FSH and TGF-beta superfamily members regulate granulosa cell connective tissue growth factor gene expression in vitro and in vivo.
ABSTRACT Connective tissue growth factor (CTGF) is a heparin-binding growth factor implicated in diverse epithelial cell types as a paracrine regulator of mitosis, angiogenesis, cellular taxis, and remodeling of the extracellular matrix. To understand the possible roles of CTGF in the ovarian paracrine system, we studied CTGF gene expression by granulosa cells in relation to their stage of cellular differentiation using both in vitro and in vivo methodologies. Untreated monolayer granulosa cell cultures from immature rats abundantly expressed the approximately 2.5-kb CTGF mRNA transcript (determined by Northern analysis), but had low levels of aromatase activity (an index of granulosa cell differentiation). Treatment for 48 h with FSH (0.1-10 ng/ml) dose-dependently inhibited (>or=50%) CTGF mRNA expression, but enhanced aromatase enzyme activity. This in vitro observation of CTGF mRNA down-regulation coinciding with FSH-induced granulosa cell maturation is substantiated by studies of in vivo ovarian CTGF expression in FSHbeta knockout mice. Northern blot and in situ hybridization analyses demonstrate high levels of CTGF expression in the granulosa cells of preantral follicles blocked from further development by the absence of FSH. The action of FSH (10 ng/ml) was mimicked in vitro by 8-bromo-cAMP (1.0 mM) and was augmented by the additional presence of androgen (1 micro M 5alpha-dihydrotestosterone), consistent with mediation by intracellular cAMP. Conversely, treatment of granulosa cell cultures with TGFbeta1 (0.1-10 ng/ml) dose-dependently increased CTGF mRNA levels up to 12-fold at a dose of 10 ng/ml, without affecting aromatase activity. Cotreatment with FSH (0.1-10 ng/ml) dose-dependently suppressed the stimulatory action of TGFbeta1 (10 ng/ml) on CTGF mRNA, but substantially enhanced aromatase activity beyond levels induced by FSH alone. Importantly, other TGFbeta superfamily members known to be produced in the ovary (growth/differentiation factor-9 and activin A; 10 ng/ml) stimulated granulosa cell CTGF mRNA in a similar fashion as TGFbeta1 (10 ng/ml), and this was also inhibited by FSH (10 ng/ml). These data show that granulosa cell CTGF gene expression is inversely related to the stage of granulosa cell differentiation, being directly inhibited by FSH via cAMP-mediated signaling. CTGF mRNA abundance in nondifferentiated granulosa cells is up-regulated in vitro by TGFbeta1, growth/differentiation factor-9, and activin, suggesting paracrine roles for these growth/differentiation factors in the regulation of CTGF synthesis in mammalian ovaries.
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ABSTRACT: The development of an altered stromal microenvironment in response to carcinoma is a common feature of many tumors. We reviewed the literature describing characteristics of reactive stroma, how reactive stroma affects cancer progression and how carcinoma regulates reactive stroma. Moreover, we present a hypothesis of reactive stroma in prostate cancer and discuss how the biology of reactive stroma may be used in novel diagnostic and therapeutic approaches. An extensive literature search was performed to review reports of the general features of wound repair stroma, general stromal responses to carcinoma, and stromal biology of normal and prostate cancer tissues. These studies were analyzed and a reactive stroma hypothesis in prostate cancer was developed. Modifications to the stroma of breast, colon and prostate tumors parallel the generation of granulation tissue in wound repair. These changes include stromal cell phenotypic switching, extracellular matrix remodeling and angiogenesis induction. Therefore, it is predicted that a modified wound healing response induces the formation of reactive stroma in cancer to create a tumor promoting environment. Based on its role in wound repair and its over expression in prostate cancer, transforming growth factor-beta stands out as a potential regulator of reactive stroma. Reactive stroma in prostate cancer and granulation tissue in wound repair show similar biological responses and processes that are predicted to promote cancer progression. Further identification of specific functional and regulatory mechanisms in prostate cancer reactive stroma may aid in the use of reactive stroma for novel diagnostic and therapeutic approaches.The Journal of Urology 01/2002; 166(6):2472-83. · 3.75 Impact Factor