INK4/ARF germline alterations in pancreatic cancer patients

Germline pathogenic variants of cancer predisposition genes in a multicentre Italian cohort of pancreatic cancer patients

BACKGROUND AND AIM

Germline BRCA1-2 test is routinely recommended in Pancreatic Cancer (PC) patients, due to its clinical-epidemiological relevance. Data on the prevalence of germline pathogenic variants (gPV) in other cancer predisposition and DNA Damage Repair (DDR) system-related genes in unselected PC cases are sparce in Italy. We assessed this prevalence in a multicentre cohort, to derive recommendations for PC patients.

METHODS

Clinical data of 1200 consecutive PC patients, of any age and stage, tested with a multigene germline panel were collected. A descriptive analysis of gPV frequency and clinical variables was performed both in 1092 patients tested for an 18 genes core-panel (CP-18 cohort) and in 869 patients screened only for CDKN2A.

RESULTS

11.5 % (126/1092) of CP-18 cohort patients harbored a gPV in ≥ 1 gene. Highest gPV frequencies were detected in ATM (3.1 %), BRCA2 (2.9 %), BRCA1 (1.6 %), CHEK2 (1.1 %). Patients harboring any CP-18 gene and BRCA1-2 gPV were younger and with a higher rate of personal (PH) or family history (FH) of cancer when compared to no gPV patients. The risk of having a gPV was ≥ 7 % in all subgroups of patients, including those aged > 73, with tumor stage I-III and negative FH/PH. CDKN2A gPV were detected in 2.6 % (23/869) of patients.

CONCLUSIONS

A remarkable prevalence of gPV in cancer predisposition and DDR genes is reported in this large multicentre cohort of consecutive and unselected PC patients. Therefore, we recommend multigene germline testing (at least including BRCA1-2, ATM, CDKN2A, PALB2) for all PC patients, irrespective of age, stage, PH/FH.

Working title: Molecular involvement of p53-MDM2 interactome in gastrointestinal cancers

The interaction between murine double minute 2 (MDM2) and p53, marked by transcriptional induction and feedback inhibition, orchestrates a functional loop dictating cellular fate. The functional loop comprising p53-MDM2 axis is made up of an interactome consisting of approximately 81 proteins, which are spatio-temporally regulated and involved in DNA repair mechanisms. Biochemical and genetic alterations of the interactome result in dysregulation of the p53-mdm2 axis that leads to gastrointestinal (GI) cancers. A large subset of interactome is well known and it consists of proteins that either stabilize p53 or MDM2 and proteins that target the p53-MDM2 complex for ubiquitin-mediated destruction. Upstream signaling events brought about by growth factors and chemical messengers invoke a wide variety of posttranslational modifications in p53-MDM2 axis. Biochemical changes in the transactivation domain of p53 impact the energy landscape, induce conformational switching, alter interaction potential and could change solubility of p53 to redefine its co-localization, translocation and activity. A diverse set of chemical compounds mimic physiological effectors and simulate biochemical modifications of the p53-MDM2 interactome. p53-MDM2 interactome plays a crucial role in DNA damage and repair process. Genetic aberrations in the interactome, have resulted in cancers of GI tract (pancreas, liver, colorectal, gastric, biliary, and esophageal). We present in this article a review of the overall changes in the p53-MDM2 interactors and the effectors that form an epicenter for the development of next-generation molecules for understanding and targeting GI cancers.

Understanding the Genetic Landscape of Pancreatic Ductal Adenocarcinoma to Support Personalized Medicine: A Systematic Review

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies worldwide. While population-wide screening recommendations for PDAC in asymptomatic individuals are not achievable due to its relatively low incidence, pancreatic cancer surveillance programs are recommended for patients with germline causative variants in PDAC susceptibility genes or a strong family history. In this study, we sought to determine the prevalence and significance of germline alterations in major genes (ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, TP53) involved in PDAC susceptibility. We performed a systematic review of PubMed publications reporting germline variants identified in these genes in PDAC patients. Overall, the retrieved articles included 1493 PDAC patients. A high proportion of these patients (n = 1225/1493, 82%) were found to harbor alterations in genes (ATM, BRCA1, BRCA2, PALB2) involved in the homologous recombination repair (HRR) pathway. Specifically, the remaining PDAC patients were reported to carry alterations in genes playing a role in other cancer pathways (CDKN2A, STK11, TP53; n = 181/1493, 12.1%) or in the mismatch repair (MMR) pathway (MLH1, MSH2, MSH6, PMS2; n = 87/1493, 5.8%). Our findings highlight the importance of germline genetic characterization in PDAC patients for better personalized targeted therapies, clinical management, and surveillance.

Pancreatic Cancer: From Genetic Mechanisms to Translational Challenges

Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive malignancies in industrialized countries, is predicted to become the second leading cause of cancer deaths by 2040 [...].

