TP53 mutation in plasma should be significantly related to disease recurrence. These data suggest that patients with a high risk of recurrence can be identified by means of the analysis of tumor-derived plasma DNA with the use of fairly non-invasive techniques.

Epigenetic modulation of estrogen receptor-alpha by pRb family proteins: a novel mechanism in breast cancer

Estrogen receptor-alpha (ER-alpha) plays a crucial role in normal breast development and has also been linked to mammary carcinogenesis and clinical outcome in breast cancer patients. However, ER-alpha gene expression can change during the course of disease and, consequently, therapy resistance can occur. The molecular mechanism governing ER-alpha transcriptional activity and/or silencing is still unclear. Here, we showed that the presence of a specific pRb2/p130 multimolecular complex on the ER-alpha promoter strongly correlates with the methylation status of this gene. Furthermore, we suggested that pRb2/p130 could cooperate with ICBP90 (inverted CCAAT box binding protein of 90 kDa) and DNA methyltransferases in maintaining a specific methylation pattern of ER-alpha gene. The sequence of epigenetic events for establishing and maintaining the silenced state of ER-alpha gene can be locus- or pathway- specific, and the local remodeling of ER-alpha chromatin structure by pRb2/p130 multimolecular complexes may influence its susceptibility to specific DNA methylation. Our novel hypothesis could provide a basis for understanding how the complex pattern of ER-alpha methylation and transcriptional silencing is generated and for understanding the relationship between this pattern and its function during the neoplastic process.

Interplay between the retinoblastoma related pRb2/p130 and E2F-4 and -5 in relation to JCV-TAg

Human polyomaviruses, which include JC virus (JCV) and BK virus (BKV), as well as the simian virus 40 (SV40), have been associated with human tumors and have been shown to be highly tumorigenic in experimental animal models. Although the mechanism by which JCV induces tumorigenesis is not entirely clear, earlier studies point to the involvement of the viral early protein T-antigen which has the ability to bind and inactivate tumor suppressors and cell cycle regulatory proteins, such as the retinoblastoma family proteins and p53. We investigated if the distribution between nucleus and cytoplasm of the transcription factors E2F4 and E2F5 is mediated by pRb2/p130 and if the presence of JCV T-antigen may impair this shuttling by sequestering pRb2/p130. The results showed that E2F4 was prevalently localized in the nucleus of both T-antigen positive and -negative R503 cells independently of the cell cycle phase. E2F5 instead was prevalently localized in the cytoplasmic fraction in G(0)/G(1), S-phase synchronized, and asynchronous R503 and R503 T-Ag positive cells. The presence of T-antigen did not influence the subcellular localization of these transcription factors E2F4 and E2F5, at least in this murine cellular model. Moreover, Small interference RNA experiments directed toward silencing the Rb2/p130 gene demonstrated that pRb2/p130 does not play a predominant role in the nuclear transportation of E2F4 and E2F5.

Transcription and epigenetic profile of the promoter, first exon and first intron of the human tyrosine hydroxylase gene

The transcriptional and chromatin profile of the promoter, first exon and first intron of the human TH gene were analyzed in human neuroblastoma BE(2)-C-16 and human renal carcinoma 293FT cell lines. The latter is a cell culture system that is not permissive for TH gene expression, whereas the former has a 50% cell fraction that tests positive for TH. The engineering of a 6.3 kb recombinant human TH promoter revealed the presence of repressors of transcription between positions (-6,244/-194). The addition of a 1.2 kb fragment of the first intron of the human TH gene (+730/+1,653) enhanced transcriptional activity of the recombinant promoter. However, both constructs were not specific for TH-positive BE(2)-C-16 cells. Chromatin immunoprecipitation (Chip) analysis was carried out on BE(2)-C-16 and 293FT cells to probe sequences of promoter, first exon and first intron of the human TH gene from position (-448/+1,204). The presence of nucleosomes was observed approximately from position (-20/+473) in both cell lines. Chip analysis was then conducted to determine the acetylation of various lysine residues of H3 and H4 in both cell lines. All analyzed lysine residues of H3 and H4 were acetylated in BE(2)-C-16 cells, whereas 293FT cells tested positive for acetylation only in the external lysine residues of the histone tail. Our data are compatible with an active TH gene expression in a 50% cell fraction of BE(2)-C-16 cells. Further analysis of epigenetic programming might lead to the identification of the factors that determine TH gene expression specifically in dopaminergic neurons.

