Doxycycline (Doxiciclina) belongs to the tetracycline class of antibiotics and is a broad-spectrum metalloproteinase (MMP) inhibitor with oral activity. Doxycycline has antibacterial activity and antitumor activity.

METHODS: Twenty-two tumor cells were treated with Doxycycline for 48 h. Cell viability was measured by MTT.
RESULTS: Lung cancer cells were more sensitive to Doxycycline than most other cell lines. NCI-H446 and A549 cells were sensitive to Doxycycline with IC50s of 1.70 μM and 1.06 μM, respectively. [1]
METHODS: Human pancreatic cancer cells PANC-1 were treated with Doxycycline (10-40 μg/mL) for 8-24 h. The cell cycle was detected by Flow Cytometry.
RESULTS: Doxycycline caused the cells to arrest in the G1-S phase of the cell cycle. [2]

METHODS: To detect anti-tumor activity in vivo, Doxycycline (50 mg/kg) was administered intraperitoneally once daily for fifteen days to BALB/c mice harboring human mammary carcinoma tumor 4T1.
RESULTS: Doxycycline delayed tumor growth and reduced the number of tumor-associated macrophages and blood vessels. [3]
METHODS: To assay antimicrobial activity in vivo, Doxycycline (40 mg/kg) was administered intraperitoneally to BALB/c mice exposed to B. pseudomallei 1026b twice daily for two weeks.
RESULTS: Doxycycline-treated mice survived 100% of the time, and no B. pseudomallei DNA was amplified from the lungs or spleens of the majority of the surviving mice. [4]