Original research study - OA Publishing London · 2012. 11. 22. · Yat-sen University Cancer Centre, Guangzhou, China 4 Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou,

of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.

Original research study

For citation purposes: Chen SW, Zhang Q, Yang AK, Li Z, Zhong Y, Li H, et al. Overexpression and cytoplasmic localisa-tion of Sam68 correlates with tumour progression and poor prognosis in patients with clinically N0 oral tongue cancer. Head Neck Oncol. 2012 Sep 9;4(2):61.

Copyright © 2012 OA Publishing London

AbstractSrc-associated protein in mitosis (Sam68, 68 kDa), the substrate of Src in mitosis, has been reported to cor-relate with the progression and out-come of many tumour types. In this study, we report Sam68 overexpres-sion in clinically N0 (cN0) oral tongue cancer and its correlation with the clinicopathologic characteristics and prognosis of patients. Analysis of oral tongue cancer cell lines and cancer-ous tissues revealed that Sam68 was up-regulated at both the messen-ger ribonucleic acid and the protein level. Immunohistochemical study of Sam68 protein expression and locali-sation in 181 cN0 oral tongue cancer samples confirmed the results, which showed significantly shorter overall and disease-free survival after sur-gery in cases with higher Sam68 ex-pression (p = 0.009 and p = 0.002, respectively) and cytoplasmic locali-sation of Sam68 (p



Page 2 of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.


transduction and activation of RNA8–10. Src-associated protein in mitosis (Sam68, 68 kDa), originally identified as a substrate of Src in mitosis11, is the best characterised prototypical member of the STAR family. This so-called superSTAR protein is impli-cated in a multitude of cellular pro-cesses including signal transduction, transcription, RNA metabolism, cell cycle regulation and apoptosis12. Accumulating experimental evidence suggests that Sam68 plays a principal role in regulating various biological processes during tumourigenesis and correlates with the progression and outcome of many tumour types. Sam68 has been recently considered to be a potential therapeutic target for cancer13. In this study, we investi-gated the expression level of Sam68 in a series of cN0 oral tongue cancer patients. We aimed to investigate the clinical significance of Sam68 in the development and progression of cN0 oral tongue cancer. We also ex-plored the application of Sam68 in the differentiation of patients har-bouring occult micrometastases and those who require a more aggressive treatment.

Materials and methodsPatients and tissue specimensNone of the patients included in the study had received therapy before surgery. Twelve paired fresh tissues were obtained from glossectomy specimens of 12 patients diagnosed with cN0 oral tongue cancer for quantitative polymerase chain reac-tion (qPCR) and Western blotting analysis. The specimens used for im-munohistochemical analysis were obtained from 181 patients with cN0 oral tongue cancer, which had been formalinfixed, paraffinembedded and clinically and histopathologically diagnosed at the Sun Yat-sen University Cancer Centre between 1998 and 2005, with clinical follow-up for a minimum of five years or until death. All patients were treated with standard therapy based on the clinical

stage. Briefly, patients at an early stage (stages I and II) underwent surgery alone, whereas those at an ad-vanced stage (stages III and IV) under-went combination therapy of surgery and successive radiation. The patients were followedup for 67.8 ± 35.6 months (mean ± SD). Clinical informa-tion of the patients is summarised in Table 1. The specimens were used with prior patient consent and the ap-proval of the Insti tutional Research Ethics Committee of the Sun Yat-sen University Cancer Centre.

Cell linesFive human oral tongue cancer cell lines (SCC9, SCC25, CAL27, TSCCa and Tca-8113) were obtained from the American Type Culture Collection (the former three) and the Cell Bank of Type Culture Collection of Chinese Academy of Sciences (the latter two). SCC9, SCC25 and CAL27 were maintained in Dulbecco’s Modified Eagle Medium (Invitrogen) supple-mented with 10% foetal bovine se-rum (HyClone Laboratories, Logan, UT). TSCCa and Tca-8113 were cul-tured in RPMI-1640 medium (GIBCO BRL, Rockville, MD) supplemented with 10% foetal bovine serum (HyClone Laboratories, Logan, UT). Cells were grown in a 5% CO2 humid-ified atmosphere at 37°C.

