Gene Summary

Gene:SLC34A2; solute carrier family 34 member 2
Aliases: NPTIIb, NAPI-3B, NAPI-IIb
Summary:The protein encoded by this gene is a pH-sensitive sodium-dependent phosphate transporter. Phosphate uptake is increased at lower pH. Defects in this gene are a cause of pulmonary alveolar microlithiasis. Three transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, May 2010]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:sodium-dependent phosphate transport protein 2B
Source:NCBIAccessed: 16 March, 2017


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: SLC34A2 (cancer-related)

Clavé S, Gimeno J, Muñoz-Mármol AM, et al.
ROS1 copy number alterations are frequent in non-small cell lung cancer.
Oncotarget. 2016; 7(7):8019-28 [PubMed] Free Access to Full Article Related Publications
OBJECTIVES: We aimed to determine the prevalence and partners of ROS1 rearrangements, to explore the correlation between FISH and IHC assays, and to investigate clinical implications of ROS1 copy number alterations (CNAs).
METHODS: A total of 314 NSCLC patients were screened using ROS1 FISH break-apart probes. Of these, 47 surgical tumors were included in TMAs to analyze ROS1 heterogeneity assessed either by FISH and IHC, and chromosome 6 aneusomy. To characterize ROS1 partners, probes for CD74, EZR, SLC34A2 and SDC3 genes were developed. ROS1 positive FISH cases were screened also by IHC.
RESULTS: Five patients were ROS1 positive (1.8%). We identified two known fusion partners in three patients: CD74 and SLC34A2. Four out of five ROS1 rearranged patients were female, never smokers and with adenocarcinoma histology. Rearranged cases were also positive by IHC as well. According to ROS1 CNAs, we found a prevalence of 37.8% gains/amplifications and 25.1% deletions.
CONCLUSIONS: This study point out the high prevalence of ROS1 CNAs in a large series of NSCLC. ROS1 gains, amplifications and deletions, most of them due to chromosome 6 polysomy or monosomy, were heterogeneous within a tumor and had no impact on overall survival.

Ge G, Zhou C, Ren Y, et al.
Enhanced SLC34A2 in breast cancer stem cell-like cells induces chemotherapeutic resistance to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling.
Tumour Biol. 2016; 37(4):5049-62 [PubMed] Related Publications
Even though early detection methods and treatment options are greatly improved, chemoresistance is still a tremendous challenge for breast cancer therapy. Breast cancer stem cells (BCSCs) represent a subpopulation that is central to chemoresistance. We aim to investigate the relationship between SLC34A2 and chemoresistance in BCSCs and identify the underlying mechanisms by which SLC34A2 regulates chemoresistance in BCSCs. Fluorescence Activated Cell Sorting (FACS) analysis showed the presence of a variable fraction of CD44(+)CD24(-) cells in 25 out of 25 breast cancer samples. We cultured primary breast cancer sample cells and breast cancer cell line cells to induce sphere formation in serum-free medium. Following sorting of CD44(+)CD24(-) cells from spheres, we showed that CD44(+)CD24(-) cells displayed stem cell-like features and were resistant to chemotherapy drug doxorubicin. Significantly, enhanced SLC34A2 expression correlated with chemoresponse and survival of breast cancer patients. We subsequently indicated that increased SLC34A2 expression in BCSCs directly contributed to their chemoresistance by a series of in vitro and in vivo experiments. Furthermore, we demonstrated that SLC34A2 induced chemoresistance in BCSCs via SLC34A2-Bmi1-ABCC5 signaling. Finally, we showed that ABCC5 was a direct transcriptional target of Bmi1 by chromatin immunoprecipitation (ChIP). In conclusion, our work indicated that decreased SLC34A2 expression sensitized BCSCs to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling and shed new light on understanding the mechanism of chemoresistance in BCSCs. This study not only bridges the missing link between stem cell-related transcription factor (Bmi1) and ABC transporter (ABCC5) but also contributes to development of potential therapeutics against breast cancer.

Wang Y, Yang W, Pu Q, et al.
The effects and mechanisms of SLC34A2 in tumorigenesis and progression of human non-small cell lung cancer.
J Biomed Sci. 2015; 22:52 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: SLC34A2 with highest expressions in lung, small intestine and kidney encoded a type 2b sodium-dependent phosphate transporter (NaPi-IIb). In lung, SLC34A2 only expressed in the apical membrane of type II alveolar epithelium cells (ATII cells) and played a pivotal role during the fetal lung development and embryonic development. ATII cells acting as multifunctional stem cells might transform into NSCLC after undergoing exogenous or endogenous factors. Increasing evidences showed that the genes performing critical roles during embryogenesis were also expressed during the development of cancer. In addition, recent research found the expression of SLC34A2 had a significant difference between the surgical samples of NSCLC and normal tissues, and SLC34A2 was down-regulated in lung adenocarcinoma cell line A549 and up-regulation expression of SLC34A2 could significantly inhibit cell viability and invasion of A549 in vitro. These results suggested SLC34A2 might play an important role in the development of NSCLC. However, the role of SLC34A2 in tumorigenesis and progression of NSCLC remains unknown.
RESULTS: Our study found that SLC34A2 was also significantly down-regulated in 14/15 of examined NSCLC tissues. Moreover, we found that expressions of SLC34A2 were reduced in six NSCLC cell lines for the first time. Our result also revealed a dramatic inhibitory effects of SLC34A2 on cell growth, migration and invasion of several NSCLC cell lines. SLC34A2 also strongly inhibited tumor growth and metastasis ability in A549 subcutaneous tumor model and lung metastasis model, respectively. Further studies found that the suppressive effects of SLC34A2 on tumorigenesis and progression might be associated with the down-regulation of related protein in PI3K/Akt and Ras/Raf/MEK signal pathway.
CONCLUSIONS: For the first time, our data indicated that SLC34A2 could exert significantly suppressive effects on tumorigenesis and progression of NSCLC. SLC34A2 might provide new insights for further understanding the early pathogenesis of human NSCLC.

