SMAD4 levels and response to 5-fluorouracil in colorectal cancer.

We have recently reported that low tumor levels of SMAD4, a key mediator of transforming growth factor-beta superfamily signaling, can predict the probability of recurrence in patients with Dukes C colorectal cancer who had surgery as the only form of treatment. However, standard treatment for Dukes C colorectal cancer patients currently involves the administration of 5-fluorouracil (5-FU)-based adjuvant chemotherapy after surgery. Approximately 30% to 40% of these patients present with recurrence and die within 5 years, and there is great need for markers capable of predicting poor prognosis after the combined surgery/adjuvant treatment.

Gene-expression profiling predicts recurrence in Dukes' C colorectal cancer.

Background & Aims: Although approximately 50% of Dukes' C colorectal cancer patients are surgically cured, it is currently not possible to distinguish these patients from those at high risk of recurrence. The recent advent of routine adjuvant chemotherapy for these patients has greatly complicated the identification of new markers predicting the response to surgery, which is now reliant on archived materials. Microarray analysis allows fine tumor classification but cannot be used with paraffin-embedded archival samples.

Preferential amplification of AURKA 91A (Ile31) in familial colorectal cancers.

In a previous genome-wide effort we identified a novel candidate colorectal cancer (CRC) susceptibility locus by allelotyping tumors from familial and sporadic CRC patients. Familial cases harbored amplifications significantly more frequently in 20q13, indicating the presence of a putative oncogene within the amplicon. A kinase-encoding AURKA is located in 20q13 and recently a Phe31Ile (91T > A) change of AURKA was suggested to function as a low penetrance tumor-susceptibility factor.

Mutations in two short noncoding mononucleotide repeats in most microsatellite-unstable colorectal cancers.

DNA mismatch repair (MMR)-deficient cells typically accumulate mutations in short repetitive DNA tracts. This microsatellite instability (MSI) facilitates malignant transformation when affecting genes with growth-related and caretaker functions. To date, several putative MSI target genes have been proposed mainly based on high mutation frequency within their coding regions.

SMAD4 as a prognostic marker in colorectal cancer.

More than 50% of patients with Dukes C colorectal cancer have disease recurrence and die within 5 years after surgical removal of their primary tumor. It is currently not possible to distinguish patients with good and bad prognosis. SMAD4 is an important tumor suppressor gene that mediates transforming growth factor-beta superfamily signaling and is located in chromosome 18q21, a region with frequent genetic losses in these tumors.

Colorectal pretumor progression before and after loss of DNA mismatch repair.

A pretumor progression model predicts many oncogenic cancer mutations may first accumulate in normal appearing colon. Although direct observations of early pretumor mutations are impractical, it may be possible to retrospectively reconstruct tumor histories from contemporary cancer mutations. To infer when and in what order mutations occur during occult pretumor progression, we examined 14 cancers from individuals with heterozygous germline mutations in DNA mismatch repair (MMR) genes or hereditary nonpolyposis colorectal cancer (HNPCC).

Differentially expressed genes in nonsmall cell lung cancer: expression profiling of cancer-related genes in squamous cell lung cancer.

The expression patterns of cancer-related genes in 13 cases of squamous cell lung cancer (SCC) were characterized and compared with those in normal lung tissue and 13 adenocarcinomas (AC), the other major type of nonsmall cell lung cancer (NSCLC). cDNA array was used to screen the gene expression levels and the array results were verified using a real-time reverse-transcriptase-polymerase chain reaction (RT-PCR). Thirty-nine percent of the 25 most upregulated and the 25 most downregulated genes were common to SCC and AC.

Biallelic inactivation of fumarate hydratase (FH) occurs in nonsyndromic uterine leiomyomas but is rare in other tumors.

Germline mutations in the fumarate hydratase (FH) gene at 1q43 predispose to dominantly inherited cutaneous and uterine leiomyomas, uterine leiomyosarcoma, and papillary renal cell cancer (HLRCC syndrome). To evaluate the role of FH inactivation in sporadic tumorigenesis, we analyzed a series of 299 malignant tumors representing 10 different malignant tumor types for FH mutations. Additionally, 153 uterine leiomyomas from 46 unselected individuals were subjected to and informative in loss of heterozygosity analysis at the FH locus, and the five (3.

