https://www.gastrojournal.org/article/S0016-5085(10)00169-1/pdf

Microsatellite Instability in Colorectal Cancer

Glioblastoma is the most frequent and most malignant human brain tumor. The prognosis remains very poor, with most patients dying within 1 year after diagnosis. Primary and secondary glioblastoma constitute distinct disease subtypes, affecting patients of different age and developing through different genetic pathways. The majority of cases (>90%) are primary glioblastomas that develop rapidly de novo, without clinical or histological evidence of a less malignant precursor lesion. They affect mainly the elderly and are genetically characterized by loss of heterozygosity 10q (70% of cases), EGFR amplification (36%), p16INK4a deletion (31%), and PTEN mutations (25%). Secondary glioblastomas develop through progression from low-grade diffuse astrocytoma or anaplastic astrocytoma and manifest in younger patients. In the pathway to secondary glioblastoma, TP53 mutations are the most frequent and earliest detectable genetic alteration, already present in 60% of precursor low-grade astrocytomas. The mutation pattern is characterized by frequent G:C→A:T mutations at CpG sites. During progression to glioblastoma, additional mutations accumulate, including loss of heterozygosity 10q25-qter (∼70%), which is the most frequent genetic alteration in both primary and secondary glioblastomas. Primary and secondary glioblastomas also differ significantly in their pattern of promoter methylation and in expression profiles at RNA and protein levels. This has significant implications, particularly for the development of novel, targeted therapies, as discussed in this review.

/pdf/genetic-pathways-to-primary-and-secondary-glioblastoma-54aazofmor.pdf

Genetic Pathways to Primary and Secondary Glioblastoma

We have come a long way since the first reports of the existence of aberrant DNA methylation in human cancer. Hypermethylation of CpG islands located in the promoter regions of tumor suppressor genes is now firmly established as an important mechanism for gene inactivation. CpG island hypermethylation has been described in almost every tumor type. Many cellular pathways are inactivated by this type of epigenetic lesion: DNA repair (hMLH1, MGMT), cell cycle (p16INK4a, p15INK4b, p14ARF), apoptosis (DAPK), cell adherence (CDH1, CDH13), detoxification (GSTP1), etc … However, we still know little of the mechanisms of aberrant methylation and why certain genes are selected over others. Hypermethylation is not an isolated layer of epigenetic control, but is linked to the other pieces of the puzzle such as methyl-binding proteins, DNA methyltransferases and histone deacetylase, but our understanding of the degree of specificity of these epigenetic layers in the silencing of specific tumor suppressor genes remains incomplete. The explosion of user-friendly technologies has given rise to a rapidly increasing list of hypermethylated genes. Careful functional and genetic studies are necessary to determine which hypermethylation events are truly relevant for human tumorigenesis. The development of CpG island hypermethylation profiles for every form of human tumors has yielded valuable pilot clinical data in monitoring and treating cancer patients based in our knowledge of DNA methylation. Basic and translational will both be needed in the near future to fully understand the mechanisms, roles and uses of CpG island hypermethylation in human cancer. The expectations are high.

CpG island hypermethylation and tumor suppressor genes: a booming present, a brighter future.

Only advances that occurred from 2011–2014 that either strengthen the previous 2011 guidelines [1;2] or lead to changes or additional guidelines are reviewed here. Advances and modifications in the treatment of advanced metastatic disease is only briefly dealt with here as it is covered in a separate chapter, similar to the 2011 guideline format [3]. The format used here is the same as used in the 2011 guidelines with page references to the appropriate section inserted [1;2] and this document is meant as a supplement to these guidelines and does not reiterate all of the points made in the previous guidelines, only changes, supporting findings or modifications of the 2011 guidelines are thus covered here.

As in the previous F-p-NET guidelines [1], the F-p-NETs will be considered in three groups: the more frequent gastrinomas and insulinomas considered independently and all the rare functional p-NETs (RFTs) considered together and as a separate category (Annex 1 and Table 1).