Lin K, Rubinfeld B, Zhang C, et al.
Preclinical Development of an Anti-NaPi2b (SLC34A2) Antibody-Drug Conjugate as a Therapeutic for Non-Small Cell Lung and Ovarian Cancers.
Clin Cancer Res. 2015; 21(22):5139-50 [PubMed] Related Publications
PURPOSE: Antibody-drug conjugates (ADC) selectively deliver a cytotoxic drug to cells expressing an accessible antigenic target. Here, we have appended monomethyl auristatin E (MMAE) to an antibody recognizing the SLC34A2 gene product NaPi2b, the type II sodium-phosphate cotransporter, which is highly expressed on tumor surfaces of the lung, ovary, and thyroid as well as on normal lung pneumocytes. This study evaluated its efficacy and safety in preclinical studies.
EXPERIMENTAL DESIGN: The efficacy of anti-NaPi2b ADC was evaluated in mouse ovarian and non-small cell lung cancer (NSCLC) tumor xenograft models, and its toxicity was assessed in rats and cynomolgus monkeys.
RESULTS: We show here that an anti-NaPi2b ADC is effective in mouse ovarian and NSCLC tumor xenograft models and well-tolerated in rats and cynomolgus monkeys at levels in excess of therapeutic doses. Despite high levels of expression in normal lung of non-human primate, the cross-reactive ADC exhibited an acceptable safety profile with a dose-limiting toxicity unrelated to normal tissue target expression. The nonproliferative nature of normal pneumocytes, together with the antiproliferative mechanism of MMAE, likely mitigates the potential liability of this normal tissue expression.
CONCLUSIONS: Overall, our preclinical results suggest that the ADC targeting NaPi2b provides an effective new therapy for the treatment of NSCLC and ovarian cancer and is currently undergoing clinical developments.

Lindegren S, Andrade LN, Bäck T, et al.
Binding Affinity, Specificity and Comparative Biodistribution of the Parental Murine Monoclonal Antibody MX35 (Anti-NaPi2b) and Its Humanized Version Rebmab200.
PLoS One. 2015; 10(5):e0126298 [PubMed] Free Access to Full Article Related Publications
The aim of this preclinical study was to evaluate the characteristics of the monoclonal antibody Rebmab200, which is a humanized version of the ovarian-specific murine antibody MX35. This investigation contributes to the foundation for future clinical α-radioimmunotherapy of minimal residual ovarian cancer with 211At-Rebmab200. Here, the biodistribution of 211At-Rebmab200 was evaluated, as was the utility of 99mTc-Rebmab200 for bioimaging. Rebmab200 was directly compared with its murine counterpart MX35 in terms of its in-vitro capacity for binding the immobilized NaPi2B epitope and live cells; we also assessed its biodistribution in nude mice carrying subcutaneous OVCAR-3 tumors. Tumor antigen and cell binding were similar between Rebmab200 and murine MX35, as was biodistribution, including normal tissue uptake and in-vivo tumor binding. We also demonstrated that 99mTc-Rebmab200 can be used for single-photon emission computed tomography of subcutaneous ovarian carcinomas in tumor-bearing mice. Taken together, our data support the further development of Rebmab200 for radioimmunotherapy and diagnostics.

Cargnelutti M, Corso S, Pergolizzi M, et al.
Activation of RAS family members confers resistance to ROS1 targeting drugs.
Oncotarget. 2015; 6(7):5182-94 [PubMed] Free Access to Full Article Related Publications
The ROS1 tyrosine kinase is activated in lung cancer as a consequence of chromosomal rearrangement. Although high response rates and disease control have been observed in lung cancer patients bearing rearranged ROS1 tumors (ROS1+) treated with the kinase inhibitor crizotinib, many of these patients eventually relapse.To identify mechanisms of resistance to ROS1 inhibitors we generated resistant cells from HCC78 lung cancer cells bearing the SLC34A2-ROS1 rearrangement. We found that activation of the RAS pathway in the HCC78 cell model, due to either KRAS/NRAS mutations or to KRAS amplification, rendered the cells resistant to ROS1 inhibition. These cells were cross-resistant to different ROS1 inhibitors, but sensitive to inhibitors of the RAS signaling pathway. Interestingly, we identified focal KRAS amplification in a biopsy of a tumor from a patient that had become resistant to crizotinib treatment.Altogether our data suggest that the activation of members of the RAS family can confer resistance to ROS1 inhibitors. This has important clinical implications as: (i) RAS genetic alterations in ROS1+ primary tumors are likely negative predictors of efficacy for targeted drugs and (ii) this kind of resistance is unlikely to be overcome by the use of more specific or more potent ROS1 targeting drugs.

