Prognostic values of L-type amino acid transporter 1 and CD98hc expression in breast cancer.

AIMS: L-type amino acid transporter 1 (LAT1) is a major Na+-independent neutral amino acid transporter, forming a complex with CD98hc. The aim of this study is to investigate the significance of LAT1 and CD98hc in invasive breast cancer. METHODS: LAT1 and CD98hc expression was immunohistochemically assessed in 280 invasive breast cancers and analysed for association with clinicopathological features. RESULTS: High levels of LAT1 and CD98hc were observed in triple-negative breast cancers (TNBCs) possessing negative immunoreactivity with oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2, compared with non-TNBCs (NTNBCs), and were associated with lymph-node metastasis and higher nuclear grade. The high-LAT1-expression group showed a poor prognosis in NTNBC and TNBC, however, high-CD98hc-expression group showed a poor prognosis only in NTNBC. LAT1 and CD98hc expression could be the prognostic factors in univariate analyses, but not in multivariate analyses. Further, we found that invasive tumour components showed higher LAT1 and CD98hc expression than non-invasive tumour components. CONCLUSIONS: LAT1 and CD98hc may possess prognostic values in invasive breast cancer. LAT1 may be linked with cancer cell activities and disease progression in breast cancer.

Biomarker Analyses in Patients With Advanced Solid Tumors Treated With the LAT1 Inhibitor JPH203.

BACKGROUND/AIM: Amino acids are among the most important nutrients for supplying energy and building protein blocks in cancers. L-type amino acid transporter (LAT) 1 is known to play a critical role in cancer growth. We have completed the first-in-human phase I study using the LAT1-specific inhibitor JPH203. PATIENTS AND METHODS: We evaluated plasma free amino acids (PFAAs), body mass index (BMI), and efficacy of JPH203 in patients enrolled in the phase I study. RESULTS: LAT1-substrate PFAAs and branched chain amino acids (BCAAs) were higher in patients with biliary tract cancer (BTC) than in those with other cancers. High inhibition of uptake of LAT1-substrate PFAAs was associated with survival. BMI of more than the median was associated with disease control and survival. BCAAs tended to be associated with BMI. CONCLUSION: BCAAs and BMI are useful predictors of the efficacy of JPH203, which shows promising activity against BTC.

Positive correlation of expression of L-type amino-acid transporter 1 with colorectal tumor progression and prognosis: Higher expression in sporadic colorectal tumors compared with ulcerative colitis-associated neoplasia.

The role of L-type amino-acid transporter 1 (LAT1), an oncofetal protein, in tumor progression is not well known, although it is important for the survival and proliferation of cancer cells. LAT1 expression was immunohistochemically analyzed and compared in sporadic (conventional) colorectal tumors and ulcerative colitis (UC)-associated neoplasia development and progression. LAT1 expression showed a significant stepwise increase in the order: conventional low-grade tubular adenoma, high-grade tubular adenoma, and invasive adenocarcinoma. Similarly, the same increasing trend in LAT1 expression was found in UC-associated low-grade dysplasia, high-grade dysplasia, and adenocarcinoma, whereas expression was significantly lower compared with that in an adenoma-adenocarcinoma series. LAT1 expression was predominant in the upper half of mucosal lesions in low-grade adenoma. This localized difference in LAT1 expression between the upper and lower halves of mucosal lesions disappeared in conventional high-grade adenoma and adenocarcinoma. LAT1 expression in the colorectal mucosa was significantly increased in the order: nontumor mucosa, quiescent phase of UC, and active phase of UC. Considering the histological pattern of Ki-67 labeling, LAT1 expression appeared partly related to cell proliferation, but this was not significant. In relation to the prognosis of patients with sporadic phase IV colorectal adenocarcinoma, this was significantly poorer in the group with high LAT1 expression compared with that with low LAT1 expression. This suggests LAT1 expression may be used as a companion biomarker for anti-cancer therapy targeting the LAT1 molecule in colorectal cancers.

Vitamin A Inhibits Development of Dextran Sulfate Sodium-Induced Colitis and Colon Cancer in a Mouse Model.

