Plasmas for Treating Cancer: Opportunities for Adaptive and Self-Adaptive Approaches.

Plasma is an ionized gas that is typically formed under high-temperature laboratory conditions. Recent progress in atmospheric plasmas has led to cold atmospheric plasma (CAP) devices with ion temperatures close to room temperature. The unique chemical and physical properties of CAP have led to its use in various biomedical applications including cancer therapy. CAP exhibits a spontaneous transition from a spatially homogeneous state to a modifiable pattern that is subject to self-organization. In this Opinion article, we discuss some new applications for plasma in cancer therapy based on plasma self-organization, which enables adaptive features in plasma-based therapeutic systems.

Cold atmospheric plasma treatment selectively targets head and neck squamous cell carcinoma cells.

The treatment of locoregional recurrence (LRR) of head and neck squamous cell carcinoma (HNSCC) often requires a combination of surgery, radiation therapy and/or chemotherapy. Survival outcomes are poor and the treatment outcomes are morbid. Cold atmospheric plasma (CAP) is an ionized gas produced at room temperature under laboratory conditions. We have previously demonstrated that treatment with a CAP jet device selectively targets cancer cells using in vitro melanoma and in vivo bladder cancer models. In the present study, we wished to examine CAP selectivity in HNSCC in vitro models, and to explore its potential for use as a minimally invasive surgical approach that allows for specific cancer cell or tumor tissue ablation without affecting the surrounding healthy cells and tissues. Four HNSCC cell lines (JHU-022, JHU-028, JHU-029, SCC25) and 2 normal oral cavity epithelial cell lines (OKF6 and NOKsi) were subjected to cold plasma treatment for durations of 10, 30 and 45 sec, and a helium flow of 20 l/min-1 for 10 sec was used as a positive treatment control. We showed that cold plasma selectively diminished HNSCC cell viability in a dose-response manner, as evidenced by MTT assays; the viability of the OKF6 cells was not affected by the cold plasma. The results of colony formation assays also revealed a cell-specific response to cold plasma application. Western blot analysis did not provide evidence that the cleavage of PARP occurred following cold plasma treatment. In conclusion, our results suggest that cold plasma application selectively impairs HNSCC cell lines through non-apoptotic mechanisms, while having a minimal effect on normal oral cavity epithelial cell lines.

Differential expression of colon cancer associated transcript1 (CCAT1) along the colonic adenoma-carcinoma sequence.

BACKGROUND: The transition from normal epithelium to adenoma and, to invasive carcinoma in the human colon is associated with acquired molecular events taking 5-10 years for malignant transformation. We discovered CCAT1, a non-coding RNA over-expressed in colon cancer (CC), but not in normal tissues, thereby making it a potential disease-specific biomarker. We aimed to define and validate CCAT1 as a CC-specific biomarker, and to study CCAT1 expression across the adenoma-carcinoma sequence of CC tumorigenesis. METHODS: Tissue samples were obtained from patients undergoing resection for colonic adenoma(s) or carcinoma. Normal colonic tissue (n = 10), adenomatous polyps (n = 18), primary tumor tissue (n = 22), normal mucosa adjacent to primary tumor (n = 16), and lymph node(s) (n = 20), liver (n = 8), and peritoneal metastases (n = 19) were studied. RNA was extracted from all tissue samples, and CCAT1 expression was analyzed using quantitative real time-PCR (qRT-PCR) with confirmatory in-situ hybridization (ISH). RESULTS: Borderline expression of CCAT1 was identified in normal tissue obtained from patients with benign conditions [mean Relative Quantity (RQ) = 5.9]. Significant relative CCAT1 up-regulation was observed in adenomatous polyps (RQ = 178.6 ± 157.0; p = 0.0012); primary tumor tissue (RQ = 64.9 ± 56.9; p = 0.0048); normal mucosa adjacent to primary tumor (RQ = 17.7 ± 21.5; p = 0.09); lymph node, liver and peritoneal metastases (RQ = 11,414.5 ± 12,672.9; 119.2 ± 138.9; 816.3 ± 2,736.1; p = 0.0001, respectively). qRT-PCR results were confirmed by ISH, demonstrating significant correlation between CCAT1 up-regulation measured using these two methods. CONCLUSION: CCAT1 is up-regulated across the colon adenoma-carcinoma sequence. This up-regulation is evident in pre-malignant conditions and through all disease stages, including advanced metastatic disease suggesting a role in both tumorigenesis and the metastatic process.