Wijesinghe P, Bepler G, Bollig-Fischer A
A mass spectrometry assay to simultaneously analyze ROS1 and RET fusion gene expression in non-small-cell lung cancer.
J Thorac Oncol. 2015; 10(2):381-6 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: ROS1 and RET gene fusions were recently discovered in non-small-cell lung cancer (NSCLC) as potential therapeutic targets with small-molecule kinase inhibitors. The conventional screening methods of these fusions are time-consuming and require samples of high quality and quantity. Here, we describe a novel and efficient method by coupling the power of multiplexing polymerase chain reaction and the sensitivity of mass spectrometry.
METHODS: The multiplex mass spectrometry platform simultaneously tests samples for the expression of nine ROS1 and six RET fusion genes. The assay incorporates detection of wild-type exon junctions immediately upstream and downstream of the fusion junction to exclude false-negative results. To flag false-positives, the system also comprises two independent assays for each fusion gene junction.
RESULTS: The characteristic mass spectrometric peaks of the gene fusions were obtained using engineered plasmid constructs. Specific assays targeting the wild-type gene exon junctions were validated using complimentary DNA from lung tissue of healthy individuals. The system was further validated using complimentary DNA derived from NSCLC cell lines that express endogenous fusion genes. The expressed ROS1-SLC34A2 and CCDC6-RET gene fusions from the NSCLC cell lines HCC78 and LC-2/ad, respectively, were accurately detected by the novel assay. The assay is extremely sensitive, capable of detecting an event in test specimens containing 0.5% positive tumors.
CONCLUSION: The novel multiplexed assay is robustly capable of detecting 15 different clinically relevant RET and ROS1 fusion variants. The benefits of this detection method include exceptionally low sample input, high cost efficiency, flexibility, and rapid turnover.

Lindskog C, Fagerberg L, Hallström B, et al.
The lung-specific proteome defined by integration of transcriptomics and antibody-based profiling.
FASEB J. 2014; 28(12):5184-96 [PubMed] Related Publications
The combined action of multiple cell types is essential for the physiological function of the lung, and increased awareness of the molecular constituents characterizing each cell type is likely to advance the understanding of lung biology and disease. In the current study, we used genome-wide RNA sequencing of normal lung parenchyma and 26 additional tissue types, combined with antibody-based protein profiling, to localize the expression to specific cell types. Altogether, 221 genes were found to be elevated in the lung compared with their expression in other analyzed tissues. Among the gene products were several well-known markers, but also several proteins previously not described in the context of the lung. To link the lung-specific molecular repertoire to human disease, survival associations of pneumocyte-specific genes were assessed by using transcriptomics data from 7 non-small-cell lung cancer (NSCLC) cohorts. Transcript levels of 10 genes (SFTPB, SFTPC, SFTPD, SLC34A2, LAMP3, CACNA2D2, AGER, EMP2, NKX2-1, and NAPSA) were significantly associated with survival in the adenocarcinoma subgroup, thus qualifying as promising biomarker candidates. In summary, based on an integrated omics approach, we identified genes with elevated expression in lung and localized corresponding protein expression to different cell types. As biomarker candidates, these proteins may represent intriguing starting points for further exploration in health and disease.

Chen YF, Hsieh MS, Wu SG, et al.
Clinical and the prognostic characteristics of lung adenocarcinoma patients with ROS1 fusion in comparison with other driver mutations in East Asian populations.
J Thorac Oncol. 2014; 9(8):1171-9 [PubMed] Related Publications
INTRODUCTION: The prevalence, demographic features, and clinical outcomes of lung adenocarcinoma patients with novel ROS1 oncogenic rearrangement in East Asian populations are not clear. This study aimed to investigate the clinical and prognostic characteristics of lung adenocarcinoma in patients with ROS1 fusion compared with other driver mutations.
METHODS: Multiplex reverse transcription-polymerase chain reaction was used to detect the ROS1 fusion gene in lung adenocarcinoma cases. Immunohistochemistry was used to confirm the expression of ROS1. The demographic data and clinical outcomes of patients with the ROS1 fusion gene were compared with those of patients without the ROS1 fusion gene, including those with the EGFR mutation, EML4-ALK fusion, KRAS mutation, and quadruple-negative patients.
RESULTS: Of 492 patients with lung adenocarcinoma, 12 (2.4%) had the ROS1 fusion gene. Their median age was 45.0 years, significantly younger than that of the ROS1 fusion-negative cohorts (p < 0.001). Acinar (including cribriform) and solid patterns were the two most common histologic subtypes in the ROS1 fusion tumors (7 of 12, 58.3%) and were predominantly seen in CD74-ROS1 fusion tumors (66.7%). There was no significant survival difference between the ROS1 fusion-positive and ROS1 fusion-negative cohorts in surgical group, but ROS1 fusion-positive patients might have worse outcomes than EGFR-mutant patients in the stage IV group.
CONCLUSIONS: The ROS1 fusion gene can be successfully detected in East Asian patients with lung adenocarcinoma using multiplex reverse transcription-polymerase chain reaction. These patients tend to be younger and have characteristic histologic subtypes. Due to the small number of ROS1 fusion patients, the prognostic value of ROS1 fusion need further studies to confirm.

