PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
 
FEBS J. Author manuscript; available in PMC 2017 May 1.
Published in final edited form as:
PMCID: PMC4880424
NIHMSID: NIHMS771280

KIBRA promotes prostate cancer cell proliferation and motility

Abstract

KIBRA is a regulator of the Hippo-YAP (yes-associated protein) pathway, which plays a critical role in tumorigenesis. In the current study, we show that KIBRA is a positive regulator in prostate cancer cell proliferation and motility. We found that KIBRA is transcriptionally upregulated in androgen-insensitive LNCaPC4-2 and LNCaP-C81 cells when compared to the parental androgen-sensitive LNCaP cells. Ectopic expression of KIBRA enhances cell proliferation, migration and invasion in both immortalized and cancerous prostate epithelial cells. Accordingly, knockdown of KIBRA reduces migration, invasion, and anchorage-independent growth in LNCaP-C4-2/C81 cells. Moreover, KIBRA expression is induced by androgen signaling and KIBRA is partially required for androgen receptor (AR) signaling activation in prostate cancer cells. In line with these findings, we further show that KIBRA is overexpressed in human prostate tumors. Our studies uncover unexpected results and identify KIBRA as a tumor promoter in prostate cancer.

Keywords: AR signaling, KIBRA, prostate cancer, proliferation, motility

Introduction

KIBRA (expressed in kidney and brain, also called WWC1) is one of the members of the WWC (WW and C2 domain containing, WWC1, 2, 3) family of proteins [1,2]. KIBRA is a memory performance and cognition-associated protein [39], and the KIBRA locus has been linked to brain-related disorders such as Alzheimer’s disease [1012]. KIBRA functions as an adaptor protein to transduce its biological functions in various physiological processes via interactions with many other proteins [13]. In addition to its functions in neurons, KIBRA also has multiple roles in non-neuronal cells involving cell polarity, trafficking, mitosis, cell proliferation, and cell migration [13]. For example, KIBRA positively regulates cell migration in podocytes [14], NRK cells [15], and breast cancer cells [16], while it does the opposite in immortalized breast epithelial cells [17]. KIBRA functions as a growth suppressive regulator through the Hippo pathway in Drosophila [1820]. KIBRA is phosphorylated by mitotic kinases cyclin-dependent kinase 1 (CDK1) and Aurora A during mitosis and is required for chromosome alignment [2123].

KIBRA has been linked with human cancers in several reports. Weakened expression of KIBRA in Claudin-low subtypes of breast cancer specimens correlates with poor prognosis [17]. Moreover, downregulation of KIBRA was shown to be a contributing factor to the malignancy of acute lymphocytic B-cell leukemia [24,25]. This alteration in expression in leukemia is due to epigenetic changes in the well-defined CpG island within the promoter of the KIBRA locus [24,25]. Strikingly, in common epithelial cancers such as colorectal, kidney, lung, breast and prostate there is virtually no methylation detected [24]. Instead of a tumor suppressive function of KIBRA, as suggested by the above studies, many previous reports have validated KIBRA’s role in positively regulating proliferation and motility [1416,2629] and KIBRA expression has positive clinical correlation with gastric cancer progression [30]. This duality of KIBRA’s suppression or promotion of proliferation and migration may be tissue- and context-dependent, requiring further investigation before KIBRA’s role can be fully deciphered. Furthermore, a role for KIBRA in prostate cancer has not been previously defined.

Prostate cancer is the most prevalent form of cancer in men in the United States and second only to lung cancer as the leading cause of cancer deaths in men [31]. Prostatectomy, usually the initial treatment, tends to be very effective for localized prostate cancer [32]. Tumor progression is initially androgen-dependent and androgen ablation therapy is at first very successful at reducing the tumor burden. Despite this early response, genetic alterations lead to the development of androgen-independent or castration-resistant prostate cancer (CRPC), which is almost always fatal [33]. This transition from androgen-dependent to androgen-independent growth is not well understood, and further insight into the mechanisms driving this process will help with developing target-driven therapeutics for the effective treatment of CRPC in the future.