Single nucleotide polymorphism rs17849071 G/T in the PIK3CA gene is inversely associated with follicular thyroid cancer and PIK3CA amplification.

The proto-oncogene PIK3CA has been well studied for its activating mutations and genomic amplifications but not single nucleotide polymorphism (SNP) in thyroid cancer. We investigated SNP rs17849071 (minor allele G and major allele T) in PIK3CA in thyroid tumors in 503 subjects by PCR and sequencing of a region of intron 9 carrying this SNP. This SNP was found in both normal and thyroid tumor tissues as well as in different generations of a studied family, confirming it to be a germline genetic event in thyroid tumor patients. In comparison with normal subjects, a dramatically lower prevalence of the heterozygous genotype G/T at rs17849071 was found in patients with follicular thyroid cancer (FTC). Specifically, rs17849071G/T was found in 15% (18/117) normal subjects vs. 1.3% (1/77) FTC patients, with an odds ratio of 0.07 (95% CI 0.01-0.55; P = 0.001). This represents a 93% risk reduction for FTC with this SNP. In contrast, no difference was seen with benign thyroid neoplasms in which the prevalence of rs17849071G/T was 13.1% (17/130), with an odds ratio of 0.83 (95% CI 0.40-1.69; P = 0.72). There was a trend of lower prevalences of rs17849071G/T and odds ratio in other types of thyroid cancer without statistical significance. We also found an interesting inverse relationship of rs17849071G/T with PIK3CA amplification. With copy number ≥4 defined as copy gain, 2.9% (1/34) rs17849071G/T vs. 19.0% (67/352) rs17849071T/T cases displayed PIK3CA amplification (P = 0.01). Conversely, 1.5% (1/68) cases with PIK3CA amplification vs. 10.4% (33/318) cases without PIK3CA amplification harbored rs17849071G/T (P = 0.01). This provides an explanation for the reciprocal relationship of rs17849071G/T with FTC, since PIK3CA amplification is an important oncogenic mechanism in thyroid cancer, particularly FTC. Thus, the present study uncovers an interesting phenomenon that rs17849071G/T is protective against FTC possibly through preventing PIK3CA amplifications.

A single nucleotide polymorphism in the human PIGK gene associates with low PIGK expression in colorectal cancer patients.

Colorectal cancer (CRC) represents one of the highest incidences of cancers worldwide. Phosphatidylinositol glycan, class K (PIGK), is a crucial member of the glycosyl-phosphatidylinositol transamidase (GPIT) protein complex that attaches a diverse group of macromolecules to the plasma membrane of eukaryotes. However, the precise role of PIGK in tumorigenesis remains largely unknown. Recently, we reported low expression of PIGK protein in primary tumors compared to paired normal tissues of colorectal cancer (CRC) patients. To understand the mechanism underlying this phenomenon, we performed sequencing of all 10 exons of the PIGK gene in 45 CRC patients. Corresponding PIGK protein expression was also evaluated in these patients by immunohistochemistry. No mutation was detected in the coding regions, however, we found a single nucleotide polymorphism (C/C→C/G or G/G; rs1048575) in the 3'UTR of the PIGK gene in 67% (30/45) of the patients. Most of the patients (22/26, 85%) with the altered alleles were of Jewish origin. In comparison, 47% (8/17) of the Arabian patients exhibited the altered C/G alleles. We observed a significantly low (p<0.002) expression of PIGK protein in the patients with the altered alleles (C/G or G/G) compared to the ancestral alleles (C/C). Similarly to the CRC patients, we also examined 5 HCC patients and two HCC cell lines (Hep3B and HepG2) for PIGK genotype (SNP-1048575) and corresponding protein expression. We observed altered alleles (C/G or G/G) and corresponding low PIGK protein expression in 4 out of 5 (80%) primary HCC tumors. Among the HCC cell lines, HepG2 line exhibited ancestral C/C alleles, whereas Hep3B showed altered C/G alleles. Similar to the HCC patients, Hep3B line with the altered alleles (C/G) exhibited significantly low (Student's t-test, p<0.002) PIGK protein expression compared to the Hep3B line carrying the ancestral (C/C) alleles. To examine the exogenous PIGK protein expression status, we transiently transfected both HepG2 (C/C alleles) and Hep3B (C/G alleles) cell lines with wt-PIGK constructs. We detected exogenously expressed PIGK protein in HepG2 (C/C) cells, but no PIGK expression was detectable in Hep3B (C/G) cells at either mRNA or protein level. Our results demonstrate, for the first time, a link between the SNP 1048575 and low PIGK expression in CRC/HCC patients and also suggest a possible association between altered PIGK expression and disease susceptibility.