Yang W, Wang Y, Pu Q, et al.
Elevated expression of SLC34A2 inhibits the viability and invasion of A549 cells.
Mol Med Rep. 2014; 10(3):1205-14 [PubMed] Free Access to Full Article Related Publications
Abnormal expression of solute carrier family 34 (sodium phosphate), member 2 (SLC34A2) in the lung may induce abnormal alveolar type II (AT II) cells to transform into lung adenocarcinoma cells, and may also be important in biological process of lung adenocarcinoma. However, at present, the effects and molecular mechanisms of SLC34A2 in the initiation and progression of lung cancer remain to be elucidated. To the best of our knowledge, the present study revealed for the first time that the expression levels of SLC34A2 were downregulated in the A549 and H1299 lung adenocarcinoma cell lines. Further investigation demonstrated that the elevated expression of SLC34A2 in A549 cells was able to significantly inhibit cell viability and invasion in vitro. In addition, 10 upregulated genes between the A549‑P‑S cell line stably expressing SLC34A2 and the control cell line A549‑P were identified by microarray analysis and quantitative polymerase chain reaction, including seven tumor suppressor genes and three complement genes. Furthermore, the upregulation of complement gene C3 and complement 4B preproprotein (C4b) in A549‑P‑S cells was confirmed by ELISA analysis and was identified to be correlated with recovering Pi absorption in A549 cells by the phosphomolybdic acid method by enhancing the expression of SLC34A2. Therefore, it was hypothesized that the mechanisms underlying the effect of SLC34A2 on A549 cells might be associated with the activation of the complement alternative pathway (C3 and C4b) and upregulation of the expression of selenium binding protein 1, thioredoxin‑interacting protein, PDZK1‑interacting protein 1 and dual specificity protein phosphatase 6. Downregulation of SLC34A2 may primarily cause abnormal AT II cells to escape from complement‑associated immunosurveillance and abnormally express certain tumor‑suppressor genes inducing AT II cells to develop into lung adenocarcinoma. The present study further elucidated the effects and mechanisms of SLC34A2 in the generation and development of lung cancer.

Aisner DL, Nguyen TT, Paskulin DD, et al.
ROS1 and ALK fusions in colorectal cancer, with evidence of intratumoral heterogeneity for molecular drivers.
Mol Cancer Res. 2014; 12(1):111-8 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Activated anaplastic lymphoma kinase (ALK) and ROS1 tyrosine kinases, through gene fusions, have been found in lung adenocarcinomas and are highly sensitive to selective kinase inhibitors. This study aimed at identifying the presence of these rearrangements in human colorectal adenocarcinoma specimens using a 4-target, 4-color break-apart FISH assay to simultaneously determine the genomic status of ALK and ROS1. Among the clinical colorectal cancer specimens analyzed, rearrangement-positive cases for both ALK and ROS1 were observed. The fusion partner for ALK was identified as EML4 and the fusion partner for one of the ROS1-positive cases was SLC34A2, the partner for the other ROS1-positive case remains to be identified. A small fraction of specimens presented duplicated or clustered copies of native ALK and ROS1. In addition, rearrangements were detected in samples that also harbored KRAS and BRAF mutations in two of the three cases. Interestingly, the ALK-positive specimen displayed marked intratumoral heterogeneity and rearrangement was also identified in regions of high-grade dysplasia. Despite the additional oncogenic events and tumor heterogeneity observed, elucidation of the first cases of ROS1 rearrangements and confirmation of ALK rearrangements support further evaluation of these genomic fusions as potential therapeutic targets in colorectal cancer.
IMPLICATIONS: ROS1 and ALK fusions occur in colorectal cancer and may have substantial impact in therapy selection.

Fisher KE, Yin-Goen Q, Alexis D, et al.
Gene expression profiling of clear cell papillary renal cell carcinoma: comparison with clear cell renal cell carcinoma and papillary renal cell carcinoma.
Mod Pathol. 2014; 27(2):222-30 [PubMed] Related Publications
Clear cell papillary renal cell carcinoma is a distinct variant of renal cell carcinoma that shares some overlapping histological and immunohistochemical features of clear cell renal cell carcinoma and papillary renal cell carcinoma. Although the clear cell papillary renal cell carcinoma immunohistochemical profile is well described, clear cell papillary renal cell carcinoma mRNA expression has not been well characterized. We investigated the clear cell papillary renal cell carcinoma gene expression profile using previously identified candidate genes. We selected 17 clear cell papillary renal cell carcinoma, 15 clear cell renal cell carcinoma, and 13 papillary renal cell carcinoma cases for molecular analysis following histological review. cDNA from formalin-fixed paraffin-embedded tissue was prepared. Quantitative real-time PCR targeting alpha-methylacyl coenzyme-A racemase (AMACR), BMP and activin membrane-bound inhibitor homolog (BAMBI), carbonic anhydrase IX (CA9), ceruloplasmin (CP), nicotinamide N-methyltransferase (NNMT), schwannomin-interacting protein 1 (SCHIP1), solute carrier family 34 (sodium phosphate) member 2 (SLC34A2), and vimentin (VIM) was performed. Gene expression data were normalized relative to 28S ribosomal RNA. Clear cell papillary renal cell carcinoma expressed all eight genes at variable levels. Compared with papillary renal cell carcinoma, clear cell papillary renal cell carcinoma expressed more CA9, CP, NNMT, and VIM, less AMACR, BAMBI, and SLC34A2, and similar levels of SCHIP1. Compared with clear cell renal cell carcinoma, clear cell papillary renal cell carcinoma expressed slightly less NNMT, but similar levels of the other seven genes. Although clear cell papillary renal cell carcinoma exhibits a unique molecular signature, it expresses several genes at comparable levels to clear cell renal cell carcinoma relative to papillary renal cell carcinoma. Understanding the molecular pathogenesis of clear cell papillary renal cell carcinoma will have a key role in future sub-classifications of this unique tumor.

