Somatic c.34G>T KRAS mutation: a new prescreening test for MUTYH-associated polyposis?

We investigated the somatic c.34G>T KRAS transversion as a marker suggestive of MUTYH-associated polyposis (MAP). We compared 86 adenomas and 19 colorectal cancers (CRCs) of 30 MAP patients to 135 adenomas and five CRCs of 47 familial adenomatous polyposis (FAP) patients. The c.34G>T mutation was investigated by DNA sequencing. Secondly, the germline MUTYH gene sequence was analyzed in patients carrying c.34G>T in CRCs diagnosed between 2008 and 2012. The c.34G>T was present in 39.7% of MAP adenomas versus 1.6% of FAP adenomas (P < 0.01). Sensitivity and specificity for detecting MAP were 39.7% and 98%, respectively. Sensitivity increased with the number of adenomas tested (P = 0.039). KRAS exon 2 analysis was performed on 2239 CRC and 2.2% harbored the c.34G>T transversion. Among 28 carriers of the c.34G>T mutation, biallelic MUTYH mutations were detected in seven patients (25%). One patient did not have any polyp or family history and did not fulfill criteria for MUTYH testing. With high specificity, the c.34G>T mutation seems to be a useful and promising test for MAP. For polyposis, it may guide genetic testing toward APC or MUTYH. If routinely performed in CRC patients, it could help to diagnose MUTYH-mutation carriers, even when they don't fulfill genetic testing criteria.

Frequent alteration of DNA damage signalling and repair pathways in human colorectal cancers with microsatellite instability

Accumulation of frameshift mutations at genes containing coding mononucleotide repeats is thought to be the major molecular mechanism by which mismatch repair-deficient cells accumulate functional alterations. These mutations resulting from microsatellite instability (MSI) can affect genes involved in pathways with a putative oncogenic role, but may also arise in genes without any expected role in MSI carcinogenesis because of the high mutation background of these tumours. We here screened 39 MSI colorectal tumours for the presence of mutations in 25 genes involved in DNA damage signalling and repair pathways. Using a maximum likelihood statistical method, these genes were divided into two different groups that differed significantly in their mutation frequencies, and likely represent mutations that do or do not provide selective pressure during MSI tumour progression. Interestingly, the so-called real-target mutational events were found to be distributed among genes involved in different functional pathways of the DNA metabolism, for example, DNA damage signalling (DNA-PKcs, ATR), double-strand break (DSB) repair (DNA-PKcs, RAD50), mismatch repair (MSH3, MSH6, MBD4) and replication (POLD3). In particular, mutations in MRE11 and/or RAD50 were observed in the vast majority of the tumours and resulted in the concomitant loss of immunohistochemical expression of both proteins. These data might explain why MSI colorectal cancers (CRC) behave differently in response to a wide variety of chemotherapeutic agents, notably those targeting DNA. More generally, they give further insights into how MSI leads to functional changes with synergistic effects in oncogenic pathways.

The eating disturbed spectrum in relation with coping and interpersonal functioning

Although much has been written with regards to the interpersonal functioning of eating-disordered women, research in the domain of eating disorders (ED) has still overlooked the complex relationships between stressful life events, coping styles, social and marital support while considering the ED spectrum.

OBJECTIVE

This study evaluates to what extent stressful life events, coping styles, and social support represent useful concepts for differentiating between four groups of participants with varying severity of eating preoccupations and disturbances.

METHOD

One hundred twenty-five participants were divided into four groups: 40 women suffering from ED, 21 women in remission from an ED, 33 women with intense weight and shape preoccupations, and 31 women without eating preoccupations. Each participant completed the Eating Disorder Evaluation, as well as questionnaires concerning stressful life events, coping styles, social support, and couple satisfaction.

RESULTS

There were significant differences between the groups in terms of negative impact of stressful events, social support, as well as task-oriented and emotion-oriented coping styles. Significant differences were not found between the groups for couple satisfaction.

CONCLUSION

It appears that accurate cognitive appraisal of stressful situations, adaptive coping styles and improvement of the social network represent interesting dimensions to include in prevention and treatment programs for ED. Moreover, for women in remission from an ED, an effective relapse prevention strategy could be to learn to make better use of their social network.