Metaplastic Cells in the Stomach Arise, Independently of Stem Cells, via Dedifferentiation or Transdifferentiation of Chief Cells

Abstract

Spasmolytic polypeptide-expressing metaplasia (SPEM) develops in patients with chronic atrophic gastritis due to infection with Helicobacter pylori; it might be a precursor to intestinal metaplasia and gastric adenocarcinoma. Lineage tracing experiments of the gastric corpus in mice have not established whether SPEM derives from proliferating stem cells or differentiated, post-mitotic zymogenic chief cells in the gland base. We investigated whether differentiated cells can give rise to SPEM using a nongenetic approach in mice. Mice were given intraperitoneal injections of 5-fluorouracil, which blocked gastric cell proliferation, plus tamoxifen to induce SPEM. Based on analyses of molecular and histologic markers, we found SPEM developed even in the absence of cell proliferation. SPEM therefore did not arise from stem cells. In histologic analyses of gastric resection specimens from 10 patients with adenocarcinoma, we found normal zymogenic chief cells that were transitioning into SPEM cells only in gland bases, rather than the proliferative stem cell zone. Our findings indicate that SPEM can arise by direct reprogramming of existing cells-mainly of chief cells.

Keywords: Cancer; Development; Differentiation; Exocrine Cell.

Figure 1. SPEM can occur without proliferation

A) IHC staining for BrdU after one dose of 5FU (150mg/kg; intraperitoneal injection). Eosin Y counterstain. B) Experimental timeline and proliferation quantification. C) 5FU+HDT experimental timeline and proliferation quantification. D) Immunofluorescence of stomachs after 72h vehicle, 5FU, HDT, or 5FU+HDT treatment (red, GIF; green, GSII; blue, DAPI). Dotted line: gastric unit. E) Cell populations quantified, # indicates significance compared to vehicle, * indicates significance between treatment groups. R is significance between red columns, Y between yellow columns. F) Immunofluorescence of stomachs (red, GIF; green, Clusterin; blue, DAPI). *p≤0.05, **p≤0.01 ***p≤0.001, variance analyzed with ANOVA/Tukey (N ≥ 3 mice/group)

Figure 2. Metaplastic cells arise below the isthmus

A) Immunofluorescence of stomachs after 72h vehicle, 5FU, HDT, or 5FU+HDT (green, GSII; red, GIF; white, BrdU; blue, DAPI; arrowheads, rare BrdU⁺ cells in 5FU+HDT). B) Proliferating cell populations quantified. C) Location of BrdU⁺ cells below the bottom-most AAA⁺ pit cell. D) Hematoxylin & eosin of early human SPEM (yellow circle) E) Immunofluorescence on serial section from 2D (red, PGC; green, GSII; blue, DAPI; arrowhead: SPEM cell). Yellow circle is SPEM area. F) Human SPEM within gland base showing transitional ZC➔SPEM forms. Dotted box indicates area shown at higher magnification. Cells outlined in colors according to cell type (red, normal ZCs; blue, hybrid SPEM; yellow, full SPEM). *p≤0.05 **p≤0.01 ***p≤0.001, variance analyzed with ANOVA/Tukey (N ≥ 3 mice/group)