some very useful reports, available in full-text, from the recent conferences

General view:

* International Society for Stem Cell Research (ISSCR), Cairns, June 2007: basic side of stem cell research as well as translating research to therapy

* Meeting Report 2006: The First International Collaborative Symposium on Stem Cell Research, Seoul, Korea

Disease focused:

* Annual Meeting Reports of the International Society for Stem Cell Research (ISSCR), Cairns, Australia, June 17-20, 2007

* AACR Special Workshop Report on Cancer Stem Cells—Perspectives on Current Status and Future Directions

* Workshop on Imaging: Cancer Biology and the Tumor Microenvironment

* Annual Meeting Abstracts from the Association for Molecular Pathology, Los Angeles, California , November 7-10, 2007 (nice reference for assay/method development)

** more interested?! Here is reports on a previous year's events (something like one stop resources!)

Methods series:

A Meeting Report: "New Technologies in Stem Cell Research" ***

PS:
i) i will up-date soon with some more interesting reports, which is under reprint requisition,
ii) ***please let me know if you experience any difficulties to download the complete text so that I can share the article (and the author dr. Kathleen Sakamoto is really a sporty type!)

numbers of curiosity questions, from the previous hypothesis post (of stem-cell niche in normal and pathological conditions ...)

Though the preparations on the previous (post) mini hypothesis and giving me opportunities to read number of literatures as well as guiding me to have some depth overview on the stem-cell niche field, interestingly it’s also leaving me number of curiosity questions. such as,



I) on the part of cell-fusion:

i) In general or within the context of cancer, are there any relationships between cell-fusion and the G0/G1 cell cycle?

(thought provoking key paper:
Lizard G etal in Cell fusion of human and mouse cells as a source for new cells retaining human markers. Analysis of DNA content, membrane and cytoplasmic antigen expression. Virchows Arch B Cell Pathol Incl Mol Pathol. 1991;60(5):301-6


ii) After cell-fusion followed by reductive division explain about the presence of epithelial-mesenchymal transition (EMT) markers in the newly formed cells. Is this reductive division have any relationship with senescence?

(Key paper:
Krtolica A etal Senescent fibroblasts promote epithelial cell growth and tumorigenesis: a link between cancer and aging. Proc Natl Acad Sci U S A. 2001 Oct 9;98(21):12072-7. Epub 2001 Oct 2)


iii) Does the cell fusion process also occur between the 'cancer-associated fibroblast' (CAFs) and endothelial progenitor cells (which is recruited by CAFs)?

II) on the part of therapeutic targets:

i) apart from the identification of metalloproteinases in cancer-associated fibroblast (CAFs) (1) until now there is only one Tyrosine protein kinase (Platelet-Derived Growth Factor (PDGF), a PDGFR family) has been studied /correlated with the CAFs cells (2) so could this PDGF become a molecular therapeutic target of CAFs?

Key papers:
1.Rosenthal EL Expression of proteolytic enzymes in head and neck cancer-associated fibroblasts. Arch Otolaryngol Head Neck Surg. 2004 Aug;130(8):943-7)
2. Mueller L Imatinib mesylate inhibits proliferation and modulates cytokine expression of human cancer-associated stromal fibroblasts from colorectal metastases Cancer Lett. 2007 Jun 8; 250(2):329-38. Epub 2006 Dec 4.).

ii) Interestingly, one of the CAFs secretary factor know as S100A4 has a binding site for TCF (t-cell receptor) as well as play role with beta-catenin. So could it also become as a therapeutic target for any metastasis cancer, by interrupting their cell-cell interactions (for examples), ...?

(key paper:
Stein U etal The metastasis-associated gene S100A4 is a novel target of beta-catenin/T-cell factor signaling in colon cancer. Gastroenterology. 2006 Nov; 131(5):1486-500. Epub 2006 Aug 22)

III) in general:

i) Once a lesion initiated, CAFs have been shown to assist in proliferation and progression of cancer through the production of growth factors, chemotactic factors, angiogenesis factors, matrix metalloproteinases MMPs towards invasion and spread of cancer cells in initiated, non tumorogenic epithelial cells. Since CAFs playing the tumorigenic role within the cancer microenvironment, its ability to form cancer, ability to attract progenitors, ability to transform epithelial cells, etc shall we call these 'cancer-associated fibroblast' (CAFs) as an “unipotent progenitor cells” or ‘fibroblast-restricted progenitor cells’?

