A clinician's guide to hereditary colon cancer

Tank Binding Kinase 1 modulates spindle assembly checkpoint components to regulate mitosis in breast and lung cancer cells

Error-free progression through mitosis is critical for proper cell division and accurate distribution of the genetic material. The anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase regulates the progression from metaphase to anaphase and its activation is controlled by the cofactors Cdc20 and Cdh1. Additionally, genome stability is maintained by the spindle assembly checkpoint (SAC), which monitors proper attachment of chromosomes to spindle microtubules prior to cell division. We had shown a role for Tank Binding Kinase 1 (TBK1) in microtubule dynamics and mitosis and here we describe a novel role of TBK1 in regulating SAC in breast and lung cancer cells. TBK1 interacts with and phosphorylates Cdc20 and Cdh1 and depletion of TBK1 elevates SAC components. TBK1 inhibition increases the association of Cdc20 with APC/C and BubR1 indicating inactivation of APC/C; similarly, interaction of Cdh1 with APC/C is also enhanced. TBK1 and TTK inhibition reduces cell viability and enhances centrosome amplification and micronucleation. These results indicate that alterations in TBK1 will impede mitotic progression and combining TBK1 inhibitors with other regulators of mitosis might be effective in eliminating cancer cells.

Mitotic checkpoint kinase Mps1/TTK predicts prognosis of colon cancer patients and regulates tumor proliferation and differentiation via PKCα/ERK1/2 and PI3K/Akt pathway

Mps1/TTK plays an important role in development of many tumors. The purpose of the present study was designed to investigate the role of TTK in colon cancer. We analyzed TTK and colon cancer in the GEO database, colon cancer tissues and normal tissues were collected to verify the results by immunohistochemistry. We detected the TTK expression in the colon cancer cell lines, and overexpressed or silenced TTK expression in colon cancer cell lines. GEO database showed that the expression of TTK was higher in the colon cancer tissues than normal tissues, higher level of TTK shows unfavourable prognosis in colon patients. Furthermore, high differentiation of colon shows the lower expression of TTK. The higher expression of TTK links with the high microsatellite status. However, the expression of TTK has no significant difference among the different stages of colon cancer patients, and has no significant relationship with recurrence or relapse. Here, we also report that the differential expression of TTK in colon cancer cells alters the intrinsic negative regulation of cell proliferation and differentiation, resulting in the difference of proliferation and differentiation capacity. TTK could activate the PKCα/ERK1/2 to influence the proliferation and inactivate the PI3K/AKT pathway to inhibition the expression of MUC2 and TFF3 that related to the differentiation of colon cells. In conclusions, TTK promote the colon cancer cell proliferation via activation of PKCα/ERK1/2 and inhibit the differentiation via inactivation of PI3K/Akt pathway. TTK inhibition may be the potential therapeutic pathway for the treatment of colon cancer.

Fas/CD95 deficiency in ApcMin/+ mice increases intestinal tumor burden

BACKGROUND

Fas, a member of the tumor necrosis family, is responsible for initiating the apoptotic pathway when bound to its ligand, Fas-L. Defects in the Fas-mediated apoptotic pathway have been reported in colorectal cancer.

METHODOLOGY/PRINCIPAL FINDINGS

In the present study, a variant of the Apc(Min/+) mouse, a model for the human condition, Familial Adenomatous Polyposis (FAP), was generated with an additional deficiency of Fas (Apc(Min/+)/Fas(lpr)) by cross-breeding Apc(Min/+) mice with Fas deficient (Fas(lpr)) mice. One of the main limitations of the Apc(Min/+) mouse model is that it only develops benign polyps. However, Apc(Min/+)/Fas(lpr) mice presented with a dramatic increase in tumor burden relative to Apc(Min/+) mice and invasive lesions at advanced ages. Proliferation and apoptosis markers revealed an increase in cellular proliferation, but negligible changes in apoptosis, while p53 increased at early ages. Fas-L was lower in Apc(Min/+)/Fas(lpr) mice relative to Apc(Min/+) cohorts, which resulted in enhanced inflammation.

CONCLUSIONS/SIGNIFICANCE

This study demonstrated that imposition of a Fas deletion in an Apc(Min/+) background results in a more aggressive phenotype of the Apc(Min/+) mouse model, with more rapid development of invasive intestinal tumors and a decrease in Fas-L levels.

