To examine our results in vivo, several organs collected from BTG2-KO and BTG2 wild-type mice were subjected to immunoblot analyses, and the levels of p-mTOR-S2448 were examined. The endogenous levels of p-mTOR-S2448 were slightly elevated in the liver and lungs of BTG2-KO mice compared to those of wild-type mice (Figures 20A and 20B).
To further evaluate the importance of BTG2 expression in cancer progression, open data (OncomineTM) obtained from human breast cancer tissues were examined, and the results demonstrated a significant downregulation of BTG2 expression in malignant breast cancers compared to the expression levels observed in normal controls (Figure 20C). By contrast, expression of NFAT1 was significantly high in malignant cancers compared to that in controls (Figure 20D). It is impractical to directly measure the in vivo expression of AKT1 and AKT2 due to the absence of specific antibodies; therefore, we retrieved open data from OncomineTM to confirm the status of PHLPP2 and PHLPP1 expression in human breast cancers and control tissues. PHLPP2 expression was significantly higher in invasive breast cancers, whereas PHLPP1 expression was significantly lower (Figure 20E).
In addition, immunohistochemistry demonstrated constitutive expression of BTG2in basal cells of the human mammary duct and AKT expression in luminal epithelial cells (panel a and panel d, respectively, Figure 8A). BTG2 expression was maintained in the ductal carcinoma in situ (DCIS), but disappeared in the infiltrating ductal carcinoma (panel b and panel c, respectively, Figure 21A), suggesting a possible role of BTG2in preventing cancer cell progression from DCIS to infiltrating ductal carcinoma. Indeed, cross tabulation between BTG2 expression and lymph node invasion and analysis by Pearson’s χ2 tests (Figure 21B) revealed that the relative risk for a positive outcome was 0.1048 (0.088/0.842), with a 95% confidence interval, and the z-statistic was 4.027, with p=0.0001.
Furthermore, the open data retrieved from Kaplan-Meier Plotter (http://kmplot.com/analysis/) demonstrated that the overall survival of the BTG2 high expressers was significant only in ER-LN+ cancer patients, but not in the remaining 3 types of cancer (Figure 21C, log rank p=0.0051). In conclusion, the risk of lymph node invasion in BTG2+ breast cancer was approximately 1/10th the risk in BTG2- cancer patients. Additionally, gene expression data from the GEO dataset GSE61724
- 70 -
demonstrated that BTG2 was significantly downregulated in invasive ductal carcinoma and negatively correlated with PHLPP2 expression, whereas it was positively correlated with RICTOR (Figures 22A,B)). The GEO dataset GSE12777 demonstrated contrasting expression of BTG2 and PHLPP2 in various breast cancer cells, and the reverse correlation was more prominent in invasive cancer cells (Figures 22C,D). In addition, forced expression of BTG2 in human breast cancer cells significantly inhibited cell growth, the in vitro clonogenic ability, and in vivo tumor growth in humans (Figures 21D-H).
- 71 -
- 72 -
Figure 20. In vivo role of BTG2expression that blocks progression of breast cancers A) Endogenous activation of the mTOR complex in the liver and lungs of BTG2-KO mice.
Several organs were excised from BTG2-KO and wild-type mice, and then, expression of p-mTOR-S2448 and mTOR proteins was evaluated by immunoblot analyses. B) Immunoblot data shown in (A) were quantified using the ImageJ software, and the ratio of p- -actin is represented in the bar graph. C-E) Expressions of BTG2, NFAT1, PHLPP1, and PHLPP2 in human breast cancer tissues were retrieved from Oncomine™ containing data from 8 different laboratories. IDBC: Invasive Ductal Breast Carcinoma, IBC: Invasive Breast Carcinoma, DBC: Ductal Breast Carcinoma. p-Values are written on top of each box, and ‘Y’ axis denotes the log2 median-centered ratio. Numbers in parenthesis indicate the number of samples analyzed. Each graph represents the expression of individual genes, carried out by different laboratories.