In other words, still it’s not clear why most late-life cancers are epithelial. Since CAFs have role in senescence (1) shall we expect that the CAFs may undergo reverse phenotype (so it could able to escape from the immune system) and express its tumorogentic behaviours in those late-life cancer?

(key paper:
Krtolica A etal Senescent fibroblasts promote epithelial cell growth and tumorigenesis: a link between cancer and aging Proc Natl Acad Sci U S A. 2001 Oct 9; 98(21):12072-7. Epub 2001 Oct 2)


ii) within the stromal-cancer microenvironment, while both cancer and the CAFs cells come together, there might be possibility of excess production of the growth factor such as S100A4, SDS???, etc. does this increase level of gradients makes any effects on their behaviour (within the niche / microenvironment)?

iv) Unclear part:

its not clear if
i) there is any role of epigenetic alterations Vs CAFs, within the context of aberrant tumor microenvironment?

ii) whether the bone marrow derived (stem) cells Vs CAFs as well as cancer stem-cell Vs stromal cells share any common genetic origins?

iii) whether the cancer stem-cells also produce the CAFs?


I would be grateful if you could offer or share any of your thoughts on these questions, which would ultimately helpful for me to improve some knowledge on the field of stem-cell niche in normal and pathologic conditions . Thank you!

Have a nice day!

stem-cell niche in normal and pathological conditions ...a small hypothesis, with ‘cancer –associated fibroblasts’ (CAFs) as a model

While begun and surveying the lists of kinase family proteins (which always becoming oen of hottest field for developing drugs or drug targets..) which have been studied up-to-date in fibroblasts, one of the components of cancer (stem-cell) -stromal-niche /microenvironment, very interestingly the reading atmosphere were highly helped me to notice an un-answered question i.e., the mechanisms by which stromal cells influence the process of tumorogenesis.

Having very much interests to develop knowledge on the field of stem-cell niche I would like to develop a small hypothesis as well as some curiosity questions by utilising one of a fascinating cell called “cancer-associated fibroblasts” (CAFs) as a model, because of their interdisciplinary presence on the core area of “bone marrow derived (stem/progenitor) cells- stromal microenvironment- epithelial cells- tumorigenesis..”.

Before going in to further some basics information:

Basics of (normal) fibroblasts:
Fibroblasts are the
- Primary producers of the non-cellular scaffolds— the Extra cellular matrix,
- responsible for the deposition of the fibrillar ECM—type I, type III, and type V collagen and fibronectin as well as contribute to the formation of the basement membrane by secreting type IV collagen and laminin,
- Role in wound repair: fibroblasts are responsible for orchestrating healing, and in order to do so become ‘‘activated,’’ (help of transforming growth factor-beta (TGF-b) [1] with increased proliferation and alterations in both phenotype and secretory capacity. Production of alpha-smooth muscle actin (a-SMA) allows cells to migrate into areas of damage and contract for tissue restitution. Fibroblast activation during wound repair involves a dynamic crosstalk between the fibroblast and the injured epithelium. Direct contact with infiltrating immune cells via the adhesion molecules ICAM1 and VCAM1 [2] and response to factors secreted directly from the injured mucosa including fibroblast growth factor 2 (FGF2), platelet-derived growth factor (PDGF), epidermal growth factor (EGF) [1].

Fibroblasts within tumors:
- Fibroblasts are the main cellular component of tumor stroma comprising an integral component of the tumor,
- In some cancer types, fibroblasts constitute a larger proportion of cells within the tumor than do the cancer cells. Fibroblasts within tumors have an activated phenotype, and as such resemble fibroblasts in wound healing. These cancer-associated fibroblasts (CAFs) are functionally and phenotypically distinct from normal fibroblasts that are in the same tissue but not in the tumor environment. The distinction between these and physiologically activated fibroblasts is that they are perpetually activated, neither reverting to a normal phenotype nor undergoing apoptosis and elimination [3]
- CAFs are identified within tumor stroma by their spindyloid appearance and the expression of a-SMA; characteristics shared by activated fibroblasts in wounds, also express alpha-smooth muscle actin (alpha-SMA), vimentin, S100A4 protein/fibroblast specific protein-1 (FSP1) and type I collagen [4] stromal cell-derived factor 1 (SDF-1) [5].

