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Progesterone regulates the proliferation of breast cancer cells - in vitro evidence.

Azeez JM, Sithul H, Hariharan I, Sreekumar S, Prabhakar J, Sreeja S, Pillai MR - Drug Des Devel Ther (2015)

Bottom Line: Reports state that surgery performed at different phases of the menstrual cycle may significantly affect breast cancer treatment outcome.Therefore, we further functionally characterized the protein product of TOB-1 in vitro.These results support the hypothesis that surgery conducted during the luteal phase of the menstrual cycle may facilitate improved patient survival.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India.

ABSTRACT
Reports state that surgery performed at different phases of the menstrual cycle may significantly affect breast cancer treatment outcome. From previous studies, we identified differentially expressed genes in each menstrual cycle phase by microarray, then subjected them to functional in vitro analyses. Microarray studies disclosed genes that are upregulated in the luteal phase and follicular phase. TOB-1 is a tumor suppressor gene and was expressed exclusively in the luteal phase in our microarray study. Therefore, we further functionally characterized the protein product of TOB-1 in vitro. To our knowledge, no studies have yet been conducted on reactive oxygen species-regulated tumor suppressor interactions in accordance with the biphasic nature of progesterone. This work demonstrates that progesterone can produce reactive oxygen species in MCF-7 cells and that TOB-1 exerts a series of non-genomic interactions that regulate antiproliferative activity by modulating the antioxidant enzyme superoxide dismutase. Furthermore, this study implicates PTEN as an interacting partner for TOB-1, which may regulate the downstream expression of cell cycle control protein p27 via multiple downstream signaling pathways of progesterone through a progesterone receptor, purely in a time- and concentration-dependent manner. These results support the hypothesis that surgery conducted during the luteal phase of the menstrual cycle may facilitate improved patient survival.

No MeSH data available.


Related in: MedlinePlus

Knockdown of TOB-1 reduces p27 expression in breast cancer cells.Notes: (A) The expression of p27, the cell cycle modulator, was analyzed by immunoblotting with the corresponding antibody. (B) Relative intensities of bands were normalized to β-actin and shown as graphical representations. After growing to 50%–60% confluence in six-well plates, the MCF-7 cells were transiently transfected with the siRNA pools targeting TOB-1. (C) Expression of p27 was analyzed by Western Blot with and without PG treatment in TOB-1 silenced cells. Twenty-four hours later, the transfected cells treated with progesterone, and the expression of TOB-1 and (E) p27 were assayed by Western blot analysis. (D) and (F) show graphical representations of the relative intensities of bands that were normalized to corresponding β-actin.Abbreviations: PG, progesterone; siRNA, small interfering RNA; h, hours; min, minutes.
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f5-dddt-9-5987: Knockdown of TOB-1 reduces p27 expression in breast cancer cells.Notes: (A) The expression of p27, the cell cycle modulator, was analyzed by immunoblotting with the corresponding antibody. (B) Relative intensities of bands were normalized to β-actin and shown as graphical representations. After growing to 50%–60% confluence in six-well plates, the MCF-7 cells were transiently transfected with the siRNA pools targeting TOB-1. (C) Expression of p27 was analyzed by Western Blot with and without PG treatment in TOB-1 silenced cells. Twenty-four hours later, the transfected cells treated with progesterone, and the expression of TOB-1 and (E) p27 were assayed by Western blot analysis. (D) and (F) show graphical representations of the relative intensities of bands that were normalized to corresponding β-actin.Abbreviations: PG, progesterone; siRNA, small interfering RNA; h, hours; min, minutes.

Mentions: The earlier data indicate that progesterone influences cell cycle progression in MCF-7 cells with mild cell death associated with TOB-1 induction. However, whether the observed effect is a direct or indirect consequence of TOB-1 induction remains unclear. Therefore, we first evaluated the expression of the key cell cycle regulator p27 upon progesterone treatment at different time points (Figure 5A and B) and also in TOB-1 silenced cells (Figure 5C and D). In progesterone-treated cells, p27 expression increased to a maximum level within 12 hours (Figure 5A and B), whereas p27 expression decreased in silenced cells (Figure 5E and F). These trends may be due to the time-dependent survival signal of progesterone, as well as the interaction between TOB-1 and p27. Here, progesterone may act as a regulator of the cell cycle through TOB-1 and p27. A recent study showed that the biological activity of TOB-1 is initiated by its interaction with the key tumor suppressor protein PTEN, which inhibits the PI3K/Akt signaling pathway and has a multifunctional role in cell proliferation, migration, and invasion.18,27,28 Interestingly, silencing of TOB-1 resulted in the downregulation of PTEN (Figure 6), suggesting TOB-1-dependent PTEN signaling. Thus, progesterone can modulate the function of TOB-1, subsequently influencing the function of PTEN and ultimately leading to increased p27 expression.