- 73 -
- 74 -
- 75 -
Figure 21. Differential expressions of BTG2 and AKT in normal and infiltrating ductal carcinoma of human breast
A) Immunohistochemical staining with anti-BTG2 and anti-AKT antibodies. (a) BTG2 is strongly expressed in the basal cells of normal mammary ducts, but weakly expressed in luminal cells. (b) BTG2 expression is still intact in the basal cells of ductal carcinoma in situ (DCIS, black arrow), but not in both proliferating cells and intra-ductal carcinoma cells (blue arrow) of mammary ducts. Note BTG2 expression in basement cells. (c) BTG2 expression is present in normal epithelium of mammary duct (black arrow), but is absent in
- 76 -
infiltrating ductal carcinoma cells. (d) AKT expression is weakly positive in basal cells of normal mammary ducts as opposed to strong in luminal cells of the ducts. (e) AKT expression is weak in proliferating cells, but strong in intraductal carcinoma cells (blue arrow), as opposed to negative in the basal cells. (f) AKT expression is weak in normal ductal epithelial cells, but strong in infiltrating ductal carcinoma cells (arrow). a, b, d & e:
x200 and c & f: x400 magnification. B) Cross tabulation of BTG2 expression and lymph node invasion of human breast cancers examined by Pearson’s χ2 tests derived from the immunohistochemistry and pathological diagnosis. The risk in the BTG2+ group was 0.088 (3/34), and it was 0.842 in the BTG2- group (16/19). The relative risk for a positive outcome was 0.1048 (0.088/0.842) with a 95% confidence interval ranging from 0.035 to 0.314; the z-statistic is 4.027 and the associated p-value is 0.0001. C) Kaplan-Meier survival curves of breast cancers derived from the open data (http://kmplot.com/analysis/).
Note the statistically significant effect of the high expression of BTG2 on the survival rate of ER-LN+ cancer (log rank p=0.0051), but not in the remaining 3 types of cancers. D) Inhibition of cell proliferation by the BTG2gene. MCF-7 and MDA-MB-231 cells were infected with Ad-BTG2 at various doses, and cell growth was measured in 48 h using a hemocytometer. Note the concentration-dependent inhibition of proliferation. E) MTT assay: Note the reduced cell growth by infection with the Ad-BTG2 virus compared to that by infection with LacZ-expressing virus. F) Colony formation assay revealing significant inhibition of cell proliferation in BTG2 expressers. G) Cell cycle analysis of MDA-MB-468 cells by PI staining. Note the induction of G2/M arrest by BTG2 gene expression. H) Box plot data from the GEO GSE4922; BTG2 high expressers demonstrate smaller tumor volumes compared to those of BTG2 low expressers. D-F) All results are expressed as the mean + S.D. of two independent experiments.
- 77 -
Figure 22. GEO data analysis show positive correlation between BTG2 and RICTOR(mTORc2) but negatively with PHLPP2.
A) BTG2, PHLPP2 and RICTOR expression levels were extracted from the GEO dataset GSE61724. B) Spearmen’s rho correlation values among the genes were obtained by SPSS software. C) Expressions of BTG2, PHLPP1 and PHLPP2 in various human breast cancer cells were obtained from the GEO dataset GSE12777. Note almost absence of PHLPP1 expression in the cancer cells. D) Expressions of BTG2, PHLPP1 and PHLPP2 in breast cancer cells divided by the degree of invasiveness. Note inverse correlation between BTG2 and PHLPP2 expressions in the highly invasive cancer cells, and almost absence of PHLPP1 expression in the cancer cells.
- 78 -
IV. DISCUSSION
We herein present a mechanism of regulation of AKT1, but not AKT2, activity by the BTG2 gene in human breast cancers by inhibiting mTORc1 and enhancing mTORc2 activity (Figure Figure 23I); activation of AKT1 results in the degradation of NFAT1, which induces target genes that modulate the tumor microenvironment. The immunohistochemistry results revealed that BTG2expression, normally high in basal cells of the human mammary duct (Figure 21A), significantly decreased breast cancer invasion into the surrounding lymph nodes (Figure 21B), demonstrating the protective roles of BTG2in cancer progression across the basement membrane of mammary ducts as well as tumor growth (Figures 21D-H). Moreover, open data revealing the reverse correlation between PHLPP2 and BTG2 expression in human invasive breast cancers (Figures 20C and 20E, Figure 22B) supported the hypothesis of the effects of BTG2-AKT1 activation in breast cancers.