RNA extraction, reverse transcription (RT) and qPCRTotal RNA from cultured cells and fresh tissues were extracted using the Trizol reagent (Invitrogen, 15596-018). Two milligrams of RNA from each sample was used for cDNA synthesis using the iScript™ cDNA Synthesis Kit (Bio-Rad Laboratories, 1708891). qPCR was used to quantify fold change of the Sam68 messenger ribonucleic acid (mRNA) level using the Bio-Rad CFX96 se-quence detection system with SsoFast EvaGreen Supermix (Bio-Rad Laboratories, 1725200). Expression data were normalised to geometric mean by the housekeeping gene

Table 1 Clinicopathologic characteristics and Sam68 expression in patients with clinically N0 oral tongue cancer (n = 181) Characteristics Number of

cases (%)Gender Male Female

109 (60.2) 72 (39.8)

Age (years) < 53 ≥ 53

91 (50.3) 90 (49.7)

Pathologic stage I II III IV

82 (45.3) 67 (37.0)

17 (9.4)15 (8.3)

T classification T1 T2 T3

89 (49.2) 87 (48.1)

5 (2.7)N classification N0 N1 N2

151 (83.4)15 (8.3)15 (8.3)

Nodal status N0 N+ (N1 and N2)

151 (83.4) 30 (16.6)

Pathologic differentiation Well Moderately Poorly

138 (76.2) 36 (19.9)

7 (3.9)Recurrence No Yes

124 (68.5) 57 (31.5)

Vital status (at follow-up) Alive Dead

133 (73.5) 48 (26.5)

Expression of Sam68 Low or no

expression High expression

83 (45.9)

98 (54.1)Localisation of Sam68 Nucleus Cytoplasm

60 (36.8)103 (63.2)

of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.




SC-2004) was used as the secondary antibody. Immunoreactivity was de-tected with the Amersham ECL prime Western blotting detection reagent (GE Healthcare, RPN2232). GAPDH was used as a loading control.

ImmunohistochemistryThe immunohistochemistry proce-dure was used and the scores of Sam68 expression were determined using the previously described meth-ods15. The degree of immunostaining was reviewed and scored indepen-dently by two observers based on the proportion of positively stained tu-mour cells and the intensity of staining. Tumour cell proportion was graded as follows: 0, negative; 1, 1% –10% positive; 2, 11%–35% positive; 3, 36% –70% positive; and 4%, >70% positive. Staining intensity was scored according to the following criteria: 0, no staining; 1, weak (light yellow); 2, moderate (yellow brown); and 3, strong (brown). The staining index was calculated by multiplying the score for tumour cell proportion and the staining intensity score. An optimal cutoff value was identified using a logrank test: a staining index score of >6 was considered to indi-cate tumours with high Sam68 ex-pression level and a score of



Page 4 of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.


oral tongue cancer cases. A strong staining and a weak or a negative staining of Sam68 protein were de-tected in 98 (54.1%) and 83 (45.9%) tumours, respectively (Figure 3).

Statistical analyses were used to examine the association between Sam68 immunohistochemical ex-pression and the clinicopathologic characteristics of cN0 oral tongue cancer. As shown in Table 2, Sam68 expression strongly correlated with clinicopathologic characteristics in-cluding pathologic stage (p = 0.001), T classification (p = 0.001), N classifi-cation (p = 0.026), nodal status (p = 0.021) and recurrence (p = 0.002) of patients with cN0 oral tongue

Figure 2: Expression of Sam68 in paired oral tongue cancer (T) and adjacent normal tissues (N). (a) The average T/N ratios of Sam68 mRNA expression were quantified by qPCR. Expression levels were normalised by GAPDH. Error bars represent standard deviations (SD) calculated from three parallel experiments. “Metastatic” indicated specimens taken from patients with lymph node metas-tasis, while “Non-metastatic” indicated specimens taken from patients without lymph node metastasis, according to post-operative histological review. (b) Representative images from Western blotting results of Sam68 protein expres-sion in twelve paired tissues. Expression levels were normalised by GAPDH. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

15

10

5

01 2 3 4 5 6 7 8 9 10 11 12

11.7

6.0

2.1 2.4 2.53.2

3.84.3

1.9

5.7

4.2

2.5

Non-metasta�cMetasta�cSample

Incr

easin

g fo

ld

Sam68

GAPDH

NSample 2

N TSample 3

N TSample 4

N TSample 1

T NSample 6

N TSample 7

N TSample 8

N TSample 5

T

(a)

(b)

survival analysis was performed for all parameters that were significant in the univariate analysis using the Cox regression model. A two-sided p

of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.




staining (Figures 3a, 3b), whereas 103 cases showed cytoplasmic locali-sation of Sam68 (Figures 3c, 3d). Statistical analyses showed that cyto-plasmic localisation of Sam68 was significantly associated with patho-logic stage (p = 0.004), N classification (p = 0.002), nodal status (p = 0.001) and recurrence (p = 0.007) (Table 2), which were further confirmed by

(p



Page 6 of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.