Table 1

Functional Pancreatic endocrine tumors [F-p-NET] syndromes

/pdf/enets-consensus-guidelines-update-for-the-management-of-26i0ksndvo.pdf

ENETS Consensus Guidelines Update for the Management of Patients with Functional Pancreatic Neuroendocrine Tumors and Non-Functional Pancreatic Neuroendocrine Tumors.

SUMMARYEpigenetic changes are present in all human cancers and are now known to cooperate with genetic alterations to drive the cancer phenotype. These changes involve DNA methylation, histone modifiers and readers, chromatin remodelers, microRNAs, and other components of chromatin. Cancer genetics and epigenetics are inextricably linked in generating the malignant phenotype; epigenetic changes can cause mutations in genes, and, conversely, mutations are frequently observed in genes that modify the epigenome. Epigenetic therapies, in which the goal is to reverse these changes, are now one standard of care for a preleukemic disorder and form of lymphoma. The application of epigenetic therapies in the treatment of solid tumors is also emerging as a viable therapeutic route.

/pdf/epigenetic-determinants-of-cancer-2shl5ap23w.pdf

Epigenetic Determinants of Cancer

Phosphatidylserine (PS), which is exposed on the surface of apoptotic cells, has been implicated in immune regulation. However, the effects of PS on the maturation and function of dendritic cells (DCs), which play a central role in both immune activation and regulation, have not been described. Large unilamellar liposomes containing PS or phosphatidylcholine were used to model the plasma membrane phospholipid composition of apoptotic and live cells, respectively. PS liposomes inhibited the up-regulation of HLA-ABC, HLA-DR, CD80, CD86, CD40, and CD83, as well as the production of IL-12p70 by human DCs in response to LPS. PS did not affect DC viability directly but predisposed DCs to apoptosis in response to LPS. DCs exposed to PS had diminished capacity to stimulate allogeneic T cell proliferation and to activate IFN-γ-producing CD4 + T cells. Exogenous IL-12 restored IFN-γ production by CD4 + T cells. Furthermore, activated CTLs proliferated poorly to cognate Ag presented by DCs exposed to PS. Our findings suggest that PS exposure provides a sufficient signal to inhibit DC maturation and to modulate adaptive immune responses.

/pdf/phosphatidylserine-regulates-the-maturation-of-human-2d0wzn3uq8.pdf

Phosphatidylserine Regulates the Maturation of Human Dendritic Cells

Reoperative parathyroidectomy: an algorithm for imaging and monitoring of intraoperative parathyroid hormone levels that results in a successful focused approach.

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) removes mutagenic adducts from the O6 position of guanine, thereby protecting the genome against G to A transition mutations. MGMT is inactivated by promoter hypermethylation in many human cancers and has been associated with G to A mutations in K-ras in colorectal cancer. We hypothesized that MGMT promoter hypermethylation would be associated with an increase in G to A transitions in the p53 gene in non-small cell lung cancer (NSCLC). p53 mutations were detected by both dideoxy sequencing and p53 GeneChip analysis in 92 patients with primary NSCLC. Methylation of the promoter region of the MGMT gene was determined using methylation-specific PCR and was present in 27 of 92 (29%) tumors. Hypermethylation of the MGMT promoter was more common in adenocarcinoma than in other histological types of NSCLC and was also more common in poorly differentiated tumors. MGMT promoter hypermethylation was present significantly more often in tumors with a G to A mutation in p53 (9 of 14; 64%) than in tumors with other types of p53 mutations (11 of 41; 27%; P = 0.02) or in tumors with wild-type p53 (7 of 37; 18%; P = 0.006). MGMT promoter hypermethylation was also strongly associated with G to A transitions at CpG sites. Inactivation of the MGMT gene by promoter hypermethylation alters the pattern of p53 mutation in NSCLC.

https://cancerres.aacrjournals.org/content/canres/61/22/8113.full.pdf

O6-Methylguanine-DNA Methyltransferase Promoter Hypermethylation Shifts the p53 Mutational Spectrum in Non-Small Cell Lung Cancer

