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2001年nature刊登了一篇综述,系统介绍了肿瘤干细胞的定义及其特性。原文见:
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6 u! j8 t( G+ \5 `/ ?& B& V' Q' Nhttp://mcardle.oncology.wisc.edu/alexander/PDF/Reya.pdf
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' G _: j- K/ `) Q该文通过对造血干细胞及造血系统肿瘤干细胞特性的介绍,使我们对肿瘤干细胞有了初步的认识,其中,很多经典的图片。
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0 O& Q, W, V ], w7 l有些研究表明,阻止细胞死亡在髓性白血病发生中其重要作用, 且基因转化可局限于祖细胞:
% T' t r+ v- [( }3 f7 f35. Lagasse, E. & Weissman, I. L. bcl-2 inhibits apoptosis of neutrophils but not their engulfment by
9 I) P% H0 w9 c; Wmacrophages. J. Exp. Med. 179, 1047–1052 (1994).' Y: g6 S! c; ~: A+ C
36.Traver, D., Akashi, K., Weissman, I. L. & Lagasse, E. Mice defective in two apoptosis pathways in the( a$ V7 {; _ S" u, \" x
myeloid lineage develop acute myeloblastic leukemia. Immunity 9, 47–57 (1998).
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4 l" o2 b. h& kβ-catenin和Wnt路径的失调在癌症中很普遍,该途径的靶向过 表达可以导致转基因鼠发生肿瘤:7 h& \ _% d0 t% w
37.Polakis, P. Wnt signaling and cancer. Genes Dev. 14, 1837–1851 (2000).
7 t1 d& n# p T! y38.Tsukamoto, A., Grosschedl, R., Guzman, R., Parslow, T. & Varmus, H. E. Expression of the int-1 gene
1 y" `) Z1 m. T Ein transgenic mice is associated with mammary gland hyperplasia and adenocarcinomas in male and
2 K6 @4 m- Z0 J$ ^8 Efemale mice. Cell 55, 619–625 (1988).
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, Y9 a( H4 u/ e+ q8 y7 s4 n如果将肿瘤视为一个异常的器官,那么普通干细胞的原则也可以 用于理解肿瘤的发生:
) L' `) V0 i) J12.Weissman, I. L. Translating stem and progenitor cell biology to the clinic: barriers and opportunities.
+ U {% n% \6 b3 ^3 C; i- R% MScience 287, 1442–1446 (2000).
7 j- P$ |' h# Q44.Morrison, S. J., Shah, N. M. & Anderson, D. J. Regulatory mechanisms in stem cell biology. Cell 88,
4 I- B& `" e) s# |- J7 {0 n287–298 (1997). D+ I' M& r' z7 D! M
45.Kummermehr, J. & Trott, K.-R. in Stem Cells (ed. Potten, C. S.) 363–399 (Academic, New York, 1997).
3 k) a# h. B. j% w9 Z9 k( u7 Y2 U1 k( u0 H1 y5 B
小鼠骨髓瘤细胞在体外克隆形成中仅1/10000到1/100中可以形成 克隆。白血病细胞移植到小鼠体内,也仅1-4%可以形成克隆:, H& c- w4 B" `, _. [- U
53.Park, C. H., Bergsagel, D. E. & McCulloch, E. A. Mouse myeloma tumor stem cells: a primary cell
# r) r/ ?# s6 L& C X5 [3 k0 Zculture assay. J. Natl Cancer Inst. 46, 411–422 (1971).
- r1 P9 Q! @7 `54.Bruce, W. R. & Gaag, H. v. d. A quantitative assay for the number of murine lymphoma cells capable
% S8 [- D* X( I, @- ?4 C9 I" x7 jof proliferation in vivo. Nature 199, 79–80 (1963).
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kinetics of lymphocytic L1210 cells in vivo as determined by spleen colony assay. Cancer Chemother.. J+ G2 K; u1 ?2 U9 p8 u
Rep. 51, 415–421 (1967).; g4 B6 g, ?1 M. _
56.Bergsagel, D. E. & Valeriote, F. A. Growth characteristics of a mouse plasma cell tumor. Cancer Res. 28,
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& X; v7 Z! S& f+ p# ^
有研究者鉴别出AML中CD34+CD38-细胞具有比其他类型细胞更强 的克隆形成能力:/ @/ }' ]; E! V8 _9 v
57.Bonnet, D. & Dick, J. E. Human acute myeloid leukemia is organized as a hierarchy that originates8 e' J0 P& {# f# @" ~
from a primitive hematopoietic cell. Nature Med. 3, 730 –737 (1997).