Matsuura S, Shinmura K, Kamo T, et al.
CD74-ROS1 fusion transcripts in resected non-small cell lung carcinoma.
Oncol Rep. 2013; 30(4):1675-80 [PubMed] Related Publications
The recent discovery of fusion oncokinases in a subset of non-small cell lung carcinomas (NSCLCs) is of considerable clinical interest, since NSCLCs that express such fusion oncokinases are reportedly sensitive to kinase inhibitors. To better understand the role of recently identified ROS1 and RET fusion oncokinases in pulmonary carcinogenesis, we examined 114 NSCLCs for SLC34A2-ROS1, EZR-ROS1, CD74-ROS1 and KIF5B-RET fusion transcripts using RT-polymerase chain reaction and subsequent sequencing analyses. Although the expression of SLC34A2-ROS1, EZR-ROS1, or KIF5B-RET fusion transcripts was not detected in any of the cases, the expression of CD74-ROS1 fusion transcripts was detected in one (0.9%) of the 114 NSCLCs. The fusion occurred between exon 6 of CD74 and exon 34 of ROS1 and was an in-frame alteration. The mutation was detected in a woman without a history of smoking. Histologically, the carcinoma was an adenocarcinoma with a predominant acinar pattern; notably, a mucinous cribriform pattern and a solid signet-ring cell pattern were also observed in part of the adenocarcinoma. ROS1 protein overexpression was immunohistochemically detected in a cancer-specific manner in both the primary cancer and the lymph node metastatic cancer. No somatic mutations were detected in the mutation cluster regions of the KRAS, EGFR, BRAF and PIK3CA genes and the entire coding region of p53 in the carcinoma, and the expression of ALK fusion was negative. The above results suggest that CD74-ROS1 fusion is involved in the carcinogenesis of a subset of NSCLCs and may contribute to the elucidation of the characteristics of ROS1 fusion-positive NSCLC in the future.

Liu P, Wu Y, Sun L, et al.
ROS kinase fusions are not common in Chinese patients with cholangiocarcinoma.
Nan Fang Yi Ke Da Xue Xue Bao. 2013; 33(4):474-8 [PubMed] Related Publications
OBJECTIVE: To investigate the expressions of different forms of ROS fusions in Chinese patients with cholangiocarcinoma (CCA).
METHODS: RT-PCR was employed to examine formalin-fixed and paraffin-embedded CCA samples from stage I-IV patients for detection of ROS fusions involving Fused in Glioblastoma (FIG), solute carrier protein (SLC34A2) and major histocompatibility complex class II invariant chain (CD74). Serpin peptidase inhibitor clade A member 1 (SERPINA1) was detected as the reference gene.
RESULTS: In all the 56 CCA samples, 80.4% (45/56) were positive for SERPINA1 expression as evaluable samples. Of these evaluable samples, none expressed the ROS fusions.
CONCLUSION: ROS fusions are not common in Chinese CCA patients.

Lee J, Lee SE, Kang SY, et al.
Identification of ROS1 rearrangement in gastric adenocarcinoma.
Cancer. 2013; 119(9):1627-35 [PubMed] Related Publications
BACKGROUND: Recently, chromosomal rearrangements involving receptor tyrosine kinases (RTKs) have been described in common epithelial malignancies, including nonsmall cell lung cancer (NSCLC), colorectal cancer, and breast cancer. One of these RTKs, c-ros oncogene 1, receptor tyrosine kinase (ROS1), has been identified as a driver mutation in NSCLC, because its inhibition by crizotinib, an anaplastic lymphoma receptor tyrosine kinase (ALK)/met proto-oncogene hepatocyte growth factor receptor (MET)/ROS1 inhibitor, led to significant tumor shrinkage in ROS1-rearranged NSCLC. Currently, only human epidermal growth factor 2 (HER2)-targeted therapy in combination with chemotherapy has been successful in significantly prolonging the survival of patients with advanced gastric cancer (GC). There is a need for the discovery of additional novel targets in GC.
METHODS: Anti-ROS1 immunohistochemistry (IHC) was used to screen 495 GC samples and was followed by simultaneous ROS1 break-apart fluorescence in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses in IHC-positive samples. Fusion partners in ROS1-rearranged GC were determined by RT-PCR. In all 495 samples, HER2 amplification was identified with FISH, and MET expression was identified by IHC.
RESULTS: Twenty-three tumor samples were ROS1 IHC-positive. Three of 23 patients were ROS1 FISH positive, HER2 FISH negative, and negative for MET overexpression; and 2 of those 3 patients harbored a solute carrier family 34 (sodium phosphate), member 2 (SLC34A2)-ROS1 fusion transcripts. No fusion partner was identified in the third patient. Both patients who had SLC34A2-ROS1 transcripts had poorly differentiated histology with recurrence and death within 2 years of curative surgery. ROS1 IHC-positive status was not identified as an independent prognostic factor for overall survival.
CONCLUSIONS: In this study, an SLC34A2-ROS1 rearrangement was identified in GC, and the results provide a rationale for investigating the clinical efficacy of ROS1 inhibitors in this unique molecular subset of GC. Society.

Davies KD, Le AT, Theodoro MF, et al.
Identifying and targeting ROS1 gene fusions in non-small cell lung cancer.
Clin Cancer Res. 2012; 18(17):4570-9 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Oncogenic gene fusions involving the 3' region of ROS1 kinase have been identified in various human cancers. In this study, we sought to characterize ROS1 fusion genes in non-small cell lung cancer (NSCLC) and establish the fusion proteins as drug targets.
EXPERIMENTAL DESIGN: An NSCLC tissue microarray (TMA) panel containing 447 samples was screened for ROS1 rearrangement by FISH. This assay was also used to screen patients with NSCLC. In positive samples, the identity of the fusion partner was determined through inverse PCR and reverse transcriptase PCR. In addition, the clinical efficacy of ROS1 inhibition was assessed by treating a ROS1-positive patient with crizotinib. The HCC78 cell line, which expresses the SLC34A2-ROS1 fusion, was treated with kinase inhibitors that have activity against ROS1. The effects of ROS1 inhibition on proliferation, cell-cycle progression, and cell signaling pathways were analyzed by MTS assay, flow cytometry, and Western blotting.
RESULTS: In the TMA panel, 5 of 428 (1.2%) evaluable samples were found to be positive for ROS1 rearrangement. In addition, 1 of 48 patients tested positive for rearrangement, and this patient showed tumor shrinkage upon treatment with crizotinib. The patient and one TMA sample displayed expression of the recently identified SDC4-ROS1 fusion, whereas two TMA samples expressed the CD74-ROS1 fusion and two others expressed the SLC34A2-ROS1 fusion. In HCC78 cells, treatment with ROS1 inhibitors was antiproliferative and downregulated signaling pathways that are critical for growth and survival.
CONCLUSIONS: ROS1 inhibition may be an effective treatment strategy for the subset of patients with NSCLC whose tumors express ROS1 fusion genes.