Clinical Significance of Germline Pathogenic Variants among 51 Cancer Predisposition Genes in an Unselected Cohort of Italian Pancreatic Cancer Patients

Multigene germline panel testing is recommended for Pancreatic Cancer (PC) patients; however, for non-BRCA1/2 genes, the clinical utility is unclear. A comprehensive multi-gene assessment in unselected Italian PC patients is missing. We evaluated the prevalence and impact of Pathogenic Variants (PV) in 51 PC susceptibility genes in a real-world series of 422 Italian PC patients unselected for Family History (FH), compared the clinical characteristics and conducted survival analyses. 17% of patients had PVs (70/422), mainly in BRCA1/2 (4.5%, all <70 y), CDKN2A (4.5%, all >50 y), ATM (2.1%). PV carriers were younger (64 vs. 67; p = 0.02) and had more frequent personal/FH of PC, melanoma and breast/ovarian cancer (all p < 0.05). The Overall Survival (OS) was longer in patients carrying PVs (HR 0.78; p = 0.090), comprising ATM carriers (HR 0.33; p = 0.054). In the oxaliplatin-treated subset, PV carriers showed better control of the disease, although this was not statistically significant (67% vs. 56%). CDKN2A, BRCA2 and ATM were the most frequently altered genes. ATM PVs were positively associated with OS in 41% of PV carriers, 60% of whom carried CDKN2A,BRCA2 or ATM PVs, had negative FH and would have been missed by traditional referral. Thus, CDKN2A and ATM should be added to BRCA1/2 testing regardless of FH.

Predictors of germline status for hereditary melanoma: 5 years of multi-gene panel testing within the Italian Melanoma Intergroup

BACKGROUND

The incidence of cutaneous melanoma is increasing in Italy, in parallel with the implementation of gene panels. Therefore, a revision of national genetic assessment criteria for hereditary melanoma may be needed. The aim of this study was to identify predictors of susceptibility variants in the largest prospective cohort of Italian high-risk melanoma cases studied to date.

MATERIALS AND METHODS

From 25 Italian centers, we recruited 1044 family members and germline sequenced 940 cutaneous melanoma index cases through a shared gene panel, which included the following genes: CDKN2A, CDK4, BAP1, POT1, ACD, TERF2IP, MITF and ATM. We assessed detection rate according to familial status, region of origin, number of melanomas and presence and type of non-melanoma tumors.

RESULTS

The overall detection rate was 9.47% (5.53% analyzing CDKN2A alone), ranging from 5.14% in sporadic multiple melanoma cases (spoMPM) with two cutaneous melanomas to 13.9% in familial cases with at least three affected members. Three or more cutaneous melanomas in spoMPM cases, pancreatic cancer and region of origin predicted germline status [odds ratio (OR) = 3.23, 3.15, 2.43, P < 0.05]. Conversely, age > 60 years was a negative independent predictor (OR = 0.13, P = 0.008), and was the age category with the lowest detection rate, especially for CDKN2A. Detection rate was 19% when cutaneous melanoma and pancreatic cancer clustered together.

CONCLUSIONS

Gene panel doubled the detection rate given by CDKN2A alone. National genetic testing criteria may need a revision, especially regarding age cut-off (60) in the absence of strong family history, pancreatic cancer and/or a high number of cutaneous melanomas.

Mutations in key driver genes of pancreatic cancer: molecularly targeted therapies and other clinical implications

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a minimal difference between its incidence rate and mortality rate. Advances in oncology over the past several decades have dramatically improved the overall survival of patients with multiple cancers due to the implementation of new techniques in early diagnosis, therapeutic drugs, and personalized therapy. However, pancreatic cancers remain recalcitrant, with a 5-year relative survival rate of <9%. The lack of measures for early diagnosis, strong resistance to chemotherapy, ineffective adjuvant chemotherapy and the unavailability of molecularly targeted therapy are responsible for the high mortality rate of this notorious disease. Genetically, PDAC progresses as a complex result of the activation of oncogenes and inactivation of tumor suppressors. Although next-generation sequencing has identified numerous new genetic alterations, their clinical implications remain unknown. Classically, oncogenic mutations in genes such as KRAS and loss-of-function mutations in tumor suppressors, such as TP53, CDNK2A, DPC4/SMAD4, and BRCA2, are frequently observed in PDAC. Currently, research on these key driver genes is still the main focus. Therefore, studies assessing the functions of these genes and their potential clinical implications are of paramount importance. In this review, we summarize the biological function of key driver genes and pharmaceutical targets in PDAC. In addition, we conclude the results of molecularly targeted therapies in clinical trials and discuss how to utilize these genetic alterations in further clinical practice.

CDKN2A-Mutated Pancreatic Ductal Organoids from Induced Pluripotent Stem Cells to Model a Cancer Predisposition Syndrome

Patient-derived induced pluripotent stem cells (iPSCs) provide a unique platform to study hereditary disorders and predisposition syndromes by resembling germline mutations of affected individuals and by their potential to differentiate into nearly every cell type of the human body. We employed plucked human hair from two siblings with a family history of cancer carrying a pathogenic CDKN2A variant, P16-p.G101W/P14-p.R115L, to generate patient-specific iPSCs in a cancer-prone ancestry for downstream analytics. The differentiation capacity to pancreatic progenitors and to pancreatic duct-like organoids (PDLOs) according to a recently developed protocol remained unaffected. Upon inducible expression of KRAS^G12Dusing a piggyBac transposon system in CDKN2A-mutated PDLOs, we revealed structural and molecular changes in vitro, including disturbed polarity and epithelial-to-mesenchymal (EMT) transition. CDKN2A-mutated KRAS^G12DPDLO xenotransplants formed either a high-grade precancer lesion or a partially dedifferentiated PDAC-like tumor. Intriguingly, P14/P53/P21 and P16/RB cell-cycle checkpoint controls have been only partly overcome in these grafts, thereby still restricting the tumorous growth. Hereby, we provide a model for hereditary human pancreatic cancer that enables dissection of tumor initiation and early development starting from patient-specific CDKN2A-mutated pluripotent stem cells.