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- E. P+ t) r# ~% I! v* h实体癌中也发现细胞具有表型的不均一性,且仅少部分细胞在体 外培养或体内种植时具有克隆形成能力:$ o" \& ^, e1 x ^9 s {/ F% \* P/ C
46. Fidler, I. J. & Kripke, M. L. Metastasis results from preexisting variant cells within a malignant tumor.! n2 U# _ R, K
Science 197, 893–895 (1977).
2 w: h; k% z2 b9 `8 Z2 f47. Fidler, I. J. & Hart, I. R. Biological diversity in metastatic neoplasms: origins and implications. Science
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' I; `' O& z7 H( h9 U/ k& `48.Heppner, G. H. Tumor heterogeneity. Cancer Res. 44, 2259–2265 (1984).
0 \$ o' W" R- b49.Nowell, P. C. Mechanisms of tumor progression. Cancer Res. 46, 2203–2207 (1986).* C: N- H# o4 g4 D2 ^- G: R
58. Southam, C. M. & Brunschwig, A. Quantitative studies of autotransplantation of human cancer.( e4 |8 I, z& L; k- m
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461–463 (1977).* [$ h2 `& d% W" T2 ?- ~
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研究表明,在远离原发肿瘤的部位可以检测到播散的肿瘤细胞, 但并不一定形成远处转移:
0 R& d* C) a" h/ s58. Southam, C. M. & Brunschwig, A. Quantitative studies of autotransplantation of human cancer.# c& m0 L8 v5 A6 o8 ^% l
Cancer 14, 971–978 (1961).4 p; w$ b1 o! a) g2 V) }6 `
60. Salsbury, A. J. The significance of the circulating cancer cell. Cancer Treatment Rev. 2, 55–72 (1975).1 B% a# X Q: O# R
5 G J- q6 m+ ?7 V' W# Q/ I对该现象有两种可能的解释:1,免疫监督在形成可检测的肿瘤 前有效的杀死播散肿瘤细胞;2,大多数肿瘤细胞缺乏形成新肿 瘤的能力,该能力只有少数肿瘤干细胞具有:
8 x2 R0 F5 k! I. c4 Q V45.Kummermehr, J. & Trott, K.-R. in Stem Cells (ed. Potten, C. S.) 363–399 (Academic, New York, 1997).
) p7 D2 Y1 Q$ J5 F0 M# e" a2 ~- \, R) G$ C" H) T
0 r1 r) H. Z! @# ]/ V+ y; d1 s+ d+ @正由于肿瘤干细胞的存在,使得当前的治疗无法根除实体瘤,虽 然可以缩小转移瘤体积,但不久就会复发:3 r% D( n0 u8 m* R
61.Williams, S. D. Treatment of disseminated germ cell tumors with cisplatin, bleomycin, and either F' u" ?& [7 R3 ?; y. h9 _
vinblastine or etoposide. N. Engl. J. Med. 316, 1435– 1439 (1987).5 T& {% i# J9 B. z2 {- D
62. Stockler, M., Wilcken, N. R. C., Ghersi, D. & Simes, R. J. Systematic reviews of chemotherapy and# s: ~5 V' A: e3 F6 o1 F3 G
endocrine therapy in metastatic breast cancer. Cancer Treatment Rev. 26, 151–168 (2000).
% a% h$ g$ l. J" l) h63. Lippman, M. E. High-dose chemotherapy plus autologous bone marrow transplantation for
8 x( G% I0 n' O* L m6 g5 ometastatic breast cancer. N. Engl. J. Med. 342, 1119– 1120 (2000).$ A5 R0 q6 V0 P! ^6 w
有两种解释:1,治疗失败时由于肿瘤细胞在药物刺激过程中产 生耐药;2,是由于当前的治疗无法杀死肿瘤干细胞。
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从不同组织来源的普通干细胞比其组织来源的普通细胞更能耐受 化疗:, w5 n4 j4 v9 ?. Q$ @
64.Harrison, D. E. & Lerner, C. P. Most primitive hematopoietic stem cells are stimulated to cycle rapidly$ D+ u& s2 u& ?0 H( Z7 U$ D# n: H
after treatment with 5-fluorouracil. Blood 78, 1237– 1240 (1991).0 l9 {# p3 S. c! W* n
这可能时由于该类细胞的抗凋亡蛋白表达水平较高,
" u. S- _! [$ \ C8 V65.Bouwens, L. & DeBlay, E. Islet morphogenesis and stem cell markers in rat pancreas. J. Histochem.) J- d, {2 _( v( R4 y! w- f/ K- M* }
Cytochem. 44, 947–951 (1996).