We recently reported that YAP, the Hippo pathway effector, is upregulated in androgen-insensitive prostate cancer cells (LNCaP-C4-2 and C81) and confers castration-resistant growth in vivo [34]. During that study, we noticed that in addition to YAP, the protein levels of KIBRA were also significantly increased in LNCaP-C4-2 and LNCaP-C81 cells. Here we characterize the biological significance of KIBRA upregulation in androgen-insensitive prostate cancer cells. We show that KIBRA is a positive regulator in prostate cancer cell proliferation and motility. Moreover, increased expression of KIBRA was also observed in clinical prostate tumor samples. Thus, the current study reveals an unexpected role for KIBRA in regulating cell migration and proliferation in prostate cancer cells.

Results and Discussion

KIBRA is upregulated in androgen-insensitive prostate cancer cells

LNCaP and LNCaP-C33 cells rely on androgen to grow, while the LNCaP-C4-2 and LNCaP-C81 sublines are androgen-insensitive and can grow under androgen deprivation conditions [35,36]. We recently showed that YAP is upregulated during progression from an androgen-sensitive to an androgen-insensitive state [34]. During that work, we indeed found that KIBRA/WWC1 protein levels were also significantly increased in LNCaP-C4-2 and LNCaP-C81 cells when compared to the parental cells (Figure 1A, B). WWC2, which is in the same protein family as KIBRA, was increased in cancer cells when compared to RWPE-1 (immortalized prostate epithelial) cells; however, no significant change was observed between LNCaP and LNCaP-C4-2 cells (Figure 1A). Quantitative reverse transcription-PCR (RT-PCR) showed that the levels of KIBRA mRNA were significantly elevated in LNCaP-C4-2 and LNCaP-C81 cells (Figure 1C). Surprisingly, WWC2 and WWC3 mRNA levels were reduced in LNCaP-C4-2 and LNCaP-C81 cells when compared to LNCaP cells (Figure 1C). KIBRA protein stability/half-life is similar in both LNCaP and LNCaP-C4-2 cells (Figure 1D). Since KIBRA is induced by YAP [37] and YAP is elevated in androgen-insensitive prostate cancer cells [34], we tested whether KIBRA expression is YAP-dependent in LNCaP-C4-2 cells. Figure 1E showed that KIBRA expression was partially reduced in LNCaP-C4-2 cells with YAP knockdown (Figure 1E). Together, these observations indicate that KIBRA expression is transcriptionally increased in androgen-insensitive prostate cancer cells compared with androgen-sensitive cells and that its expression in these cells is partially regulated by YAP.

Fig.1
KIBRA is transcriptionally upregulated in androgen-insensitive prostate cancer cells

KIBRA promotes proliferation, migration and invasion in RWPE-1 cells

To determine the role of KIBRA in prostate cancer, we first established stable cell lines expressing KIBRA in RWPE-1 cells (Figure 2A). Overexpression of KIBRA did not alter the WWC2 protein and WWC3 mRNA levels (Figure 2A). Ectopic expression of KIBRA stimulated cell proliferation (Figure 2B). Overexpression of KIBRA also induced cell migration (Figure 2C, D) and invasion (Figure 2E, F). KIBRA expression was not sufficient to cause anchorage-independent growth (neoplastic transformation) of RWPE-1 cells (Figure 2G). KIBRA regulates an epithelial-mesenchymal transition (EMT) in breast epithelial cells [17]. However, KIBRA overexpression did not alter the expression of E-cadherin (an epithelial marker) and vimentin (a mesenchymal marker) (Figure 2H), suggesting that KIBRA regulates EMT in a cell type specific manner.

Fig.2
KIBRA promotes proliferation, migration and invasion in RWPE-1 cells

KIBRA promotes proliferation, migration and invasion in LNCaP cells

Next we investigated whether KIBRA plays a similar role in prostate cancer cells. LNCaP cells with stable expression of KIBRA was established (Figure 3A). No changes of WWC2 and WWC3 expression were detected in KIBRA-overexpressing cells (Figure 3A). LNCaP-KIBRA-expressing cells proliferated significantly faster than LNCaP-vector cells (Figure 3B). Similarly, KIBRA overexpression also enhanced cell migration and invasiveness in LNCaP cells (Figure 3C–F). However, ectopic expression of KIBRA did not alter the LNCaP cells’ anchorage-independent growth (Figure 3G, H).