(a)

(b)

(c)

(d)

(e)

(f)

200´

400´

Figure 3: Expression of Sam68 protein in oral tongue cancer sections as exam-ined by immunohistochemistry. (a, b) Strong Sam68 expression in the nucleus; (c, d) Strong Sam68 expression in the cytoplasm; and (e, f) Weak or negative Sam68 expression. (a, c, e, ×200; b, d, f, ×400).

Spearman correlation analysis (Supplementary Table S2).

Sam68 expression and cytoplasmic localisation were predictors of poor survivalPatient survival analysis indicated a clear negative correlation between the Sam68 protein expression level and the OS and DFS of patients with cN0 oral tongue cancer (p = 0.009 and

p = 0.002, respectively, Figures 4a, 4b). The cumulative fiveyear OS and DFS rates of patients with a high Sam68 expression were 66.7% and 61.6%, respectively, whereas those of pa-tients with a low or no Sam68 ex-pression were 84.3% and 81.7%, respectively. Similarly, patients with cytoplasmic Sam68 expression had significantly shorter OS and DFS, whereas those with nuclear Sam68

expression survived longer (p

of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.




deregulation of fundamental cellular pathways that control cell prolifera-tion, differentiation and apoptosis, which is central in cancer develop-ment, progression and metastasis7.

Sam68, the so-called superSTAR protein, performs a multitude of functions, among which modulation of RNA metabolism by linking signal transduction pathways to RNA pro-cessing through its RNA-binding abil-ity and association with signalling molecules is prominent. Recent stud-ies showed that Sam68 plays an im-portant role in regulating various biological processes during tumouri-genesis and correlates with the pro-gression and outcome of many tumour types. Although Sam68 was initially considered to be a tumour suppressor18, recent developments support an oncogenic function for Sam68 in tumourigenesis. Busà et al19 found that Sam68 was up-regulated in prostate cancer tissues, and siRNA knockdown of Sam68 in LNCaP pros-tate cancer cells delayed cell cycle progression and reduced prolifera-tion. They concluded that Sam68 ex-pression supported the proliferation of prostate cancer cells and survival to cytotoxic agents. Richard and col-leagues20 observed that Sam68 knock-down impeded mammary tumour onset and metastasis formation in nude mice. They suggested that Sam68 may be a signalling require-ment for mammary tumourigenesis

Overall survival1.0 Low or none Sam68

expression (n = 83)

High Sam68 expression(n = 98)

0.8

0.6

0.4

0.2

0.0

Cum

ula�

ve su

rviv

al (%

)

0 20 40 60 80 100 120 140Survival �me (months)

p = 0.009

Cum

ula�

ve su

rviv

al (%

)

Disease-free survival1.0

High Sam68 expression(n = 98)

0.8

0.6

0.4

0.2

0.0


p = 0.002

Low or none Sam68expression (n = 83)

Overall survival1.0

Sam68 expressed innucleus (n = 60)

Sam68 expressed incytoplasm (n = 103)

0.8

0.6

0.4

0.2

0.0

Cum

ula�

ve su

rviv

al (%

)


p < 0.001

Disease-free survival1.0 Sam68 expressed in

nucleus (n = 60)

Sam68 expressed incytoplasm (n = 103)

0.8

0.6

0.4

0.2

0.0

Cum

ula�

ve su

rviv

al (%

)


p = 0.007

(a) (b)

(c) (d)

Figure 4: Kaplan–Meier curves with univariate analyses (log-rank) for cN0 oral tongue cancer patients with a high Sam68 expression level versus a low or no Sam68 expression for overall survival (OS) (a) and disease-free survival (DFS) (b), and with cytoplasmic Sam68 expression versus nuclear Sam68 expression for OS (c) and DFS (d).

