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Induction of apoptosis of metastatic mammary carcinoma cells in vivo by disruption of tumor cell surface CD44 function.

Yu Q, Toole BP, Stamenkovic I - J. Exp. Med. (1997)

Bottom Line: To understand how the hyaluronan receptor CD44 regulates tumor metastasis, the murine mammary carcinoma TA3/St, which constitutively expresses cell surface CD44, was transfected with cDNAs encoding soluble isoforms of CD44 and the transfectants (TA3sCD44) were compared with parental cells (transfected with expression vector only) for growth in vivo and in vitro.However, although parental cells were dividing and forming clusters within lung tissue 48 h following injection, >80% of TA3sCD44 cells underwent apoptosis.Although sCD44 transfectants displayed a marked reduction in their ability to internalize and degrade hyaluronan, they elicited abundant local hyaluronan production within invaded lung tissue, comparable to that induced by parental cells.

View Article: PubMed Central - PubMed

Affiliation: Molecular Pathology Unit and MGH Cancer Center, Massachusetts General Hospital, Charlestown Navy Yard, Boston, Massachusetts 02129, USA.

ABSTRACT
To understand how the hyaluronan receptor CD44 regulates tumor metastasis, the murine mammary carcinoma TA3/St, which constitutively expresses cell surface CD44, was transfected with cDNAs encoding soluble isoforms of CD44 and the transfectants (TA3sCD44) were compared with parental cells (transfected with expression vector only) for growth in vivo and in vitro. Local release of soluble CD44 by the transfectants inhibited the ability of endogenous cell surface CD44 to bind and internalize hyaluronan and to mediate TA3 cell invasion of hyaluronan-producing cell monolayers. Mice intravenously injected with parental TA3/St cells developed massive pulmonary metastases within 21-28 d, whereas animals injected with TA3sCD44 cells developed few or no tumors. Tracing of labeled parental and transfectant tumor cells revealed that both cell types initially adhered to pulmonary endothelium and penetrated the interstitial stroma. However, although parental cells were dividing and forming clusters within lung tissue 48 h following injection, >80% of TA3sCD44 cells underwent apoptosis. Although sCD44 transfectants displayed a marked reduction in their ability to internalize and degrade hyaluronan, they elicited abundant local hyaluronan production within invaded lung tissue, comparable to that induced by parental cells. These observations provide direct evidence that cell surface CD44 function promotes tumor cell survival in invaded tissue and that its suppression can induce apoptosis of the invading tumor cells, possibly as a result of impairing their ability to penetrate the host tissue hyaluronan barrier.

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HA production at sites of  tumor invasion. (a–d) Lung sections 1 h  after tail vein injection of TA3neo No.  1 (a and c) and TA3sCD44v6-10 No. 17  (b and d) reveal no detectable HA production as assessed by staining with biotinylated HA-binding bPG. Arrows indicate invading tumor cells that display  large hyperchromatic nuclei. 48 h after  tail vein injection (e–h), both TA3 neo  No. 1 (e and g) and TA3sCD44v6-10  No. 17 (f and h) induce stromal HA production. TA3neo No. 1 cells are visible  at the sites of HA production (g, arrow)  whereas TA3sCD44v6-10 No. 17 cells  are no longer distinguishable (h, arrowhead).
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Figure 5: HA production at sites of tumor invasion. (a–d) Lung sections 1 h after tail vein injection of TA3neo No. 1 (a and c) and TA3sCD44v6-10 No. 17 (b and d) reveal no detectable HA production as assessed by staining with biotinylated HA-binding bPG. Arrows indicate invading tumor cells that display large hyperchromatic nuclei. 48 h after tail vein injection (e–h), both TA3 neo No. 1 (e and g) and TA3sCD44v6-10 No. 17 (f and h) induce stromal HA production. TA3neo No. 1 cells are visible at the sites of HA production (g, arrow) whereas TA3sCD44v6-10 No. 17 cells are no longer distinguishable (h, arrowhead).

Mentions: The impaired ability of TA3sCD44 cells to attach to, internalize, and degrade HA and penetrate HA-coated cell monolayers in vitro may translate into their inability to penetrate ECM-associated HA in host tissue in vivo. Therefore, we addressed HA production in lung tissue after TA3neo and TA3sCD44 invasion. HA production has been shown to be increased at sites of tumor invasion in some tumor models (27), and is thought to be derived mainly from stromal cells. Stromal cell HA overproduction is proposed to result, at least in part, from physical interaction between tumor and stromal cells (28). To determine whether invasion of lung tissue by TA3 cells elicits local HA production, tissue sections of lung derived from mice injected with neo- or sCD44-transfected TA3 cells were probed with biotinylated HA-binding bPG at a series of time points after injection. Neither type of tumor cell induced detectable local HA production 1 h after injection (Fig. 5, a–d). However, at 48 h, marked HA production was observed at sites of both types of tumor invasion (Fig. 5, e and f). Although tumor cell clusters were clearly visible in lung tissue from animals injected with TA3neo cells, most of the foci of HA overproduction in lungs from sCD44-TA3 cell–injected animals were either devoid of tumor cells or contained tumor cells with small, condensed nuclei (Fig. 5, g and h), consistent with the observation that most of these cells were in the process of undergoing or had already undergone apoptosis.