BRCA1 genetic testing in 106 breast and ovarian cancer families from Southern Italy (Sicily): a mutation analyses

PURPOSE

To evaluate the contribution of germline BRCA1 mutations in the incidence of hereditary and familial Breast Cancer (BC) and/or Ovarian Cancer (OC) in patients from Southern Italy (in the region of Sicily) and to identify a possible association between the higher frequency of BRCA1 mutations and a specific familial profile.

EXPERIMENTAL DESIGN

A consecutive series of 650 patients with BC and/or OC diagnosed between 1999 and 2005 were recruited from the Southern Italian region of Sicily, after interview at the "Regional Reference Centre for the Characterization and Genetic Screening of Hereditary Tumors" at the University of Palermo. Genetic counselling allowed us to recruit a total of 106 unrelated families affected with breast and/or ovarian cancer screened for mutations occurring in the whole BRCA1 gene by automatic direct sequencing.

RESULTS

Germline BRCA1 mutations were found in 17 of 106 (16%) Sicilian families. The HBOC profile had a major frequency (66%) of mutations (P < 0.01). A total of 28 sequence variants was identified. Seven of these were pathogenic, 5 unknown biological variant (UV) and 16 polymorphisms. We also identified a pathological mutation (4843delC) as a possible Sicilian founder mutation.

CONCLUSIONS

The present study is the first BRCA1 disease-associated mutations analysis in Southern Italian families. The early age of onset of such tumors and the association with the HBOC familial profile could be two valid screening factors for the identification of BRCA1 mutation carriers. Finally, we identified a BRCA1 mutation with a possible founder effect.

Rb family proteins as modulators of gene expression and new aspects regarding the interaction with chromatin remodeling enzymes

The pRb family proteins (pRb1/105, p107, pRb2/p130), collectively referred to as pocket proteins, are believed to function primarily as regulators of the mammalian cell cycle progression, and suppressors of cellular growth and proliferation. In addition, different studies suggest that these pocket proteins are also involved in development and differentiation of various tissues. Several lines of evidence indicate that generally pRb-family proteins function through their effect on the transcription of E2F-regulated genes. In fact, each of Rb family proteins binds to distinct members of the E2F transcription factors, which regulate the expression of genes whose protein products are necessary for cell proliferation and to drive cell-cycle progression. Nevertheless, pocket proteins can affect the G1/S transition through E2F-independent mechanisms. More recently, a broad range of evidences indicate that pRb-family proteins associate with a wide variety of transcription factors and chromatin remodeling enzymes forming transcriptional repressor complexes that control gene expression. This review focuses on the complex regulatory mechanisms by which pRb-family proteins tell genes when to switch on and off.

TP53 and p16INK4A, but not H-KI-Ras, are involved in tumorigenesis and progression of pleomorphic adenomas

The putative role of TP53 and p16(INK4A) tumor suppressor genes and Ras oncogenes in the development and progression of salivary gland neoplasias was studied in 28 cases of pleomorphic adenomas (PA), 4 cases of cystic adenocarcinomas, and 1 case of carcinoma ex-PA. Genetic and epigenetic alterations in the above genes were analyzed by Polymerase Chain Reaction/Single Strand Conformational Polymorphism (PCR/SSCP) and sequencing and by Methylation Specific-PCR (MS-PCR). Mutations in TP53 were found in 14% (4/28) of PAs and in 60% (3/5) of carcinomas. Mutations in H-Ras and K-Ras were identified in 4% (1/28) and 7% (2/28) of PAs, respectively. Only 20% (1/5) of carcinomas screened displayed mutations in K-Ras. p16(INK4A) promoter hypermethylation was found in 14% (4/28) of PAs and 100% (5/5) carcinomas. All genetic and epigenetic alterations were detected exclusively in the epithelial and transitional tumor components, and were absent in the mesenchymal parts. Our analysis suggests that TP53 mutations and p16(INK4A) promoter methylation, but not alterations in the H-Ras and K-Ras genes, might be involved in the malignant progression of PA into carcinoma.