Insights into Genetic Susceptibility to Melanoma by Gene Panel Testing: Potential Pathogenic Variants in ACD, ATM, BAP1, and POT1

The contribution of recently established or candidate susceptibility genes to melanoma missing heritability has yet to be determined. Multigene panel testing could increase diagnostic yield and better define the role of candidate genes. We characterized 273 CDKN2A/ARF and CDK4-negative probands through a custom-designed targeted gene panel that included CDKN2A/ARF, CDK4, ACD, BAP1, MITF, POT1, TERF2IP, ATM, and PALB2. Co-segregation, loss of heterozygosity (LOH)/protein expression analysis, and splicing characterization were performed to improve variant classification. We identified 16 (5.9%) pathogenic and likely pathogenic variants in established high/medium penetrance cutaneous melanoma susceptibility genes (BAP1, POT1, ACD, MITF, and TERF2IP), including two novel variants in BAP1 and 4 in POT1. We also found four deleterious and five likely deleterious variants in ATM (3.3%). Thus, including potentially deleterious variants in ATM increased the diagnostic yield to about 9%. Inclusion of rare variants of uncertain significance would increase the overall detection yield to 14%. At least 10% of melanoma missing heritability may be explained through panel testing in our population. To our knowledge, this is the highest frequency of putative ATM deleterious variants reported in melanoma families, suggesting a possible role in melanoma susceptibility, which needs further investigation.

CDKN2A germline alterations in melanoma patients with personal or familial history of pancreatic cancer

CDKN2A germline mutations increase the risk of melanoma development and are present in 20 and 10% of familial and multiple melanoma cases, respectively. Pancreatic cancer has been associated with CDKN2A in some populations and, accordingly, its presence in first-degree or second-degree relatives of a melanoma patient is considered as a criterion for genetic testing. In this study, we show that in an area with low melanoma incidence, CDKN2A germline mutations in patients with melanoma and personal or family history of pancreatic cancer are mainly present in the setting of familial or multiple melanoma cases. In addition, a relatively young age (≤52 years) at pancreatic diagnosis is an additional single criterion that might also be considered.

CDKN2A Germline Rare Coding Variants and Risk of Pancreatic Cancer in Minority Populations

Background: Pathogenic germline mutations in the CDKN2A tumor suppressor gene are rare and associated with highly penetrant familial melanoma and pancreatic cancer in non-Hispanic whites (NHW). To date, the prevalence and impact of CDKN2A rare coding variants (RCV) in racial minority groups remain poorly characterized. We examined the role of CDKN2A RCVs on the risk of pancreatic cancer among minority subjects.Methods: We sequenced CDKN2A in 220 African American (AA) pancreatic cancer cases, 900 noncancer AA controls, and 183 Nigerian controls. RCV frequencies were determined for each group and compared with that of 1,537 NHW patients with pancreatic cancer. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for both a case-case comparison of RCV frequencies in AAs versus NHWs, and case-control comparison between AA cases versus noncancer AA controls plus Nigerian controls. Smaller sets of Hispanic and Native American cases and controls also were sequenced.Results: One novel missense RCV and one novel frameshift RCV were found among AA patients: 400G>A and 258_278del. RCV carrier status was associated with increased risk of pancreatic cancer among AA cases (11/220; OR, 3.3; 95% CI, 1.5-7.1; P = 0.004) compared with AA and Nigerian controls (17/1,083). Further, AA cases had higher frequency of RCVs: 5.0% (OR, 13.4; 95% CI, 4.9-36.7; P < 0.001) compared with NHW cases (0.4%).Conclusions: CDKN2A RCVs are more common in AA than in NHW patients with pancreatic cancer and associated with moderately increased pancreatic cancer risk among AAs.Impact: RCVs in CDKN2A are frequent in AAs and are associated with risk for pancreatic cancer. Cancer Epidemiol Biomarkers Prev; 27(11); 1364-70. ©2018 AACR.

CDKN2A germline mutations are not associated with poor survival in an Italian cohort of melanoma patients

BACKGROUND

Cyclin dependent kinase inhibitor 2A gene (CDKN2A) germline mutations have recently been associated with poor survival in patients with melanoma. Despite the high mutation rate in our cohort (up to 10% in patients with apparently sporadic melanoma), information on the impact of CDKN2A on survival in this cohort is lacking.

OBJECTIVE

To investigate whether poor survival associated with CDKN2A germline mutations was confirmed in a high mutation-prevalence cohort of Italian patients with melanoma undergoing a mutation-based follow-up.

METHODS

A total of 1239 patients with cutaneous melanoma were tested for CDKN2A mutational status and then assigned to a follow-up scheme according not only to family history but also to CDKN2A mutational status, as follow-up intervals were more frequent for CDKN2A germline mutation-positive (MUT⁺) patients. From this cohort, we selected 106 MUT⁺ patients (with familial melanoma or apparently sporadic melanoma) and 199 CDKN2A germline mutation-negative (MUT^-) patients with sporadic melanoma who were matched by age and sex and had a similar tumor stage distribution.