BTG2-induced pAKT-S473 was sensitive to the mTOR kinase inhibitors Torin 1 and pp242, but not to rapamycin, indicating phosphorylation of AKT by mTORc2 in response to BTG2. AKT phosphorylation at S473 by mTORc2 has already been reported;
however, to the best of our knowledge, this is the first report demonstrating activation of mTORc2 by a tumor suppressor by inhibition of the mTOR-Raptor interaction and p-p70S6K. Regulation of mTORc2 activity by BTG2 was demonstrated by siRictor transfection (Figure 15A, B). BTG2 formed a stable complex with mTOR and Raptor, but not with its downstream effector, p70S6K (Figure 10). Inhibition of mTORc1 by BTG2, either by direct or indirect binding to its regulators, may further influence protein and lipid biosynthesis. Since BTG2 reduced p-p70S6K in tsc1/2 null cells (Figure 11), our present study expands the role of BTG2 as a negative regulator of mTORc1. Moreover, expression of BTG2 reduced p70S6K-T389 in tsc1/2-null MEFs, and the low expression of tsc1/2 in BTG2-KO-MEFs was recovered by BTG2 reconstitution (Figure 11D-G). At present, we cannot explain how BTG2 induced transcription of tsc1 and tsc2; however, activation of NFkB [Sundaramoorthy S et al., 2013] and Sp1 [Devanand P et al., 2014] expression by BTG2 may account for activation of the transcription factors located in the tsc1/2
- 79 -
promoters. BTG2-inhibited p70S6K phosphorylation was independent of tsc1/2 expression, implying that BTG2 can act as a substitute for tsc1/2. In human breast cancer, silencing of the tsc1 gene by promoter methylation is significantly related with clinical outcomes [Jiang WG et al., 2005], and forced expression of BTG2 downregulates DNA methyltransferase 1 expression in human bladder cancer cells [Devanand P et al., 2014], thereby indicating that BTG2 may be a potential candidate gene targeted to treat cancers with hyperactive mTORc1 and tsc1/2 mutations.
Additionally, we suggested a potential role of BTG2, wherein it activates AKT1 by downregulating the AKT1-specific phosphatase, PHLPP2. In contrast to PHLPP1, PHLPP2 expression was significantly elevated in human breast cancers (OncomineTM) compared to that in the controls (Figure 20E). Data from Oncomine as well as our results (Figures 20C and 20E, Figure 16D) demonstrating the downregulation of BTG2 and elevated level of PHLPP2 in human breast cancer, indicate a likely negative correlation between the expression of PHLPP2 and BTG2 in malignant breast cancers and could further be used to elucidate in vivo signaling of the BTG2-pAKT1-S473 axis.
Although more evidence is required, we suggest that NFAT1 may be a direct substrate of AKT1 kinase, because treatment of MDA-MB-231 cells with AKT-IV and MG132 (Figure 18G, Figures 17A,B) demonstrated a slight band shift, indirectly indicating NFAT1 phosphorylation by AKT1 in BTG2 expresser cells. This assumption was strongly supported by the results from the protein motif scanner program (http://scansite.mit.edu/), which indicated the presence of the AKT recognition motif (PQRSRSPSPQPSSHV) in NFAT1 at the S256 and S737 residues (Figures 19A,B), and the sequences were very well conserved among humans, mice and Xenopus (Figure 18H). Therefore, we hypothesize that forced expression of BTG2 causes phosphorylation of NFAT1 by mTORc2-activated pAKT1-S473, which accelerates degradation of p-NFAT1 in the proteasome. Moreover, NFAT1-induced secretion of chemokines and interleukins influences chemotaxis and distant metastasis in malignant cancer cells; therefore, it is possible that BTG2 may negatively regulate the genes involved in cancer cell invasion and chemotaxis by mediating degradation of NFAT1 (Figures 18). Furthermore, promoter analysis of PHLPP2 by PROMO [Messeguer X et al., 2002] demonstrated the presence of NFAT1 binding sites
- 80 -
in the promoter of PHLPP2 (Figure 19C). Therefore, in addition to the differential regulation of mTORc1 and mTORc2 activities by the BTG2 gene, we suggest another signaling pathway, namely, the BTG2-pAKT1-S473-pNFAT1-PHLPP2 axis.
In conclusion, breast cancer growth can be inhibited by the BTG2-tsc1/2-mTORc1-p70S6K signaling axis, whereas cancer progression is downregulated by stimulating the BTG2-mTORc2-AKT1-NFAT1-PHLPP2 axis, which inhibits gene expression, regulating the tumor microenvironment. Finally, BTG2, as a promising potential target for the treatment of infiltrating breast cancers in humans, is worth exploring.
