Mapping of a gene predisposing to familial thyroid tumors with cell oxyphilia to chromosome 19 and exclusion of JUN B as a candidate gene

Overview of the 2022 WHO Classification of Familial Endocrine Tumor Syndromes

This review of the familial tumor syndromes involving the endocrine organs is focused on discussing the main updates on the upcoming fifth edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. This review emphasizes updates on histopathological and molecular genetics aspects of the most important syndromes involving the endocrine organs. We describe the newly defined Familial Cancer Syndromes as MAFA-related, MEN4, and MEN5 as well as the newly reported pathological findings in DICER1 syndrome. We also describe the updates done at the new WHO on the syndromic and non-syndromic familial thyroid diseases. We emphasize the problem of diagnostic criteria, mention the new genes that are possibly involved in this group, and at the same time, touching upon the role of some immunohistochemical studies that could support the diagnosis of some of these conditions. As pathologists play an important role in identifying tumors within a familial cancer syndrome, we highlight the most important clues for raising the suspicious of a syndrome. Finally, we highlight the challenges in defining these entities as well as determining their clinical outcome in comparison with sporadic tumors. Instead of the usual subject review, we present the highlights of the updates on familial cancer syndromes by answering select questions relevant to practicing pathologists.

Familial nonmedullary thyroid cancer: a review of the genetics

OBJECTIVE

Thyroid cancer, the commonest of endocrine malignancies, continues to increase in incidence with over 19,000 new cases diagnosed in the European Union per year. Although nonmedullary thyroid cancer (NMTC) is mostly sporadic, evidence for a familial form, which is not associated with other Mendelian cancer syndromes (e.g., familial adenomatous polyposis and Cowden's syndrome), is well documented and thought to cause more aggressive disease. Just over a decade ago, the search for a genetic susceptibility locus for familial NMTC (FNMTC) began. This review details the genetic studies conducted thus far in the search for potential genes for FNMTC.

DESIGN

An electronic PubMed search was performed from the English literature for genetics of FNMTC and genetics of familial papillary thyroid carcinoma (subdivision of FNMTC). The references from the selected papers were reviewed to identify further studies not found in the original search criteria.

MAIN OUTCOME

Six potential regions for harboring an FNMTC gene have been identified: MNG1 (14q32), TCO (19p13.2), fPTC/PRN (1q21), NMTC1 (2q21), FTEN (8p23.1-p22), and the telomere-telomerase complex. Important genes reported to have been excluded are RET, TRK, MET, APC, PTEN, and TSHR.

CONCLUSION

The genetics of FNMTC is an exciting field in medical research that has the potential to permit individualized management of thyroid cancer. Studies thus far have been on small family groups using varying criteria for the diagnosis of FNMTC. Results have been contradictory and further large-scale genetic studies utilizing emerging molecular screening tests are warranted to elucidate the underlying genetic basis of FNMTC.

Chromosomal aberrations by comparative genomic hybridization in thyroid tumors in patients with familial nonmedullary thyroid cancer

PURPOSE

Nonmedullary thyroid cancer is the most common form of thyroid cancer and its familial form (FNMTC) is increasingly recognized as a distinct clinical entity. However, the genetic background of FNMTC is still poorly understood and the causative gene(s) have not yet been identified.

METHODS

Because comparative genomic hybridization allows for screening of the entire tumor genome simultaneously for chromosomal gains and/or losses without prior knowledge of potential aberrations, we used this technique in thyroid normal and neoplastic samples from FNMTC patients (1) to analyze whether chromosomal aberrations would correlate with inheritance pattern, and/or clinicopathologic features and (2) to compare comparative genomic hybridization (CGH) findings in familial tumors with those already known in sporadic differentiated thyroid cancers.

RESULTS

No common germline or somatic chromosomal aberrations were observed in patients with FNMTC because the frequencies and most locations of chromosomal aberrations in familial tumors were also common in sporadic tumors. However, some somatic aberrations were only found in familial tumors (gains in 2q, 3q, 18p, and 19p). Common aberrations in familial tumors corresponded to several locations of candidate genes already reported for sporadic thyroid tumorigenesis.

CONCLUSIONS

Our findings suggest that chromosomal aberrations in thyroid tumors in patients with FNMTC are not related to inheritance pattern but rather to tumorigenesis.