Hypothesis:

An increasing body of research indicates that stroma surrounding cancer cells plays an important role in the development and subsequent behaviour of the tumor. The cancers often develop resistance to these (cancer) therapies, in large part due to their genomic inherent instability. An alternative, emerging, avenue of therapy focuses on targeting various non-neoplastic cells that are associated with the tumor microenvironment, such as endothelial cells, etc. since stromal cells within the tumor are thought to be ‘normal’ and less genetically labile than the neoplastic cells, development of acquired resistance to therapy my be less likely. As such, the tumor stroma may be an excellent target for directed therapy [6].

Within the stromal-microenvironment complex, the stromal cells are also associated with epithelial cell, which promote malignant progression in genetically initiated prostatic epithelial cells resulting in tumorigenesis if there is any changes occur on these stromal-epithelial interactions [7]. Once the microenvironment encounter tissue damage/injury/ UV/ionisation effects and or inflammation followed by the initiation of progression of inflammatory pathways [8], induction of extracellular matrix-remodelling proteases etc leads to the disruptions of the normal stromal-epithelial interactions towards development of ‘reactive’ fibroblast. While forming these disorganisation and the reactive state, the bone marrow – derived (stem) cell (which already proved to be plasticity as well as have relationship with cancers such as home to tumor specific ‘pre-metastatic niche’) [9, 10] become activated and starts to support the ‘activated’ stroma towards formation of the ‘cancer –associated fibroblasts’ (CAFs), which in turn start to acts in place of the normal stromal fibroblastic cells. Here, there are two facts were supporting this thought: since the bone marrow cells contribute to cancer as means of development mimicry[11] as well as during the prostate carcinogenesis the stroma undergoes progressive loss of smooth muscle with the appearance of CAFs [7]. Since ‘cancer –associated fibroblasts’ (CAFs) have the abilities to induce the epithelial-mesenchymal transition (EMT) process, the newly formed genetic modifications will leads to formation of cell fusion between the cancer –associated fibroblasts (CAFs) and the (tumor) surrounding epithelial cells.

As a sequence of this cell-fusion and the tumor initiation, the newly formed aberrant tumor microenvironment which is not only maintained by the epigenetic alteration mechanisms in stromal cells [14] but also increased ability to support cancerous growth and further initiation process [12,13]. Followed by these newly formed, favourable ‘tumor microenvironment’, the CAFs begin to attract the endothelial progenitor cells (EPCs) by secreting a powerful chemotactic molecule also known as stromal cell-derived factor-1 (SDF-1) [5] initiating further process of trafficking/homing of the cancer –initiating (stem/progenitors) cells. As a result, the CAFs ability to migrate has increasing and begins hyperproliferation, progression to fibrosis, development of neoplasia, increasing invasiveness, and eventually metastasis.

In summary, my hypothesis is that ,

-CAFs is originated from stromal cell with the strongest support of bone marrow derived (stem) cell,

-CAFs is spreading their tumorigentic traits by cell-fusion,

-CAFs may also creates a 'mini-niche' where they may keeps the tumor-inititing cells or cancer stem cell,


References:

[1] Zeisberg M etal Role of fibroblast activation in inducing interstitial fibrosis J Nephrol. 2000 Nov-Dec;13 Suppl 3:S111-20.


[2] Clayton A etal Cellular activation through the ligation of intercellular adhesion molecule-1 J Cell Sci. 1998 Feb;111 ( Pt 4):443-53

[3]. Li H etal Tumor microenvironment: the role of the tumor stroma in cancer J Cell Biochem. 2007 Jul 1;101(4):805-15

[4] Sugimoto H, Identification of fibroblast heterogeneity in the tumor microenvironment. Cancer Biol Ther. 2006 Dec;5(12):1640-6. Epub 2006 Dec 5

[5] Orimo A Stromal fibroblasts in cancer: a novel tumor-promoting cell type Cell Cycle. 2006 Aug;5(15):1597-601. Epub 2006 Aug 1.