Sulindac treatment alters collagen and matrilysin expression in adenomas of ApcMin/+ mice

Non-steroidal anti-inflammatory drugs (NSAIDs) have shown potential as chemopreventive agents against cancer formation, especially colorectal cancers. However, the mechanisms by which these drugs act are not fully understood. In this study, Apc(Min/+) mice, a genetic model of human familial adenomatous polyposis, were treated with sulindac, and these mice demonstrated tumor reduction of >80%, consistent with previous reports. Gene microarray analyses of RNA from adenoma-derived dysplastic epithelial cells revealed that collagen genes, viz. Col1a2, Col5a2, Col6a2 and Col6a3, were upregulated, and matrilysin matrix metalloproteases-7 (Mmp7) was downregulated, in sulindac-treated mice. Reverse transcription-polymerase chain reaction validated gene expression of the Col6a2 subunit of collagen VI and of Mmp7. Confocal microscopy and immunofluorescence showed that within the tumors of non-treated mice, collagen VI was present in low amounts, but was enhanced within the tumors of sulindac-treated mice. Collagens I and V demonstrated similar patterns, but were not as prominent as collagen VI. Mmp7 was found in 'hot spot' areas within the tumors of Apc(Min/+) mice treated with the vehicle, but was greatly diminished in those mice treated with sulindac. Studies with Apc(Min/+)/Mmp7(-/-) double-deficient mice demonstrated the reciprocal relationships of Mmp7 expression and the levels of these three collagens in vivo. The results of this study demonstrated that sulindac was effective in increasing the expression of different collagens and decreasing the expression of Mmp7, effects that may contribute to altered tumor burden in cancer patients undergoing NSAIDs treatments.

Self-Surveillance for Genetic Predisposition to Cancer: Behaviors and Emotions

PURPOSE/OBJECTIVES

To describe the kinds of self-monitoring activities and the emotional responses associated with those activities in patients with a genetic predisposition to multiple endocrine neoplasia type 2a (MEN2a) or familial adenomatous polyposis (FAP).

RESEARCH APPROACH

Thematic analysis of the transcripts of patient interviews conducted for two previous grounded theory investigations of participation in lifelong surveillance for patients with cancer predisposition syndromes and their family members.

SETTING

In the original studies, participants were recruited through a high-risk gastrointestinal cancer clinic (for FAP) and pediatric and adult endocrinology clinics (for MEN2a) at two eastern U.S. medical centers and by patient referral.

PARTICIPANTS

58 transcripts of interviews with 29 patients; 17 diagnosed with FAP or the variants of Gardner syndrome and attenuated FAP and 12 patients diagnosed with MEN2a.

METHODOLOGIC APPROACH

Informants participated in two hour-long, in-depth interviews and completed a self-administered sociodemographic questionnaire.

MAIN RESEARCH VARIABLES

Types of self-surveillance activities.

FINDINGS

Patients engage in an elaborate set of self-surveillance activities that are grouped into five categories of behavior: Medication Appraisal, Phenotype Tracking, Intake and Output Monitoring, Laboratory and Treatment Recording, and Tracking of Visits. Self-surveillance behaviors are grouped independent of type of syndrome, penetrance, age, or gender of the patient. Each category comprises a variety of behaviors that correspond with treatment recommendations and understanding of the disorder.

CONCLUSIONS

Self-surveillance may be driven by a combination of anticipation and the need for control and understanding.

INTERPRETATION

Findings from the study could be used to create an assessment tool to evaluate the extent to which patients are involved in day-to-day self-monitoring. Clinicians may use the categories to better understand patients' knowledge deficits and the emotional impact of enhanced vigilance. Self-surveillance activities performed by patients with MEN2a and FAP also may be performed by patients with other cancer predisposition syndromes.

Assessment of microsatellite instability in very small microdissected samples and in tumor samples that are contaminated with normal DNA

Microsatellite instability (MSI) testing is important for the management of young patients with colonic adenocarcinoma. Biopsies can be small and can be contaminated by normal cells. It is not known how sample size or contamination by non-neoplastic cell populations affects the interpretation of MSI assays. Serial microdissection targets (0.75 to 5.5 mm) were obtained from cases with high-level MSI. Polymerase chain reaction was performed for the standard National Cancer Institute recommended markers and products were analyzed by capillary electrophoresis. DNA from a patient with a BAT25 polymorphism was used to determine the sensitivity of detecting an aberrant allele in otherwise normal DNA. In small targets, MSI was seen sporadically in the setting of low DNA concentration. The results for small targets ranged from 1/4 to 5/5 loci with MSI, secondary to allelic dropout. In the sensitivity study, the aberrant allele was detected only when present at a concentration of above 10%. Allelic dropout can lead to under-estimation of the presence of MSI in small tissue samples or samples with low DNA concentration. Contaminating normal cell DNA can mask the presence of MSI. MSI testing on tissue fragments that are <5.5 mm can lead to a false-negative MSI test.