Vitamin A is essential to mucosal immunity and cell differentiation. The fact that lack of it might involve chronic inflammation and increased risk of cancer has been reported. Little is known about the mechanism of vitamin A deficiency in the development of colitis and its influence on development of colorectal cancer. To determine the influence of vitamin A deficiency on colitis and colorectal cancer development, an experimental study using a colitis mouse model was performed. Dextran sulfate sodium (DSS) colitis was induced in vitamin A-deficient and vitamin A-supplemented mice. Further, colorectal carcinoma was induced by a combination of azoxymethane preinjection and DSS colitis. Results were compared between the two groups mainly by immunohistochemical analysis. Colitis was more severe and recovery from colitis was slower in vitamin A-deficient mice than in vitamin A-supplemented mice. Compared with vitamin A-supplemented mice, vitamin A-deficient mice had decreases in colonic subepithelial myofibroblasts and the ratio of mucosal IgA(+)/IgG(+) cells, increases in CD11c(+) dendritic cells, and a higher rate of development of colorectal carcinoma with colitis following azoxymethane. Vitamin A lipid droplets in subepithelial myofibroblasts were decreased in vitamin A-deficient mice, suggesting alterations in colonic crypt niche function. Thus, vitamin A inhibited colitis and the development of colorectal cancer.

L-Type amino acid transporter 1 (LAT1) expression in lymph node metastasis of gastric carcinoma: Its correlation with size of metastatic lesion and Ki-67 labeling.

L-Type amino acid transporter 1 (LAT1) is one of the major amino acid transporters. High levels of LAT1 expression have been reported in various tumors, which can act as a novel prognostic marker. Previously, we demonstrated that LAT1 is highly expressed in advanced gastric carcinoma with lymph node metastasis, and proposed that LAT1 is an independent prognostic factor in non-scirrhous gastric carcinoma. The aim of the present study was to investigate the relationship between LAT1 expression and the size of lymph node metastatic lesions in gastric carcinoma. LAT1 and Ki-67 expression was immunohistochemically analyzed in 64 cases of advanced gastric carcinoma with lymph node metastasis. LAT1 expression in the metastatic lymph nodes was correlated with that in the primary lesions. The high LAT1 expression group showed a larger size of metastatic lesion and a higher Ki-67 labeling index than the low LAT1 expression group. LAT1 expression had a weak association with Ki-67 labeling index and tumor diameter of lymph nodes. These results suggest that LAT1 expression is associated with disease progression in gastric carcinoma. We proposed that LAT1 could be a potential therapeutic target for gastric carcinoma cases with large lymph node metastasis.

L-amino acid transporter 1 may be a prognostic marker for local progression of prostatic cancer under expectant management.

BACKGROUND: Oncocytic L-amino acid transporter (LAT) 1 could be a target of new molecular therapy against malignancies. OBJECTIVE: To assess the correlation between overexpression of LAT1 and local progression (LP) in prostatic carcinoma (PC) patients under expectant management (EM). METHODS: This retrospective study analyzed 109 patients with PC who received EM from 1991 to 2006. The expression of LAT1, LAT2, and CD98, as well as Ki-67 labeling indices (LI), was analyzed immunohistochemically in first biopsy or TUR samples diagnosed as adenocarcinomas. RESULTS: Of the 109 patients, 44 (40%) showed LP on clinical examinations, whereas 65 showed stable disease (SD). LAT1 score and intensity were significantly higher in the LP than in the SD group, as well as among Gleason score (GS)-low (GS < 7) patients who were associated with low-risk. When the LP group was subdivided by D'Amico risk category (low-, intermediate- and high-risk groups), each showed higher LAT1 expression than the SD group. LAT1 expression did not correlate with GS or Ki-67 LI. CONCLUSIONS: Independently of GS, aberrant overexpression of LAT1 in prostatic adenocarcinoma could predict LP under EM. Although prostate biopsy samples are small, LAT1 may be a novel prognostic biomarker of LP.

High expression of L-type amino acid transporter 1 as a prognostic marker in bile duct adenocarcinomas.

Oncocytic L-type amino acid transporter (LAT) 1 may be a prognostic indicator and target of new molecular therapeutic agents against malignancies. To investigate whether LAT1 expression influence the outcomes of patients with bile duct cancer, the expression of LAT1, LAT2, CD98, and Ki-67 was investigated immunohistochemically in 134 surgically resected bile duct adenocarcinomas, including 84 distal extrahepatic bile duct adenocarcinomas, 21 hilar cholangiocarcinomas, 15 intrahepatic cholangiocarcinomas, and 14 ampullary adenocarcinomas. LAT1 expression was weakly correlated with CD98 expression and Ki-67 labeling index (LI). Kaplan-Meier analysis showed a significant difference in prognosis between patients with bile duct adenocarcinomas having LAT1-high and -low scores, whereas LAT2 and CD98 expression and Ki-67 LI were not predictive of poor prognosis. Prognosis tended to be worse in patients having tumors with LAT1-high/LAT2-low than LAT1-low/LAT2-high scores (P = 0.0686). Multivariable analyses revealed that LAT1 expression, surgical margin, pT stage were independent prognostic factors. In conclusion, aberrant overexpression of LAT1 in bile duct adenocarcinoma predicts poor prognosis, suggesting that LAT1 may be a potential target of anticancer therapy.

