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MicroRNA let-7c is downregulated in prostate cancer and suppresses prostate cancer growth.

Nadiminty N, Tummala R, Lou W, Zhu Y, Shi XB, Zou JX, Chen H, Zhang J, Chen X, Luo J, deVere White RW, Kung HJ, Evans CP, Gao AC - PLoS ONE (2012)

Bottom Line: Lentiviral-mediated re-expression of let-7c was utilized to assess the effects on human PCa xenografts.Overexpression of let-7c decreased while downregulation of let-7c increased cell proliferation, clonogenicity and anchorage-independent growth of PCa cells in vitro.Furthermore, let-7c expression is downregulated in clinical PCa specimens compared to their matched benign tissues, while the expression of Lin28, a master regulator of let-7 miRNA processing, is upregulated in clinical PCa specimens.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, University of California Davis, Sacramento, California, United States of America. nnadiminty@ucdavis.edu

ABSTRACT

Purpose: Prostate cancer (PCa) is characterized by deregulated expression of several tumor suppressor or oncogenic miRNAs. The objective of this study was the identification and characterization of miR-let-7c as a potential tumor suppressor in PCa.

Experimental design: Levels of expression of miR-let-7c were examined in human PCa cell lines and tissues using qRT-PCR and in situ hybridization. Let-7c was overexpressed or suppressed to assess the effects on the growth of human PCa cell lines. Lentiviral-mediated re-expression of let-7c was utilized to assess the effects on human PCa xenografts.

Results: We identified miR-let-7c as a potential tumor suppressor in PCa. Expression of let-7c is downregulated in castration-resistant prostate cancer (CRPC) cells. Overexpression of let-7c decreased while downregulation of let-7c increased cell proliferation, clonogenicity and anchorage-independent growth of PCa cells in vitro. Suppression of let-7c expression enhanced the ability of androgen-sensitive PCa cells to grow in androgen-deprived conditions in vitro. Reconstitution of Let-7c by lentiviral-mediated intratumoral delivery significantly reduced tumor burden in xenografts of human PCa cells. Furthermore, let-7c expression is downregulated in clinical PCa specimens compared to their matched benign tissues, while the expression of Lin28, a master regulator of let-7 miRNA processing, is upregulated in clinical PCa specimens.

Conclusions: These results demonstrate that microRNA let-7c is downregulated in PCa and functions as a tumor suppressor, and is a potential therapeutic target for PCa.

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Let-7c inhibits growth of human PCa cells in vitro.LNCaP (A), C4-2B (B), DU145 (C), LN-IL6+ (D) and LNCaP-S17 (E) cells were transfected with let-7c or empty vector (Con) and cell numbers were determined after 24 and 48 h. Growth of PCa cells was suppressed by let-7c. Insets show the levels of expression of let-7c plasmid. F) Cell death was analyzed in LNCaP, DU145, LNCaP-S17 and LN-IL6+ cells transfected with let-7c or empty vector (Con). Let-7c induced apoptotic cell death of prostate cancer cells. G) LNCaP cells transfected with anti-sense oligos against let-7c or scrambled oligos (Con) were grown in FBS and CS-FBS and cell numbers determined. Inset shows the downregulation of expression of let-7c by anti-sense oligos. LNCaP cells with downregulated expression of let-7c exhibited faster growth in CS-FBS compared to controls. Data points represent mean ± SD of triplicate samples from two independent experiments. Error bars denote ± SD (*p < 0.05).
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pone-0032832-g003: Let-7c inhibits growth of human PCa cells in vitro.LNCaP (A), C4-2B (B), DU145 (C), LN-IL6+ (D) and LNCaP-S17 (E) cells were transfected with let-7c or empty vector (Con) and cell numbers were determined after 24 and 48 h. Growth of PCa cells was suppressed by let-7c. Insets show the levels of expression of let-7c plasmid. F) Cell death was analyzed in LNCaP, DU145, LNCaP-S17 and LN-IL6+ cells transfected with let-7c or empty vector (Con). Let-7c induced apoptotic cell death of prostate cancer cells. G) LNCaP cells transfected with anti-sense oligos against let-7c or scrambled oligos (Con) were grown in FBS and CS-FBS and cell numbers determined. Inset shows the downregulation of expression of let-7c by anti-sense oligos. LNCaP cells with downregulated expression of let-7c exhibited faster growth in CS-FBS compared to controls. Data points represent mean ± SD of triplicate samples from two independent experiments. Error bars denote ± SD (*p < 0.05).

Mentions: To determine whether let-7c affects the growth of PCa cells, LNCaP, C4-2B, DU145, LNCaP-S17 and LN-IL6+ cells were transfected with plasmids encoding let-7c or empty vector and cell numbers were counted after 24 and 48 h. Cell numbers of all PCa cell lines overexpressing let-7c were reduced by ∼40% at 48 h (Fig. 3A-E). Insets show the levels of expression of let-7c plasmid in these cells. To determine whether the observed decrease in cell growth was due to apoptotic cell death, DNA fragmentation was analyzed by Cell Death Detection ELISA. As shown in Fig. 3F, apoptosis in cells overexpressing let-7c was enhanced compared to the controls, suggesting that the inhibition in cell growth induced by let-7c is partly due to increased apoptotic cell death.