Nuclear and cytoplasmic interaction of pRb2/p130 and ER-β in MCF-7 breast cancer cells

Estrogens exhibit important biological functions and influence several pathological processes of hormone-dependent diseases. The biological actions of estrogens require their interaction with two estrogen receptors (ER-alpha and ER-beta), which are ligand-dependent transcription factors. ER-alpha and ER-beta exhibit distinct tissue expression patterns as well as show different patterns of gene regulation. In addition, it has been suggested that ER-beta works as a counter partner of ER-alpha through inhibition of the transactivating functions of ER-alpha. For instance, ER-beta seems to play a different role in breast tumorigenesis than ER-alpha, as ER-beta decreased expression in breast cancer has been correlated with bad prognosis. Biological activities of ER-alpha and ER-beta could be controlled by a number of interacting proteins such as activators/inhibitors, ligand binding and kinases. We have previously reported that pRb2/p130, retinoblastoma related protein, could be involved in the silencing of ER-alpha gene during breast tumorigenesis. Here, we report that ER-beta and pRb2/p130 proteins co-immunoprecipitate in both nucleus and cytoplasm of MCF-7 breast cancer cells. Our hypothesis is that the interaction of pRb2/130 with ER-beta may have a functional significance in regulating ER-beta activity.

[The hemodialysed patient and his/her family caregiver. Comparison of perceptions of the chronic illness]

BACKGROUND

According to health psychology, the family caregiver (fc), i.e. the person who takes care of a hemodialysed patient, plays a pivotal role in coping with dialysis. This study explored and compared the lifestyle and the main needs of a cohort of hemodialysis patients, with reduced personal autonomy, to their fc, evaluating some psychological functional parameters, such as the perception of familial and social support, the psychological quality of life, the disability due to chronic illness, and the communication style.

METHODS

An anonymous multiple versions questionnaire, administered according to the caregiver's family relationship, was given for self assessment to 54 couples of patients and related fc (spouse, son/daughter and brother/sister), mean age 66 and 60, respectively; mean dialytic patients' age: 8 years and 6 months. The questionnaire consisted of three different sections, demographics, renal disease and psychological evaluation, with 4 standard scales (Social Support Satisfaction, Marital Communication, Psychological General Well-Being Index and Evaluation of Needs). A multivariate variance analysis (MANOVA) was subsequently performed.

RESULTS

Women have a higher perception of their lifestyle change after dialysis, and, in general, patients communicate more easily with their fc than vice versa. Communication problems are more common in patients with a recent diagnosis. Patients and fc mostly need a better dialogue with their nephrologists and urge some psychological help.

CONCLUSIONS

The quality of the relationship between physicians, patients and their families is a key element in the process of healing.

TP53 mutations and S-phase fraction but not DNA-ploidy are independent prognostic indicators in laryngeal squamous cell carcinoma

To prospectively evaluate the prognostic significance of TP53, H-, K-, and N-Ras mutations, DNA-ploidy and S-phase fraction (SPF) in patients affected by locally advanced laryngeal squamous cell carcinoma (LSCC). Eight-one patients (median follow-up was 71 months) who underwent resective surgery for primary operable locally advanced LSCC were analyzed. Tumor DNA was screened for mutational analysis by PCR/SSCP and sequencing. DNA-ploidy and SPF were performed by flow cytometric analyses. Thirty-six patients (44%) had, at least, a mutation in the TP53 gene. Of them, 22% (8/36) had double mutations and 3% (1/36) had triple mutations. In total, 46 TP53 mutations were observed. The majority (41%) of these occur in exon 5 (19/46), while the mutations in exons 6, 7, and 8 were represented in 14, 7, and 6 patients, respectively (31%, 15%, and 16%). Five LSCC patients (6%) showed a mutation in H-Ras gene. Sixty-three percent of the cases (51/81) were DNA aneuploidy, 14% of these (7/51) were multiclonal. Thirty-nine patients (48%) had an high SPF value. At Univariate analysis, the DNA aneuploidy, high SPF (>15.1%), TP53 mutations and, in particular, the mutations that occur in exons 5 and 8 were significantly related to quicker disease relapse and short OS. At Multivariate analysis, the major significant predictors for both disease relapse and death were high SPF and any TP53 mutations. While histological grade G3 was an independent factor only for relapse. In conclusions, any TP53 mutations and high SPF are important biological indicators to predict the outcome of LSCC patients.

An updated study of mortality among North American synthetic rubber industry workers

AIM

This study evaluated the mortality experience of workers from the styrene-butadiene industry.

METHODS

The authors added seven years of follow up to a previous investigation of mortality among 17 924 men employed in the North American synthetic rubber industry. Analyses used the standardised mortality ratios (SMRs) to compare styrene-butadiene rubber workers' cause specific mortality (1943-98) with those of the United States and the Ontario general populations.