Rimkunas VM, Crosby KE, Li D, et al.
Analysis of receptor tyrosine kinase ROS1-positive tumors in non-small cell lung cancer: identification of a FIG-ROS1 fusion.
Clin Cancer Res. 2012; 18(16):4449-57 [PubMed] Related Publications
PURPOSE: To deepen our understanding of mutant ROS1 expression, localization, and frequency in non-small cell lung cancer (NSCLC), we developed a highly specific and sensitive immunohistochemistry (IHC)-based assay that is useful for the detection of wild-type and mutant ROS1.
EXPERIMENTAL DESIGN: We analyzed 556 tumors with the ROS1 D4D6 rabbit monoclonal antibody IHC assay to assess ROS1 expression levels and localization. A subset of tumors was analyzed by FISH to determine the percentage of these tumors harboring ROS1 translocations. Using specific and sensitive IHC assays, we analyzed the expression of anaplastic lymphoma kinase (ALK), EGFR L858R, and EGFR E746-A750del mutations in a subset of lung tumors, including those expressing ROS1.
RESULTS: In our NSCLC cohort of Chinese patients, we identified 9 (1.6%) tumors expressing ROS1 and 22 (4.0%) tumors expressing ALK. FISH identified tumors with ALK or ROS1 rearrangements, and IHC alone was capable of detecting all cases with ALK and ROS1 rearrangements. ROS1 fusion partners were determined by reverse transcriptase PCR identifying CD74-ROS1, SLC34A2-ROS1, and FIG-ROS1 fusions. Some of the ALK and ROS1 rearranged tumors may also harbor coexisting EGFR mutations.
CONCLUSIONS: NSCLC tumors with ROS1 rearrangements are uncommon in the Chinese population and represent a distinct entity of carcinomas. The ROS1 IHC assay described here is a valuable tool for identifying patients expressing mutant ROS1 and could be routinely applied in clinical practice to detect lung cancers that may be responsive to targeted therapies.

Soares IC, Simões K, de Souza JE, et al.
In silico analysis and immunohistochemical characterization of NaPi2b protein expression in ovarian carcinoma with monoclonal antibody Mx35.
Appl Immunohistochem Mol Morphol. 2012; 20(2):165-72 [PubMed] Related Publications
INTRODUCTION: Ovarian adenocarcinoma is frequently detected at the late stage, when therapy efficacy is limited and death occurs in up to 50% of the cases. A potential novel treatment for this disease is a monoclonal antibody that recognizes phosphate transporter sodium-dependent phosphate transporter protein 2b (NaPi2b).
MATERIALS AND METHODS: To better understand the expression of this protein in different histologic types of ovarian carcinomas, we immunostained 50 tumor samples with anti-NaPi2b monoclonal antibody MX35 and, in parallel, we assessed the expression of the gene encoding NaPi2b (SCL34A2) by in silico analysis of microarray data.
RESULTS: Both approaches detected higher expression of NaPi2b (SCL34A2) in ovarian carcinoma than in normal tissue. Moreover, a comprehensive analysis indicates that SCL34A2 is the only gene of the several phosphate transporters genes whose expression differentiates normal from carcinoma samples, suggesting it might exert a major role in ovarian carcinomas. Immunohistochemical and mRNA expression data have also shown that 2 histologic subtypes of ovarian carcinoma express particularly high levels of NaPi2b: serous and clear cell adenocarcinomas. Serous adenocarcinomas are the most frequent, contrasting with clear cell carcinomas, rare, and with worse prognosis.
CONCLUSION: This identification of subgroups of patients expressing NaPi2b may be important in selecting cohorts who most likely should be included in future clinical trials, as a recently generated humanized version of MX35 has been developed.

Ricketts CJ, Morris MR, Gentle D, et al.
Genome-wide CpG island methylation analysis implicates novel genes in the pathogenesis of renal cell carcinoma.
Epigenetics. 2012; 7(3):278-90 [PubMed] Free Access to Full Article Related Publications
In order to identify novel candidate tumor suppressor genes (TSGs) implicated in renal cell carcinoma (RCC), we performed genome-wide methylation profiling of RCC using the HumanMethylation27 BeadChips to assess methylation at > 14,000 genes. Two hundred and twenty hypermethylated probes representing 205 loci/genes were identified in genomic CpG islands. A subset of TSGs investigated in detail exhibited frequent tumor methylation, promoter methylation associated transcriptional silencing and reactivation after demethylation in RCC cell lines and down-regulation of expression in tumor tissue (e.g., SLC34A2 specifically methylated in 63% of RCC, OVOL1 in 40%, DLEC1 in 20%, TMPRSS2 in 26%, SST in 31% and BMP4 in 35%). As OVOL1, a putative regulator of c-Myc transcription, and SST (somatostatin) had not previously been linked to cancer and RCC, respectively, we (1) investigated their potential relevance to tumor growth by RNAi knockdown and found significantly increased anchorage-independent growth and (2) demonstrated that OVOL1 knockdown increased c-Myc mRNA levels.