3 f* e8 W* n) L66.Peters, R., Leyvraz, S. & Perey, L. Apoptotic regulation in primitive hematopoietic precursors. Blood+ Q$ p a! U8 u; P5 J" C- |
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67. Domen, J., Gandy, K. L. & Weissman, I. L. Systemic overexpression of BCL-2 in the hematopoietic system
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and Bax expression in relation to cell turnover and epithelial differentiation markers in the nonlactating, Q5 Y$ j: }5 ^- l+ j" L
human mammary gland epithelium. Cell Tissue Res. 299, 47 –58 (2000).
0 A1 N \5 j/ U7 U- \或者由于多药耐药基因等ABC转运体的过表达:+ p a3 Y4 ` ?5 J1 z& g; H
69. Zhou, S. et al. The ABC transporter Bcrp1/ABCG2 is expressed in
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造血干细胞可以分化成其他非造血性组织或器官,如脑,肝等:
" V {4 @) f9 C, e6. Petersen, B. E. et al. Bone marrow as a potential source of hepatic oval cells. Science 284, 1168–1170 (1999).' t% t! C6 ^4 s0 O* h
7. Brazelton, T. R., Rossi, F. M. V., Keshet, G. I. & Blau, H. M. From marrow to brain: expression of: j; H$ C0 q9 S9 |7 \% w, S
neuronal phenotypes in adult mice. Science 290, 1775– 1779 (2000).
, ~# G% _0 ?1 y) b# P' h8. Mezey, E., Chandross, K. J., Harta, G., Maki, R. A. & McKercher, S. R. Turning blood into brain: cells
R# E |# r. ^( ^/ n! F- dbearing neuronal antigens generated in vivo from bone marrow. Science 290, 1779–1782 (2000).5 \) i r" Z5 C! U
9. Lagasse, E. et al. Purified hematopoietic stem cells can differentiate to hepatocytes in vivo. Nature& x" j; }9 ?( L+ U
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10.Krause, D. S. et al.Multi-organ, multi-lineage engraftment by a single bone marrow derived stem cell.3 f% Q- [. Y' q
Cell 105, 369–377 (2001).# W7 a! r% l* n) c* \+ B, O. E
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/ g7 _" l1 @+ S( J3 V原始造血多能干细胞可以分化成三类细胞:长期自我更新造血干 细胞,短期自我更新造血干细胞和不具有自我更新能力的多功能 祖细胞:
8 _4 j' ]4 ?2 z3 Y& a. Q2. Morrison, S. J. & Weissman, I. L. The long-term repopulating subset of hematopoietic stem cells is c* S7 I. k$ p' T$ U3 y
deterministic and isolatable by phenotype. Immunity 1, 661–673 (1994).
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~, c4 U) U g g, jlineage of multipotent hematopoietic progenitors. Development 124, 1929–1939 (1997).& A% e; I* Q+ C5 G5 O! H
* s8 p/ O7 T7 h& I! J5 ]7 I/ z, {# a) S
3 B/ t$ D. h4 h7 Y8 P造血干细胞的表型和功能特性见以下综述:, k7 f# Q2 ]& Z+ k$ B: R8 b9 N: }
12.Weissman, I. L. Translating stem and progenitor cell biology to the clinic: barriers and opportunities.
( e) r* d8 Y, o! k. uScience 287, 1442–1446 (2000).