[6] West RB, etal Experimental approaches to the study of cancer-stroma interactions: recent findings suggest a pivotal role for stroma in carcinogenesis Lab Invest. 2007 Oct;87(10):967-70. Epub 2007 Aug 13


[7] Cunha GR, Role of stroma in carcinogenesis of the prostate Differentiation. 2002 Dec;70(9-10):473-85

[8] Mueller L etal Stromal Fibroblasts in Colorectal Liver Metastases Originate From Resident Fibroblasts and Generate an Inflammatory Microenvironment. Am J Pathol. 2007 Oct 4; [Epub ahead of print]


[9] Wu XZ Bone marrow-derived cells: roles in solid tumor. Minireview Neoplasma. 2007;54(1):1-6

[10] Kaplan RN VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche. Nature. 2005 Dec 8;438(7069):820-7

[11] Cogle CR Bone marrow contributes to epithelial cancers in mice and humans as developmental mimicry. Stem Cells. 2007 Aug;25(8):1881-7. Epub 2007 May 3


[12] Olumi AF Carcinoma-associated fibroblasts direct tumor progression of initiated human prostatic epithelium. Cancer Res. 1999 Oct 1;59(19):5002-11

[13] Orimo A, Stromal fibroblasts present in invasive human breast carcinomas promote tumor growth and angiogenesis through elevated SDF-1/CXCL12 secretion Cell. 2005 May 6;121(3):335-48


[14] Rajasekhar VK Stem Cells, Cancer, and Context Dependence. Stem Cells. 2007 Oct 25; [Epub ahead of print]

Survey Part- A ] Serine/Threonine and Tyrosine Protein Kinases in "Fibroblast" of Stroma (cancer) Microenvironment

Independent role of Serine/Threonine and Tyrosine Protein Kinases in "Fibroblast" of Stroma (cancer) Microenvironment:


e) Churg-Strauss syndrome (CSS): is a systemic disease that shows marked eosinophilia along with eosinophil infiltration in the tissue. Prolonged eosinophil survival plays an important role in the pathogenesis of CSS(1), which is also invole development of lipoma, a very rare benign tumor of the tracheobronchial tree(2).

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase, and its ligand is collagen. DDR1 was expressed in human leukocytes and fibroblasts, and it plays an important role in leukocyte cytokine production and fibroblast survival in an NF-kappaB-dependent manner, as well as (DDR1) contributes to the eosinophil survival in the tissue microenvironment of CSS and that it might be involved in the development of CSS.

References:
1 Matsuyama W etal Discoidin domain receptor 1 contributes to eosinophil survival in an NF-kappaB-dependent manner in Churg-Strauss syndrome Blood. 2007 Jan 1;109(1):22-30..

2 Ergan-Arsava B etal Endobronchial lipoma in a patient with Churg-Strauss syndrome Thorac Cardiovasc Surg. 2006 Jun;54(4):283-5.


f) inducible fibroblast growth factor receptor-1 (iFGFR1):
Using an inducible transgenic mouse model of preneoplastic progression in the mammary gland, the authors discovered that activation of inducible fibroblast growth factor receptor-1 (iFGFR1) in the mammary epithelium rapidly increased the expression of several genes involved in the inflammatory response, which induced recruitment of macrophages (responsible for preneoplastic progression) to the epithelium and continued association with the alveolar hyperplasias that developed following long-term activation. Further more studies also showed that iFGFR1-induced expression of the macrophage chemoattractant osteopontin was required for macrophage recruitment in vitro.

Reference:
Schwertfeger KL etal A critical role for the inflammatory response in a mouse model of preneoplastic progression Cancer Res. 2006 Jun 1;66(11):5676-85


g) isozyme of 6-phosphofructo-2 kinase (iPFK-2):

Tumor cells maintain an especially high glycolytic rate to supply the anabolic precursors essential for de novo nucleotide synthesis. We recently cloned an inducible isozyme of 6-phosphofructo-2 kinase (iPFK-2) that bears an oncogene-like regulatory element in its mRNA and functions to produce fructose-2,6-bisphosphate, which is a powerful allosteric activator of glycolysis. Rapidly proliferating cancer cells constitutively express iPFK-2 in vitro, and inhibition of iPFK-2 expression decreases tumor growth in experimental animal models.

In particular, iPFK-2 expression was found to be markedly elevated in multiple aggressive primary neoplasms, including colon, breast, ovarian, and thyroid carcinomas. iPFK-2 mRNA and protein expression were induced by hypoxia in cultured human colon adenocarcinoma cells, and an examination of normal lung fibroblasts showed that iPFK-2 and fructose-2,6-bisphosphate levels increased specifically during the S phase of the cell cycle. These data indicate that iPFK-2 is abundantly expressed in human tumors in situ and may serve as an essential regulator of glycolysis during cell cycle progression and growth in an hypoxic microenvironment.