RESULTS

We found no difference in overall survival (hazard ratio, 0.85; 95% confidence interval, 0.48-1.52; P = .592,) or melanoma-specific survival (hazard ratio, 0.86; 95% confidence interval, 0.38-1.95; P = .718,) between MUT⁺ and MUT^- patients. MUT⁺ patients were more likely to develop multiple melanomas and to undergo surgical excision of dysplastic nevi than were MUT^- patients.

LIMITATIONS

Retrospective study.

CONCLUSION

CDKN2A mutations were not associated with survival in our cohort.

Genetic Alterations of Periampullary and Pancreatic Ductal Adenocarcinoma: An Overview

Pancreatic Ductal AdenoCarcinoma (PDAC) is one of the most lethal malignancies of all solid cancers. Precancerous lesions for PDAC include PanIN, IPMNs and MCNs. PDAC has a poor prognosis with a 5-year survival of approximately 6%. Whereas Periampulary AdenoCarcinoma (PAC) having four anatomic subtypes, pancreatic, Common Bile Duct (CBD), ampullary and duodenum shows relative better prognosis. The highest incidence of PDAC has been reported with black with respect to white population. Similarly, incidence rate of PAC also differs with different ethnic populations. Several lifestyle, environmental and occupational exposures including long-term diabetes, obesity, and smoking, have been linked to PDAC, however, for PAC the causal risk factors were poorly described. It is now clear that PDAC and PAC are a multi-stage process resulting from the accumulation of genomic alterations in the somatic DNA of normal cells as well as inherited mutations. Approximately 10% of PDAC have a familial inheritance. Germline mutations in CDKN2A, BRCA2, STK11, PALB2, PRSS1, etc., as well as certain syndromes have been well associated with predisposition to PDAC. KRAS, CDKN2A, TP53 and SMAD4 are the 4 "mountains" (high-frequency driver genes) which have been known to earliest somatic alterations for PDAC while relatively less frequent in PAC. Our understanding of the molecular carcinogenesis has improved in the last few years due to extensive research on PDAC which was not well explored in case of PAC. The genetic alterations that have been identified in PDAC and different subgroups of PAC are important implications for the development of genetic screening test, early diagnosis, and prognostic genetic markers. The present review will provide a brief overview of the incidence and prevalence of PDAC and PAC, mainly, increased risk in India, the several kinds of risk factors associated with the diseases as well as required genetic alterations for disease initiation and progression.

Functional analysis of a CDKN2A 5'UTR germline variant associated with pancreatic cancer development

CDKN2A coding region germline variants are associated with pancreatic adenocarcinoma (PC) susceptibility. Recently, we described functional germline 5’UTR CDKN2A variants from melanoma patients affecting the post-transcriptional regulation of p16^INK4a mRNA that is dependent, at least in part, on an Internal Ribosome Entry Site (IRES) in the 5’UTR region. Here we describe a 5’UTR c.-201_-198delinsCTTT CDKN2A variant (frequency 0.0028 based on 350 PC patients), which seems to be private to PC, since it has never been found in public databases nor in thousands of melanoma patients tested. Functional analyses confirmed IRES activity of the 5’UTR in BX-PC3 PC cells and revealed a functional impact of the identified variant. Using gene reporter assays we observed reduced translation potential in cells treated with the mTOR inhibitor Torin1, a condition that favors the assessment of IRES activity. At the endogenous gene level we quantified allelic imbalance among polysome-associated mRNAs using a patient-derived cell line heterozygous for the c.-201_-198delinsCTTT. Overall, we conclude that this very rare private variant can be considered a potential mutation, specifically associated with PC. Our data indicate that sequencing of the entire 5'UTR of CDKN2A should be included in routine screening of PC cases with suspected inherited susceptibility.

Multiple rare variants in high-risk pancreatic cancer-related genes may increase risk for pancreatic cancer in a subset of patients with and without germline CDKN2A mutations

The risk of pancreatic cancer (PC) is increased in melanoma-prone families but the causal relationship between germline CDKN2A mutations and PC risk is uncertain, suggesting the existence of non-CDKN2A factors. One genetic possibility involves patients having mutations in multiple high-risk PC-related genes; however, no systematic examination has yet been conducted. We used next-generation sequencing data to examine 24 putative PC-related genes in 43 PC patients with and 23 PC patients without germline CDKN2A mutations and 1001 controls. For each gene and the four pathways in which they occurred, we tested whether PC patients (overall or CDKN2A+ and CDKN2A- cases separately) had an increased number of rare nonsynonymous variants. Overall, we identified 35 missense variants in PC patients, 14 in CDKN2A+ and 21 in CDKN2A- PC cases. We found nominally significant associations for mismatch repair genes (MLH1, MSH2, MSH6, PMS2) in all PC patients and for ATM, CPA1, and PMS2 in CDKN2A- PC patients. Further, nine CDKN2A+ and four CDKN2A- PC patients had rare potentially deleterious variants in multiple PC-related genes. Loss-of-function variants were only observed in CDKN2A- PC patients, with ATM having the most pathogenic variants. Also, ATM variants (n = 5) were only observed in CDKN2A- PC patients with a family history that included digestive system tumors. Our results suggest that a subset of PC patients may have increased risk because of germline mutations in multiple PC-related genes.