Thioridazine induces apoptosis by targeting the PI3K/Akt/mTOR pathway in cervical and endometrial cancer cells.

Recently, thioridazine (10-[2-(1-methyl-2-piperidyl) ethyl]-2-methylthiophenothiazine), a well-known anti-psychotic agent was found to have anti-cancer activity in cancer cells. However, the molecular mechanism of the agent in cellular signal pathways has not been well defined. Thioridazine significantly increased early- and late-stage apoptotic fraction in cervical and endometrial cancer cells, suggesting that suppression of cell growth by thioridazine was due to the induction of apoptosis. Cell cycle analysis indicated thioridazine induced the down-regulation of cyclin D1, cyclin A and CDK4, and the induction of p21 and p27, a cyclin-dependent kinase inhibitor. Additionally, we compared the influence of thioridazine with cisplatin used as a control, and similar patterns between the two drugs were observed in cervical and endometrial cancer cell lines. Furthermore, as expected, thioridazine successfully inhibited phosphorylation of Akt, phosphorylation of 4E-BP1 and phosphorylation of p70S6K, which is one of the best characterized targets of the mTOR complex cascade. These results suggest that thioridazine effectively suppresses tumor growth activity by targeting the PI3K/Akt/mTOR/p70S6K signaling pathway.

Tumor suppressor BLU enhances pro-apoptotic activity of sMEK1 through physical interaction.

BLU is a tumor suppressor that acts as a transcriptional regulator through the association with cellular components. However, the working mechanism of BLU in cellular functions was not understood. We found that BLU directly interacts with sMEK1, a regulatory subunit of protein phosphatase 4. Furthermore, we determined the binding domains that are required for interaction between BLU and sMEK1. The N-terminal of BLU was observed to interact with the C-terminal of sMEK1. Binding activity was confirmed by the BLU-dependent increase of sMEK1 expression, as well as by the induced apoptotic activity. Also, expression of BLU and sMEK1 was down-regulated in ovarian and cervical patients, and was hypermethylated. These findings indicate that BLU can mediate the pro-apoptotic activity through the induction of sMEK1.

Development of a microRNA-based molecular assay for the detection of papillary thyroid carcinoma in aspiration biopsy samples.