RESULTS

Overall, the observed/expected numbers of deaths were 6237/7242 for all causes (SMR = 86, 95% CI 84 to 88) and 1608/1741 for all cancers combined (SMR = 92, 95% CI 88 to 97), 71/61 for leukaemia, 53/53 for non-Hodgkin's lymphoma, and 26/27 for multiple myeloma. The 16% leukaemia increase was concentrated in hourly paid subjects with 20-29 years since hire and 10 or more years of employment in the industry (19/7.4, SMR = 258, 95% CI 156 to 403) and in subjects employed in polymerisation (18/8.8, SMR = 204, 95% CI 121 to 322), maintenance labour (15/7.4, SMR = 326, 95% CI 178 to 456), and laboratory operations (14/4.3, SMR = 326, 95% CI 178-546).

CONCLUSION

The study found that some subgroups of synthetic rubber workers had an excess of mortality from leukaemia that was not limited to a particular form of leukaemia. Uncertainty remains about the specific agent(s) that might be responsible for the observed excesses and about the role of unidentified confounding factors. The study did not find any clear relation between employment in the industry and other forms of lymphohaematopoietic cancer. Some subgroups of subjects had more than expected deaths from colorectal and prostate cancers. These increases did not appear to be related to occupational exposure in the industry.

Cytoplasmic and nuclear interaction between Rb family proteins and PAI-2: a physiological crosstalk in human corneal and conjunctival epithelial cells

Extracellular plasminogen activator inhibitor type-2 (PAI-2) is a potent inhibitor of urokinase-type plasminogen activator (u-PA) and also acts as a multifunctional protein. However, the biological activity of intracellular PAI-2, as well as its intracellular targets, until now remain an enigma. Here, we show that pRb2/p130 and Rb1/p105, but not p107, interact with PAI-2 in both the cytoplasm and nucleus of normal primary human corneal and conjunctival epithelial cells. We provided the first in vivo evidence that a specific fragment of the PAI-2 promoter is bound simultaneously by pRb2/ p130, PAI-2, E2F5, histone deacetylase 1 (HDAC1), DNA methyltransferase 1 (DNMT1), and histone methyltransferase (SUV39H1), in normal primary human corneal epithelial cells, and by pRb2/p130, PAI-2, E2F5, HDAC1, and DNMT1, in normal primary human conjunctiva epithelial cells. Our results strongly indicate a physiological interaction between pRb family members and PAI-2, suggesting the hypothesis that pRb2/p130 and PAI-2 may cooperate in modulating PAI-2 gene expression by chromatin remodeling, in normal corneal and conjunctival cells.

Genetic and epigenetic alterations of RB2/p130 tumor suppressor gene in human sporadic retinoblastoma: implications for pathogenesis and therapeutic approach

Human retinoblastoma occurs in two forms (familial and sporadic) both due to biallelic mutation of the RB1/p105 gene even if its loss is insufficient for malignancy. We have recently reported that loss of expression of the retinoblastoma-related protein pRb2/p130 correlates with low apoptotic index, suggesting that RB2/p130 gene could be involved in retinoblastoma. Mutational analysis of RB2/p130 in primary tumors showed a tight correlation between Exon 1 mutations and pRb2/p130 expression level in sporadic retinoblastoma. These mutations are located within a CpG-enriched region prone to de novo methylation. Analysis of RB2/p130 methylation status revealed that epigenetic events, most probably consequent to the Exon 1 mutations, determined the observed phenotype. Treatment of Weri-Rb1 cell line by 5-Aza-dC induced an increase in expression level of pRb2/p130, E2F1, p73 and p53. Overall, our results highlight a crucial role of epigenetic events in sporadic retinoblastoma, which opens a perspective for new therapeutic approaches.

Modulation of Cell Cycle Components by Epigenetic and Genetic Events

Cell cycle progression is monitored by surveillance mechanisms, or cell cycle checkpoints, that ensure that initiation of a later event is coupled with the completion of an early cell cycle event. Deregulated proliferation is a characteristic feature of tumor cells. Moreover, defects in many of the molecules that regulate the cell cycle have been implicated in cancer formation and progression. Key among these are p53, the retinoblastoma protein (pRb) and its related proteins, p107 and pRb2/p130, and cdk inhibitors (p15, p16, p18, p19, p21, p27), all of which act to keep the cell cycle from progressing until all repairs to damaged DNA have been completed. The pRb (pRb/p16(INK4a)/cyclin D1) and p53 (p14(ARF)/mdm2/p53) pathways are the two main cell-cycle control pathways frequently targeted in tumorigenesis, and the alterations occurring in each pathway depend on the tumor type. Virtually all human tumors deregulate either the pRb or p53 pathway, and oftentimes both pathways simultaneously. This review focuses on the genetic and epigenetic alterations affecting the components of mechanisms regulating the progression of the cell cycle and leading to cancer formation and progression.