Epidemiological and genetic factors underlying melanoma development in Italy

Among human cancers, melanoma remains one of the malignancies with an ever-growing incidence in white populations. Recent advances in biological and immunological therapeutic approaches as well as increased efforts for secondary prevention are contributing to improve the survival rates. It is likely that a significant fall in mortality rates for melanoma will be achieved by further increase of the early detection through a more accurate selection of the higher-risk individuals (i.e., carriers of predisposing genetic alterations). A similar scenario occurs in Italy. In the present review, we have considered data on incidence, survival and mortality rates of melanoma in Italian population, including evaluation of the main risk factors and genetic mutations underlying disease susceptibility.

Prevalence of the E318K MITF germline mutation in Italian melanoma patients: associations with histological subtypes and family cancer history

A French and an Australian study have recently identified a rare germline functional variant in the microphthalmia-associated transcription factor (MITF) (E318K) that predisposes to familial and sporadic melanoma and to renal cell carcinoma (RCC), showing a new link between two tumour types with different risk factors and between deregulated sumoylation and cancer. The aim of this study was to test the prevalence of the MITF E318K mutation in 667 Italian melanoma patients. We observed significant associations between histological subtypes and family cancer history. Carriers exhibited a nearly threefold higher risk of developing melanoma compared with controls. Carriers were also more likely to have developed multiple primary melanomas (6.40-fold), compared with wt patients. Carriers with a personal and/or family history of pancreatic cancer and kidney cancer had a nearly 31- and eightfold higher risk of developing melanoma compared with wt patients. Our findings further support MITF as a medium-penetrance melanoma susceptibility gene, highlight a potential association with histological subtypes and suggest that MITF may predispose to pancreatic cancer.

Contribution of germline mutations in the BRCA and PALB2 genes to pancreatic cancer in Italy

Pancreatic adenocarcinoma (PC) is the third most common cancer associated with BRCA mutations. Most notice has been given to BRCA2, while the association between BRCA1 and PC is less widely reported. Recently, PALB2 has been implicated in both PC and breast cancer (BC) susceptibility. We selected 29 Italian PC patients from a case-control study of PC according to their personal and family history of both PC and breast/ovarian cancer (BC/OC) and tested them for presence of germline mutations in BRCA1, BRCA2 and PALB2. We identified no germline mutations or deletions in PALB2, but detected 7 BRCA mutations (4 in BRCA1 and 3 in BRCA2). These findings suggest that PALB2 does not play a major role in PC susceptibility in our population. As we found an almost equal frequency of germline mutations in BRCA1 and BRCA2, germline alterations in either of these genes may explain a subset of Italian families presenting both PC and BC/OC. Moreover, as we began the observation of these families from probands who are affected by PC, we provide here a direct assessment of the role of PALB2 and BRCA mutations in PC susceptibility.

IRF-2 is over-expressed in pancreatic cancer and promotes the growth of pancreatic cancer cells

Pancreatic cancer is one of the most malignant diseases in the world. Interferon regulator factor 2 (IRF-2), an interferon regulatory factor, has been known to act as an oncogene in distinct types of cancer. In this study, we found that the expression of IRF-2 was up-regulated in primary pancreatic cancer samples and associated with tumor size, differentiation, tumor-node-metastasis stage, and survival of the patients. In pancreatic cancer cells, knockdown on the expression of IRF-2 inhibited cell growth in the liquid culture and on the soft agar. Mechanistically, IRF-2 modulated the growth of pancreatic cancer cells through regulating proliferation and apoptosis effectors, such as cyclin D1 and BAX. Collectively, these results suggest that IRF-2 plays an important role in the tumorigenesis of pancreatic cancer and down-regulation of IRF-2 would be a new treatment target for pancreatic cancer.

p16(Ink4a) overexpression in cancer: a tumor suppressor gene associated with senescence and high-grade tumors

p16(Ink4a) is a protein involved in regulation of the cell cycle. Currently, p16(Ink4a) is considered a tumor suppressor protein because of its physiological role and downregulated expression in a large number of tumors. Intriguingly, overexpression of p16(Ink4a) has also been described in several tumors. This review attempts to elucidate when and why p16(Ink4a) overexpression occurs, and to suggest possible implications of p16(Ink4a) in the diagnosis, prognosis and treatment of cancer.

Prevalence of CDKN2A mutations in pancreatic cancer patients: implications for genetic counseling

Germline mutations in CDKN2A have been reported in pancreatic cancer families, but genetic counseling for pancreatic cancer risk has been limited by lack of information on CDKN2A mutation carriers outside of selected pancreatic or melanoma kindreds. Lymphocyte DNA from consecutive, unselected white non-Hispanic patients with pancreatic adenocarcinoma was used to sequence CDKN2A. Frequencies of mutations that alter the coding of p16INK4 or p14ARF were quantified overall and in subgroups. Penetrance and likelihood of carrying mutations by family history were estimated. Among 1537 cases, 9 (0.6%) carried germline mutations in CDKN2A, including three previously unreported mutations. CDKN2A mutation carriers were more likely to have a family history of pancreatic cancer (P=0.003) or melanoma (P=0.03), and a personal history of melanoma (P=0.01). Among cases who reported having a first-degree relative with pancreatic cancer or melanoma, the carrier proportions were 3.3 and 5.3%, respectively. Penetrance for mutation carriers by age 80 was calculated to be 58% for pancreatic cancer (95% confidence interval (CI) 8-86%), and 39% for melanoma (95% CI 0-80). Among cases who ever smoked cigarettes, the risk for pancreatic cancer was higher for carriers compared with non-carriers (HR 25.8, P=2.1 × 10⁻¹³), but among nonsmokers, this comparison did not reach statistical significance. Germline mutations in CDKN2A among unselected pancreatic cancer patients are uncommon, although notably penetrant, especially among smokers. Carriers of germline mutations of CDKN2A should be counseled to avoid tobacco use to decrease risk of pancreatic cancer in addition to taking measures to decrease melanoma risk.

