DOG1 (clone K9) is seldom expressed and not useful in the evaluation of pancreatic neoplasms. Appl Immunohistochem Mol Morphol. 2012;20:397-401. [PMID: 22495382 DOI: 10.1097/pai.0b013e318246c345]

Transmembrane protein 16A in the digestive diseases: A review of its physiology, pharmacology, and therapeutic opportunities

Transmembrane protein 16A (TMEM16A) is a Ca2+-activated Cl- channel that is widely expressed in the digestive system, and numerous compounds have been developed for targeting TMEM16A. This review summarizes the current state of knowledge of physiological and pathological roles of TMEM16A in the digestive system, and discuss the potential therapeutic uses and challenges of TMEM16A modulators, with a focus on their selectivity, potency and molecular mechanisms as well as off-target tissue effects. We propose that TMEM16A exerts physiological and pathological roles in a tissue-specific or disease-specific way, and try to establish the idea that TMEM16A modulators are promising for therapeutic uses in digestive diseases such as secretory diarrhea, gastrointestinal motility disorders, and hepatobiliary and pancreatic diseases, as well as various cancers.

DOG1 is commonly expressed in pancreatic adenocarcinoma but unrelated to cancer aggressiveness

BACKGROUND

DOG1 (ANO1; TMEM16A) is a voltage-gated calcium-activated chloride and bicarbonate channel. DOG1 is physiologically expressed in Cajal cells, where it plays an important role in regulating intestinal motility and its expression is a diagnostic hallmark of gastrointestinal stromal tumors (GIST). Data on a possible role of DOG1 in pancreatic cancer are rare and controversial. The aim of our study was to clarify the prevalence of DOG1 expression in pancreatic cancer and to study its association with parameters of cancer aggressiveness.

METHODS

DOG1 expression was analyzed by immunohistochemistry in 599 pancreatic cancers in a tissue microarray format and in 12 cases of pancreatitis on large tissue sections.

RESULTS

DOG1 expression was always absent in normal pancreas but a focal weak expression was seen in four of 12 cases of pancreatitis. DOG1 expression was, however, common in pancreatic cancer. Membranous and cytoplasmic DOG1 expression in tumor cells was highest in pancreatic ductal adenocarcinomas (61% of 444 interpretable cases), followed by cancers of the ampulla Vateri (43% of 51 interpretable cases), and absent in 6 acinus cell carcinomas. DOG1 expression in tumor associated stroma cells was seen in 76 of 444 (17%) pancreatic ductal adenocarcinomas and in seven of 51 (14%) cancers of the ampulla Vateri. Both tumoral and stromal DOG1 expression were unrelated to tumor stage, grade, lymph node and distant metastasis, mismatch repair protein deficiency and the density of CD8 positive cytotoxic T-lymphocytes in the subgroups of ductal adenocarcinomas and cancers of ampulla Vateri. Overall, the results of our study indicate that DOG1 may represent a potential biomarker for pancreatic cancer diagnosis and a putative therapeutic target in pancreatic cancer. However, DOG1 expression is unrelated to pancreatic cancer aggressiveness.

Typing of pancreatic cancer-associated fibroblasts identifies different subpopulations

AIM

To determine whether it is possible to identify different immune phenotypic subpopulations of cancer-associated fibroblasts (CAFs) in pancreatic cancer (PC).

METHODS

We defined four different stromal compartments in surgical specimens with PC: The juxtatumoural, peripheral, lobular and septal stroma. Tissue microarrays were produced containing all pre-defined PC compartments, and the expression of 37 fibroblast (FB) and 8 extracellular matrix (ECM) markers was evaluated by immunohistochemistry, immunofluorescence (IF), double-IF, and/or in situ hybridization. The compartment-specific mean labelling score was determined for each marker using a four-tiered scoring system. DOG1 gene expression was examined by quantitative reverse transcription PCR (qPCR).

RESULTS

CD10, CD271, cytoglobin, DOG1, miR-21, nestin, and tenascin C exhibited significant differences in expression profiles between the juxtatumoural and peripheral compartments. The expression of CD10, cytoglobin, DOG1, nestin, and miR-21 was moderate/strong in juxtatumoural CAFs (j-CAFs) and barely perceptible/weak in peripheral CAFs (p-CAFs). The upregulation of DOG1 gene expression in PC compared to normal pancreas was verified by qPCR. Tenascin C expression was strong in the juxtatumoural ECM and barely perceptible/weak in the peripheral ECM. CD271 expression was barely perceptible in j-CAFs but moderate in the other compartments. Galectin-1 was stronger expressed in j-CAFs vs septal fibroblasts, PDGF-Rβ, tissue transglutaminase 2, and hyaluronic acid were stronger expressed in lobular fibroblasts vs p-CAFs, and plectin-1 was stronger expressed in j-CAFs vs l-FBs. The expression of the remaining 33 markers did not differ significantly when related to the quantity of CAFs/FBs or the amount of ECM in the respective compartments.