Reference:
Atsumi T etal High expression of inducible 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (iPFK-2; PFKFB3) in human cancers Cancer Res. 2002 Oct 15;62(20):5881-7



-> to be continued..;becasue of likes to do some correlated studies---<-

Survey Part- A ] Serine/Threonine and Tyrosine Protein Kinases in "Fibroblast" of Stroma (cancer) Microenvironment

d) Serine/threonine protein kinases: AGC group: (AKT family - AKT; RAC serine/threonine-protein kinase) and associated proteins:

The stromal microenvironment influences many steps of tumor progression through the elaboration of signals from myofibroblasts. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway transduces signals initiated by growth factors and is involved in colonic epithelial proliferation. Utilizing a novel proteomic approach, the authors have identify distinct protein profiles in myofibroblasts of polyps compared with stromal cells of normal mucosa. Moreover, myofibroblasts can stimulate indirectly PI3K activity and enhance colon cancer cell proliferation. These findings suggest that targeted therapy to signaling pathways in myofibroblasts may be useful in colorectal cancer chemoprevention and possible treatment.

hint: polyp myofibroblasts enhanced proliferation of the cancer cells to a greater extent than normal myofibroblasts.(1)

To assess microenvironment-mediated survival signals, B-CLL cells were cultured with a murine fibroblast cell line, Ltk-, with and without an agonistic antibody to CD40. Spontaneous apoptosis was associated with the loss of Akt and NF-kappaB activities. Interactions with fibroblasts sustained a basal level of Akt and NF-kappaB activities, which was dependent on phosphatidylinositol-3 kinase (PI3K). Constitutive activity of the PI3K pathway in B-CLL cells when cultured with fibroblasts prevented the downregulation of the prosurvival Bcl-2 family protein Bcl-xL and the caspase inhibitor proteins FLIPL and XIAP, and consequently caspase-3 activation and apoptosis. CD40 crosslinking in B-CLL cells did not further prevent murine fibroblasts-mediated apoptosis but induced cell proliferation, which was associated with an increase of Akt and NF-kappaB activation compared with cells cultured with fibroblasts alone. The PI3K pathway seems to play a pivotal role in B-CLL cell survival and growth.(2)


1Chen AL etal Proteomic analysis of colonic myofibroblasts and effect on colon cancer cell proliferation
Surgery. 2005 Aug;138(2):382-90

2Cuní S etal A sustained activation of PI3K/NF-kappaB pathway is critical for the survival of chronic lymphocytic leukemia B cells Leukemia. 2004 Aug;18(8):1391-400


For quick references/basic-facts:

Tsai KK etal Cellular mechanisms for low-dose ionizing radiation-induced perturbation of the breast tissue microenvironment Cancer Res. 2005 Aug 1;65(15):6734-44

Radiation exposure is an important form of environmental carcinogen and has been associated with increased risk of breast cancer. Epigenetic events, especially those involving alterations in the breast stromal microenvironment, may play an important role in radiation-induced carcinogenesis but remain not well understood. We here show that human mammary stromal fibroblasts respond to protracted low-dose ionizing radiation exposures by displaying a senescence-like phenotype. Using a three-dimensional coculture system to model the interactions of different mammary cell types with their neighbors and with their environment, we provide a direct experimental proof that ionizing radiation-induced senescence-like fibroblasts significantly perturb the mammary stromal microenvironment, which is highlighted by impaired formation of pseudopodia networks due to marked cytoskeletal alterations in senescence-like fibroblasts and increased extracellular matrix degradation because of the up-regulation of multiple secreted matrix metalloproteinases. Within such a perturbed environment, mammary ductal morphogenesis is completely disrupted and epithelial cells instead grow into enlarged cystic structures, which further develop and become disorganized cell masses on inactivation of cellular death pathways. Breast carcinoma cells growing in such an environment are enabled to fully express their malignant potential as evidenced by the alpha6beta4 integrin/phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway-dependent invasive growth. Our results suggest that ionizing radiation, in addition to causing gene mutations in epithelial cells, can contribute to breast carcinogenesis by perturbing the tissue microenvironment that leads to dysregulated cell-cell and cell-matrix interactions.