L-type amino acid transporter 1 expression increases in well-differentiated but decreases in poorly differentiated endometrial endometrioid adenocarcinoma and shows an inverse correlation with p53 expression.

OBJECTIVES: The aims of this study were to determine whether the altered L-type amino acid transporter 1 (LAT1) expression is related to clinicopathologic factors, expressions of Ki-67, p53, estrogen receptor, and progesterone receptor and clarify the significance of LAT1 as a prognostic factor and the novel possibility of using it to treat endometrial endometrioid adenocarcinoma. METHODS: The LAT1 expression was analyzed immunohistochemically in atrophic (6 cases), secretory phase (6 cases), proliferative phase endometria (6 cases), atypical hyperplasia (6 cases), and endometrioid adenocarcinoma (26 well-differentiated [G1], 17 moderately differentiated, and 11 poorly differentiated [G3] adenocarcinoma patients). RESULTS: The LAT1 expression was observed in the cell membrane. Its expression increased in the atrophic, secretory, and proliferative phases of the endometrium in that order. There was no difference between the proliferative phase endometrium, atypical hyperplasia, and G1 adenocarcinoma. The LAT1 expression in G1 adenocarcinoma was significantly higher than that in G3 adenocarcinoma. The LAT1 expression was inversely correlated with p53 expression but not with those of Ki-67, estrogen receptor, or progesterone receptor. CONCLUSIONS: It is suggested that the significance of LAT1 as a prognostic factor is low because LAT expression was low in G3 adenocarcinoma, not correlated with the International Federation of Gynecology and Obstetrics stage and proliferative activity and inversely correlated with p53. The LAT1 inhibitors can be used as anticancer drugs for G1 and moderately differentiated adenocarcinoma that express high LAT1.

Unique and selective expression of L-amino acid transporter 1 in human tissue as well as being an aspect of oncofetal protein.

Dysregulated expression of L-type amino acid transporter 1 (LAT1), which transports large neutral amino acids, is a characteristic of various human cancers and possibly offers a molecular target for chemotherapy. LAT2, in contrast, shows lower expression in neoplasms. LAT1 is presumed to be a biomarker of many cancers, suggesting a kind of oncoprotein. However, no precise analysis of LAT1 and LAT2 expression has been performed in systemic normal tissues. To see characteristics of LAT1 and LAT2, immunohistochemical expression of LAT1 and LAT2 was assessed and compared in normal human systemic organs and tissues from 3 adults, 3 children and 3 fetuses in the present study. Cardiac muscles, hepatocytes, thymic epithelial cells and primitive neuroectodermal cells in fetus were positive with LAT1, whereas no expression was found in the respective adult tissues, indicating an aspect of oncofetal protein. In adult tissues, LAT1 was found to be expressed proximal to proliferative zones in gastrointestinal mucosa by double immunostaining of LAT1 and Ki-67. Testicular Sertoli cells, ovarian follicular cells, and pancreatic islet cells showed strong expression. Although the systemic capillary endothelium did not express LAT1, but did express LAT2, capillaries corresponding to the blood-brain, blood-follicle, and blood-retinal barriers demonstrated strong LAT1 immunoreactions. In conclusion, LAT1 was expressed in gonad tissues and several kinds of cells having special functions, as well as being discovered to be an aspect of oncofetal protein. In addition, ubiquitous LAT2 expression was confirmed immunohistochemically in systemic tissues, indicating constitutional function.

Small gastrointestinal stromal tumor in the stomach: identification of precursor for clinical gastrointestinal stromal tumor using c-kit and α-smooth muscle actin expression.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract. To find precursors for clinical GISTs of the stomach, small gastric stromal tumors of less than 3 cm were collected and examined immunohistochemically with analysis of the KIT mutation. Sixty-eight of 74 lesions were classified into 4 representative groups according to the expression of c-kit and α-smooth muscle actin (αSMA): group A, c-kit diffusely positive and αSMA negative (18 cases); group B, c-kit diffusely positive and αSMA focally positive (13); group C, c-kit focally positive and αSMA diffusely positive (27); and group D, c-kit negative and αSMA diffusely positive (10). Of the 4 groups, groups A and B of c-kit diffuse expression showed higher cellularity and labeling indices of p27(Kip1) and Ki-67 than did groups C and D of diffuse αSMA expression. Incidence of KIT exon 11 mutation in groups A and B was 86% (25/29), whereas that in groups C and D was 0% (0/20). Small gastric stromal tumors with c-kit diffuse expression were considered precursors for clinical GIST because they were significantly different from c-kit focally positive or negative tumors. The mutation of KIT is considered as an early event in tumorigenesis of GIST.

