Limits...
The proprotein convertase PC5/6 is protective against intestinal tumorigenesis: in vivo mouse model.

Sun X, Essalmani R, Seidah NG, Prat A - Mol. Cancer (2009)

Bottom Line: This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype.Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice.Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, affiliated to the University of Montreal, Montreal, Quebec, Canada. sunx@ircm.qc.ca

ABSTRACT

Background: The secretory basic amino acid-specific proprotein convertases (PCs) have often been associated with cancer/metastasis. By controlling the cleavage of cancer-associated proteins, PCs play key roles in multiple steps of cancer development. Most analyses of the implication of PCs in cancer/metastasis relied on the use of in vitro overexpression systems or inhibitors that can affect more than one PC. Aside from the role of furin in salivary gland tumorigenesis, no other in vivo genetic model of PC-knockout was reported in relation to cancer development.

Results: Since PC5/6 is highly expressed in the small intestine, the present study examined its in vivo role in intestinal tumorigenesis. Analysis of human intestinal tumors at various stages showed a systematic down-regulation of PC5/6 expression. Since gene inactivation of PC5/6 leads to lethality at birth, we generated mice lacking PC5/6 in enterocytes and analyzed the impact of the presence or absence of this PC in the mouse ApcMin/+ model that develops numerous adenocarcinomas along the intestinal tract. This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype. The data showed that by themselves ApcMin/+ tumors express lower levels of PC5/6 mRNA, and that the lack of PC5/6 in enterocytes results in a significantly higher tumor number in the duodenum, with a similar trend in other intestinal segments. Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice.

Conclusion: Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.

Show MeSH

Related in: MedlinePlus

Decreased expression of PC5/6 in intestinal tumors versus adjacent normal tissues. (A) RNA samples from human colonic adenocarcinomas (stage I, II, III or IV) and their adjacent normal tissues were submitted to QPCR analysis (n = 6, 7, 7 and 2 for stages I, II, III and IV, respectively). (B) In each small intestine section (duodenum, jejunum and ileum) from 3 ApcMin/+ mice, 2 tumors and their adjacent normal tissue (6 couples/section) were dissected and assessed for the expression levels of furin, PC5/6, PACE4 and PC7 by QPCR. Normalized expression values are shown for the 18 samples of normal tissues and 18 samples of tumors. (C) Expression of PC5/6 and furin in tumors was also analyzed by intestinal section. All mRNA levels in tumors were normalized to their respective normal tissue expression and have been log2 transformed, with the median of the total 18 samples set to 0. *, P < 0.05; **, P < 0.005; ***, P < 5.10-11 (Student's t test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2746178&req=5

Figure 1: Decreased expression of PC5/6 in intestinal tumors versus adjacent normal tissues. (A) RNA samples from human colonic adenocarcinomas (stage I, II, III or IV) and their adjacent normal tissues were submitted to QPCR analysis (n = 6, 7, 7 and 2 for stages I, II, III and IV, respectively). (B) In each small intestine section (duodenum, jejunum and ileum) from 3 ApcMin/+ mice, 2 tumors and their adjacent normal tissue (6 couples/section) were dissected and assessed for the expression levels of furin, PC5/6, PACE4 and PC7 by QPCR. Normalized expression values are shown for the 18 samples of normal tissues and 18 samples of tumors. (C) Expression of PC5/6 and furin in tumors was also analyzed by intestinal section. All mRNA levels in tumors were normalized to their respective normal tissue expression and have been log2 transformed, with the median of the total 18 samples set to 0. *, P < 0.05; **, P < 0.005; ***, P < 5.10-11 (Student's t test).

Mentions: Mining cancer gene expression database revealed that PC5/6 expression was significantly reduced in 7 out of 10 tumor types (P < 0.0001); [see Additional file 1: figure S1]. Since PC5/6 expression is highest in the adult small intestine [29,31], and as no data were available for intestinal cancers, PC5/6 mRNA levels were analyzed by QPCR in 22 human colon tumors at stages I, II, III or IV and compared to those of their match-paired normal adjacent tissue (Figure 1A). PC5/6 expression was on average ~ 7.6-fold lower in these human tumors. To assess whether PC5/6 was similarly regulated in mouse, we used the ApcMin/+ mice, which spontaneously develop numerous tumors in the small intestine due to the heterozygote mutation Min in the Apc gene. This mutation was originally discovered in patients suffering from familial adenomatous polyposis and frequently found in sporadic colorectal cancers [38,39]. ApcMin/+-induced tumors in the mouse small intestine constitute a good model for colonic tumorigenesis in human. We first quantified the expression levels of furin, PC5/6, PACE4 and PC7, which transit through the constitutive secretory pathway and cleave their substrates after basic residues [2]. While PACE4 and PC7 did not show any significant change, furin and PC5/6 mRNA levels were on average ~ 1.5-fold higher (P = 0.003) and lower (P = 0.0008), respectively (Figure 1B). Closer analysis of the duodenum-, jejunum- and ileum-associated tumors versus their adjacent normal tissues revealed a 1.9-, 1.2- and 1.4-fold higher furin levels, respectively, and a 2-, 1.7- and 1.1-fold lower PC5/6 expression, respectively (Figure 1C). Using specific primers, we showed that this lower level primarily affected PC5/6B transcripts [see Additional file 22: figure S2], which dominate in intestine [31]. The above data thus indicated that PC5/6 is down-regulated in many tumor types, including intestinal ones, and that in the latter furin undergoes an opposite up-regulation. Both PC5/6 and furin exhibited the greatest changes in the duodenum. These data prompted us to verify if intestinal tumorigenesis was favored in absence of PC5/6.