Fig.3
KIBRA promotes proliferation, migration and invasion in LNCaP cells

We recently showed that YAP overexpression converted LNCaP cells from androgen-sensitive to androgen-insensitive growth [34], we also tested whether KIBRA plays a role in androgen sensitivity. Under androgen-deprivation conditions, both LNCaP-vector and LNCaP-KIBRA cells failed to divide, suggesting that enhanced expression of KIBRA was not sufficient to promote androgen-insensitive growth in LNCaP cells (Figure 3I).

KIBRA knockdown impairs migration, invasion and anchorage-independent growth in prostate cancer cells

To explore the significance of KIBRA upregulation in androgen-insensitive prostate cancer cells, we reduced KIBRA expression using a validated shRNA against KIBRA [21] in LNCaP-C4-2 and LNCaP-C81 cells (Figure 4A). In contrast to the gain of function phenotypes in LNCaP and RWPE-1 cells, knockdown of KIBRA did not alter the proliferation rates in LNCaP-C4-2 and LNCaP-C81 cells (Figure 4B). Interestingly, knockdown of KIBRA greatly reduced migration and invasion (Figure 4C–E) and anchorage-independent growth (Figure 4F) in these cells. Together, these data revealed that KIBRA is a positive regulator in prostate cancer cell proliferation and motility.

Fig.4
KIBRA knockdown impairs motility and anchorage-independent growth in prostate cancer cells

KIBRA is induced by AR signaling

Consistent with the results from RWPE-1 cells, KIBRA overexpression or knockdown did not alter the expression of E-cadherin, an epithelial marker (Figure 5A). N-cadherin and vimentin (both are mesenchymal markers) were not detectable in LNCaP or LNCaP-C4-2 cells. AR protein levels were not affected by KIBRA expression either (Figure 5A). AR signaling activity is higher in LNCaP C4-2 and LNCaP-C81 cells than in LNCaP cells [34,38]. To analyze whether KIBRA expression is regulated by AR signaling, we treated the LNCaP cells with R1881, an analog of androgen ligand, to activate the AR signaling. Interestingly, KIBRA protein levels were dramatically increased upon R1881 treatment (Figure 5B). Similar findings were also observed in androgen-insensitive cells (LNCaP-C4-2 and LNCaP-C81) (Figure 5C). However, the levels of mRNA of KIBRA were not altered in the presence of R1881 (Figure 5D, E). The expression of prostate-specific antigen (PSA), a known target of AR, was induced (Figure 5D, E). KIBRA protein stability was not significantly affected in the presence of R1881 (Figure 5F). In future studies, we will explore the underlying mechanisms through which AR signaling activation by R1881 induces KIBRA expression.

Fig. 5
KIBRA is induced by R1881 and is required for AR signaling activation

Interestingly, mRNA levels of PSA were significantly reduced in KIBRA knockdown LNCaP-C4-2 cells, suggesting that KIBRA is required for full activation of AR signaling (Figure 5G). However, it is not known how KIBRA regulates AR activity and the downstream signaling. Previous reports showed that both Lats2 [39] and YAP [39] associate with AR, and that KIBRA interacts with Lats2 [37]. Therefore, KIBRA may form a complex with AR through other binding partners to regulate AR activity though KIBRA expression did not affect the Lats1 kinase activity and YAP phosphorylation in prostate cancer cells (Figure 5H).

KIBRA is upregulated in prostate tumors

Having established the role of KIBRA in prostate cancer with cell culture systems, we wanted to determine the clinical relevance of KIBRA in prostate cancer. Publically available data demonstrated that mRNA levels of KIBRA were significantly higher in prostate tumors than normal prostate tissue (Figure 6A–D). Moreover, KIBRA protein levels were also greatly increased in prostate tumors than normal prostate tissue in another set of samples (Figure 6E).

Fig. 6
KIBRA is overexpressed in prostate cancer

In conclusion, the results show that ectopic expression of KIBRA promotes prostate cancer cell proliferation and motility. KIBRA knockdown impairs migration and invasion in androgen-insensitive prostate cancer cells. KIBRA expression is induced by AR signaling and is increased in prostate tumors. Our findings reveal a pro-tumor function for KIBRA in prostate cancer.