- 81 -
V. CONCLUSION & SCHEMETIC DIAGRAM
Schematic diagram showing the inhibitory signals of cancer growth and malignant progression by BTG2 gene. (a) In the absence of BTG2 expression, myristoylated AKT1 induces NFAT1 degradation, which downregulates expression of the target gene involved in the regulation of the tumor microenvironment and cancer progression, but maintains cancer cell growth by mTORc1 activation. (b) However, active expression of BTG2 inhibits cancer growth by blocking protein synthesis via inhibition of mTORc1 by BTG2-Raptor interaction along with transcriptional upregulation of tsc1, and inhibits tumorigenesis via interfering with cancer progression by degradation of NFAT1, which reduces expression of target genes, e.g., CCR7, CXCR4, IL4, and PHLPP2, via enhancing p-AKT1-S473 by mTORc2 activation. Taken together, we suggest that breast cancer cell growth can be inhibited through the BTG2-tsc1/2-mTORc1-p70S6K axis, and cancer progression is downregulated through the BTG2-mTORc2-AKT1-NFAT1- PHLPP2 signaling pathways.
- 82 - .
Table 1
- 83 -
REFERENCES
1. Alkalay I, Yaron A, Hatzubai A, Orian A, Ciechanover A, Ben-Neriah Y: Stimulation-dependent I kappa B alpha phosphorylation marks the NF-kappa B inhibitor for degradation via the ubiquitin-proteasome pathway. Proc Natl Acad Sci USA 1995, 92:10599–10603.
2. Arboleda MJ, Lyons JF, Kabbinavar FF, Bray MR, Snow BE, Ayala R, et al.
Overexpression of AKT2/protein kinase Bbeta leads to up-regulation of beta1 integrins, increased invasion, and metastasis of human breast and ovarian cancer cells.
Cancer research 2003, 63(1): 196-206.
3. Bellacosa A, Kumar CC, Di Cristofano A, Testa JR. Activation of AKT kinases in cancer: implications for therapeutic targeting. Advances in cancer research 2005, 94:
29-86.
4. Bellacosa A, Testa JR, Staal SP, Tsichlis PN. A retroviral oncogene, akt, encoding a serine-threonine kinase containing an SH2-like region. Science 1991, 254(5029): 274-277.
5. Bhandari D, Raisch T, Weichenrieder O, Jonas S, Izaurralde E. Structural basis for the Nanos-mediated recruitment of the CCR4-NOT complex and translational repression.
Genes & development 2014, 28(8): 888-901.
6. Boiko AD, Porteous S, Razorenova OV, Krivokrysenko VI, Williams BR, Gudkov AV:
A systematic search for downstream mediators of tumor suppressor function of p53 reveals a major role of BTG2 in suppression of Rasinduced transformation. Genes Dev 2006, 20:236–252.
7. Bradbury A, Possenti R, Shooter EM, Tirone F: Molecular cloning of PC3, a putatively secreted protein whose mRNA is induced by nerve growth factor and depolarization. Proc Natl Acad Sci USA 1991, 88:3353–3357.
8. Bravard A, Sabatier L, Hoffschir F, Ricoul M, Luccioni C, Dutrillaux B: SOD2: a new type of tumor-suppressor gene? Int J Cancer 1992, 51:476–480.
9. Buganim Y, Solomon H, Rais Y, Kistner D, Nachmany I, Brait M, Madar S, Goldstein I, Kalo E, Adam N, Gordin M, Rivlin N, Kogan I, Brosh R, Sefadia-Elad G, Goldfinger N, Sidransky D, Kloog Y, Rotter V: p53 regulates the Ras circuit to inhibit
- 84 -
the expression of a cancer-related gene signature by various molecular pathways.
Cancer Res 2010, 70:2274–2284.
10. Burdon RH, Gill V: Cellularly generated active oxygen species and HeLa cell proliferation. Free Radic Res Commun 1993, 19:203–213.
11. Chaudhary SC, Kurundkar D, Elmets CA, Kopelovich L, Athar M: Metformin, an antidiabetic agent reduces growth of cutaneous squamous cell carcinoma by targeting mTOR signaling pathway. Photochem Photobiol 2012, 88:1149–56.