Germline MLH1 and MSH2 mutations in Italian pancreatic cancer patients with suspected Lynch syndrome

Lynch syndrome is an inherited cancer syndrome caused by germline mutations in mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. LS predisposes to high risk of early-onset colorectal, endometrial and other tumors. Patients with Lynch syndrome have also been shown to have an elevated risk for pancreatic cancer (PC). In this study, we aimed to estimate the frequency of suspected Lynch syndrome among a series of 135 PC patients. Further, we wanted to determine the frequency of MMR gene mutations in the suspected Lynch syndrome cases. We also aimed to verify the pathogenicity of any novel non-truncating variants we might detect with a functional assay. Based on personal and/or familial cancer history, 19 patients were classified as suspected Lynch syndrome cases. DNA material for mutation analysis was available for eleven of them. Four patients were found to carry a total of five MLH1 or MSH2 variants. Of these, MSH2-Q402X, MSH2-G322D, and MLH1-K618A had been previously reported, while the MSH2-E205Q and MSH2-V367I variants were novel. MSH2-Q402X is a known stop mutation and reported here for the first time here in association with PC. MLH1-K618A was found in the unaffected branch of a kindred, suggesting that it may be a polymorphism or a low penetrance variant. MSH2-G322D likely does not cause a MMR defect, although this variant has also been associated with breast cancer as indeed seen in our patient. The novel variants MSH2-E205Q and MSH2-V367I were found in the same patient. Both novel variants were however functional in the applied MMR assay. Our findings suggest that only a small subset of pancreatic cancer patients carry pathogenic MMR mutations.

Selection criteria for genetic assessment of patients with familial melanoma

Approximately 5% to 10% of melanoma may be hereditary in nature, and about 2% of melanoma can be specifically attributed to pathogenic germline mutations in cyclin-dependent kinase inhibitor 2A (CDKN2A). To appropriately identify the small proportion of patients who benefit most from referral to a genetics specialist for consideration of genetic testing for CDKN2A, we have reviewed available published studies of CDKN2A mutation analysis in cohorts with invasive, cutaneous melanoma and found variability in the rate of CDKN2A mutations based on geography, ethnicity, and the type of study and eligibility criteria used. Except in regions of high melanoma incidence, such as Australia, we found higher rates of CDKN2A positivity in individuals with 3 or more primary invasive melanomas and/or families with at least one invasive melanoma and two or more other diagnoses of invasive melanoma and/or pancreatic cancer among first- or second-degree relatives on the same side of the family. The work summarized in this review should help identify individuals who are appropriate candidates for referral for genetic consultation and possible testing.

Clinical genetic testing for familial melanoma in Italy: a cooperative study

BACKGROUND

The Italian Society of Human Genetics' (SIGU) recommendations on genetic counseling and testing for hereditary melanoma state that clinical genetic testing can be offered to Italian melanoma families with at least two affected members.

OBJECTIVE

In the framework of a cooperative study, we sought to establish the frequency of cyclin-dependent kinase inhibitor 2A mutations in melanoma families that underwent clinical genetic counseling and testing in accordance with the SIGU recommendations at 9 centers in different Italian regions.

METHODS

Cyclin-dependent kinase inhibitor 2A testing was conducted by direct sequencing and multiplex ligation-dependent probe amplification analysis in melanoma families with at least two affected members.

RESULTS

A total of 33% (68/204) of the families harbored cyclin-dependent kinase inhibitor 2A mutations. In the 145 families with two affected members the mutation frequency was 25%. Three novel mutations, L94P, A86T, and c.407dupG, were identified among the cases and not in 200 controls.

LIMITATIONS

We were unable to perform separate analyses for individual centers, as in some cases the number of families was too small.

CONCLUSIONS

The availability of clinical genetic testing for melanoma to families with just two affected members in the same branch is justified in Italy in terms of the likelihood of identifying a mutation.

Molecular biology of pancreatic cancer

Pancreatic cancer is a leading cause of cancer death. This devastating disease has the horrible honour of close to equal incidence and mortality rates. Late diagnosis and a constitutive resistance to every chemotherapy approach are responsible for this scenario. However, molecular biology tools in cooperation with translational efforts have dissected several secrets that underlie pancreatic cancer. Progressive acquisition of malignant, invasive phenotypes from pre-malignant lesions, recent revelations on core signalling pathways and new targeted designed trials offer a better future for pancreatic cancer patients. This review will summarise recent advances in the molecular biology of pancreatic cancer.