Altered expression of MLH1, MSH2, and MSH6 in predisposition to hereditary nonpolyposis colorectal cancer.

Purpose: A considerable fraction (30% to 70%) of families with verified or putative hereditary nonpolyposis colorectal cancer fails to show mutations in DNA mismatch repair (MMR) genes. Our purpose was to address the genetic etiology of such families.

Materials And Methods: We scrutinized a population-based cohort of 26 families from Finland that had screened mutation-negative by previous techniques.

Little evidence for involvement of MLH3 in colorectal cancer predisposition.

Mutations in the DNA MMR genes MSH2, MLH1, MSH6 and PMS2 underlie a large subset of HNPCC cases, and a hallmark of the tumors is MSI. In many HNPCC families, however, a causative mutation has not been found. Therefore, the involvement of additional, thus far unknown, genes in MSI as well as MSS colorectal tumor predisposition is possible.

Genome-wide allelotyping of 104 Finnish colorectal cancers reveals an excess of allelic imbalance in chromosome 20q in familial cases.

We have allelotyped a series of 104 Finnish colorectal cancers (CRCs) using 372 polymorphic markers spaced, on average, at 10 cM intervals, and have made a comparison of the differences in the frequency of allelic imbalance (AI) between familial and sporadic cases. Differences in the frequency of allelic imbalance (loss of heterozygosity or amplification) at a number of loci were detected and these were evaluated through analysis of additional series of cancers using specific markers. The most consistent difference was observed at chromosome 20q13.

Induction of cyclooxygenase-2 in a mouse model of Peutz-Jeghers polyposis.

Inactivating germ-line mutations of LKB1 lead to Peutz-Jeghers syndrome (PJS). We have generated mice heterozygous for a targeted inactivating allele of Lkb1 and found that they develop severe gastrointestinal polyposis. In all cases, the polyps arising in the Lkb1+/- mice were found to be hamartomas that were histologically indistinguishable from polyps resected from PJS patients, indicating that Lkb1+/- mice model human PJS polyposis.

Few FH mutations in sporadic counterparts of tumor types observed in hereditary leiomyomatosis and renal cell cancer families.

Loss of function mutations in the fumarate hydratase (fumarase, FH) gene were recently identified as the cause for dominantly inherited uterine and cutaneous leiomyomas and renal cell cancer. To further evaluate the role of FH in tumorigenesis, we screened FH mutations from tumor types seen in hereditary leiomyomatosis and renal cell cancer mutation carriers-41 uterine and 10 cutaneous leiomyomas, 52 renal cell carcinomas, 53 sarcomas, 29 prostate carcinomas, and 15 lobular breast carcinomas. Few mutations were detected.

PTEN mutational spectra, expression levels, and subcellular localization in microsatellite stable and unstable colorectal cancers.

PTEN on 10q23.3 encodes a dual-specificity phosphatase that negatively regulates the phosphoinositol-3-kinase/Akt pathway and mediates cell-cycle arrest and apoptosis. Germline PTEN mutations cause Cowden syndrome and a range of several different hamartoma-tumor syndromes.

PolyA deletions in hereditary nonpolyposis colorectal cancer: mutations before a gatekeeper.

Microsatellite instability (MSI) secondary to loss of DNA mismatch repair (MMR) is present in adenomas and colorectal carcinomas from individuals with hereditary nonpolyposis colorectal cancer (HNPCC). To better characterize when MMR loss occurs during HNPCC progression, the extent of deletions in noncoding polyA sequences were compared between 6 adenomas (all < or = 1.0 cm in size) and 10 cancers.

Germline mutations in FH predispose to dominantly inherited uterine fibroids, skin leiomyomata and papillary renal cell cancer.

Uterine leiomyomata (fibroids) are common and clinically important tumors, but little is known about their etiology and pathogenesis. We previously mapped a gene that predisposes to multiple fibroids, cutaneous leiomyomata and renal cell carcinoma to chromosome 1q42.3-q43 (refs 4-6).