Survey Part- A ] Serine/Threonine and Tyrosine Protein Kinases in "Fibroblast" of Stroma (cancer) Microenvironment

c) Serine/threonine protein kinases: CMGC group(MAPK family - ERK1_2; extracellular signal-regulated kinase ½) and associated proteins:

i) Cancer cell migration:
Protease-activated receptors (PAR) are G protein-coupled receptors that function as cell-surface sensors for coagulant proteases, as well as other proteases associated with the tumor microenvironment. PAR1 is activated by thrombin whereas the upstream coagulant protease VIIa bound to tissue factor and Xa can activate both PAR1 and PAR2. PAR1 has been implicated in tumor cell growth, migration, and invasion whereas the function of PAR2 in these processes is largely unknown.

Studies with siRNA strongly suggest that PAR2 is critical for MDA-MB-231 and BT549 breast cancer cell migration and invasion towards NIH 3T3 fibroblast conditioned medium. Together, these studies reveal the novel findings that PAR2, a second protease-activated G protein-coupled receptor, has a critical role in breast cancer cell migration and invasion and functions as the endogenous receptor for coagulant proteases VIIa and Xa in these cells (1).

ii) Carcinoma of the prostate (CaP):

- the inhibition of MMP-2 and MMP-9 in DU145 cells by EGCG is mediated via inhibition of phosphorylation of ERK1/2 and p38 pathways, and inhibition of activation of transcription factors c-jun and NF-kappaB. EGCG may play a role in prevention of invasive metastatic processes of both androgen-dependent and -independent prostate carcinoma.
Practical hint: Since fibroblast conditioned medium (FCM) partially mimics in vivo tumor-host microenvironment, DU145 cells were co-cultured in FCM.

References:

1 Morris DR etal Protease-activated receptor-2 is essential for factor VIIa and Xa-induced signaling, migration, and invasion of breast cancer cells Cancer Res. 2006 Jan 1;66(1):307-14

2 Vayalil PK etal Treatment of epigallocatechin-3-gallate inhibits matrix metalloproteinases-2 and -9 via inhibition of activation of mitogen-activated protein kinases, c-jun and NF-kappaB in human prostate carcinoma DU-145 cells Prostate. 2004 Apr 1;59(1):33-42.

Survey Part- A ] Serine/Threonine and Tyrosine Protein Kinases in "Fibroblast" of Stroma (cancer) Microenvironment

b) TGF-Beta: Serine/threonine protein kinases: TKL group(TGFBR2 family - Transforming growth factor, beta receptor II) and associated proteins:


Transforming growth factor-beta (TGF-beta) plays complex dual roles as an inhibitor and promoter of tumor progression. Although the influence of the stromal microenvironment on tumor progression is well recognized, little is known about the functions of TGF-beta signaling in the stroma during tumor progression. In a co-xenograft model, the authors have demonstrated that TGF-bR2(FspKO) fibroblasts enhance mammary carcinoma growth and metastasis in mice while increasing hepatocyte growth factor (HGF) expression and c-Met signaling downstream pathways including signal transducers and activators of transcription 3 (Stat3) and p42/44 mitogen-activated protein kinase (MAPK). The results show that TGF-beta signaling in fibroblasts suppresses tumor metastasis by antagonizing HGF/c-Met signaling within tumor epithelial cells. Furthermore, this co-xenograft model represents a unique context to study stromal TGF-beta and HGF signaling in mammary tumorigenesis(1).

Independent studies:
In Crouzon's syndrome: demonstrated about the in vitro differences between normal and Crouzon fibroblasts may be due to an imbalance in TGF beta and bFGF levels which alters the microenvironment where morphogenesis takes place. Further studies also proved that a TM domain (transmembrane domains of receptor tyrosine kinases (RTKs)) pathogenic mutation is the Ala391-->Glu mutation in fibroblast growth factor receptor 3 (FGFR3), linked to Crouzon syndrome with acanthosis nigricans, as well as to bladder cancer(2, 3)

In idiopathic pulmonary fibrosis (IPF): is characterized by fibroblast expansion and extracellular matrix accumulation. Some secreted matrix metalloproteinases (MMPs) as MMP2 are highly upregulated in IPF lungs(4), also a most common lung disease predisposing lung cancer (5) where also showed the cross-talk of epithelial abnormalities and the involvement of up-regulated p63-jag1 pathway (5).