12. Cheng J, Phong B, Wilson DC, Hirsch R, Kane LP: Akt fine-tunes NF-Κb -dependent gene expression during T cell activation. J Biol Chem 2011, 286:36076–36085.
13. Chin YR, Toker A. The actin-bundling protein palladin is an Akt1-specific substrate that regulates breast cancer cell migration. Molecular cell 2010, 38(3): 333-344.
14. Choi JA, Jung YS, Kim JY, Kim HM, Lim IK. Inhibition of breast cancer invasion by TIS21/BTG2/Pc3-Akt1-Sp1-Nox4 pathway targeting actin nucleators, mDia genes.
Oncogene 2016, 35(1): 83-93.
15. Choi JA, Lim IK. TIS21/BTG2 inhibits invadopodia formation by downregulating reactive oxygen species level in MDA-MB-231 cells. Journal of cancer research and clinical oncology 2013, 139(10): 1657-1665.
16. Choi YW, Park TJ, Kim HS, Lim IK: Signals regulating necrosis of cardiomyoblast by BTG2/TIS21/PC3 via activation of GSKβ and opening of mitochondrial permeability transition pore in response to H2O2. Biochem Biophys Res Commun 2013, 434:559 17. Church SL, Grant JW, Ridnour LA, Oberley LW, Swanson PE, Meltzer PS, Trent JM:
Increased manganese superoxide dismutase expression suppresses the malignant phenotype of human melanoma cells. Proc Natl Acad Sci USA 1993, 90:3113–3117.
18. Corrente G, Guardavaccaro D, Tirone F: PC3 potentiates NGF-induced differentiation and protects neurons from apoptosis. Neuroreport 2002, 25:417–422.
19. Devanand P, Kim SI, Choi YW, Sheen SS, Yim H, Ryu MS, et al. Inhibition of bladder cancer invasion by Sp1-mediated BTG2 expression via inhibition of DNA methyltransferase 1. The FEBS journal 2014, 281(24): 5581-5601.
20. Dhar SK, Clair DK St: Manganese superoxide dismutase regulation and cancer. Free Radic Biol Med 2012, 52:2209–2222.
21. DiDonato J, Mercurio F, Rosette C, Wu-Li J, Suyang H, Ghosh S, Karin M: Mapping
- 85 -
of the inducible IkappaB phosphorylation sites that signal its ubiquitination and degradation. Mol Cell Biol 1996, 16(4):1295–1304.
22. Ezzeddine N, Chang TC, Zhu W, Yamashita A, Chen CY, Zhong Z, et al. Human TOB, an antiproliferative transcription factor, is a poly(A)-binding protein-dependent positive regulator of cytoplasmic mRNA deadenylation. Molecular and cellular biology 2007, 27(22): 7791-7801.
23. Farioli-Vecchioli S, Cinà I, Ceccarelli M, Micheli L, Leonardi L, Ciotti MT, De Bardi M, Di Rocco C, Pallini R, Cavallaro S, Tirone F: TIS21 knock-out enhances the frequency of medulloblastoma in Patched1 heterozygous mice by inhibiting the Cxcl3-dependent migration of cerebellar neurons. J Neurosci 2012, 32:15547–15564.
24. Farioli-Vecchioli S, Tanori M, Micheli L, Mancuso M, Leonardi L, Saran A, et al.
Inhibition of medulloblastoma tumorigenesis by the antiproliferative and pro-differentiative gene PC3. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 2007, 21(9): 2215-2225.
25. Feng J, Park J, Cron P, Hess D, Hemmings BA. Identification of a PKB/Akt hydrophobic motif Ser-473 kinase as DNA-dependent protein kinase. The Journal of biological chemistry 2004, 279(39): 41189-41196.
26. Ficazzola MA, Fraiman M, Gitlin J, Woo K, Melamed J, Rubin MA, et al.
Antiproliferative B cell translocation gene 2 protein is down-regulated post-transcriptionally as an early event in prostate carcinogenesis. Carcinogenesis 2001, 22(8): 1271-1279.
27. Ficazzola MA, Fraiman M, Gitlin J, Woo K, Melamed J, Rubin MA, Walden PD:
Antiproliferative B cell translocation gene 2 protein is down-regulated post-transcriptionally as an early event in prostate carcinogenesis. Carcinogenesis 2001, 22:1271–1279.