Induction of apoptosis of metastatic mammary carcinoma cells in vivo by disruption of tumor cell surface CD44 function.

Yu Q, Toole BP, Stamenkovic I - J. Exp. Med. (1997)

HA production at sites of  tumor invasion. (a–d) Lung sections 1 h  after tail vein injection of TA3neo No.  1 (a and c) and TA3sCD44v6-10 No. 17  (b and d) reveal no detectable HA production as assessed by staining with biotinylated HA-binding bPG. Arrows indicate invading tumor cells that display  large hyperchromatic nuclei. 48 h after  tail vein injection (e–h), both TA3 neo  No. 1 (e and g) and TA3sCD44v6-10  No. 17 (f and h) induce stromal HA production. TA3neo No. 1 cells are visible  at the sites of HA production (g, arrow)  whereas TA3sCD44v6-10 No. 17 cells  are no longer distinguishable (h, arrowhead).
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Related In: Results  -  Collection

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Figure 5: HA production at sites of tumor invasion. (a–d) Lung sections 1 h after tail vein injection of TA3neo No. 1 (a and c) and TA3sCD44v6-10 No. 17 (b and d) reveal no detectable HA production as assessed by staining with biotinylated HA-binding bPG. Arrows indicate invading tumor cells that display large hyperchromatic nuclei. 48 h after tail vein injection (e–h), both TA3 neo No. 1 (e and g) and TA3sCD44v6-10 No. 17 (f and h) induce stromal HA production. TA3neo No. 1 cells are visible at the sites of HA production (g, arrow) whereas TA3sCD44v6-10 No. 17 cells are no longer distinguishable (h, arrowhead).
Mentions: The impaired ability of TA3sCD44 cells to attach to, internalize, and degrade HA and penetrate HA-coated cell monolayers in vitro may translate into their inability to penetrate ECM-associated HA in host tissue in vivo. Therefore, we addressed HA production in lung tissue after TA3neo and TA3sCD44 invasion. HA production has been shown to be increased at sites of tumor invasion in some tumor models (27), and is thought to be derived mainly from stromal cells. Stromal cell HA overproduction is proposed to result, at least in part, from physical interaction between tumor and stromal cells (28). To determine whether invasion of lung tissue by TA3 cells elicits local HA production, tissue sections of lung derived from mice injected with neo- or sCD44-transfected TA3 cells were probed with biotinylated HA-binding bPG at a series of time points after injection. Neither type of tumor cell induced detectable local HA production 1 h after injection (Fig. 5, a–d). However, at 48 h, marked HA production was observed at sites of both types of tumor invasion (Fig. 5, e and f). Although tumor cell clusters were clearly visible in lung tissue from animals injected with TA3neo cells, most of the foci of HA overproduction in lungs from sCD44-TA3 cell–injected animals were either devoid of tumor cells or contained tumor cells with small, condensed nuclei (Fig. 5, g and h), consistent with the observation that most of these cells were in the process of undergoing or had already undergone apoptosis.

Bottom Line: To understand how the hyaluronan receptor CD44 regulates tumor metastasis, the murine mammary carcinoma TA3/St, which constitutively expresses cell surface CD44, was transfected with cDNAs encoding soluble isoforms of CD44 and the transfectants (TA3sCD44) were compared with parental cells (transfected with expression vector only) for growth in vivo and in vitro.However, although parental cells were dividing and forming clusters within lung tissue 48 h following injection, >80% of TA3sCD44 cells underwent apoptosis.Although sCD44 transfectants displayed a marked reduction in their ability to internalize and degrade hyaluronan, they elicited abundant local hyaluronan production within invaded lung tissue, comparable to that induced by parental cells.

View Article: PubMed Central - PubMed

Affiliation: Molecular Pathology Unit and MGH Cancer Center, Massachusetts General Hospital, Charlestown Navy Yard, Boston, Massachusetts 02129, USA.

ABSTRACT
To understand how the hyaluronan receptor CD44 regulates tumor metastasis, the murine mammary carcinoma TA3/St, which constitutively expresses cell surface CD44, was transfected with cDNAs encoding soluble isoforms of CD44 and the transfectants (TA3sCD44) were compared with parental cells (transfected with expression vector only) for growth in vivo and in vitro. Local release of soluble CD44 by the transfectants inhibited the ability of endogenous cell surface CD44 to bind and internalize hyaluronan and to mediate TA3 cell invasion of hyaluronan-producing cell monolayers. Mice intravenously injected with parental TA3/St cells developed massive pulmonary metastases within 21-28 d, whereas animals injected with TA3sCD44 cells developed few or no tumors. Tracing of labeled parental and transfectant tumor cells revealed that both cell types initially adhered to pulmonary endothelium and penetrated the interstitial stroma. However, although parental cells were dividing and forming clusters within lung tissue 48 h following injection, >80% of TA3sCD44 cells underwent apoptosis. Although sCD44 transfectants displayed a marked reduction in their ability to internalize and degrade hyaluronan, they elicited abundant local hyaluronan production within invaded lung tissue, comparable to that induced by parental cells. These observations provide direct evidence that cell surface CD44 function promotes tumor cell survival in invaded tissue and that its suppression can induce apoptosis of the invading tumor cells, possibly as a result of impairing their ability to penetrate the host tissue hyaluronan barrier.

Show MeSH
Related in: MedlinePlus