Chromosomal aberrations by comparative genomic hybridization in hürthle cell thyroid carcinomas are associated with tumor recurrence

Hürthle cell thyroid neoplasms are classified as variants of follicular neoplasms, but they have distinct clinicopathological features. Chromosomal aberrations by comparative genomic hybridization (CGH) are common in Hürthle cell neoplasms. However, there is currently only limited information concerning the relationship between the chromosomal aberrations by CGH and tumor behavior. We, therefore, investigated chromosomal aberrations in primary Hürthle cell neoplasms (13 carcinomas and 15 adenomas) using CGH and correlated the aberrations identified with tumor node metastasis (TNM) stage, tumor differentiation, capsular invasion, and tumor recurrence. Chromosomal aberrations were found in 62% (8 of 13) of carcinomas and 60% (9 of 15) of adenomas. Overall, common chromosomal gains were found on 5p (29%), 5q (36%), 7 (29%), 12p (14%), 12q (21%), 17p (29%), 17q (32%), 19p (32%), 19q (25%), 20p (21%), 20q (29%), and 22q (18%). Common chromosomal losses were found on 2q (18%) and 9q (18%). Thirty-eight percent (5 of 13) of carcinomas were TNM stage III, 31% (4 of 13) were moderately to poorly differentiated, and 46% (6 of 13) were intermediately to widely invasive. Recurrence occurred in 38% (5 of 13). Carcinomas that subsequently recurred had a greater number of chromosomal gains (9.0 vs. 1.3; <0.005) and had more frequent chromosomal gains on 12q, 19q, and 20p (<0.001), 5p, 7, 19p, and 20q (<0.005), and 12p (<0.01) than those that did not recur. Five of the eight (63%) patients with aberrations developed recurrence, whereas none of the five patients without aberrations developed recurrence. In conclusion, chromosomal gains by CGH on 5p, 7, 12p, 12q, 19p, 19q, 20p, and 20q in Hürthle cell carcinomas are associated with tumor recurrence. Such chromosomal aberrations may be predictive for recurrent disease in patients with Hürthle cell thyroid carcinoma.

Characterization and in silico mapping of a novel murine zinc finger transcription factor

Transcription factors play important roles in development and homeostasis. We have completed an embryonic stem cell-based neural differentiation screen, which was carried out with a view to isolating early regulators of neurogenesis. Fifty eight of the expressed sequence tags isolated from this screen represent known transcription factors or sequences containing transcription factor motifs. We have determined the full-length sequence of a novel mouse zinc finger-containing gene (ZFEND; also known as Mus musculus zinc finger protein 358 (Zfp358)) that was identified from this screen. ZFEND has 87% nucleotide and 86% amino acid identity to a previously identified human cDNA, FLJ10390, which is moderately similar to zinc finger protein 135. Northern blotting and RPAs demonstrate highest expression of ZFEND during mid-late mouse embryogenesis. Expression is also observed in several adult tissues with highest expression in heart, brain, and liver. Whole-mount in situ hybridization studies reveal apparent ubiquitous expression of ZFEND during mid-gestation stages (embryonic days 11.5, 12.5), while sections of whole-mount embryos reveal much higher expression levels in the neural folds during neural tube closure and at the boundary between the forelimb buds and the body wall. Bioinformatic analysis maps ZFEND to mouse chromosome 8pter, while FLJ10390 resides on 19p13.3-p13.2, a gene-rich region to which a number of disorders have been mapped. More precise mapping indicates that the involvement of FLJ10390 in atherogenic lipoprotein phenotype, familial febrile convulsions 2, and psoriasis susceptibility cannot be ruled out.

Differentiated thyroid carcinoma: a polygenic disease

Differentiated thyroid cancer is a rare disease and until recently was considered to be sporadic. However, increasing evidence has been found for a genetic basis of this disease. In approximately 5% of patients the differentiated thyroid cancer is dominantly inherited. Several families with different syndromes, of which differentiated thyroid cancer is a feature, have already been described. However, until now, single genes explain only a minority of cases. We hypothesize that differentiated thyroid cancer is a polygenic disease. Data from epidemiologic studies, about occult and multifocal carcinomas and the different response to specific risk factors contribute to this hypothesis.

Interaction of MCC2, a novel homologue of MCC tumor suppressor, with PDZ-domain Protein AIE-75

AIE-75 is a protein identified as an autoantigen in patients with autoimmune enteropathy and as a colon cancer-related antigen. It has recently been assigned to be a causative gene for Usher type 1C congenital syndromic hearing loss. The novel protein has three PSD-95/Dlg/ZO-1 (PDZ) protein-protein interaction domains and is therefore implicated to function as a molecular anchor or sorter. We have identified a novel protein that binds to AIE-75 by yeast two-hybrid screening. The protein has a high homology to the tumor suppressor MCC (mutated in colon cancer; or MCC1 hereafter) and was named MCC2. MCC2 protein binds the first PDZ domain of AIE-75 with its C-terminal amino acids -DTFL. Since the MCC1 does not bind to AIE-75 and the MCC2 displays different expression patterns in various organs compared to MCC1, they appear to play distinct roles in cells. The MCC2 gene is located on chromosome 19p13 in the vicinity of APCL gene, while MCC1 maps near to APC tumor suppressor gene. Because of negative expression of MCC2 in a panel of cancer cell-lines compared to the corresponding normal tissues, we suggest that further study is necessary to investigate a possible role of MCC2 as a tumor suppressor.