Objective: To determine whether surgical volume influences the cause of operative failures after parathyroidectomy for hyperparathyroidism. Summary and Background Data: The surgical success rate for hyperparathyroidism from high-volume centers exceeds 95%, but some patients have unsuccessful parathyroidectomies. Although operative failure can be due to hyperfunctioning parathyroid glands in ectopic locations, less experienced surgeons may be more likely to miss an abnormal parathyroid in normal anatomic locations, which we describe as "preventable operative failure." Methods: We used 2 prospective databases containing over 2000 consecutive patients who underwent parathyroidectomy. We identified 159 patients with persistent/recurrent hyperparathyroidism subsequently cured with additional surgery. The initially failed operations were classified as being performed at high- (>50 cases/yr) or low-volume (<50 cases/yr) hospitals. Hospital volume was obtained from a Wisconsin state database of 89 hospitals, which reported 6336 parathyroid operations during the same decade. Results: Patients who initially failed their operation performed at the high-or low-volume centers were similar with regard to age, laboratory values, gender, and parathyroid weights. Despite a higher incidence of multigland disease (which increases the likelihood of operative failure) in the high-volume group, patients in the low-volume group were more likely to have a missed parathyroid gland in a normal anatomic location (89% vs. 13%, P < 0.0001), and thus a higher proportion of preventable operative failures. Conclusions: Surgical volume influences the failure pattern after parathyroidectomy for hyperparathyroidism. Preventable operative failures are more common in low-volume centers.

Operative failures after parathyroidectomy for hyperparathyroidism: the influence of surgical volume.

Microsatellite alterations are useful clonal markers for the early detection of cancer. An increase in microsatellite instability has been observed at certain tetranucleotide repeat markers (AAAGn) in lung, head and neck, and bladder cancer. However, the genetic mechanism underlying these elevated microsatellite alterations at selected tetranucleotide repeat (EMAST) tumors is still unknown. The p53 gene plays an important role in maintaining genome integrity by repairing damaged DNA. Therefore, we tested 88 non-small cell lung cancers with a panel of 13 microsatellite markers previously shown to exhibit frequent instability and also performed p53 sequence analysis in these tumors. Thirty-one of these 88 cancers (35%) demonstrated a novel allele [EMAST(+)] in > or =1 of these 13 microsatellite markers. p53 mutations were detected in 50 of 88 (57%) cancers and were significantly (P = 0.001) more common in EMAST(+) tumors (25 of 31; 81%) than in EMAST(-) tumors (25 of 57; 44%). Among squamous cell cancers, p53 mutations were detected significantly (P = 0.04) more frequently in EMAST(+) tumors (17 of 19; 89%) than in EMAST(-) tumors (10 of 18; 55%). Similarly, among primary adenocarcinomas, p53 mutations were present in 67% of the EMAST(+) tumors and in 35% of EMAST(-) adenocarcinomas. None of the 31 EMAST(+) tumors demonstrated high frequency microsatellite instability when examined with a reference panel of five mono- and dinucleotide markers. Primary lung cancers with microsatellite alterations at selected tetranucleotide repeats have a high frequency of p53 mutations and do not display a phenotype consistent with defects in mismatch repair.

https://cancerres.aacrjournals.org/content/canres/60/9/2488.full.pdf

Kara Doffek

Papers

Phosphatidylserine Regulates the Maturation of Human Dendritic Cells

Reoperative parathyroidectomy: an algorithm for imaging and monitoring of intraoperative parathyroid hormone levels that results in a successful focused approach.

O6-Methylguanine-DNA Methyltransferase Promoter Hypermethylation Shifts the p53 Mutational Spectrum in Non-Small Cell Lung Cancer

Operative failures after parathyroidectomy for hyperparathyroidism: the influence of surgical volume.

Microsatellite instability at selected tetranucleotide repeats is associated with p53 mutations in non-small cell lung cancer.