], ]/ q7 U) X7 X; g& k& x0 m& v5 R8 J W/ m1 R1 V: m
/ j1 n0 j$ c/ f! U2 p. m- t9 v鉴定出保持造血干细胞活性的培养条件:
* |; p8 Y; M r c13.Miller, C. L. & Eaves, C. J. Expansion in vitro of adult murine hematopoietic stem cells with transplantable
, r1 b" W, w6 [; f$ Ulympho-myeloid reconstituting ability. Proc. Natl Acad. Sci. USA 94, 13648–13653 (1997): E% o( i4 H6 I# [% r
4 q: C' v+ o2 Z- g8 U+ Y
; x( c0 }, O4 @8 {有证据显示,与癌症相关的一些通路也与调节正常干细胞发育的通路相关。见图2:" _- M4 A: h* W! c- D
WNT通路相关肿瘤为结肠癌和上皮肿瘤:
! C/ P1 n) V; Z& t P/ {& u! k25.Zhu, A. J. & Watt, F. M. b-catenin signalling modulates proliferative potential of human epidermal
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/ t r/ y8 q' }8 _24.Van Den Berg, D. J., Sharma, A. K., Bruno, E. & Hoffman, R. Role of members of the Wnt gene family
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NOTCH途径相关肿瘤为T细胞性白血病:
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基因芯片技术可用于分析恶性肿瘤细胞的基因表达情况,从而将 肿瘤细胞分成不同亚组,他们具有不同的突变表型:
' o6 z) H8 @2 i5 k4 z" o1 Y ^71.Bittner, M. et al.Molecular classification of cutaneous malignant melanoma by gene expression4 n: G4 |, Q$ I' e6 P! v: V: c3 v
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* v% [- \2 }5 H( U( {显微解剖形态学相似的肿瘤细胞群体有助于获得同质细胞群体的 特性:
/ F) w5 Z- T5 L% F% S8 G8 H0 P6 f75.Sgroi, D. C. et al. In vivo gene expression profile analysis of human breast cancer progression. Cancer+ p$ `) g2 [$ |% ]$ ]4 L4 S1 p
Res. 59, 5656–5661 (1999).- T0 g5 q: T* k
76.Leethanakul, C. et al. Distinct pattern of expression of differentiation and growth-related genes in
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+ R* O& T. m; k- ]9 p P. O; B; o2 s7 ~3 ?* T5 F# F- O
总结:
4 V. S) i: R. D3 Z1,自我更新是正常组织或肿瘤中干细胞的标志性特点;
+ M3 P% s6 s. m2,在造血系统,长期自我更新细胞局限于少数长期HSC和一些淋 巴细胞,其他细胞类型无自我更新潜能;1 E5 \) p+ |+ o2 L! n5 u* _
3,长期存在的细胞更可能累计突变从而导致肿瘤形成。因此, 导致髓性白血病的基因改变必定发生在长期HSC或其获得自我更 新能力的后代上。白血病患者中,长期HSC细胞中常有白血病相 关异位现象,该现象强烈支持白血病突变常常在HSC中累积,导 致某些淋巴瘤的突变可能在淋巴细胞中累积,从而使其具有长期 自我更新能力;
" }6 I/ C H8 T4,其他正常组织也具有自我更新能力的干细胞,如上皮,实体 肿瘤发展过程中基因改变的逐步累积也发生在干细胞或其具有自 我更新能力的后代上; D' x8 I, b. j- A
5,不同组织中,有不同信号途径控制干细胞的自我更新。但在 个别组织中,普通干细胞和肿瘤细胞通过同一信号途径控制细胞 增值,例如,WNT途径调节血液和上皮中干细胞的自我更新,但 在有些上皮细胞癌中,也同样有WNT信号通路的激活;
& J6 d+ N( H5 w6,理解了信号途径在普通干细胞和肿瘤细胞中的作用,有助于 利用普通干细胞再生药物和鉴别出肿瘤干细胞的靶点从而为开发 抗肿瘤药物服务;! M* w* W8 M$ q. y$ ^$ H# g
7,大部分肿瘤组织中有肿瘤干细胞的存在,它们可以无限制的 自我更新,而大部分干细胞仅具有有限的增值潜能;
9 i) K" U9 S% U4 m8,为了治愈癌症,必须杀死肿瘤干细胞。为此,必须鉴别出该 类细胞的特性。
0 a. v+ R, c$ L& c* V8 N
! O4 T9 m' e" N/ k. _6 J( _例如,为了阻止凋亡发生,增强癌基因bcl-2的表达,结果导致 体内的造血干细胞数目增加,提示,细胞死亡在调节造血干细胞 稳态中起作用:4 ?9 m. \9 E8 D3 x. L* ]
14. Domen, J., Gandy, K. L. & Weissman, I. L. Systemic overexpression of BCL-2 in the hematopoietic system
. z t; b _4 Q6 zprotects transgenic mice from the consequences of lethal irradiation. Blood 91, 2272–2282 (1998).9 }& e W7 ?3 {
15.Domen, J. & Weissman, I. L. Hematopoietic stem cells need two signals to prevent apoptosis; BCL |
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