Materials and Methods

Expression constructs and cell culture

The human KIBRA cDNA and shRNA constructs have been previously described [37]. LNCaP-C4-2 cell lines with shControl or shYAP have been described in [34]. RWPE-1 and LNCaP cell lines and related media and supplements were purchased from American Type Culture Collection (ATCC, Manassas, VA, USA), and the cell lines were cultured following ATCC’s instructions. LNCaP-C4-2 was provided by Dr. Kaustubh Datta (University of Nebraska Medical Center) [40]. LNCaP-C33 and LNCaP-C81 cell lines were obtained from Dr. Ming-Fong Lin (University of Nebraska Medical Center) [41,42]. R1881 (an androgen analog) was purchased from PerkinElmer (Waltham, MA, USA). All other chemicals were either from Sigma (St. Louis, MO, USA) or Thermo Fisher (Waltham, MA, USA).

Generation of cell lines

Ectopic expression of empty vector (control) or KIBRA in the RWPE-1 and LNCaP cell lines was achieved by a retrovirus-mediated approach. ShRNA-mediated knockdown of KIBRA in LNCaP-C4-2 or LNCaP-C81 cells was achieved similarly. Virus packaging, infection, and resistance selection were done as described [37].

Antibodies

Mouse monoclonal antibodies against human KIBRA have been described [21] and were used for Western blot analysis throughout the study. Anti-WWC2 antibodies were purchased from Sigma. Anti-β-actin antibodies were from Santa Cruz Biotechnology (Dallas, TX, USA). Anti-YAP, anti-vimentin, and anti-E-cadherin antibodies were from Cell Signaling Technology (Danvers, MA, USA). Anti-N-cadherin antibodies were provided by Dr. Keith Johnson [43]. Total cell lysate preparation and Western blotting assays were done as previously described [21].

Cell proliferation, migration, invasion, and colony assays

Cell proliferation assays were performed as described in [44]. Cells (3,000/well) were seeded in a 24-well plate in triplicate. Colony assays (to assess anchorage-independent growth in soft agar) were done in 6-well plates as we have described [45]. In vitro cell migration and invasion assays were assessed using the Transwell system (Corning Inc., Corning, NY, USA) and BioCoat invasion system (BD BioSciences, San Jose, CA, USA), respectively, according to the manufacturer’s instructions. Cells (50,000 or 100,000) were seeded for each Transwell/Insert in duplicate and repeated twice [34]. The migratory and invasive cells were stained with ProLong Gold Antifade Reagent with DAPI [16,46] and counted under a 20X lens. The rates are the average of counts in five fields of view per Transwell/Insert.

Quantitative real time-PCR

Total RNA isolation, RNA reverse transcription, and PCR were done with SYBR green (Bio-Rad) as previously described [37]. Primer sequences were as follows: WWC2: 5’-tctggcctccagacattttt (forward); 5’-tctcacacaagcttattctcagg (reverse); WWC3: 5’-agttcgtccccaacacaatc (forward); 5’-cgcgtcttttacattgacca (reverse). Other primers used in this study were listed in [34,37].

Prostate tumor samples

Normal prostate and tumor samples/proteins were obtained from Protein Biotechnologies and the Tissue Bank at the University of Nebraska Medical Center.

Statistical analysis

Statistical significance was analyzed using a two-tailed, unpaired Student’s t-test.

Acknowledgments

We wish to thank Drs. Ming-Fong Lin and Kaustubh Datta (University of Nebraska Medical Center) for providing us the LNCaP-C33 (equivalent to LNCaP)/LNCaP-C81 and LNCaP-C4-2 cell lines. We also thank Dr. Keith Johnson for the anti-N-cadherin antibodies. Four prostate tissue samples were provided by the University of Nebraska Medical Center (UNMC) Tissue Bank. Support for research facilities at the UNMC is contributed by the Fred & Pamela Buffett Cancer Center’s NCI Cancer Center Support Grant (P30 CA036727). Research in the Dong laboratory is supported in part by grants P30 GM106397, R01 GM109066 from the National Institutes of Health and W81XWH-14-1-0150 from the Department of Defense Health Program, through Prostate Cancer Research Program. We also thank Dr. Joyce Solheim for critical reading and comments on the manuscript.