Genome analysis identifies the p15ink4b tumor suppressor as a direct target of the ZNF217/CoREST complex

The ZNF217 oncoprotein is a constituent of a core transcriptional complex that includes CoREST, histone deacetylase 1/2, lysine demethylase 1, and the C-terminal binding protein 1/2. We have combined genome-wide expression profiling and chromatin immunoprecipitation with directed selection and ligation (ChIP-DSL) to identify a subset of genes directly regulated by ZNF217. Our results establish p15(ink4b) as a direct target of the ZNF217 complex. Downregulation of ZNF217 in MCF-7 breast cancer cells resulted in a dramatic increase in p15(ink4b) expression and coincided with increases in dimethylation of H3-K4 and, surprisingly, a decrease in K9/K14-H3 acetylation. Stimulation of HaCaT cells with transforming growth factor beta (TGF-beta) resulted in a release of ZNF217 and a concomitant binding of SMAD2 to the proximal promoter, which preceded increases in ink4b protein expression. Furthermore, the changes in chromatin marks at the p15(ink4b) promoter following TGF-beta stimulation were similar to those observed following ZNF217 downregulation. Collectively, these results establish the ZNF217 complex as a novel negative regulator of the p15(ink4b) gene and may constitute an important link between amplification of ZNF217 and the loss of TGF-beta responsiveness in breast cancer.

Updated efficacy and toxicity analysis of irinotecan and oxaliplatin (IROX) : intergroup trial N9741 in first-line treatment of metastatic colorectal cancer

BACKGROUND

Efficacy and toxicity of oxaliplatin (Eloxatin; Sanofi-Aventis, Paris, France) combined with irinotecan (IROX) were examined in 383 patients enrolled on the IROX arm of Intergroup Study N9741.

METHODS

This IROX regimen was oxaliplatin 85 mg/m(2) and irinotecan 200 mg/m(2) administered every 3 weeks. The relation between adverse events on IROX to selected characteristics was analyzed. Time to progression (TTP), response rate, and overall survival for patients treated with IROX compared with patients treated with oxaliplatin with 5- fluorouracil (FOLFOX) were updated in this article.

RESULTS

Grade >or=3 gastrointestinal and hematologic toxicities were common with 39% patients experiencing neutropenia, 28% diarrhea, and 21% vomiting. Patients ages >70 years experienced higher rates of grade >or=3 toxicity, with significantly higher rates of grade >or=3 hematologic toxicities (P = .02). Long-term toxicity was uncommon, and nearly all cases of grade >or=3 neurotoxicity resolved within 10 months. Fifty-two percent of patients required dose reductions for adverse events, and 26% experienced 119 hospitalizations related to complications of treatment or their disease, with 5 treatment-related deaths. This analysis confirmed prior findings that FOLFOX is superior to IROX in terms of response rate (43% vs 36%, p = 0.002), TTP (9.2 months vs 6.7 months, P < .0001), and overall survival (19.5 months vs 17.3 months, P = .0001).

CONCLUSIONS

IROX was found to be less active than FOLFOX but with a similar toxicity profile except in patients ages >70 years. Although IROX may be considered in patients intolerant of 5-FU or in patients known to have a dihydropyrimidine dehydrogenase (DPD) deficiency, it should be used with caution in older patients.

Hereditary cancer syndrome diagnosis: molecular genetic clues and cancer control

Oncologists who are aware of the progress in hereditary cancer syndrome diagnosis, and, in particular, of how this effort may be effectively facilitated through a comprehensive family history in concert with molecular genetic studies, are in the envious position of designing highly targeted screening and management programs for the membership of these cancer-prone families. The Lynch syndrome is discussed as a clinical model wherein the presence of mismatch repair mutations provides a high level of diagnostic certainty for the initiation of targeted cancer screening and management. The familial atypical multiple mole melanoma-pancreatic cancer (FAMMM-PC) syndrome, on the other hand, provides another model with cancer-control potential. Given its phenotypic features of multiple atypical nevi, high total body mole count and cutaneous malignant melanoma, coupled with the integral association of PC in a subset of FAMMM kindreds with the CDKN2A germline mutation, this may result in a perhaps lower level of diagnostic certainty when compared with the Lynch syndrome. This knowledge may impact upon progress in the earlier diagnosis of melanoma and provide an impetus for creative diagnostic methods in PC, a disease that, at this time, demonstrates a mortality rate virtually identical to its incidence rate.

A Randomised Phase II Study of Irinotecan in Combination with 5-FU/FA Compared with Irinotecan Alone as Second-Line Treatment of Patients with Metastatic Colorectal Carcinoma

BACKGROUND

We conducted a randomised phase II study to compare irinotecan monotherapy with irinotecan in combination with infusional 5-fluorouracil/folinic acid (5-FU/FA) regarding efficacy and safety of these regimens in second-line therapy after failed fluoropyrimidine therapy in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

55 patients with mCRC after failure of a first-line therapy were randomised to receive either irinotecan 80 mg/m2 followed by FA 500 mg/m2 and 5-FU 2,000 mg/m2 24 h weekly for 6 weeks, with courses repeated on day 50 (arm A), or irinotecan 125 mg/m2 weekly for 4 weeks, with cycles repeated on day 43 (Arm B).

RESULTS

Both regimens yielded a partial response rate of 11% with identical progression-free survival (3.7 months for both regimens) and similar overall survival (9.5 months for the combination therapy vs. 10.7 months for the monotherapy). Both regimens were very well tolerated, and the combination of irinotecan with 5-FU/FA did not result in increased toxicity.