Supplementary Table S3 Univariate and multivariate analyses of various prognostic parameters in patients with clinically N0 oral tongue cancer with Cox-regression modelParameters Univariate analysis Multivariate analysis

p value Regression coefficient (SE) p value RR 95% confidence intervalPathologic stage < 0.001 0.133

T classification 0.012 0.248N classification < 0.001 0.176 < 0.001 1.746 0.660–4.620

Nodal status < 0.001 0.303

Recurrence < 0.001 0.346

Sam68 expression 0.011 0.318 0.032 2.019 1.062–3.839Sam68 localisation 0.001 0.440 0.023 2.778 1.153–6.691

Cancer is considered to be a ge-netic disease. It is generally accepted that post-transcriptional regulation of gene expression is often implicated

in tumourigenesis. RNA-binding pro-teins (RBPs) are mediators of post-transcriptional control that are often disrupted in cancer17. This leads to



Page 8 of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.


7. Scholzová E, Malík R, Sevcík J, Kleibl Z. RNA regulation and cancer development. Cancer Lett. 2007 Feb;246(1–2):12–23. 8. Vernet C, Artzt K. STAR, a gene family involved in signal transduction and acti-vation of RNA. Trends Genet. 1997 Dec; 13(12):479–84. 9. Lukong KE, Richard S. Sam68, the KH domain-containing superSTAR. Biochim Biophys Acta. 2003 Dec;1653(2):73–86. 10. Chen T, Damaj BB, Herrera C, Lasko P, Richard S. Self-association of the single-KH-domain family members Sam68, GRP33, GLD1, and Qk1: role of the KH domain. Mol Cell Biol. 1997 Oct;17(10):5707–18. 11. Fumagalli S, Totty NF, Hsuan JJ, Courtneidge SA. A target for Src in mito-sis. Nature. 1994 Apr;368(6474):871–4. 12. Rajan P, Gaughan L, Dalgliesh C, El-Sherif A, Robson CN, Leung HY, et al. Regulation of gene expression by the RNA-binding protein Sam68 in cancer. Biochem Soc Trans. 2008 Jun;36(Pt 3):505–7. 13. Lukong KE, Richard S. Targeting the RNA-binding protein Sam68 as a treat-ment for cancer? Future Oncol. 2007 Oct; 3(5):539–44. 14. Li Z, Yu CP, Zhong Y, Liu TJ, Huang QD, Zhao XH, et al. Sam68 expression and cy-toplasmic localization is correlated with lymph node metastasis as well as progno-sis in patients with early-stage cervical cancer. Ann Oncol. 2012 Mar;23(3):638–46. 15. Song LB, Liao WT, Mai HQ, Zhang HZ, Zhang L, Li MZ, et al. The clinical signifi-cance of twist expression in nasopharyn-geal carcinoma. Cancer Lett. 2006 Oct; 242(2):258–65. 16. Schantz SP, Yu GP. Head and neck can-cer incidence trends in young Americans, 1973–1997, with a special analysis for tongue cancer. Arch Otolaryngol Head Neck Surg. 2002 Mar;128(3):268–74. 17. Guo X, Hartley R. MicroRNARNA binding protein face-off in cancer. Cell Cycle. 2010 Apr;9(7):1234–5. 18. Liu K, Li L, Nisson PE, Gruber C, Jessee J, Cohen SN. Neoplastic transformation and tumorigenesis associated with sam68 protein deficiency in cultured murine fi-broblasts. J Biol Chem. 2000 Dec;275(51): 40195–201. 19. Busà R, Paronetto MP, Farini D, Pierantozzi E, Botti F, Angelini DF, et al. The RNA-binding protein Sam68 contrib-utes to proliferation and survival of human prostate cancer cells. Oncogene. 2007 Jun;26(30):4372–82.

those who require a more aggressive treatment.

Abbreviations listcN0, clinically N0; GAPDH, glyceral-dehyde-3-phosphate dehydrogenase; DFS, disease-free survival; OS, overall survival; PBS, phosphate-buffered saline; qPCR, quantitative polymerase chain reaction; RBPs, RNA-binding proteins; RIPA, radio immunoprecipi-tation assay; TBST, Tris-buffered saline with 0.1% Tween-20.

AcknowledgementSW Chen, Q Zhang and AK Yang con-tributed equally to this study. This study was supported by grants from the National Natural Science Founda-tion of China (No. 81172568) and the Medical Research Fund of Guangdong Province (No. A2012201).