MicroRNA let-7c is downregulated in prostate cancer and suppresses prostate cancer growth.

Nadiminty N, Tummala R, Lou W, Zhu Y, Shi XB, Zou JX, Chen H, Zhang J, Chen X, Luo J, deVere White RW, Kung HJ, Evans CP, Gao AC - PLoS ONE (2012)

Let-7c inhibits growth of human PCa cells in vitro.LNCaP (A), C4-2B (B), DU145 (C), LN-IL6+ (D) and LNCaP-S17 (E) cells were transfected with let-7c or empty vector (Con) and cell numbers were determined after 24 and 48 h. Growth of PCa cells was suppressed by let-7c. Insets show the levels of expression of let-7c plasmid. F) Cell death was analyzed in LNCaP, DU145, LNCaP-S17 and LN-IL6+ cells transfected with let-7c or empty vector (Con). Let-7c induced apoptotic cell death of prostate cancer cells. G) LNCaP cells transfected with anti-sense oligos against let-7c or scrambled oligos (Con) were grown in FBS and CS-FBS and cell numbers determined. Inset shows the downregulation of expression of let-7c by anti-sense oligos. LNCaP cells with downregulated expression of let-7c exhibited faster growth in CS-FBS compared to controls. Data points represent mean ± SD of triplicate samples from two independent experiments. Error bars denote ± SD (*p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316551&req=5

pone-0032832-g003: Let-7c inhibits growth of human PCa cells in vitro.LNCaP (A), C4-2B (B), DU145 (C), LN-IL6+ (D) and LNCaP-S17 (E) cells were transfected with let-7c or empty vector (Con) and cell numbers were determined after 24 and 48 h. Growth of PCa cells was suppressed by let-7c. Insets show the levels of expression of let-7c plasmid. F) Cell death was analyzed in LNCaP, DU145, LNCaP-S17 and LN-IL6+ cells transfected with let-7c or empty vector (Con). Let-7c induced apoptotic cell death of prostate cancer cells. G) LNCaP cells transfected with anti-sense oligos against let-7c or scrambled oligos (Con) were grown in FBS and CS-FBS and cell numbers determined. Inset shows the downregulation of expression of let-7c by anti-sense oligos. LNCaP cells with downregulated expression of let-7c exhibited faster growth in CS-FBS compared to controls. Data points represent mean ± SD of triplicate samples from two independent experiments. Error bars denote ± SD (*p < 0.05).
Mentions: To determine whether let-7c affects the growth of PCa cells, LNCaP, C4-2B, DU145, LNCaP-S17 and LN-IL6+ cells were transfected with plasmids encoding let-7c or empty vector and cell numbers were counted after 24 and 48 h. Cell numbers of all PCa cell lines overexpressing let-7c were reduced by ∼40% at 48 h (Fig. 3A-E). Insets show the levels of expression of let-7c plasmid in these cells. To determine whether the observed decrease in cell growth was due to apoptotic cell death, DNA fragmentation was analyzed by Cell Death Detection ELISA. As shown in Fig. 3F, apoptosis in cells overexpressing let-7c was enhanced compared to the controls, suggesting that the inhibition in cell growth induced by let-7c is partly due to increased apoptotic cell death.

Bottom Line: Lentiviral-mediated re-expression of let-7c was utilized to assess the effects on human PCa xenografts.Overexpression of let-7c decreased while downregulation of let-7c increased cell proliferation, clonogenicity and anchorage-independent growth of PCa cells in vitro.Furthermore, let-7c expression is downregulated in clinical PCa specimens compared to their matched benign tissues, while the expression of Lin28, a master regulator of let-7 miRNA processing, is upregulated in clinical PCa specimens.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, University of California Davis, Sacramento, California, United States of America. nnadiminty@ucdavis.edu

ABSTRACT

Purpose: Prostate cancer (PCa) is characterized by deregulated expression of several tumor suppressor or oncogenic miRNAs. The objective of this study was the identification and characterization of miR-let-7c as a potential tumor suppressor in PCa.

Experimental design: Levels of expression of miR-let-7c were examined in human PCa cell lines and tissues using qRT-PCR and in situ hybridization. Let-7c was overexpressed or suppressed to assess the effects on the growth of human PCa cell lines. Lentiviral-mediated re-expression of let-7c was utilized to assess the effects on human PCa xenografts.

Results: We identified miR-let-7c as a potential tumor suppressor in PCa. Expression of let-7c is downregulated in castration-resistant prostate cancer (CRPC) cells. Overexpression of let-7c decreased while downregulation of let-7c increased cell proliferation, clonogenicity and anchorage-independent growth of PCa cells in vitro. Suppression of let-7c expression enhanced the ability of androgen-sensitive PCa cells to grow in androgen-deprived conditions in vitro. Reconstitution of Let-7c by lentiviral-mediated intratumoral delivery significantly reduced tumor burden in xenografts of human PCa cells. Furthermore, let-7c expression is downregulated in clinical PCa specimens compared to their matched benign tissues, while the expression of Lin28, a master regulator of let-7 miRNA processing, is upregulated in clinical PCa specimens.

Conclusions: These results demonstrate that microRNA let-7c is downregulated in PCa and functions as a tumor suppressor, and is a potential therapeutic target for PCa.

Show MeSH
Related in: MedlinePlus