In lung fibroblasts, TGF-beta1 induced a strong upregulation of MT3-MMP, both at the gene and protein level. This effect was blocked by genistein, a protein tyrosin kinase inhibitor and partially repressed by SB203580 a p38 MAP kinase inhibitor. Interestingly MT3-MMP (Type 3 transmembrane) that was found in fibroblastic foci was upregulated in vitro by TGF-beta1 a potent profibrotic mediator(4)

In skin tumor: Keloids are abnormal fibrous growths of the dermis that develop only in response to wounding and represent a form of benign skin tumor. Previous studies have shown increased protein levels of TGF-beta in keloid tissue, suggesting a strong association with keloid formation. Further immunoblotting analysis demonstrated that p38 MAPK was phosphorylated within 15 min and was maintained at a high level in keloid human fibroblasts (KFs) but not in normal human fibroblasts (NFs). The transcription factors activating transcription factor-2 and Elk-1 are activated by p38 MAPK, and also showed rapid and prolonged phosphorylation kinetics in KFs but not in NFs. In conclusion, increased TGF-beta2 transcription in response to serum stimulation in KFs appears to be mediated by the p38 MAPK pathway. This suggests the mechanism of keloid pathogenesis may be due in part to an inherent difference in how the fibroblasts respond to wounding(6)

Epidermal growth factor (EGF) Vs Gangliosides:
Gangliosides are shed by tumor cells and can bind to normal cells in the tumor microenvironment and affect their function. Exposure of fibroblasts to exogenous gangliosides increases epidermal growth factor (EGF)-induced fibroblast proliferation and enhances EGF receptor (EGFR)-mediated activation of the mitogen-activated protein kinase signaling pathway (Li, R., Liu, Y., and Ladisch, S. (2001) J. Biol. Chem. 276, 42782-42792).

The authors concluded that membrane ganglioside enrichment of normal fibroblasts (such as by tumor cell ganglioside shedding) facilitates receptor-receptor interactions (possibly by altering membrane topology), causing ligand-independent EGFR dimerization and, in turn, enhanced EGF signaling(7).

References:

1Cheng N etal Enhanced hepatocyte growth factor signaling by type II transforming growth factor-beta receptor knockout fibroblasts promotes mammary tumorigenesis Cancer Res. 2007 May 15;67(10):4869-77

2Baroni T etal Crouzon's syndrome: differential in vitro secretion of bFGF, TGFbeta I isoforms and extracellular matrix macromolecules in patients with FGFR2 gene mutation Cytokine. 2002 Jul 21;19(2):94-101.

3 Li E etal FGFR3 dimer stabilization due to a single amino acid pathogenic mutation J Mol Biol. 2006 Feb 24;356(3):600-12

4García-Alvarez J etal Membrane type-matrix metalloproteinases in idiopathic pulmonary fibrosis Sarcoidosis Vasc Diffuse Lung Dis. 2006 Mar;23(1):13-21

5 Murata K etal p63 - Key molecule in the early phase of epithelial abnormality in idiopathic pulmonary fibrosis Exp Mol Pathol. 2007 Apr 10;

6 Xia W etal P38 MAP kinase mediates transforming growth factor-beta2 transcription in human keloid fibroblasts Am J Physiol Regul Integr Comp Physiol. 2006 Mar;290(3):R501-8.

7 Liu Y etal Exogenous ganglioside GD1a enhances epidermal growth factor receptor binding and dimerization J Biol Chem. 2004 Aug 27;279(35):36481-9.