Abbreviations

AR
androgen receptor
CRPC
castration-resistant prostate cancer
EMT
epithelial-mesenchymal transition
PSA
prostate-specific antigen
WWC1–3
WW and C2 domain containing protein 1–3
YAP
yes-associated protein

Footnotes

Author contributions

JD and SS designed and wrote the paper. SS, XC, LZ, and YC performed the experiments, analyzed the data and interpreted the results. YC also provided technical support. All authors reviewed and approved the manuscript prior to submission.

References

1. Kremerskothen J, Plaas C, Buther K, Finger I, Veltel S, Matanis T, Liedtke T, Barnekow A. Characterization of KIBRA, a novel WW domain-containing protein. Biochem Biophys Res Commun. 2003;300:862–867. [PubMed]
2. Yoshihama Y, Chida K, Ohno S. The KIBRA-aPKC connection: A potential regulator of membrane trafficking and cell polarity. Commun Integr Biol. 2012;5:146–151. [PMC free article] [PubMed]
3. Papassotiropoulos A, Stephan DA, Huentelman MJ, Hoerndli FJ, Craig DW, Pearson JV, Huynh KD, Brunner F, Corneveaux J, Osborne D, Wollmer MA, Aerni A, Coluccia D, Hanggi J, Mondadori CR, Buchmann A, Reiman EM, Caselli RJ, Henke K, de Quervain DJ. Common Kibra alleles are associated with human memory performance. Science. 2006;314:475–478. [PubMed]
4. Makuch L, Volk L, Anggono V, Johnson RC, Yu Y, Duning K, Kremerskothen J, Xia J, Takamiya K, Huganir RL. Regulation of AMPA receptor function by the human memory-associated gene KIBRA. Neuron. 2011;71:1022–1029. [PMC free article] [PubMed]
5. Almeida OP, Schwab SG, Lautenschlager NT, Morar B, Greenop KR, Flicker L, Wildenauer D. KIBRA genetic polymorphism influences episodic memory in later life, but does not increase the risk of mild cognitive impairment. J Cell Mol Med. 2008;12:1672–1676. [PMC free article] [PubMed]
6. Bates TC, Price JF, Harris SE, Marioni RE, Fowkes FG, Stewart MC, Murray GD, Whalley LJ, Starr JM, Deary IJ. Association of KIBRA and memory. Neurosci Lett. 2009;458:140–143. [PubMed]
7. Schaper K, Kolsch H, Popp J, Wagner M, Jessen F. KIBRA gene variants are associated with episodic memory in healthy elderly. Neurobiol Aging. 2008;29:1123–1125. [PubMed]
8. Schneider A, Huentelman MJ, Kremerskothen J, Duning K, Spoelgen R, Nikolich K. KIBRA: A New Gateway to Learning and Memory? Front Aging Neurosci. 2010;2:4. [PMC free article] [PubMed]
9. Yasuda Y, Hashimoto R, Ohi K, Fukumoto M, Takamura H, Iike N, Yoshida T, Hayashi N, Takahashi H, Yamamori H, Morihara T, Tagami S, Okochi M, Tanaka T, Kudo T, Kamino K, Ishii R, Iwase M, Kazui H, Takeda M. Association study of KIBRA gene with memory performance in a Japanese population. World J Biol Psychiatry. 2010;11:852–857. [PubMed]
10. Corneveaux JJ, Liang WS, Reiman EM, Webster JA, Myers AJ, Zismann VL, Joshipura KD, Pearson JV, Hu-Lince D, Craig DW, Coon KD, Dunckley T, Bandy D, Lee W, Chen K, Beach TG, Mastroeni D, Grover A, Ravid R, Sando SB, Aasly JO, Heun R, Jessen F, Kolsch H, Rogers J, Hutton ML, Melquist S, Petersen RC, Alexander GE, Caselli RJ, Papassotiropoulos A, Stephan DA, Huentelman MJ. Evidence for an association between KIBRA and late-onset Alzheimer's disease. Neurobiol Aging. 2010;31:901–909. [PMC free article] [PubMed]
