PubMed · 93699
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L Georgescu, M Drăgan, H Hornyatschek-Purea. [Ultrastructural changes in keratoacanthoma].. https://pubmed.ncbi.nlm.nih.gov/93699/
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Amphicrine carcinomas of the stomach, defined by dual exocrine and neuroendocrine differentiation within the same neoplastic cell, are exceedingly rare. MUTYH-associated polyposis (MAP) is an autosomal recessive polyposis syndrome characterized by multiple colorectal adenomas and variable upper gastrointestinal involvement; however, amphicrine carcinomas have not been previously documented in this setting. We report a gastric amphicrine carcinoma arising in the background of extensive fundic gland polyposis in a patient with MAP. Endoscopy revealed a 3.5-cm flat elevated lesion in the gastric fundus amid extensive fundic gland polyposis. Histologically, the tumor consisted of a single population of cells exhibiting combined glandular and neuroendocrine differentiation without zonal or biphasic architecture, and many of these cells demonstrated true amphicrine morphology. Immunohistochemistry confirmed co-expression of cytokeratin and the neuroendocrine markers chromogranin A and synaptophysin in the same cell population. Germline targeted next-generation sequencing identified biallelic MUTYH variants in trans (c.733C>T, p.Arg245Cys [likely pathogenic]; c.842C>T, p.Ala281Val [variant of uncertain significance]), supporting a diagnosis of MAP. To our knowledge, this is the first reported case of a gastric amphicrine carcinoma in a MAP patient, expanding the spectrum of MAP-associated upper gastrointestinal neoplasia and underscoring the importance of vigilant endoscopic surveillance in hereditary polyposis syndromes.
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Expression of the cysteine proteinase cathepsin B and its physiological inhibitor cystatin C was analyzed in vitro in 1 human fibrosarcoma and 4 human colon carcinoma cell lines. Cystatin C antigen as well as cathepsin B activity were detected in the conditioned media of the 5 cell lines. The corresponding cell extracts expressed high levels of cathepsin B activity, whereas only trace amounts of cystatin C antigen could be found. Northern-blot analysis revealed the presence in the 5 cell lines of a 0.8-kb cystatin C mRNA transcript and 2 cathepsin B transcripts of 2.3 and 4.3 kb. Pepsin treatment of tumor-cell-released cathepsin B induced an average 7.3-fold increase in activity, indicating that the enzyme was mainly present as a latent form in conditioned medium. The pepsin-activated cathepsin B from one colon carcinoma cell line was further characterized using the cysteine proteinase inhibitors E-64, recombinant cystatin C, a cystatin-C-derived peptidyl inhibitor (Z-LVG-CHN2), and cathepsin-B-specific diazomethyl ketone inhibitors (Z-FT(OBzl)-CHN2, Z-FS(OBzl)-CHN2). This activity was totally neutralized by recombinant cystatin C, suggesting a potential for interaction between released extracellular cathepsin B and cystatin C. In vitro assays of degradation of extracellular matrix showed that cysteine proteinase inhibitors could decrease matrix degradation induced by pepsin-activated conditioned media. With colon cells, this inhibition was not observed, indicating a requirement for an extracellular activation of latent cathepsin B. Our data provide evidence that cystatin C and latent cathepsin B are both released extracellularly by colon carcinoma cells in vitro. They suggest that cystatin C and cathepsin B interactions may participate, in an as yet unelucidated way, in the modulation of the invasive phenotype of human colonic tumors.