CONCLUSION

Our study confirms that irinotecan alone or in combination with infusional 5-FU/FA is an effective and safe regimen for CRC patients who failed first-line therapies. However, the role of 5-FU in addition to irinotecan for fluoropyrimidine failures remains unclear. Due to the small sample size, a decision cannot be made which therapy should be preferred, and a significant contribution to the efficacy of single-agent irinotecan is not obvious from this small randomised phase II trial.

Cell cycle arrest by the isoprenoids perillyl alcohol, geraniol, and farnesol is mediated by p21(Cip1) and p27(Kip1) in human pancreatic adenocarcinoma cells

Pancreatic cancer, the fourth leading cause of cancer-associated mortality in the United States, usually presents in an advanced stage and is generally refractory to chemotherapy. As such, there is a great need for novel therapies for this disease. The naturally derived isoprenoids perillyl alcohol, farnesol, and geraniol have chemotherapeutic potential in pancreatic and other tumor types. However, their mechanisms of action in these systems are not completely defined. In this study, we investigated isoprenoid effects on the cell cycle and observed a similar antiproliferative mechanism of action among the three compounds. First, when given in combination, the isoprenoids exhibited an additive antiproliferative effect against MIA PaCa-2 human pancreatic cancer cells. Furthermore, all three compounds induced a G(0)/G(1) cell cycle arrest that coincided with an increase in the expression of the cyclin kinase inhibitor proteins p21(Cip1) and p27(Kip1) and a reduction in cyclin A, cyclin B1, and cyclin-dependent kinase (Cdk) 2 protein levels. Immunoprecipitation studies demonstrated increased association of both p21(Cip1) and p27(Kip1) with Cdk2 as well as diminished Cdk2 kinase activity after isoprenoid exposure, indicating a cell cycle-inhibitory role for p21(Cip1) and p27(Kip1) in pancreatic adenocarcinoma cells. When siRNA was used to inhibit expression of p21(Cip1) and p27(Kip1) proteins in MIA PaCa-2 cells, conditional resistance to all three isoprenoid compounds was evident. Given similar findings in this cell line and in BxPC-3 human pancreatic adenocarcinoma cells, we conclude that the chemotherapeutic isoprenoid compounds perillyl alcohol, farnesol, and geraniol invoke a p21(Cip1)- and p27(Kip1)-dependent antiproliferative mechanism in human pancreatic adenocarcinoma cells.

Impact of E27X, a novel CDKN2A germ line mutation, on p16 and p14ARF expression in Italian melanoma families displaying pancreatic cancer and neuroblastoma

Mutations in the CDKN2A gene underlie melanoma susceptibility in as many as 50% of melanoma kindreds in selected populations, and several CDKN2A founder mutations have been described. Inherited mutations in CDKN2A have been found to be associated with other, non-melanoma cancers including pancreatic cancer (PC) and neural system tumors (NST). Here we report a novel germline mutation in exon 1 of the CDKN2A gene, E27X, which we first detected in melanoma patients living in or originally from a small geographic area bordering Liguria in north-western Italy. A subset of melanoma kindreds positive for this mutation displayed PC and neuroblastoma. E27X generates a premature stop codon, leading to dramatically reduced protein levels of p16 and leaving p14ARF unaltered. As PC and NSTs have been postulated to be preferentially associated with CDKN2A mutations located in exon 2 and/or affecting p14ARF alone, the position of E27X in exon 1alpha provides interesting insights towards clarifying the mechanisms by which the CDKN2A/ARF locus is involved in cancer predisposition.

NF-kappaB activation in melanoma

Metastatic melanoma is an aggressive skin cancer that is notoriously resistant to current cancer therapies. In human melanoma, nuclear factor-kappa B (NF-kappaB) is upregulated, leading to the deregulation of gene transcription. In this review, we discuss (i) the relationship between gene alteration in melanoma and upregulation of NF-kappaB, (ii) mechanisms by which activated NF-kappaB switch from pro-apoptotic to anti-apoptotic functions in melanoma and (iii) autocrine mechanisms that promote constitutive activation of NF-kappaB in metastatic melanoma.

Early onset may predict G101W CDKN2A founder mutation carrier status in Ligurian melanoma patients

Although the presence of multiple cases of melanoma on the same side of a family is the best predictor of germline CDKN2A mutation, other features (i.e. early age at onset) may be useful to identify carriers. We analysed the records of 682 hospital-based Ligurian melanoma patients. Of these, 238 cases (34 familial, 14 non-familial multiple primary and 190 non-familial single primary melanomas) were consecutively enrolled for screening of the CDKN2A and CDK4 genes. Screening of the 34 familial patients revealed that nine were carriers of the CDKN2A G101W founder mutation. Of the 14 non-familial multiple primary melanoma patients, three carried the G101W founder mutation and one the P48T mutation. For the non-familial patients with a single melanoma, 17 of 190 carried germline CDKN2A mutations, with most (16/17) carrying the G101W Ligurian founder mutation and one a novel single base pair substitution, D74Y. The effect of mutation on age at diagnosis was significant (P=0.012) after correcting for melanoma type (familial or non-familial), number of primaries (single or multiple), gender and disease occurrence (incident or prevalent). Early age at onset may be a good predictor of CDKN2A mutation in Liguria, where the G101W founder mutation is prevalent among melanoma patients, independent of family history.