Abstracts for basic references/facts:

i) Alvarez RJ etal Biosynthetic and proliferative characteristics of tubulointerstitial fibroblasts probed with paracrine cytokines Kidney Int. 1992 Jan;41(1):14-23

Fibroblasts in parenchymal organs potentially contribute extracellular matrix to local fibrogenic processes. This contribution, in some circumstances, may be initiated by cytokines disseminated from inflammatory lesions. Different populations of fibroblasts, however, might respond distinctively to this cytokine bath depending on the microenvironment in which they reside. We have begun to explore this issue using syngeneic, low-passage fibroblasts cultured in serum-free media that were derived originally from the dermis (DFBs) and from tubulointerstitium (TFBs) of the kidney. Our findings indicate that, while fibroblasts from each compartment appear similar at the ultrastructural level, there are a variety of functional differences which distinguish their proliferative response, and their collagen secretory response (types I, III, IV, and V) following challenge with various doses of immune-relevant cytokines (TGF beta, EGF, IL-1, IL-2 and gamma IFN) in culture. DFBs, for example, express more surface EGF receptors than do TFBs, and, as a consequence, exhibit a more robust proliferative response to EGF in serum-free media. Unstimulated DFBs also secrete more collagen types I and III than TFBs, while unstimulated TFBs secrete more types IV and V. The expression of these collagens in TFBs was confirmed by Northern blot hybridization. When these sets of fibroblasts were further stimulated by cytokines, some of the cytokines not only differentially effect the secretion of various species of collagens within the same group of cells, but also between cells from populations which are anatomically distinct. DFBs, furthermore, at mid-level doses of cytokine, demonstrated a general trend towards less secretion of all types of collagen (particularly for TGF beta, EGF, and IL-2), while TFBs seemed less repressive. In TFBs the cytokine-induced responses for collagen types I and III tended to be discordant, and for types I and IV EGF inhibited, while TGF beta stimulated the secretory process. These findings speak collectively for the presence of a functional heterogeneity among organ-based populations of syngeneic fibroblasts in normal tissues.

ii) Chesi M etal Activated fibroblast growth factor receptor 3 is an oncogene that contributes to tumor progression in multiple myeloma Blood. 2001 Feb 1;97(3):729-36.


The t(4;14) translocation occurs frequently in multiple myeloma (MM) and results in the simultaneous dysregulated expression of 2 potential oncogenes, FGFR3 (fibroblast growth factor receptor 3) from der(14) and multiple myeloma SET domain protein/Wolf-Hirschhorn syndrome candidate gene 1 from der(4). It is now shown that myeloma cells carrying a t(4;14) translocation express a functional FGFR3 that in some cases is constitutively activated by the same mutations that cause thanatophoric dysplasia. As with activating mutations of K-ras and N-ras, which are reported in approximately 40% of patients with MM, activating mutations of FGFR3 occur during tumor progression. However, the constitutive activation of ras and FGFR3 does not occur in the same myeloma cells. Thus the activated forms of these proteins appear to share an overlapping role in tumor progression, suggesting that they also share the signaling cascade. Consistent with this prediction, it is shown that activated FGFR3-when expressed at levels similar to those seen in t(4;14) myeloma-is an oncogene that acts through the MAP kinase pathway to transform NIH 3T3 cells, which can then generate tumors in nude mice. Thus, FGFR3, when overexpressed in MM, may be not only oncogenic when stimulated by FGF ligands in the bone marrow microenvironment, but is also a target for activating mutations that enable FGFR3 to play a ras-like role in tumor progression.

iii) Kerry A Brenner Regulation of fibronectin matrix assembly by activated Ras in transformed cells Oncogene (2000) 19, 3156-3163

Fibronectin extracellular matrix plays a critical role in the microenvironment of cells. Loss of this matrix frequently accompanies oncogenic transformation, allowing changes in cell growth, morphology, and tissue organization. The HT1080 human fibrosarcoma cell line is deficient in formation of fibronectin matrix fibrils but assembly can be induced by the glucocorticoid dexamethasone. Here we show that fibronectin assembly can also be restored by stimulation of alpha5beta1 integrin with activating antibody or with Mn2+ suggesting that integrin activity is reduced in these cells. While dexamethasone promoted actin stress fiber formation, actin filaments remained cortical following Mn2+ treatment showing that the dexamethasone effect is not due solely to cytoskeletal changes. HT1080 cells have one activated allele of N-ras and PD98059 inhibition of signaling from Ras through ERK increased fibronectin matrix accumulation. Conversely, the p38 MAP kinase inhibitor SB203580 blocked induction of matrix and increased ERK phosphorylation. Thus, two MAP kinase pathways contribute to the control of integrin-mediated fibronectin assembly. ERK activity and fibronectin assembly were linked in three different ras-transformed cell lines but not in SV40- or RSV-transformed cells indicating that oncogenic Ras uses a distinct mechanism to down-regulate cell-fibronectin interactions.