References1. Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statis-tics. CA Cancer J Clin. 2011 MarApr; 61(2):69–90. 2. Moore SR, Johnson NW, Pierce AM, Wilson DF. The epidemiology of tongue cancer: a review of global incidence. Oral Dis. 2000 Mar;6(2):75–84. 3. Jemal A, Clegg LX, Ward E, Ries LA, Wu X, Jamison PM, et al. Annual report to the nation on the status of cancer, 1975–2001, with a special feature re-garding survival. Cancer. 2004 Jul; 101(1):3–27. 4. D’Cruz AK, Siddachari RC, Walvekar RR, Pantvaidya GH, Chaukar DA, Deshpande MS, et al. Elective neck dissection for the management of the N0 neck in early can-cer of the oral tongue: need for a random-ized controlled trial. Head Neck. 2009 May;31(5):618–24. 5. Häyry V, Mäkinen LK, Atula T, Sariola H, Mäkitie A, Leivo I, et al. Bmi-1 expression predicts prognosis in squamous cell car-cinoma of the tongue. Br J Cancer. 2010 Mar;102(5):892–7. 6. Ferlito A, Shaha AR, Rinaldo A. The inci-dence of lymph node micrometastases in patients pathologically staged N0 in can-cer of oral cavity and oropharynx. Oral Oncol. 2002 Jan;38(1):3–5.

and metastasis. Other studies further supported these results, suggesting that Sam68 might be a useful prog-nostic marker and a potential target for human breast cancer21,22. Similar results were also obtained in renal cell carcinoma23.

In the current study, we investi-gated the expression level of Sam68 in a series of cN0 oral tongue cancer. We found that Sam68 was up- regulated in cN0 oral tongue cancer cell lines and tissues at both the tran-scriptional and the translational level, which was consistent with the former results supporting Sam68 as an oncogene. We also found that the expression level of Sam68 protein is positively related to the clinicopatho-logic characteristics of cN0 oral tongue cancer, including neck metas-tasis. cN0 oral tongue cancer patients with higher Sam68 expression level had significantly shorter OS and DFS time than patients with a lower or no Sam68 expression (p = 0.009 and p = 0.002, respectively). Similar re-sults were found in the analyses of as-sociation between Sam68 localisation and the above clinical features. Our results indicate that Sam68 repre-sents a risk factor for cN0 oral tongue cancer. Up-regulation and cytoplas-mic localisation of Sam68 expression portends a poor prognosis in cN0 oral tongue cancer patients. In future, by detecting Sam68 expression in cN0 oral tongue cancer, we may be able to identify high-risk tumour phe-notypes requiring a more aggressive primary surgical treatment or an adjuvant treatment following surgery.

In conclusion, Sam68 could serve as an independent prognostic factor in cN0 oral tongue cancer and may be used in conjunction with the current TNM classification to enable better risk stratification and selection for adjuvant therapy. We recommend the detection of Sam68 expression in cN0 oral tongue cancer to aid the differen-tiation of those patients who are har-bouring occult micrometastases and

of 9

Com

petin

g in

tere

sts:

non

e de

clar

ed. C

onfli

ct o

f int

eres

ts: n

one

decl

ared

.Al

l aut

hors

con

trib

uted

to th

e co

ncep

tion,

des

ign,

and

pre

para

tion

of th

e m

anus

crip

t, as

wel

l as r

ead

and

appr

oved

the

final

man

uscr

ipt.

All a

utho

rs a

bide

by

the

Asso

ciati

on fo

r Med

ical

Eth

ics (

AME)

eth

ical

rule

s of d

isclo

sure

.




23. Zhang Z, Li J, Zheng H, Yu C, Chen J, Liu Z, et al. Expression and cytoplasmic localization of SAM68 is a significant and independent prognostic marker for renal cell carcinoma. Cancer Epidemiol Biomarkers Prev. 2009 Oct;18(10): 2685–93.

and its down-regulation inhibits, prolifera-tion and tumourigenicity of breast cancer cells. J Pathol. 2010 Nov;222(3):227–37. 22. Elliott DJ, Rajan P. The role of the RNAbinding protein Sam68 in mammary tu-mourigenesis. J Pathol. 2010 Nov;222(3): 223–6.

20. Richard S, Vogel G, Huot ME, Guo T, Muller WJ, Lukong KE. Sam68 haploinsufficiency delays onset of mammary tumorigenesis and metastasis. Oncogene. 2008 Jan;27(4):548–56. 21. Song L, Wang L, Li Y, Xiong H, Wu J, Li J, et al. Sam68 up-regulation correlates with,

Documents

Original research study - OA Publishing London · 2012. 11. 22. · Yat-sen University Cancer Centre, Guangzhou, China 4 Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou,