ABSTRACT
BACKGROUND: Cellular proteases are thought to increase the likelihood of cancer cell infiltration and metastasis by degrading constituents of the extracellular matrix (ECM). Measuring activities of these proteases may be used as tumor markers for early diagnosis, prognosis, and as a possible target for treatment plan. OBJECTIVE: The aim of the current study is to evaluate cysteine cathepsins (CTSK and CTSL) and matrix metalloproteases-2 (MMP-2) and 9 (MMP-9) activities in human breast tumor tissue. METHODS: A comparative cross-sectional study plan was devised to study the enzymatic activities ofCTSK and CTSL andMMP-2 and MMP-9 via zymographic detection method. Sites of tissue sample collection were St Paul's Millennium Medical College, Menelik II Hospital and Zewditu Memorial Hospital, Addis Ababa, Ethiopia. A total of 36 breast cancer patients were recruited and tissue samples were collected for the study. RESULTS: Activities of CTSK and CTSL were significantly elevated in cancerous tissue than the adjacent normal non-cancerous breast tissue of the same patients (n = 36, p ≤ 0.05). Also, activities ofMMP-2 and MMP-9 were increased significantly in tumor tissues than normal tissues (n = 36, P ≤ 0.05). CONCLUSION: It is found that there are different patterns of protease enzymatic activity expression between normal and tumor tissue using zymography. Compared with normal tissue samples, the protease enzymatic activity in cancerous tissue is higher. Thus, tissue proteases can be used in conjunction with histological techniques to identify patients in the same clinical group.
ABSTRACT
Repetitive excessive alcohol intoxication leads to neuronal damage and brain shrinkage. We examined cytoskeletal protein expression in human post-mortem tissue from Brodmann's area 9 of the prefrontal cortex (PFC). Brain samples from 44 individuals were divided into equal groups of 11 control, 11 alcoholic, 11 non-alcoholic suicides, and 11 suicide alcoholics matched for age, sex, and post-mortem delay. Tissue from alcoholic cohorts displayed significantly reduced expression of α- and ß-tubulins, and increased levels of acetylated α-tubulin. Protein levels of histone deacetylase-6 (HDAC6), and the microtubule-associated proteins MAP-2 and MAP-tau were reduced in alcoholic cohorts, although for MAPs this was not significant. Tubulin gene expressions increased in alcoholic cohorts but not significantly. Brains from rats administered alcohol for 4 weeks also displayed significantly reduced tubulin protein levels and increased α-tubulin acetylation. PFC tissue from control subjects had reduced tubulin protein expression that was most notable from the sixth to the eighth decade of life. Collectively, loss of neuronal tubulin proteins are a hallmark of both chronic alcohol consumption and natural brain ageing. The reduction of cytosolic tubulin proteins could contribute to the brain volumetric losses reported for alcoholic patients and the elderly.
ABSTRACT
Histone deacetylases (HDACs) control fundamental physiological processes such as proliferation and differentiation. HDAC inhibitors (HDACi) induce cell cycle arrest and apoptosis of tumor cells. Therefore, they represent promising cancer therapeutics that appear particularly useful in combination therapies. Although HDACi are tested in current clinical trials, the molecular mechanisms modulating the cellular responses toward HDACi are incompletely understood. To gain insight into pathways that limit HDACi efficacy in gastric cancer, we treated a panel of gastric cancer cells with the clinically relevant HDACi suberoylanilide hydroxamic acid (SAHA). We report that higher expression levels of the anti-apoptotic BCL2 family members MCL1 and BCL(XL) were detectable in cells with high inhibitory concentration 50 (IC(50)) values for SAHA. Using RNAi, we show that MCL1 and BCL(XL) lower the efficacy of SAHA. To find strategies to interfere with MCL1 and BCL(XL) expression, we investigated molecular regulation of both proteins. We show that specific siRNAs against c-MYC as well as pharmacological inhibition of this cancer-relevant transcription factor reduced MCL1 and BCL(XL) expression. Subsequently, we observed an increase in SAHA efficacy. Our data furthermore demonstrate that two different molecular mechanisms are responsible for the modulation of these factors. Whereas c-MYC controls transcription of MCL1 directly, regulation of BCL(XL) was due to c-MYC's capability to regulate the eIF4E gene, which encodes a rate-limiting factor of eukaryotic translation. Our data reveal a new molecular mechanism for how c-MYC controls cell autonomous apoptosis and provide a rationale for a concerted inhibition of HDACs and c-MYC in gastric cancer.