The proprotein convertase PC5/6 is protective against intestinal tumorigenesis: in vivo mouse model.

Sun X, Essalmani R, Seidah NG, Prat A - Mol. Cancer (2009)

Decreased expression of PC5/6 in intestinal tumors versus adjacent normal tissues. (A) RNA samples from human colonic adenocarcinomas (stage I, II, III or IV) and their adjacent normal tissues were submitted to QPCR analysis (n = 6, 7, 7 and 2 for stages I, II, III and IV, respectively). (B) In each small intestine section (duodenum, jejunum and ileum) from 3 ApcMin/+ mice, 2 tumors and their adjacent normal tissue (6 couples/section) were dissected and assessed for the expression levels of furin, PC5/6, PACE4 and PC7 by QPCR. Normalized expression values are shown for the 18 samples of normal tissues and 18 samples of tumors. (C) Expression of PC5/6 and furin in tumors was also analyzed by intestinal section. All mRNA levels in tumors were normalized to their respective normal tissue expression and have been log2 transformed, with the median of the total 18 samples set to 0. *, P < 0.05; **, P < 0.005; ***, P < 5.10-11 (Student's t test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2746178&req=5

Figure 1: Decreased expression of PC5/6 in intestinal tumors versus adjacent normal tissues. (A) RNA samples from human colonic adenocarcinomas (stage I, II, III or IV) and their adjacent normal tissues were submitted to QPCR analysis (n = 6, 7, 7 and 2 for stages I, II, III and IV, respectively). (B) In each small intestine section (duodenum, jejunum and ileum) from 3 ApcMin/+ mice, 2 tumors and their adjacent normal tissue (6 couples/section) were dissected and assessed for the expression levels of furin, PC5/6, PACE4 and PC7 by QPCR. Normalized expression values are shown for the 18 samples of normal tissues and 18 samples of tumors. (C) Expression of PC5/6 and furin in tumors was also analyzed by intestinal section. All mRNA levels in tumors were normalized to their respective normal tissue expression and have been log2 transformed, with the median of the total 18 samples set to 0. *, P < 0.05; **, P < 0.005; ***, P < 5.10-11 (Student's t test).
Mentions: Mining cancer gene expression database revealed that PC5/6 expression was significantly reduced in 7 out of 10 tumor types (P < 0.0001); [see Additional file 1: figure S1]. Since PC5/6 expression is highest in the adult small intestine [29,31], and as no data were available for intestinal cancers, PC5/6 mRNA levels were analyzed by QPCR in 22 human colon tumors at stages I, II, III or IV and compared to those of their match-paired normal adjacent tissue (Figure 1A). PC5/6 expression was on average ~ 7.6-fold lower in these human tumors. To assess whether PC5/6 was similarly regulated in mouse, we used the ApcMin/+ mice, which spontaneously develop numerous tumors in the small intestine due to the heterozygote mutation Min in the Apc gene. This mutation was originally discovered in patients suffering from familial adenomatous polyposis and frequently found in sporadic colorectal cancers [38,39]. ApcMin/+-induced tumors in the mouse small intestine constitute a good model for colonic tumorigenesis in human. We first quantified the expression levels of furin, PC5/6, PACE4 and PC7, which transit through the constitutive secretory pathway and cleave their substrates after basic residues [2]. While PACE4 and PC7 did not show any significant change, furin and PC5/6 mRNA levels were on average ~ 1.5-fold higher (P = 0.003) and lower (P = 0.0008), respectively (Figure 1B). Closer analysis of the duodenum-, jejunum- and ileum-associated tumors versus their adjacent normal tissues revealed a 1.9-, 1.2- and 1.4-fold higher furin levels, respectively, and a 2-, 1.7- and 1.1-fold lower PC5/6 expression, respectively (Figure 1C). Using specific primers, we showed that this lower level primarily affected PC5/6B transcripts [see Additional file 22: figure S2], which dominate in intestine [31]. The above data thus indicated that PC5/6 is down-regulated in many tumor types, including intestinal ones, and that in the latter furin undergoes an opposite up-regulation. Both PC5/6 and furin exhibited the greatest changes in the duodenum. These data prompted us to verify if intestinal tumorigenesis was favored in absence of PC5/6.

Bottom Line: This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype.Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice.Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, affiliated to the University of Montreal, Montreal, Quebec, Canada. sunx@ircm.qc.ca

ABSTRACT

Background: The secretory basic amino acid-specific proprotein convertases (PCs) have often been associated with cancer/metastasis. By controlling the cleavage of cancer-associated proteins, PCs play key roles in multiple steps of cancer development. Most analyses of the implication of PCs in cancer/metastasis relied on the use of in vitro overexpression systems or inhibitors that can affect more than one PC. Aside from the role of furin in salivary gland tumorigenesis, no other in vivo genetic model of PC-knockout was reported in relation to cancer development.

Results: Since PC5/6 is highly expressed in the small intestine, the present study examined its in vivo role in intestinal tumorigenesis. Analysis of human intestinal tumors at various stages showed a systematic down-regulation of PC5/6 expression. Since gene inactivation of PC5/6 leads to lethality at birth, we generated mice lacking PC5/6 in enterocytes and analyzed the impact of the presence or absence of this PC in the mouse ApcMin/+ model that develops numerous adenocarcinomas along the intestinal tract. This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype. The data showed that by themselves ApcMin/+ tumors express lower levels of PC5/6 mRNA, and that the lack of PC5/6 in enterocytes results in a significantly higher tumor number in the duodenum, with a similar trend in other intestinal segments. Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice.

Conclusion: Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.

Show MeSH
Related in: MedlinePlus