11. Rodriguez-Rodriguez E, Infante J, Llorca J, Mateo I, Sanchez-Quintana C, Garcia-Gorostiaga I, Sanchez-Juan P, Berciano J, Combarros O. Age-dependent association of KIBRA genetic variation and Alzheimer's disease risk. Neurobiol Aging. 2009;30:322–324. [PubMed]
12. Beecham GW, Martin ER, Li YJ, Slifer MA, Gilbert JR, Haines JL, Pericak-Vance MA. Genome-wide association study implicates a chromosome 12 risk locus for late-onset Alzheimer disease. Am J Hum Genet. 2009;84:35–43. [PubMed]
13. Zhang L, Yang S, Wennmann DO, Chen Y, Kremerskothen J, Dong J. KIBRA: In the brain and beyond. Cell Signal. 2014;26:1392–1399. [PMC free article] [PubMed]
14. Duning K, Schurek EM, Schluter M, Bayer M, Reinhardt HC, Schwab A, Schaefer L, Benzing T, Schermer B, Saleem MA, Huber TB, Bachmann S, Kremerskothen J, Weide T, Pavenstadt H. KIBRA modulates directional migration of podocytes. J Am Soc Nephrol. 2008;19:1891–1903. [PubMed]
15. Rosse C, Formstecher E, Boeckeler K, Zhao Y, Kremerskothen J, White MD, Camonis JH, Parker PJ. An aPKC-exocyst complex controls paxillin phosphorylation and migration through localised JNK1 activation. PLoS Biol. 2009;7:e1000235. [PMC free article] [PubMed]
16. Yang S, Ji M, Zhang L, Chen Y, Wennmann DO, Kremerskothen J, Dong J. Phosphorylation of KIBRA by the extracellular signal-regulated kinase (ERK)-ribosomal S6 kinase (RSK) cascade modulates cell proliferation and migration. Cell Signal. 2014;26:343–351. [PMC free article] [PubMed]
17. Moleirinho S, Chang N, Sims AH, Tilston-Lunel AM, Angus L, Steele A, Boswell V, Barnett SC, Ormandy C, Faratian D, Gunn-Moore FJ, Reynolds PA. KIBRA exhibits MST-independent functional regulation of the Hippo signaling pathway in mammals. Oncogene. 2013;32:1821–1830. [PubMed]
18. Baumgartner R, Poernbacher I, Buser N, Hafen E, Stocker H. The WW domain protein Kibra acts upstream of Hippo in Drosophila. Dev Cell. 2010;18:309–316. [PubMed]
19. Genevet A, Wehr MC, Brain R, Thompson BJ, Tapon N. Kibra is a regulator of the Salvador/Warts/Hippo signaling network. Dev Cell. 2010;18:300–308. [PMC free article] [PubMed]
20. Yu J, Zheng Y, Dong J, Klusza S, Deng WM, Pan D. Kibra functions as a tumor suppressor protein that regulates Hippo signaling in conjunction with Merlin and Expanded. Dev Cell. 2010;18:288–299. [PMC free article] [PubMed]
21. Xiao L, Chen Y, Ji M, Volle DJ, Lewis RE, Tsai MY, Dong J. KIBRA protein phosphorylation is regulated by mitotic kinase aurora and protein phosphatase 1. J Biol Chem. 2011;286:36304–36315. [PMC free article] [PubMed]
22. Ji M, Yang S, Chen Y, Xiao L, Zhang L, Dong J. Phospho-regulation of KIBRA by CDK1 and CDC14 phosphatase controls cell-cycle progression. Biochem J. 2012;447:93–102. [PubMed]
23. Zhang L, Iyer J, Chowdhury A, Ji M, Xiao L, Yang S, Chen Y, Tsai MY, Dong J. KIBRA Regulates Aurora Kinase Activity and Is Required for Precise Chromosome Alignment During Mitosis. J Biol Chem. 2012;287:34069–34077. [PMC free article] [PubMed]
