Knockdown of tripartite motif 59 (TRIM59) inhibits tumor growth in prostate cancer

OBJECTIVE

Members of the tripartite motif (TRIM) protein family contain a highly conserved N-terminal really interesting new gene (RING) domain that is involved in regulating transcriptional factors and tumor suppressors. In this study, the effects of TRIM59 expression on tumor growth were investigated in prostate cancer.

MATERIALS AND METHODS

The expression of TRIM59 in prostate cancer tissues (n = 15) and prostate cancer cell lines was determined by quantitative reverse transcriptase-PCR (qRT-PCR), Western blotting, and immunohistochemistry. A specific shRNA targeting TRIM59 was employed to knockdown TRIM59 expression in the prostate cancer cell lines PC3 and DU145. The effects of TRIM59 knockdown on cell proliferation were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. The effects on cell cycle progression were determined by flow cytometry, and a xenograft mouse model of prostate cancer was generated to determine the in vivo effects of TRIM59 knockdown. The effects on cell cycle regulators were determined by Western blotting.

RESULTS

TRIM59 was highly expressed in prostate cancer tissues. Knockdown of TRIM59 significantly inhibited cell proliferation and colony formation, and cell cycle analysis showed that TRIM59-depleted cells accumulated in S-phase. TRIM59 knockdown was shown to inhibit tumorigenesis in mice. In addition, the cell cycle regulators CDC25A, CDC2, and cyclin B1 were decreased by TRIM59 shRNA-mediated knockdown.

CONCLUSIONS

Our study suggests that TRIM59 promotes prostate cancer cell proliferation, possibly through its effects on cell cycle progression.

Report of sexually transmitted diseases by HIV infected men during follow up: time to target the HIV infected?

OBJECTIVES

To compare the rate of self reported sexually transmitted diseases (STDs) among HIV infected men with men who remained HIV negative during follow up of a Harare male factory cohort.

METHODS

Male factory workers were offered enrolment and behavioural data were collected at entry then every 6 months, along with HIV testing. Self report of STDs was used to calculate incidence per 100 person years. Cox proportional hazards models examined independent risk factors for STDs, with hazard ratios (HRs).

RESULTS

At entry 20% of men were HIV infected and 11% reported STDs in the previous year. A total of 2777 (82%) of 3383 men enrolled were followed at least once. Compared with men who remained HIV negative, seroconverters had the highest incidence of STDs (16.8 per 100 person years; IRR = 3.3, 95% CI = 2.5-4.3); men enrolled HIV positive also reported higher STD incidence (14.5 per 100 person years, IRR = 2.8; 95% CI 2.3-5.5). Among HIV positive men, the only independent risk factor for report of urethral discharge was history of multiple partners (HR = 10, 95% CI 1.4-73.2).

CONCLUSION

HIV positive men reported threefold higher incidence of STDs than HIV negative men, many related to high risk sexual behaviour.