Digital PCR identifies changes in CDH1 (E-cadherin) transcription pattern in intestinal-type gastric cancer

Abstract

E-cadherin is a cell-cell adhesion protein encoded by CDH1 tumor-suppressor gene. CDH1 inactivating mutations, leading to loss of protein expression, are common in gastric cancer of the diffuse histotype, while alternative mechanisms modulating E-cadherin expression characterize the more common intestinal histotype. These mechanisms are still poorly understood. CDH1 intron 2 has recently emerged as a cis-modulator of E-cadherin expression, encoding non-canonical transcripts. One in particular, CDH1a, proved to be expressed in gastric cancer cell lines, while being absent in the normal stomach. For the first time, we evaluated by digital PCR the expression of CDH1 and CDH1a transcripts in cancer and normal tissue samples from 32 patients with intestinal-type gastric cancer. We found a significant decrease in CDH1 expression in tumors compared to normal counterparts (P = 0.001), which was especially evident in 76% of cases. CDH1a was detected at extremely low levels in 47% of tumors, but not in normal mucosa. A trend was observed of having less CDH1 in tumors expressing CDH1atranscript. The majority of tumors with both a decrease in CDH1 and presence of CDH1a also showed a decrease in miR-101 expression levels. On the whole, the decrease of CDH1 transcript, corresponding to the canonical protein, and the presence of CDH1a, corresponding to an alternative isoform, are likely to perturb E-cadherin-mediated signaling and cell-cell adhesion, thus contributing to intestinal-type gastric carcinogenesis.

Bioinformatics and functional analyses of key genes and pathways in human clear cell renal cell carcinoma

“…CDH1 , as a member of the cadherin superfamily, may serve a critical role in apoptotic process and cell-cell adhesion ( 38 ). A previous study demonstrated that CDH1 expression was lower in gastric cancer and this decrease contributed to intestinal-type gastric carcinogenesis ( 39 ). Another study reported that attenuated expression of CDH1 had a key role in tumor invasion and metastasis ( 40 ).…”

Detection of a <em>CDH1</em> Rare Transcript Variant in Fresh-frozen Gastric Cancer Tissues by Chip-based Digital PCR

“…dPCR was originally developed for DNA molecular measurements 10,11,12,13 and in time this technology was adapted for the quantification of microRNAs and RNA transcripts 5,14,15 .…”

“…Hold the lid carefully by its side, peel away the protective film, and place the lid with the sticky face up in the correct orientation. 5. Carefully pick up a chip, taking care not to touch the internal part, and load it onto the chip nest in the correct position by pressing down the lever to open the clamp.…”

“…Loss of E-cadherin protein as a result of deleterious germline or somatic alterations of CDH1 has been associated with the development of GC 2,3 . Non-canonical transcripts arising from intron 2 of the gene have also been hypothesized to play a role in gastric carcinogenesis 4,5 . In particular, one such transcript, CDH1a, has been shown to be expressed in GC cell lines but is absent from the normal stomach 4 .…”

“…In particular, one such transcript, CDH1a, has been shown to be expressed in GC cell lines but is absent from the normal stomach 4 . We recently detected CDH1a in GC tissue samples from GC patients using chip-based dPCR 5 . dPCR was used to evaluate, for the first time, the presence of the CDH1a gene transcript in intestinal GC and in normal tissue.…”