24. Hill VK, Dunwell TL, Catchpoole D, Krex D, Brini AT, Griffiths M, Craddock C, Maher ER, Latif F. Frequent epigenetic inactivation of KIBRA, an upstream member of the Salvador/Warts/Hippo (SWH) tumor suppressor network, is associated with specific genetic event in B-cell acute lymphocytic leukemia. Epigenetics. 2011;6:326–332. [PMC free article] [PubMed]
25. Shinawi T, Hill V, Dagklis A, Baliakas P, Stamatopoulos K, Agathanggelou A, Stankovic T, Maher ER, Ghia P, Latif F. KIBRA gene methylation is associated with unfavorable biological prognostic parameters in chronic lymphocytic leukemia. Epigenetics. 2012;7:211–215. [PubMed]
26. Hilton HN, Stanford PM, Harris J, Oakes SR, Kaplan W, Daly RJ, Ormandy CJ. KIBRA interacts with discoidin domain receptor 1 to modulate collagen-induced signalling. Biochim Biophys Acta. 2008;1783:383–393. [PubMed]
27. Rayala SK, den Hollander P, Manavathi B, Talukder AH, Song C, Peng S, Barnekow A, Kremerskothen J, Kumar R. Essential role of KIBRA in co-activator function of dynein light chain 1 in mammalian cells. J Biol Chem. 2006;281:19092–19099. [PubMed]
28. Yoshihama Y, Sasaki K, Horikoshi Y, Suzuki A, Ohtsuka T, Hakuno F, Takahashi S, Ohno S, Chida K. KIBRA suppresses apical exocytosis through inhibition of aPKC kinase activity in epithelial cells. Curr Biol. 2011;21:705–711. [PubMed]
29. Yang S, Ji M, Zhang L, Chen Y, Wennmann DO, Kremerskothen J, Dong J. Phosphorylation of KIBRA by the extracellular signal-regulated kinase (ERK)-ribosomal S6 kinase (RSK) cascade modulates cell proliferation and migration. Cell Signal. 2013;26:343–351. [PMC free article] [PubMed]
30. Yoshihama Y, Izumisawa Y, Akimoto K, Satoh Y, Mizushima T, Satoh K, Chida K, Takagawa R, Akiyama H, Ichikawa Y, Kunisaki C, Inayama Y, Endo I, Nagashima Y, Ohno S. High expression of KIBRA in low atypical protein kinase C-expressing gastric cancer correlates with lymphatic invasion and poor prognosis. Cancer Sci. 2013;104:259–265. [PubMed]
31. Siegel R, Ma J, Zou Z, Jemal A. Cancer statistics, 2014. CA Cancer J Clin. 2014;64:9–29. [PubMed]
32. DeSantis CE, Lin CC, Mariotto AB, Siegel RL, Stein KD, Kramer JL, Alteri R, Robbins AS, Jemal A. Cancer treatment and survivorship statistics, 2014. CA Cancer J Clin. 2014;64:252–271. [PubMed]
33. Isaacs W, De Marzo A, Nelson WG. Focus on prostate cancer. Cancer Cell. 2002;2:113–116. [PubMed]
34. Zhang L, Yang S, Chen X, Stauffer S, Yu F, Lele SM, Fu K, Datta K, Palermo N, Chen Y, Dong J. The Hippo Pathway Effector YAP Regulates Motility, Invasion, and Castration-Resistant Growth of Prostate Cancer Cells. Mol Cell Biol. 2015;35:1350–1362. [PMC free article] [PubMed]
35. Karan D, Kelly DL, Rizzino A, Lin MF, Batra SK. Expression profile of differentially-regulated genes during progression of androgen-independent growth in human prostate cancer cells. Carcinogenesis. 2002;23:967–975. [PubMed]
36. Karan D, Schmied BM, Dave BJ, Wittel UA, Lin MF, Batra SK. Decreased androgen-responsive growth of human prostate cancer is associated with increased genetic alterations. Clin Cancer Res. 2001;7:3472–3480. [PubMed]
37. Xiao L, Chen Y, Ji M, Dong J. KIBRA regulates Hippo signaling activity via interactions with large tumor suppressor kinases. J Biol Chem. 2011;286:7788–7796. [PMC free article] [PubMed]