BACKGROUND: Although thyroid nodules are common and diagnosed in over 5% of the adult population, only 5% harbor malignancy. Patients with clinically suspicious thyroid nodules need to undergo fine-needle aspiration biopsy (FNAB). The main limitation of FNAB remains indeterminate cytopathology. Only 20%-30% of the indeterminate nodules harbor malignancy, and therefore up to 80% of patients undergo unnecessary thyroidectomy. The aim of this study was to identify and validate a panel of microRNAs (miRNAs) that could serve as a platform for an FNAB-based diagnostic for thyroid neoplasms. METHODS: The study population included 27 consecutive patients undergoing total thyroidectomy for FNAB-based papillary thyroid cancer (n = 20) and benign disorders (n = 7). Aspiration biopsy was performed from the index lesion and from the opposite lobe normal tissue in all study patients at the time of operation. RNA was extracted from all aspiration biopsy samples. Quantitative polymerase chain reaction on a panel of previously selected miRNAs was performed. Polymerase chain reaction results were compared with final histopathology. miRNA from tumor tissues was amplified using the highest value of each miRNA expression in normal tissue as a threshold for malignancy detection. RESULTS: Diagnostic characteristics were most favorable for mir-221 in differentiating benign from malignant thyroid pathology. mir-221 was overexpressed in 19 patients (p < 0.0001) with a sensitive yield of 95%. Specificity, negative and positive predictive value, and accuracy of the miRNA panel were 100%, 96%, 100%, and 98%, respectively. CONCLUSIONS: miRNA quantification for differential diagnosis of thyroid neoplasms within aspiration biopsy samples is feasible and may improve the accuracy of FNAB cytology.

The BRAFT1799A mutation confers sensitivity of thyroid cancer cells to the BRAFV600E inhibitor PLX4032 (RG7204).

Aberrant signaling of the Ras-Raf-MEK-ERK (MAP kinase) pathway driven by the mutant kinase BRAF(V600E), as a result of the BRAF(T1799A) mutation, plays a fundamental role in thyroid tumorigenesis. This study investigated the therapeutic potential of a BRAF(V600E)-selective inhibitor, PLX4032 (RG7204), for thyroid cancer by examining its effects on the MAP kinase signaling and proliferation of 10 thyroid cancer cell lines with wild-type BRAF or BRAF(T1799A) mutation. We found that PLX4032 could effectively inhibit the MAP kinase signaling, as reflected by the suppression of ERK phosphorylation, in cells harboring the BRAF(T1799A) mutation. PLX4032 also showed a potent and BRAF mutation-selective inhibition of cell proliferation in a concentration-dependent manner. PLX4032 displayed low IC(50) values (0.115-1.156µM) in BRAF(V600E) mutant cells, in contrast with wild-type BRAF cells that showed resistance to the inhibitor with high IC(50) values (56.674-1349.788µM). Interestingly, cells with Ras mutations were also sensitive to PLX4032, albeit moderately. Thus, this study has confirmed that the BRAF(T1799A) mutation confers cancer cells sensitivity to PLX4032 and demonstrated its specific potential as an effective and BRAF(T1799A) mutation-selective therapeutic agent for thyroid cancer.

Presence of 5-methylcytosine in CpNpG trinucleotides in the human genome.

While the methylation machinery of mammalian cells has been shown to be capable of both maintenance and de novo methylation at CpNpG sites, CpNpG methylation in the human genome has not been demonstrated. Here, we report the first observation of 5-methylcytosines in CpNpG triplets in the human genome. We identify the existence of CpNpG methylation in a number of genes which contain trinucleotide repeat regions, including the androgen receptor (AR). We further analyzed DNA extracted from primary tissue samples and found the same pattern of CpNpG methylation. To confirm our results, we performed Southern blot analysis by analyzing the cleavage sites of restriction enzymes within exon 1 of the AR gene and found direct evidence of the presence of 5mCs in CpNpG triplets in the human genome. Our results also suggest that this methylation pattern may be due to the human DNA methyltransferases DNMT1 and DNMT3A. Although the functional significance needs to be tested further, the discovery of inheritable CpNpG methylation in the human genome may have important implications in our understanding of gene regulation and of the development of various diseases, including cancer.

Neurofilament heavy polypeptide regulates the Akt-beta-catenin pathway in human esophageal squamous cell carcinoma.

