Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014 Jun 3;111(22):8179-84.
doi: 10.1073/pnas.1321884111. Epub 2014 May 19.

Trichomonas Vaginalis Homolog of Macrophage Migration Inhibitory Factor Induces Prostate Cell Growth, Invasiveness, and Inflammatory Responses

Affiliations
Free PMC article

Trichomonas Vaginalis Homolog of Macrophage Migration Inhibitory Factor Induces Prostate Cell Growth, Invasiveness, and Inflammatory Responses

Olivia Twu et al. Proc Natl Acad Sci U S A. .
Free PMC article

Abstract

The human-infective parasite Trichomonas vaginalis causes the most prevalent nonviral sexually transmitted infection worldwide. Infections in men may result in colonization of the prostate and are correlated with increased risk of aggressive prostate cancer. We have found that T. vaginalis secretes a protein, T. vaginalis macrophage migration inhibitory factor (TvMIF), that is 47% similar to human macrophage migration inhibitory factor (HuMIF), a proinflammatory cytokine. Because HuMIF is reported to be elevated in prostate cancer and inflammation plays an important role in the initiation and progression of cancers, we have explored a role for TvMIF in prostate cancer. Here, we show that TvMIF has tautomerase activity, inhibits macrophage migration, and is proinflammatory. We also demonstrate that TvMIF binds the human CD74 MIF receptor with high affinity, comparable to that of HuMIF, which triggers activation of ERK, Akt, and Bcl-2-associated death promoter phosphorylation at a physiologically relevant concentration (1 ng/mL, 80 pM). TvMIF increases the in vitro growth and invasion through Matrigel of benign and prostate cancer cells. Sera from patients infected with T. vaginalis are reactive to TvMIF, especially in males. The presence of anti-TvMIF antibodies indicates that TvMIF is released by the parasite and elicits host immune responses during infection. Together, these data indicate that chronic T. vaginalis infections may result in TvMIF-driven inflammation and cell proliferation, thus triggering pathways that contribute to the promotion and progression of prostate cancer.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
(A) Multiple Sequence Comparison by Log-Expectation (MUSCLE) alignment of TvMIF and HuMIF sequences with nine invariant residues (39) shown in red. Carats (^) indicate five residues comprising the tautomerase active site. (B) TvMIF tautomerase activity was measured using 10 μg/mL recombinant TvMIF or HuMIF; assays were carried out in triplicate, and data shown are mean ± SE. (C) Immunofluorescence image and phase (Inset) using anti-HA antibody (green) and DAPI stain (blue) on parasites expressing TvMIF-HA. (Magnification: 100×.) (D) Immunoblot analyses of supernatant and pellet fractions of T. vaginalis transfectants expressing TvMIF-HA incubated at 37 °C or 16 °C (secretion negative control). Anti-HA antibodies detect MIF. Anti–β-tubulin (Anti-tubulin) and anti-neomycin (Anti-neo) phosphotransferase antibodies serve as negative controls for cell lysis.
Fig. 2.
Fig. 2.
TvMIF (1 ng/mL) or HuMIF (1 ng/mL) induces IL-8 production from human monocytes. Data shown are representative; the experiment was repeated using three different donors, and the same trend in IL-8 production was consistently observed. Data are the mean of quadruplicates per one assay ± SEM.
Fig. 3.
Fig. 3.
TvMIF interacts with the HuMIF receptor CD74. (A) NMR spectra of TvMIF and sCD74114–232 show incomplete overlap of red and black peaks, indicating that TvMIF and CD74 interact. (B) Surface plasmon resonance plots of various concentrations of TvMIF or HuMIF flowed over immobilized sCD74114–232 reveal that TvMIF and HuMIF have similar Kd values for the human receptor CD74.
Fig. 4.
Fig. 4.
TvMIF activates ERK1/2 and Akt/BAD pathways in BPH-1 and PC3 cells, resulting in increased cell proliferation and invasion. (A) Serum-starved BPH-1 cells were exposed to 80 pM endotoxin-free rTvMIF or rHuMIF and tested by immunoblot analysis for phosphorylated-ERK Thr202/Tyr204 (p-ERK1/2), total ERK1/2 (ERK1/2), phosphorylated Akt (p-Akt), total Akt (Akt), BAD phosphorylated at ser136 (p-BAD), total BAD (BAD), and a β-tubulin (Tubulin) loading control, using the corresponding antibodies. (B) Serum-starved PC3 cells were exposed to 80 pM endotoxin-free TvMIF (Tv-4h) or HuMIF (Hu-4h) for 4 h and probed for p-ERK1/2, ERK1/2, and a β-tubulin loading control. The time course and quantification of BPH-1 and PC3 data are provided in Fig. S2. Negative (Neg) = 1× PBS vehicle control, and positive (Pos) = 5% FBS. (C) BPH-1 or PC3 cells were plated and dosed with 80 pM LPS-free rTvMIF or rHuMIF every 24 h for 72 h. Cell numbers were then assessed colorimetrically. The addition of either 1 ng/mL TvMIF or HuMIF increases proliferation. Mean fold increase in proliferation (∼1.2-fold for BPH-1 cells and ∼1.4-fold for PC3 cells) over untreated cells from three independent experiments done in quadruplicate, with ±SEM, is shown. (D) BPH-1 or PC3 cells preincubated with 80 pM LPS-free rTvMIF or rHuMIF for 24 h were added to BD Fluorblok Tumor Invasion Plates in the presence of 80 pM TvMIF or HuMIF for 48 h. Fold increase in invasion over vehicle control-treated cells ± SEM of three independent experiments in triplicate is shown. *P < 0.05.

Similar articles

See all similar articles

Cited by 39 articles

See all "Cited by" articles

Publication types

MeSH terms

Substances

Feedback