28. Fletcher BS, Lim RW, Varnum BC, Kujubu DA, Koski RA, Herschman HR: Structure and expression of TIS21, a primary response gene induced by growth factors and tumor promoters. J Biol Chem 1991, 2661:4511–14518.
29. Frampton AE, Castellano L, Colombo T, Giovannetti E, Krell J, Jacob J, et al.
Integrated molecular analysis to investigate the role of microRNAs in pancreatic tumour growth and progression. Lancet 2015, 385 Suppl 1: S37.
- 86 -
30. Franke TF. PI3K/Akt: getting it right matters. Oncogene 2008, 27(50): 6473-6488.
31. Gao T, Furnari F, Newton AC. PHLPP: a phosphatase that directly dephosphorylates Akt, promotes apoptosis, and suppresses tumor growth. Molecular cell 2005, 18(1):
13-24.
32. Guardavaccaro D, Corrente G, Covone F, Micheli L, D'Agnano I, Starace G, et al.
Arrest of G(1)-S progression by the p53-inducible gene PC3 is Rb dependent and relies on the inhibition of cyclin D1 transcription. Molecular and cellular biology 2000, 20(5): 1797-1815.
33. Guardavaccaro D, Corrente G, Covone F, Micheli L, D’Agnano I, Starace G, Caruso M, Tirone F: Arrest of G(1)-S progression by the p53-inducible gene PC3 is Rb dependent and relies on the inhibition of cyclin D1 transcription. Mol Cell Biol 2000, 20:1797–1815.
Roles of nuclear factor-kappaB, p53, and p21/WAF1 in daunomycininduced cell cycle arrest and apoptosis. J Pharmacol Exp Ther 2000, 295:870–878.
36. Holley AK, Bakthavatchalu V, Velez-Roman JM, Clair DK St: Manganese superoxide dismutase: guardian of the powerhouse. Int J Mol Sci 2011, 12:7114–7162.
37. Hong JW, Ryu MS, Lim IK: Phosphorylation of serine 147 of tis21/BTG2/ pc3 by p-Erk1/2 induces Pin-1 binding in cytoplasm and cell death. J Biol Chem 2005, 280:21256–21263.
38. Horiuchi M, Takeuchi K, Noda N, Muroya N, Suzuki T, Nakamura T, et al. Structural basis for the antiproliferative activity of the Tob-hCaf1 complex. The Journal of biological chemistry 2009, 284(19): 13244-13255.
39. Hussain AR, Ahmed SO, Ahmed M, Khan OS, Al Abdulmohsen S, Platanias LC, Al-Kuraya KS, Uddin S: Cross-talk between NFkB and the PI3-kinase/AKT pathway can be targeted in primary effusion lymphoma (PEL) cell lines for efficient apoptosis.
PLoS One 2012, 7:e39945.
- 87 - Domany E, Givol D: DNA microarrays identification of primary and secondary target genes regulated by p53. Oncogene 2001, 20:2225–2234.
43. Kannan K, Amariglio N, Rechavi G, Jakob-Hirsch J, Kela I, Kaminski N, et al. DNA microarrays identification of primary and secondary target genes regulated by p53.
Oncogene 2001, 20(18): 2225-2234.
44. Karve TM, Rosen EM: B-cell translocation gene 2 (BTG2) stimulates cellular antioxidant defenses through the antioxidant transcription factor NFE2L2 in human mammary epithelial cells. J Biol Chem 2012, 287:31503–31514.
45. Kaunisto A, Henry WS, Montaser-Kouhsari L, Jaminet SC, Oh EY, Zhao L, et al.
NFAT1 promotes intratumoral neutrophil infiltration by regulating IL8 expression in breast cancer. Molecular oncology 2015, 9(6): 1140-1154.
46. Kawakubo H, Brachtel E, Hayashida T, Yeo G, Kish J, Muzikansky A, et al. Loss of B-cell translocation gene-2 in estrogen receptor-positive breast carcinoma is associated with tumor grade and overexpression of cyclin d1 protein. Cancer research 2006, 66(14): 7075-7082.
47. Kawakubo H, Carey JL, Brachtel E, Gupta V, Green JE, Walden PD, et al. Expression of the NF-kappaB-responsive gene BTG2 is aberrantly regulated in breast cancer.
47. Kawakubo H, Carey JL, Brachtel E, Gupta V, Green JE, Walden PD, et al. Expression of the NF-kappaB-responsive gene BTG2 is aberrantly regulated in breast cancer.