Aerobic glycolysis and mitochondrial dysfunction are common features of aggressive cancer growth. We observed promoter methylation and loss of expression in neurofilament heavy polypeptide (NEFH) in a significant proportion of primary esophageal squamous cell carcinoma (ESCC) samples that were of a high tumor grade and advanced stage. RNA interference-mediated knockdown of NEFH accelerated ESCC cell growth in culture and increased tumorigenicity in vivo, whereas forced expression of NEFH significantly inhibited cell growth and colony formation. Loss of NEFH caused up-regulation of pyruvate kinase-M2 type and down-regulation of pyruvate dehydrogenase, via activation of the Akt/beta-catenin pathway, resulting in enhanced aerobic glycolysis and mitochondrial dysfunction. The acceleration of glycolysis and mitochondrial dysfunction in NEFH-knockdown cells was suppressed in the absence of beta-catenin expression, and was decreased by the treatment of 2-Deoxyglucose, a glycolytic inhibitor, or API-2, an Akt inhibitor. Loss of NEFH activates the Akt/beta-catenin pathway and increases glycolysis and mitochondrial dysfunction. Cancer cells with methylated NEFH can be targeted for destruction with specific inhibitors of deregulated downstream pathways.

BRAF mutation-selective inhibition of thyroid cancer cells by the novel MEK inhibitor RDEA119 and genetic-potentiated synergism with the mTOR inhibitor temsirolimus.

We examined the therapeutic potential of a novel MEK inhibitor, RDEA119, and its synergism with the mTOR inhibitor, temsirolimus, in thyroid cancer cell lines. RDEA119 potently inhibited the proliferation of the 4 cell lines that harbored BRAF mutation but had no or modest effects on the other 4 cells that harbored wild-type BRAF (IC(50) of 0.034-0.217 µM vs. 1.413-34.120 µM). This inhibitory effect of RDEA119 in selected cell lines OCUT1 (BRAF V600E(+), PIK3CA H1047R(+)) and SW1376 (BRAF V600E(+)) was enhanced by combination with the mTOR inhibitor, temsirolimus. The PTEN-deficient cell FTC133 was highly sensitive to temsirolimus but insensitive to RDEA119, and simultaneous treatment with the latter enhanced the sensitivity of the cell to the former. The KAT18 (wild-type) cell was not sensitive to either drug alone but became sensitive to the combination of the 2 drugs. The drug synergy was confirmed by combination index and isobologram analyses. RDEA119 and temsirolimus also showed synergistic effects on autophagic death of OCUT1 and KAT18 cells selectively tested. Dramatic synergistic effects of the 2 drugs were also seen on the growth of FTC133 xenograft tumors in nude mice. Overall, the effects of the 2 drugs on cell proliferation or autophagic death, either alone or in combination, were more pronounced in cells that harbored genetic alterations in the MAP kinase and PI3K/Akt pathways. Thus, these results demonstrated the important therapeutic potential of the novel MEK inhibitor RDEA119 and its synergism with temsirolimus in thyroid cancer.

Phospho-DeltaNp63alpha/NF-Y protein complex transcriptionally regulates DDIT3 expression in squamous cell carcinoma cells upon cisplatin exposure.

Cisplatin remains the most important chemotherapeutic agent for patients with human head and neck cancer. However, tumor cells often develop resistance to cisplatin-induced apoptosis. We previously found that head and neck squamous cell carcinoma (HNSCC) cells exposed to cisplatin display a marked ATM-induced phosphorylation of DeltaNp63alpha. However, the mutated Np63-S385G failed to undergo phosphorylation by ATM kinase. We used HNSCC cell lines expressing the wild type DeltaNp63alpha or mutated DeltaNp63alpha-S385G to determine the effect of S385G mutation on the DeltaNp63alpha transcriptional activity and protein-protein interactions. The S385G mutation in DeltaNp63alpha dramatically abolished the upregulation/downregulation of downstream gene targets and the binding of DeltaNp63alpha-S385G to certain promoters. In contrast to the non-phosphorylated DeltaNp63alpha-S385G, the phospho-DeltaNp63alpha forms protein-protein complexes with NF-YA transcription factor and regulates the transcription of DDIT3 gene implicated in the programmed cell death of HNSCC cells upon cisplatin exposure. We suggest that the transcriptional activation of DeltaNp63alpha through its phosphorylation by ATM kinase in HNSCC cells exposed to cisplatin is a critical step in the subsequent sensitivity of certain human head and neck cancers to platinum therapy.