Shyian M, Gryshkova V, Kostianets O, et al.
Quantitative analysis of SLC34A2 expression in different types of ovarian tumors.
Exp Oncol. 2011; 33(2):94-8 [PubMed] Related Publications
AIM: The main purpose of this study was to estimate the SLC34A2 gene expression in normal ovary and different types of ovarian tumors.
METHODS: We have investigated SLC34A2 gene expression level in papillary serous, endometrioid, unspecified adenocarcinomas, benign tumors, and normal ovarian tissues using real-time PCR analysis. Differences in gene expression were calculated as fold changes in gene expression in ovarian carcinomas and benign tumors compared to normal ovary.
RESULTS: We have found that SLC34A2 gene was highly expressed in well-differentiated endometrioid and papillary serous ovarian carcinomas compared to low-differentiated endometrioid carcinomas, benign serous cystoadenomas and normal ovary. Analysis of SLC34A2 gene expression according to tumor differentiation level (poor- and well-differentiated) showed that SLC34A2 is up-regulated in well differentiated tumors.
CONCLUSION: Upregulation of SLC34A2 gene expression in well-differentiated tumors may reflect cell differentiation processes during ovarian cancerogenesis and could serve as potential marker for ovarian cancer diagnosis and prognosis.

Kim HS, Kim DH, Kim JY, et al.
Microarray analysis of papillary thyroid cancers in Korean.
Korean J Intern Med. 2010; 25(4):399-407 [PubMed] Free Access to Full Article Related Publications
BACKGROUND/AIMS: Papillary thyroid cancer (PTC) is the most common malignancy of the thyroid gland. It involves several molecular mechanisms. The BRAF V600E mutation has been identified as the most common genetic abnormality in PTC. Moreover, it is known to be more prevalent in Korean PTC patients than in patients from other countries. We investigated distinct genetic profiles in Korean PTC through cDNA microarray analysis.
METHODS: Transcriptional profiles of five PTC samples and five paired normal thyroid tissue samples were generated using cDNA microarrays. The tumors were genotyped for BRAF mutations. The results of the cDNA microarray gene expression analysis were confirmed by real-time PCR and immunohistochemistry analysis of 35 PTC patients.
RESULTS: Four of the five patients whose PTC tissues were subjected to microarray analysis were found to carry the BRAF V600E mutation. Microarrays analysis of the five PTC tissue samples showed the expression of 96 genes to be increased and that of 16 genes decreased. Real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmed increased expression of SLC34A2, TM7SF4, COMP, KLK7, and KCNJ2 and decreased expression of FOXA2, SLC4A4, LYVE-1, and TFCP2L1 in PTC compared with normal tissue. Of these genes, TFCP2L1, LYVE-1, and KLK7 were previously unidentified in PTC microarray analysis. Notably, Foxa2 activity in PTC was reduced, as shown by its cytoplasmic localization, in immunohistochemical analyses.
CONCLUSIONS: These findings demonstrate both similarities and differences between our results and previous reports. In Korean cases of PTC, Foxa2 activity was reduced with its cytoplasmic accumulation. Further studies are needed to confirm the relationship between FOXA2 and BRAF mutations in Korean cases of PTC.

Chen DR, Chien SY, Kuo SJ, et al.
SLC34A2 as a novel marker for diagnosis and targeted therapy of breast cancer.
Anticancer Res. 2010; 30(10):4135-40 [PubMed] Related Publications
The purpose of this study was to estimate the role of the SLC34A2 gene in breast cancer. A total of 146 samples were collected from breast cancer tissues and their adjacent normal breast tissues. Reverse transcription and real-time polymerase chain reaction were used to estimate gene expression levels. There was a significantly increased gene expression of SLC34A2 (normal tissues: 6.71±0.77; tumour tissues: 10.29±0.80) among breast cancer tissues compared with normal tissues. However, there was no significant association between overall survival and the gene expression level of SLC34A2. Moreover, a significant overexpression of CA125 (normal tissues: 7.26±0.62; tumour tissues: 10.51±0.58) in breast cancer tissues and a significant correlation between SLC34A2 and CA125 gene expressions were found. Our results suggested SLC34A2 to be involved in the development of breast cancer; this gene may therefore be a novel marker for the detection of breast cancer and act as a target gene in therapeutic strategies.

Kopantzev EP, Monastyrskaya GS, Vinogradova TV, et al.
Differences in gene expression levels between early and later stages of human lung development are opposite to those between normal lung tissue and non-small lung cell carcinoma.
Lung Cancer. 2008; 62(1):23-34 [PubMed] Related Publications
We, for the first time, directly compared gene expression profiles in human non-small cell lung carcinomas (NSCLCs) and in human fetal lung development. Previously reported correlations of gene expression profiles between lung cancer and lung development, deduced from matching data on mouse development and human cancer, have brought important information, but suffered from different timing of mouse and human gene expression during fetal development and fundamental differences in tumorigenesis in mice and humans. We used the suppression subtractive hybridization technique to subtract cDNAs prepared from human fetal lung samples at weeks 10-12 and 22-24 and obtained a cDNA library enriched in the transcripts more abundant at the later stage. cDNAs sequencing and RT-PCR analysis of RNAs from human fetal and adult lungs revealed 12 differentially transcribed genes: ADH1B, AQP1, FOLR1, SLC34A2, CAV1, INMT, TXNIP, TPM4, ICAM-1, HLA-DRA, EFNA1 and HLA-E. Most of these genes were found up-regulated in mice and rats at later stages than in human lung development. In surgical samples of NSCLC, these genes were down-regulated as compared to surrounding normal tissues and normal lungs, thus demonstrating opposite expression profiles for the genes up-regulated during fetal lung development.