High expression of L-type amino acid transporter 1 (LAT1) predicts poor prognosis in pancreatic ductal adenocarcinomas.

BACKGROUND AND AIMS: Molecular target therapy against L-type amino acid transporter 1 (LAT1) is unique and expected to be developed soon. LAT1 expression was investigated in pancreatic cancer as a prognostic predictor. METHODS: Surgically resected pancreatic ductal adenocarcinomas (PDAC, n=66) were investigated using immunohistochemistry. For reference, intraductal papillary mucinous carcinomas (IPMC, including intraductal papillary mucinous neoplasm (IPMN) with high-grade dysplasia or with an associated invasive carcinoma, n=13) and adenomas (IPMA, including IPMN with low- and intermediate-grade dysplasia, n=5) were also examined. RESULTS: LAT1 expression scores increased from PDAC to IPMA to IPMC. Kaplan-Meier analysis showed significant differences between LAT1-high and -low scores in PDAC. Even in each Ki-67-labelling index (LI) low and high PDAC group (cut off 40%), high LAT1 expression could also predict poor prognosis. Multivariable analysis showed that LAT1 expression, Ki-67 LI, tumour differentiation and size were individual prognostic factors. CONCLUSIONS: LAT1 aberrant overexpression in PDAC predicts poor prognosis, independent of Ki-67 LI, and offers a potential target for future anticancer therapy with its inhibitors.

Cytoglobin expression of rectal subepithelial myofibroblasts: significant alterations of cytoglobin+ stromal cells in long-standing ulcerative colitis.

Cytoglobin/stellate cell activation-associated protein (Cygb/STAP), a hemoprotein, functions as part of an O2 reservoir with protective effects against oxidative stress in hepatic stellate cells. Heterogeneous expression of the neural cell adhesion molecule (NCAM)+ and/or α-smooth muscle actin (αSMA)+ has been noted in subepithelial myofibroblasts and interstitial cells of the same lineage in the colorectum. We have demonstrated that early genomic instability of both epithelial and stromal cells in ulcerative colitis (UC) is important for colorectal tumorigenesis, as well as for mucosal remodeling. To further clarify possible roles of stromal cells in mucosal remodeling and tumor development in UC, we here focused on Cygb expression of subepithelial myofibroblasts and interstitial cells, as well as αSMA and HSP47. Noncancerous mucosa of resected rectae from UC patients with or without colorectal neoplasia (14 and 20 cases, respectively) and of sporadic rectal cancer cases (16) was analyzed immunohistochemically, as well as by immuno-fluorescence and electron microscopy. The results, heterogeneous phenotypes of Cygb+, αSMA+ and HSP47+ subepithelial myofibroblasts and interstitial cells, corresponding to rectal stellate cells, were demonstrated. A decrease of Cygb+ subepithelial myofibroblasts and an increase of αSMA+ interstitial cells were significant in UC, as compared to normal rectal mucosa. Furthermore, a decrease of Cygb+ subepithelial myofibroblasts, correlating with αSMA+ and HSP47+ cells, was significant in long-standing UC with neoplasia. In conclusion, there are heterogeneous phenotypes of Cygb+, αSMA+ and HSP47+ subepithelial myofibroblasts and interstitial cells in the rectal mucosa. Mucosal remodeling with alterations of Cygb+ and/or αSMA+/HSP47+ stromal cells might have some relation to UC-associated tumorigenesis.

Mucosal remodeling in long-standing ulcerative colitis with colorectal neoplasia: significant alterations of NCAM+ or alpha-SMA+ subepithelial myofibroblasts and interstitial cells.

Evidence has been provided in ulcerative colitis (UC) that early genomic instability of both epithelial and stromal cells is important for colorectal tumorigenesis, as well as remodeling and morphological alterations of mucosal crypts. To clarify roles of stromal cells in tumor development in UC, the present study focused on heterogeneous phenotypes of subepithelial myofibroblasts and interstitial cells, in association with mucosal remodeling. To clarify the relationship of alterations to tumorigenesis, mucosa of resected rectae from patients with UC (n= 49) and sporadic cancer (n= 10) were analyzed on immunohistochemistry and also on immunoelectron microscopy. Heterogeneous phenotypes of neural cell adhesion molecule (NCAM)+ and/or alpha-smooth muscle actin (alpha-SMA)+ subepithelial myofibroblasts and interstitial cells were demonstrated, corresponding to colonic stellate cells. Decrease of NCAM+ subepithelial myofibroblasts and interstitial cells, and increase of alpha-SMA+ interstitial cells were significant in UC with neoplasia as compared to without neoplasia. alpha-SMA+ muscularis mucosae was significantly more thickened in tumor cases. Deposits of Masson's trichrome+ and type III and I collagen in the muscularis mucosae and lamina propria appeared to increase in relation to the numbers of alpha-SMA+ interstitial cells. Mucosal remodeling with alterations of NCAM+ or alpha-SMA+ subepithelial and interstitial cells may play a critical role in UC-associated tumorigenesis.