Loss of DeltaNp63alpha promotes invasion of urothelial carcinomas via N-cadherin/Src homology and collagen/extracellular signal-regulated kinase pathway.

p63 plays a critical role in normal development and maintenance of stratified epithelia, including the urothelium. In the normal urothelium, urothelial cells in the basal layers abundantly express the predominant p63 isoform DeltaNp63alpha. We previously showed that (a) DeltaNp63alpha expression at the similar level to the normal urothelium is retained in most low-grade papillary noninvasive (LPN) tumors, whereas frequently lost in high-grade invasive carcinomas, and that (b) loss of DeltaNp63alpha is associated with poor prognosis of invasive bladder urothelial carcinoma patients. However, a functional role of DeltaNp63alpha in progression of urothelial carcinomas remains to be elucidated. Here, we show that loss of DeltaNp63alpha expression promotes invasion of urothelial carcinoma cells. In 5637 cells substantially expressing only DeltaNp63alpha isoform at the protein level, knockdown of endogenous p63 upregulated N-cadherin, which recruited more Src homology and collagen to N-cadherin and activated extracellular signal-regulated kinase (ERK) signaling, and consequently potentiated cell motility, excretion of matrix metalloproteinase-9, and invasion. In T24 cells originally lacking endogenous DeltaNp63alpha expression, exogenous expression of DeltaNp63alpha attenuated invasion by downregulating N-cadherin expression and ERK activity, confirming an invasion-suppressive role of DeltaNp63alpha in urothelial carcinoma cells. We further documented loss of DeltaNp63 expression accompanied by N-cadherin upregulation during muscle-invasive recurrence in patients whose bladder cancer had progressed from LPN tumors to muscle-invasive disease. These results suggest that loss of DeltaNp63alpha and subsequent upregulation of N-cadherin is one of the mechanisms underlying progression of bladder cancer.

ATM kinase is a master switch for the Delta Np63 alpha phosphorylation/degradation in human head and neck squamous cell carcinoma cells upon DNA damage.

We previously found that the pro-apoptotic DNA damaging agent, cisplatin, mediated the proteasome-dependent degradation of Delta Np63 alpha associated with its increased phosphorylated status. Since Delta Np63 alpha usually plays an opposite role to p53 and TAp63 in human cancers, we tested the notion that phosphorylation events induced by DNA damage would affect the protein degradation of Delta Np63 alpha in HNSCC cells upon cisplatin exposure. We found that Delta Np63 alpha is phosphorylated in the time-dependent fashion at the following positions: S385, T397 and S466, which were surrounded by recognition motifs for ATM, CDK2 and p70s6K kinases, respectively. We showed that chemical agents or siRNA inhibiting the activity of ATM, CDK2 and p70s6K kinases blocked degradation of Delta Np63 alpha in HNSCC cells after cisplatin exposure. Site-specific mutagenesis of Delta Np63 alpha residues targeted for phosphorylation by ATM, CDK2 or p70s6k led to dramatic modulation of Delta Np63 alpha degradation. Finally, we demonstrated that the Delta Np63 alpha protein is a target for direct in vitro phosphorylation by ATM, CDK2 or p70s6K. Our results implicate specific kinases, and target phosphorylation sites in the degradation of Delta Np63 alpha following DNA damage.

ssDNA-binding protein 2 is frequently hypermethylated and suppresses cell growth in human prostate cancer.