38. Qin J, Xie Y, Wang B, Hoshino M, Wolff DW, Zhao J, Scofield MA, Dowd FJ, Lin MF, Tu Y. Upregulation of PIP3-dependent Rac exchanger 1 (P-Rex1) promotes prostate cancer metastasis. Oncogene. 2009;28:1853–1863. [PMC free article] [PubMed]
39. Powzaniuk M, McElwee-Witmer S, Vogel RL, Hayami T, Rutledge SJ, Chen F, Harada S, Schmidt A, Rodan GA, Freedman LP, Bai C. The LATS2/KPM tumor suppressor is a negative regulator of the androgen receptor. Mol Endocrinol. 2004;18:2011–2023. [PubMed]
40. Thalmann GN, Anezinis PE, Chang SM, Zhau HE, Kim EE, Hopwood VL, Pathak S, von Eschenbach AC, Chung LW. Androgen-independent cancer progression and bone metastasis in the LNCaP model of human prostate cancer. Cancer Res. 1994;54:2577–2581. [PubMed]
41. Lin MF, Meng TC, Rao PS, Chang C, Schonthal AH, Lin FF. Expression of human prostatic acid phosphatase correlates with androgen-stimulated cell proliferation in prostate cancer cell lines. J Biol Chem. 1998;273:5939–5947. [PubMed]
42. Igawa T, Lin FF, Lee MS, Karan D, Batra SK, Lin MF. Establishment and characterization of androgen-independent human prostate cancer LNCaP cell model. Prostate. 2002;50:222–235. [PubMed]
43. Johnson KR, Lewis JE, Li D, Wahl J, Soler AP, Knudsen KA, Wheelock MJ. P- and E-cadherin are in separate complexes in cells expressing both cadherins. Exp Cell Res. 1993;207:252–260. [PubMed]
44. Zhou Z, Hao Y, Liu N, Raptis L, Tsao MS, Yang X. TAZ is a novel oncogene in non-small cell lung cancer. Oncogene. 2011;30:2181–2186. [PubMed]
45. Dong J, Feldmann G, Huang J, Wu S, Zhang N, Comerford SA, Gayyed MF, Anders RA, Maitra A, Pan D. Elucidation of a universal size-control mechanism in Drosophila and mammals. Cell. 2007;130:1120–1133. [PMC free article] [PubMed]
46. Yang S, Zhang L, Liu M, Chong R, Ding SJ, Chen Y, Dong J. CDK1 Phosphorylation of YAP Promotes Mitotic Defects and Cell Motility and Is Essential for Neoplastic Transformation. Cancer Res. 2013;73:6722–6733. [PMC free article] [PubMed]
47. Su AI, Welsh JB, Sapinoso LM, Kern SG, Dimitrov P, Lapp H, Schultz PG, Powell SM, Moskaluk CA, Frierson HF, Jr, Hampton GM. Molecular classification of human carcinomas by use of gene expression signatures. Cancer Res. 2001;61:7388–7393. [PubMed]
48. Singh D, Febbo PG, Ross K, Jackson DG, Manola J, Ladd C, Tamayo P, Renshaw AA, D'Amico AV, Richie JP, Lander ES, Loda M, Kantoff PW, Golub TR, Sellers WR. Gene expression correlates of clinical prostate cancer behavior. Cancer Cell. 2002;1:203–209. [PubMed]
49. Lapointe J, Li C, Higgins JP, van de Rijn M, Bair E, Montgomery K, Ferrari M, Egevad L, Rayford W, Bergerheim U, Ekman P, DeMarzo AM, Tibshirani R, Botstein D, Brown PO, Brooks JD, Pollack JR. Gene expression profiling identifies clinically relevant subtypes of prostate cancer. Proc Natl Acad Sci U S A. 2004;101:811–816. [PubMed]
50. Henshall SM, Afar DE, Hiller J, Horvath LG, Quinn DI, Rasiah KK, Gish K, Willhite D, Kench JG, Gardiner-Garden M, Stricker PD, Scher HI, Grygiel JJ, Agus DB, Mack DH, Sutherland RL. Survival analysis of genome-wide gene expression profiles of prostate cancers identifies new prognostic targets of disease relapse. Cancer Res. 2003;63:4196–4203. [PubMed]