Progesterone regulates the proliferation of breast cancer cells - in vitro evidence.

Azeez JM, Sithul H, Hariharan I, Sreekumar S, Prabhakar J, Sreeja S, Pillai MR - Drug Des Devel Ther (2015)

Knockdown of TOB-1 reduces p27 expression in breast cancer cells.Notes: (A) The expression of p27, the cell cycle modulator, was analyzed by immunoblotting with the corresponding antibody. (B) Relative intensities of bands were normalized to β-actin and shown as graphical representations. After growing to 50%–60% confluence in six-well plates, the MCF-7 cells were transiently transfected with the siRNA pools targeting TOB-1. (C) Expression of p27 was analyzed by Western Blot with and without PG treatment in TOB-1 silenced cells. Twenty-four hours later, the transfected cells treated with progesterone, and the expression of TOB-1 and (E) p27 were assayed by Western blot analysis. (D) and (F) show graphical representations of the relative intensities of bands that were normalized to corresponding β-actin.Abbreviations: PG, progesterone; siRNA, small interfering RNA; h, hours; min, minutes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644174&req=5

f5-dddt-9-5987: Knockdown of TOB-1 reduces p27 expression in breast cancer cells.Notes: (A) The expression of p27, the cell cycle modulator, was analyzed by immunoblotting with the corresponding antibody. (B) Relative intensities of bands were normalized to β-actin and shown as graphical representations. After growing to 50%–60% confluence in six-well plates, the MCF-7 cells were transiently transfected with the siRNA pools targeting TOB-1. (C) Expression of p27 was analyzed by Western Blot with and without PG treatment in TOB-1 silenced cells. Twenty-four hours later, the transfected cells treated with progesterone, and the expression of TOB-1 and (E) p27 were assayed by Western blot analysis. (D) and (F) show graphical representations of the relative intensities of bands that were normalized to corresponding β-actin.Abbreviations: PG, progesterone; siRNA, small interfering RNA; h, hours; min, minutes.
Mentions: The earlier data indicate that progesterone influences cell cycle progression in MCF-7 cells with mild cell death associated with TOB-1 induction. However, whether the observed effect is a direct or indirect consequence of TOB-1 induction remains unclear. Therefore, we first evaluated the expression of the key cell cycle regulator p27 upon progesterone treatment at different time points (Figure 5A and B) and also in TOB-1 silenced cells (Figure 5C and D). In progesterone-treated cells, p27 expression increased to a maximum level within 12 hours (Figure 5A and B), whereas p27 expression decreased in silenced cells (Figure 5E and F). These trends may be due to the time-dependent survival signal of progesterone, as well as the interaction between TOB-1 and p27. Here, progesterone may act as a regulator of the cell cycle through TOB-1 and p27. A recent study showed that the biological activity of TOB-1 is initiated by its interaction with the key tumor suppressor protein PTEN, which inhibits the PI3K/Akt signaling pathway and has a multifunctional role in cell proliferation, migration, and invasion.18,27,28 Interestingly, silencing of TOB-1 resulted in the downregulation of PTEN (Figure 6), suggesting TOB-1-dependent PTEN signaling. Thus, progesterone can modulate the function of TOB-1, subsequently influencing the function of PTEN and ultimately leading to increased p27 expression.

Bottom Line: Reports state that surgery performed at different phases of the menstrual cycle may significantly affect breast cancer treatment outcome.Therefore, we further functionally characterized the protein product of TOB-1 in vitro.These results support the hypothesis that surgery conducted during the luteal phase of the menstrual cycle may facilitate improved patient survival.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India.

ABSTRACT
Reports state that surgery performed at different phases of the menstrual cycle may significantly affect breast cancer treatment outcome. From previous studies, we identified differentially expressed genes in each menstrual cycle phase by microarray, then subjected them to functional in vitro analyses. Microarray studies disclosed genes that are upregulated in the luteal phase and follicular phase. TOB-1 is a tumor suppressor gene and was expressed exclusively in the luteal phase in our microarray study. Therefore, we further functionally characterized the protein product of TOB-1 in vitro. To our knowledge, no studies have yet been conducted on reactive oxygen species-regulated tumor suppressor interactions in accordance with the biphasic nature of progesterone. This work demonstrates that progesterone can produce reactive oxygen species in MCF-7 cells and that TOB-1 exerts a series of non-genomic interactions that regulate antiproliferative activity by modulating the antioxidant enzyme superoxide dismutase. Furthermore, this study implicates PTEN as an interacting partner for TOB-1, which may regulate the downstream expression of cell cycle control protein p27 via multiple downstream signaling pathways of progesterone through a progesterone receptor, purely in a time- and concentration-dependent manner. These results support the hypothesis that surgery conducted during the luteal phase of the menstrual cycle may facilitate improved patient survival.

No MeSH data available.


Related in: MedlinePlus