PURPOSE: Prostate cancer is a major cause of cancer death among men and the development of new biomarkers is important to augment current detection approaches. EXPERIMENTAL DESIGN: We identified hypermethylation of the ssDNA-binding protein 2 (SSBP2) promoter as a potential DNA marker for human prostate cancer based on previous bioinformatics results and pharmacologic unmasking microarray. We then did quantitative methylation-specific PCR in primary prostate cancer tissues to confirm hypermethylation of the SSBP2 promoter, and analyzed its correlation with clinicopathologic data. We further examined SSBP2 expression in primary prostate cancer and studied its role in cell growth. RESULTS: Quantitative methylation-specific PCR results showed that the SSBP2 promoter was hypermethylated in 54 of 88 (61.4%) primary prostate cancers versus 0 of 23 (0%) in benign prostatic hyperplasia using a cutoff value of 120. Furthermore, we found that expression of SSBP2 was down-regulated in primary prostate cancers and cancer cell lines. Hypermethylation of the SSBP2 promoter and its expression were closely associated with higher stages of prostate cancer. Reactivation of SSBP2 expression by the demethylating agent 5-aza-2'-deoxycytidine in prostate cancer cell lines confirmed epigenetic inactivation as one major mechanism of SSBP2 regulation. Moreover, forced expression of SSBP2 inhibited prostate cancer cell proliferation in the colony formation assay and caused cell cycle arrest. CONCLUSION: SSBP2 inhibits prostate cancer cell proliferation and seems to represent a novel prostate cancer-specific DNA marker, especially in high stages of human prostate cancer.

Midkine induces epithelial-mesenchymal transition through Notch2/Jak2-Stat3 signaling in human keratinocytes.

Epithelial-to-mesenchymal transition (EMT) underlies cell plasticity and embryonic development and is frequently observed in advanced tumorigenesis. We demonstrated that midkine (MK), a retinoic acid-inducible heparin-binding mitogen, promotes EMT in immortalized HaCaT keratinocytes. We showed that MK binds to the Notch2 receptor in HaCaT keratinocytes. We further found that MK activates Notch2 signaling leading to protein/protein interactions between Hes1 and Jak2/Stat3 intermediates. We thus suggest that MK-induced cross talk of Notch2/Jak2/Stat3 signaling pathways can regulate cell plasticity and motility contributing to the EMT and later stages of tumorigenesis.

Profiling the expression pattern of GPI transamidase complex subunits in human cancer.

The glycosylphosphatidylinositol transamidase complex (GPIT) consists of five subunits: PIG-U, PIG-T, GPAA1, PIG-S and GPI8, and is important in attaching GPI anchors to target proteins. On the basis of our previous reports incriminating PIG-U as an oncogene in bladder cancer and PIG-T and GPAA1 as oncogenes in breast cancer, we evaluated the expression pattern of the GPIT subunits in 19 different human cancers at both mRNA and protein levels. In general, our results demonstrate a more frequent expression of GPIT subunits in cancers than in normal. Among the 19 anatomic sites compared; breast, ovary and uterus showed consistent evidence of overexpression of specific GPIT subunits. There was also overexpression of PIG-U and GPI8 in lymphoma. In addition, non-small cell lung carcinoma showed significant overexpression of the GPIT subunits as compared to small cell lung carcinoma and normal lung tissue. Also, deregulation of specific GPIT subunits was seen in various other cancers. Forced overexpression of two GPIT subunits; PIG-S and GPI8 alone or in combination induced increased proliferation and invasion of breast cancer cells. Collectively, our study defines a trend involving the deregulated expression and the functional contribution of the GPIT subunits in various cancers with potential implications in diagnosis, prognosis and therapeutic intervention.

Overexpression of AQP5, a putative oncogene, promotes cell growth and transformation.

Overexpression of several aquaporins has been reported in different types of human cancer but the role of AQPs in human carcinogenesis has not yet been clearly defined. Here, we demonstrate that ectopic expression of human AQP5 (hAQP5), a water channel expressed in lung, salivary glands, and kidney, induces many phenotypic changes characteristic of transformation both in vitro and in vivo. Furthermore, the cell proliferative ability of AQP5 appears to be dependent upon the phosphorylation of a cAMP-protein kinase (PKA) consensus site located in a cytoplasmic loop of AQP5. In addition, phosphorylation of the PKA consensus site was found to be phosphorylated preferentially in tumors. These findings altogether indicate that hAQP5 plays an important role in human carcinogenesis and, furthermore, provide an attractive therapeutic target.