Yin BW, Kiyamova R, Chua R, et al.
Monoclonal antibody MX35 detects the membrane transporter NaPi2b (SLC34A2) in human carcinomas.
Cancer Immun. 2008; 8:3 [PubMed] Free Access to Full Article Related Publications
Mouse monoclonal antibody MX35 was developed against ovarian cancer. The antibody showed homogeneous reactivity with approximately 90% of human ovarian epithelial cancers and with a limited number of normal tissues by immunohistochemistry. Although mAb MX35 has been used in a number of clinical trials in ovarian cancer, it has been difficult to define the molecular identity of MX35. We report here that mAb MX35 recognizes the sodium-dependent phosphate transport protein 2b (NaPi2b) in human cancer cells. This conclusion is based on several lines of experimental evidence, including 1) the identification of SLC34A2, the gene coding for NaPi2b, by immunoscreening an ovarian cancer cell line cDNA expression library with mAb MX35; 2) mass spectrometry sequencing of peptides obtained by fragmentation from mAb MX35 affinity-purified antigen, which show complete sequence homology to amino acid sequences in NaPi2b; 3) selective down-regulation of SLC34A2 gene expression by RNA interference and the resulting loss of mAb MX35 binding to MX35-expressing human cancer cells; and 4) the demonstration of specific mAb MX35 reactivity with recombinant fusion proteins and with synthetic peptides of the putative largest extracellular loop of NaPi2b. We further show that NaPi2b in cancer cells is expressed on the cell surface as a heavily N-glycosylated protein, with evidence of additional post-translational modifications such as palmitoylation and the formation of disulfide bridges in the major extracellular loop. Membrane transporter molecules, such as NaPi2b, represent a new family of potential cell surface targets for the immunotherapy of cancer with monoclonal antibodies.

Jarzab B, Wiench M, Fujarewicz K, et al.
Gene expression profile of papillary thyroid cancer: sources of variability and diagnostic implications.
Cancer Res. 2005; 65(4):1587-97 [PubMed] Related Publications
The study looked for an optimal set of genes differentiating between papillary thyroid cancer (PTC) and normal thyroid tissue and assessed the sources of variability in gene expression profiles. The analysis was done by oligonucleotide microarrays (GeneChip HG-U133A) in 50 tissue samples taken intraoperatively from 33 patients (23 PTC patients and 10 patients with other thyroid disease). In the initial group of 16 PTC and 16 normal samples, we assessed the sources of variability in the gene expression profile by singular value decomposition which specified three major patterns of variability. The first and the most distinct mode grouped transcripts differentiating between tumor and normal tissues. Two consecutive modes contained a large proportion of immunity-related genes. To generate a multigene classifier for tumor-normal difference, we used support vector machines-based technique (recursive feature replacement). It included the following 19 genes: DPP4, GJB3, ST14, SERPINA1, LRP4, MET, EVA1, SPUVE, LGALS3, HBB, MKRN2, MRC2, IGSF1, KIAA0830, RXRG, P4HA2, CDH3, IL13RA1, and MTMR4, and correctly discriminated 17 of 18 additional PTC/normal thyroid samples and all 16 samples published in a previous microarray study. Selected novel genes (LRP4, EVA1, TMPRSS4, QPCT, and SLC34A2) were confirmed by Q-PCR. Our results prove that the gene expression signal of PTC is easily detectable even when cancer cells do not prevail over tumor stroma. We indicate and separate the confounding variability related to the immune response. Finally, we propose a potent molecular classifier able to discriminate between PTC and nonmalignant thyroid in more than 90% of investigated samples.

Rangel LB, Sherman-Baust CA, Wernyj RP, et al.
Characterization of novel human ovarian cancer-specific transcripts (HOSTs) identified by serial analysis of gene expression.
Oncogene. 2003; 22(46):7225-32 [PubMed] Related Publications
A better understanding of changes in gene expression during ovarian tumorigenesis and the identification of specific tumor markers may lead to novel strategies for diagnosis and therapy for this disease. Using our serial analysis of gene expression (SAGE) data, as well as public SAGE databases that contained a total of 137 SAGE libraries representing a wide variety of normal and neoplastic tissues, we identified five novel SAGE tags specifically expressed in ovarian cancer. Database analysis, cloning and, sequencing of the corresponding expressed sequence tags revealed details about these transcripts that we named human ovarian cancer-specific transcripts (HOSTs). HOST1 was found to be identical to the gene encoding ovarian marker CA125 (MUC16). HOST2 is a novel gene containing multiple copies of retroviral-related sequences without an obvious open reading frame. HOST3 encodes the tight-junction protein claudin-16 (CLDN16). HOST4 encodes a poorly characterized proteoglycan link protein (LP), and HOST5 codes for a type II sodium-dependent phosphate transporter (SLC34A2). Except for MUC16, these genes have not previously been shown to be expressed in ovarian or other cancers. Northern blot analysis confirmed that HOST genes are rarely expressed in normal tissues or nonovarian cancers, but are frequently expressed in ovarian cancer-derived cell lines and primary tumors. Moreover, HOST genes are upregulated in all four major subtypes of ovarian cancer compared to cultivated ovarian surface epithelial cells, as concluded by real-time reverse transcription (RT)-PCR using a panel of microdissected ovarian tumors. The sodium-dependent phosphate transporter (HOST5/SLC34A2) expression was associated with increased differentiation in ovarian serous tumors. While the roles of HOSTs in ovarian malignant transformation remain unclear, we propose that HOSTs may represent alternative targets for diagnosis and therapy and of this deadly disease.

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