Correlation of enhanced cell turnover with prognosis of gastrointestinal stromal tumors of the stomach: relevance of cellularity and p27kip1.

The aim of the present study was to determine whether expression of molecules associated with cell cycle regulation and apoptosis might reflect tumor grade and patients' prognosis of gastrointestinal stromal tumor (GIST). Forty-nine cases of gastric GIST were divided into three grades; low, intermediate, and high risk. Ki-67, cyclin A, cyclin D1, cyclin E, p16(Ink4), p21(Waf1), p27(Kip1), cyclin-dependent kinase (cdk)2, cdk4 and single-strand DNA (ssDNA) were immunohistochemically stained and assessed. Ki-67, ssDNA, cyclin A and cdk2 had higher labeling indices (LI) in high-risk than in low-risk cases. Cyclin E expression was greater in the intermediate- than in the low-risk grade. On Kaplan-Meier analysis, tumor size, necrosis, cellularity, Ki-67, ssDNA, and cyclin A LI were significantly correlated with disease-free survival. Necrosis, cellularity, and Ki-67 LI were significant as prognostic factors on univariate, and Ki-67 LI on multivariate Cox hazard tests. Within the high-risk grade, high cellularity and low p27(Kip1) subgroups had the worst prognosis. The histological grade is related to cell turnover, assessed in terms of Ki-67, ssDNA, cyclin A, cyclin E, and cdk2 levels. Ki-67, ssDNA, and cyclin A are useful for prediction of prognosis, with cellularity and p27(Kip1) expression as further prognostic factors in high-risk cases.

Significant increase of colonic mutated crypts correlates with age in sporadic cancer and diverticulosis cases, with higher frequency in the left- than right-side colorectum.

Mild periodic acid-Schiff (mPAS) staining can discriminate non-O-acetylated (mPAS-positive) from O-acetylated (mPAS-negative) epithelial sialoglycoproteins in human colonic mucosa, allowing the three haplotypes expressed from a single polymorphic autosomal gene (oat) to be distinguished. In heterozygotes, we previously demonstrated wholly mPAS-positive (stem cell mutated) crypts and clusters of two or more mPAS-positive crypts to be significantly increased with duration of ulcerative colitis. To establish whether such an increase in the number of mutated crypts with age also occurs in normal individuals or in cases with diverticulosis, the O-acetylation phenotype in the non-cancerous colonic mucosa of 47 sporadic colorectal cancer patients who were heterozygotes for oat was tested with mild-PAS staining. PAS-positive crypts were assessed histologically in relation to age and compared between the left (sigmoid colon and rectum) and right (cecum and ascending colon) sides of the colorectum. Wholly mPAS-positive (stem cell mutated) crypts and foci in heterozygotes were found to be increased significantly (P < 0.0001) in the left side with aging (r = 0.598 and 0.643, respectively). Such a positive correlation with aging was also confirmed in 19 diverticulosis cases without cancer (r = 0.797 and 0.793, respectively). The frequency of mutated crypts and foci on the right side was significantly lower than on the left side in both spontaneous colorectal cancer and diverticulosis cases. The results provide support for an intimate relationship between accumulation of mutated crypts with aging, possibly with significance for colorectal cancer development. Furthermore, the environment in the right side of the colon may be different from that in the left side in this regard.

Significant increase of colonic mutated crypts in ulcerative colitis correlatively with duration of illness.

Mild periodic acid-Schiff (mPAS) staining can discriminate non-O-acetylated(mPAS positive) from O-acetylated (mPAS negative) epithelial sialoglycoproteins in human colonic mucosa, giving three haplotypes of expression of a single polymorphic autosomal gene (oat). Increase in mPAS-positive crypts in heterozygotes is an indication of mutations, and wholly mPAS-positive (stem cell mutated) crypts and clusters of two or more mPAS-positive crypts in heterozygotes of ulcerative colitis (P < 0.0001) were found to be increased significantly, compared with controls. The observed correlation with ulcerative colitis duration (r = 0.892 and 0.853, respectively) supports a chronic inflammation-carcinoma sequence.