Insulinoma-associated protein 1 (INSM1) is an important biomarker of Achaete-scute homolog-like 1-driven pathways. For diagnosis of pancreatic neuroendocrine tumors (PanNET), chromogranin A (CGA), synaptophysin (SYP), and neural cell adhesion molecule (NCAM) were also considered as potential biomarkers. However, it is often difficult to diagnose it immunohistochemically. Hence, we examined the expression pattern of INSM1 in pancreatic solid tumors. We detected INSM1, CGA, SYP, and NCAM immunohistochemically, in 27 cases of NET [pure type: 25 cases, mixed adenoneuroendocrine carcinoma (MANEC): 2 cases]. We included 5 cases of solid-pseudopapillary neoplasm (SPN), 7 cases of acinar cell carcinoma (ACC), and 15 cases of pancreatic ductal adenocarcinoma (PDAC) as the control group. Nuclear expression of INSM1 was found in all PanNET pure type cases. However, expression of INSM1 was negative in PDAC, ACC, and SPN in all cases, whereas faint expression was seen in the cytoplasm from SPN. MANEC comprises of two components: neuroendocrine carcinoma and adenocarcinoma components. The NET component was positive for INSM1 expression, whereas the PDAC component does not express INSM1, which aids in distinguishing these components. Our results suggest that INSM1 is a useful immunohistochemical marker for diagnosing pancreatic neuroendocrine tumor.
Background/Aim: Lenvatinib is a potent inhibitor of receptor tyrosine kinases, targeting vascular endothelial growth factor receptors (VEGFR1-3), fibroblast growth factor receptors (FGFR1-4), KIT, and RET. Here, we investigated the antiproliferative effects of lenvatinib in liver cancer cells in vitro and in vivo. Materials and Methods: Eleven hepatocellular carcinoma cell lines and two combined hepatocellular/cholangiocarcinoma cell lines were treated with 0-30 μM lenvatinib. Cell growth, apoptosis and the expression of FGFR1-4, FGF19, fibroblast growth factor receptor substrate (FRS)2α and RET were examined. Two HCC cell lines were subcutaneously implanted on nude mice and mice were treated with 3, 10, 30 mg/kg/day of lenvatinib or vehicle for 14 consecutive days. Tumor volume was measured every 3 days. Mice were sacrificed on day 15 and tumors were processed for histological examination. Blood vessels, microvessel density, necrosis, and apoptosis were also examined. Results: Lenvatinib dose-and timedependently inhibited growth of all cell lines; however, sensitivity to lenvatinib varied. Apoptosis was not observed in any cell line, and expression of FGFR1, FGF19, FRS2α, and RET were observed in these cell lines. Cell lines with high expression of these factors showed higher response to lenvatinib. In mice, lenvatinib dosedependently suppressed tumor growth. Blood vessels and microvessel density were significantly reduced and the rate of necrosis was significantly increased by lenvatinib; apoptosis was not observed. Conclusion: Antiproliferative effects of lenvatinib on liver cancer cells were observed in vitro and in vivo. Lenvatinib may suppress tumor formation by inhibiting angiogenesis, and via an additional direct antiproliferative effect in some liver cancer cells.
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