CONCLUSION

Different immune phenotypic CAF subpopulations can be identified in PC, using markers such as cytoglobin, CD271, and miR-21. Future studies should determine whether CAF subpopulations have different functional properties.

Is DOG1 Immunoreactivity Specific to Gastrointestinal Stromal Tumor?

BACKGROUND

DOG1 is a novel gene on gastrointestinal stromal tumors (GISTs) that encodes the chloride channel protein anoctamin 1, also known as discovered on GIST-1 (DOG1) protein. DOG1 antibodies are a sensitive and specific marker against GIST positive for CD117 and CD34 and negative for CD117 and CD34. DOG1 is also independent of KIT or PDGFRA mutation status and considered specific for GIST when it was first discovered in 2004.

METHODS

The previous 10 years of literature was searched for articles relating to DOG1. We critically reviewed 12 studies that showed DOG1 was positive in 250 cases of 2,360 tested non-GIST neoplasms (10.6%) at different anatomical sites using monoclonal, polyclonal, or nonspecified antibodies. Criteria for positivity varied between the studies.

RESULTS

Monoclonal and polyclonal DOG1 antibodies were reactive in various different non-GIST tumor types spanning 9 organ systems in addition to normal salivary and pancreatic tissues. The tumors included were renal oncocytoma (100%), renal cell carcinoma chromophobe type (86%), solid pseudopapillary neoplasm of the pancreas (51%), neoplastic salivary tissue (17%), synovial sarcoma (15%), leiomyoma (10%), pancreatic adenocarcinoma (7%), and leiomyosarcoma (4%).

CONCLUSIONS

By contrast to the original concept that DOG1 antibodies are specific to GIST neoplasms, the studies reviewed showed that the data suggest DOG1 positivity in select non-GIST tumors. Only in the appropriate clinical and pathological context is DOG1 positivity specific and helpful in the diagnosis of GIST.

Novel Use for DOG1 in Discriminating Breast Invasive Carcinoma from Noninvasive Breast Lesions

Aims. DOG1 has proven to be a useful marker of gastrointestinal stromal tumors (GISTs). Recently, DOG1 expression has also been reported in some non-GIST malignant tumors, but the details related to DOG1 expression in breast tissue remain unclear. The aim of this study was to detect the expression of DOG1 in the human breast and to evaluate the feasibility of using DOG1 to discriminate between invasive breast carcinoma and noninvasive breast lesions. Methods and Results. A total of 210 cases, including both invasive and noninvasive breast lesions, were collected to assess DOG1 expression immunohistochemically. DOG1 expression was consistently positive in breast myoepithelial cells (MECs), which was similar to the results obtained for three other MEC markers: calponin, smooth muscle myosin heavy chain (SMMHC), and P63 (P > 0.05 in all). Importantly, DOG1 was useful in discriminating invasive breast carcinoma from noninvasive breast lesions (P < 0.05). Conclusions. DOG1 is a useful marker of breast MECs, and adding DOG1 to the MEC identification panel will provide more sophisticated information when diagnosing uncertain cases in the breast.

Diagnosis and molecular aspects of solid-pseudopapillary neoplasms of the pancreas

Solid-pseudopapillary neoplasm of the pancreas (SPN) is an uncommon low-grade malignant neoplasm occurring mostly in young women. In addition to its distinctive pathological appearance of pseudopapillae with poorly cohesive neoplastic cells, rare variants exist raising the differential diagnosis especially with neuroendocrine neoplasms. The overall prognosis for patients with SPNs is excellent after surgical resection. Nevertheless, 10% of cases may have malignant behavior characterized by tumor recurrence and/or metastasis. Despite numerous studies, the histogenesis of this neoplasm remains unclear. Distinctive molecular alterations such as the presence of CTNNB1 mutations are observed in nearly all cases, while mutations classically observed in ductal adenocarcinoma, such as KRAS, TP53, and SMAD4, are not observed in SPNs, reinforcing its distinct nature compared to all other pancreatic neoplasms. Recent transcriptional studies have shown that activation of the Wnt/beta-catenin pathway in these tumors is associated with the upregulation of genes belonging to Notch, Hedgehog, and androgen receptor signaling pathways.