Angiotensin II (Ang-II) is a bioactive peptide associated closely with the progression and metastasis of colorectal cancer (CRC). We examined the expression and role of 2 Ang-II receptor types in 20 cases of CRC. Ang-II type 1 receptor (AT1R) protein was localized to the plasma membrane, whereas Ang-II type 2 receptor (AT2R) protein was localized to the nuclei. AT1R expression showed a direct correlation with tumor stage and liver metastasis, whereas AT2R expression showed an inverse correlation. A knockdown study of the AT1R or AT2R with Ang-II treatment was performed to reveal their individual roles in a mouse rectal cell line CMT93, which expresses both Ang-II receptor types. AT2R knockdown showed that the AT1R was associated with tumor growth, survival, invasion and VEGF-A secretion in CMT93 cells in a dose-dependent manner. In contrast, AT1R knockdown showed that the AT2R was associated with increased VEGF-A secretion at low Ang-II concentrations, whereas high concentrations of Ang-II inhibited tumor growth, survival, invasion and VEGF-A secretion. Thus, the AT1R showed a monophasic protumoral effect, while the AT2R showed a biphasic amphitumoral effect. Our findings suggest that a high angiotensinogen condition in the liver might evoke the antitumoral role of the AT2R in CRC cells.

MAS1 is a receptor for angiotensin 1-7 (A1-7), which is derived from angiotensin II (A-II) by the action of angiotensin converting enzyme (ACE) 2. MAS1 induces anti-A-II phenotypes, such as vessel dilation and depression of blood pressure. Using immunohistochemistry, we examined the role of MAS1 in 132 cases of invasive ductal carcinoma (IDC) of the breast. While benign mammary tissues expressed MAS1 at high levels, MAS1 expression was attenuated in all IDC, especially in scirrhous IDC. The decrease in MAS1 expression was associated with tumor growth, lymph node metastasis, and grade. MAS1 expression was inversely associated with the proliferation index and epidermal growth factor receptor and human epidermal growth factor receptor-2 expression. Of the 132 cases, 12 (9.1%) were triple-negative breast cancer (TNBC) cases. All TNBC cases (the 12 cases and the additional 36 cases using a tissue array) expressed MAS1. Using the TNBC cell lines 4T1 and MDA-MB-468, which expresses MAS1, we found that cell growth, anti-apoptotic survival and invasion were suppressed by MAS1 activation with A1-7 treatment and enhanced by MAS1 knockdown. In contrast, synergic effect was found between tamoxifen and A1-7 in a luminal A breast cancer cell line, MCF-7. Combination treatment with cisplatin, an ACE2 activator, and an A-II type 1 receptor blocker showed synergic effects on tumor growth inhibition of 4T1 tumors in a syngeneic mouse model. These findings suggest that MAS1 might act as an inhibitory regulator of breast cancer and may be a possible molecular target for this malignancy.

AKT is a protein in the phosphatidylinositol-3 kinase (PI3K) pathway and associated with diverse pro-tumoral responses. Activation of the human telomere reverse transcriptase (hTERT) is one of AKT's tumorigenic effects. In this study, the significance of AKT phosphorylation and hTERT on prognosis of gastric cancer were examined. AKT activation by epidermal growth factor increased hTERT expression and telomerase activity. In contrast, AKT inactivation by inhibitors and knockdown decreased hTERT expression and telomerase activity in MKN28 gastric cancer cells. In 40 gastric cancer tissues, significant correlations were found among the levels of phosphorylated AKT (pAKT), hTERT expression, and telomer length. The pAKT levels or the levels of pAKT/hTERT were not associated with clinicopathological parameters, including stage and nodal metastasis. However, survival rates of the pAKT-high patients or the pAKT-high and hTERT-high patients were significantly poorer than those in other patients. These findings suggest that AKT and hTERT are good molecular targets for the treatment of gastric cancer.

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Lysophosphatidic acid (LPA) interacts with at least six G protein-coupled transmembrane LPA receptors. Recently, it has been demonstrated that each LPA receptor acts as a positive or negative regulator of cellular function. In the present study, to assess a biological role of LPA receptors on cell migration of pancreatic cancer cells, we generated LPA receptor-1 (LPA(1)) and LPA(3) knockdown cells from hamster pancreatic cancer cells by transfection with short hairpin RNA plasmids and measured their cell motile and invasive abilities. In cell motility and invasion assay, a Cell Culture Insert, coated with or without a Matrigel, was used. While the cell motility and invasion of Lpar1 knockdown cells were markedly enhanced than those of control cells, Lpar3 knockdown cells showed significantly lower cell motility and invasion. Moreover, to investigate an involvement of LPA(1) and LPA(3) in the development of pancreatic cancers, we also measured the expression levels of Lpar1 and Lpar3 genes in hamster pancreatic duct adenocarcinomas (PDAs) induced by a nitroso compound. The expressions of Lpar1 gene in PDAs were significantly lower than those in normal pancreatic tissues. By contrast, the elevated expressions of Lpar3 gene were detected in PDAs. We thus demonstrate that LPA(1) and LPA(3) play the different roles on cell migration ability of pancreatic cancer cells, suggesting the opposite effects via LPA(1) and LPA(3) may contribute to the pathogenesis of pancreatic cancers in hamsters.