salicylates and Prostatic-Neoplasms

Radiotherapy (RT) is a key therapeutic modality for prostate cancer (PrCa), but RT resistance necessitates dose-escalation, often causing bladder and rectal toxicity. Aspirin, a prodrug of salicylate (SAL), has been associated with improved RT response in clinical PrCa cases, but the potential mechanism mediating this effect is unknown. SAL activates the metabolic stress sensor AMP-activated protein kinase (AMPK), which inhibits de novo lipogenesis, and protein synthesis via inhibition of Acetyl-CoA Carboxylase (ACC), and the mammalian Target of Rapamycin (mTOR), respectively. RT also activates AMPK through a mechanism distinctly different from SAL. Therefore, combining these two therapies may have synergistic effects on suppressing PrCa. Here, we examined the potential of SAL to enhance the response of human PrCa cells and tumors to RT.. Androgen-insensitive (PC3) and -sensitive (LNCaP) PrCa cells were subjected to proliferation and clonogenic survival assays after treatment with clinically relevant doses of SAL and RT. Balb/c nude mice with PC3 xenografts were fed standard chow diet or chow diet supplemented with 2.5 g/kg salsalate (SAL pro-drug dimer) one week prior to a single dose of 0 or 10 Gy RT. Immunoblotting analysis of signaling events in the DNA repair and AMPK-mTOR pathways and lipogenesis were assessed in cells treated with SAL and RT.. SAL inhibited proliferation and clonogenic survival in PrCa cells and enhanced the inhibition mediated by RT. Salsalate, added to diet, enhanced the anti-tumor effects of RT in PC3 tumor xenografts. RT activated genotoxic stress markers and the activity of mTOR pathway and AMPK and mediated inhibitory phosphorylation of ACC. Interestingly, SAL enhanced the effects of RT on AMPK and ACC but blocked markers of mTOR activation.. Our results show that SAL can enhance RT responses in PrCa. Salsalate is a promising agent to investigate this concept in prospective clinical trials of PrCa in combination with RT.

Topics: Administration, Oral; AMP-Activated Protein Kinase Kinases; Animals; Cell Proliferation; Cell Survival; Combined Modality Therapy; Humans; Lipogenesis; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Prostatic Neoplasms; Prostatic Neoplasms, Castration-Resistant; Protein Kinases; Radiation-Sensitizing Agents; Salicylates; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

MUC1 is a transmembrane mucin that can promote cancer progression, and its upregulation correlates with a worse prognosis in colon cancer. We examined the effects of overexpression of MUC1 in colon cancer cells, finding that it induced epithelial to mesenchymal transition (EMT), including enhanced migration and invasion, and increased Akt phosphorylation. When the clones were treated with the aspirin metabolite salicylate, Akt phosphorylation was decreased and EMT inhibited. As the salicylate motif is necessary for the activity of the lysine acetyltransferase (KAT) inhibitor anacardic acid, we hypothesized these effects were associated with the inhibition of KAT activity. This was supported by anacardic acid treatment producing the same effect on EMT. In vitro KAT assays confirmed that salicylate directly inhibited PCAF/Kat2b, Tip60/Kat5 and hMOF/Kat8, and this inhibition was likely involved in the reversal of EMT in the metastatic prostate cancer cell line PC-3. Salicylate treatment also inhibited EMT induced by cytokines, illustrating the general effect it had on this process. The inhibition of both EMT and KATs by salicylate presents a little explored activity that could explain some of the anti-cancer effects of aspirin.

Topics: Anacardic Acids; Cell Line, Tumor; Cell Proliferation; Cell Survival; Colorectal Neoplasms; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; HT29 Cells; Humans; Lysine Acetyltransferases; Male; Mucin-1; Neoplasms; Phosphorylation; Prostatic Neoplasms; Proto-Oncogene Proteins c-akt; Salicylates

Although major improvements have been made in surgical management, chemotherapeutic, and radiotherapeutic of prostate cancer, many prostate cancers remain refractory to treatment with standard agents. Therefore, the identification of new molecular targets in cancer progression and development of novel therapeutic strategies to target them are very necessary for achieving better survival for patients with prostate cancer. Activation of small GTPases such as Ras and Arf1 is a critical component of the signaling pathways for most of the receptors shown to be upregulated in advanced prostate cancer.. The drug effects on cell proliferation were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay. The drug effects on cell migration and invasion were determined by Radius™ 24-well and Matrigel-coated Boyden chambers. The drug effects on apoptosis were assessed by FITC Annexin V Apoptosis Detection Kit with 7-AAD and Western blot with antibodies against cleaved PARP and Caspase 3. A NOD/SCID mouse model generated by subcutaneous injection was used to assess the in vivo drug efficacy in tumor growth. ERK activation and tumor cell proliferation in xenografts were examined by immunohistochemistry.. We show that Exo2, a small-molecule inhibitor that reduces Arf1 activation, effectively suppresses prostate cancer cell proliferation by blocking ERK1/2 activation. Exo2 also has other effects, inhibiting migration and invasion of PCa cells and inducing apoptosis. The Ras inhibitor salirasib augments Exo2-induced cytotoxicity in prostate cancer cells partially by enhancing the suppression of ERK1/2 phosphorylation. In a xenograft mouse model of prostate cancer, Exo2 reduces prostate tumor burden and inhibits ERK1/2 activation at a dose of 20 mg/kg. Synergistic treatment of salirasib and Exo2 exhibits a superior inhibitory effect on prostate tumor growth compared with either drug alone, which may be attributed to the more efficient inhibition of ERK1/2 phosphorylation.. This study suggests that simultaneous blockade of Arf1 and Ras activation in prostate cancer cells is a potential targeted therapeutic strategy for preventing prostate cancer development.

Topics: ADP-Ribosylation Factor 1; Animals; Antineoplastic Agents; Apoptosis; Benzaldehydes; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Synergism; Farnesol; Humans; Male; Mice; Prostatic Neoplasms; Pyrimidines; ras Proteins; Salicylates; Signal Transduction; Xenograft Model Antitumor Assays

Prostate cancer is one of the most frequently diagnosed cancers in human males. Progression of these tumors is facilitated by autocrine/paracrine growth factors which activate critical signaling cascades that promote prostate cancer cell growth, survival and migration. Among these, Ras pathways have a major role. Here we examined the effect of the Ras inhibitor S-trans, trans-farnesylthiosalicylic acid (FTS), on growth and viability of androgen-dependent and androgen-independent prostate cancer cells. FTS downregulated Ras, inhibited signaling to Akt and reduced the levels of cell-cycle regulatory proteins including cyclin D1, p-RB, E2F-1 and cdc42 in LNCaP and PC3 cells. Consequently the anchorage-dependent and anchorage-independent growth of LNCaP and PC3 cells were inhibited. FTS also induced apoptotic cell death which was inhibited by the broad-spectrum caspases inhibitor, Boc-asp-FMK. Our study demonstrated that androgen-dependent and androgen-independent prostate cancer cells require active Ras for growth and survival. Ras inhibition by FTS results in growth arrest and cell death. FTS may be qualified as a potential agent for the treatment of prostate cancer.

Topics: Amino Acid Chloromethyl Ketones; Androgens; Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin D1; Dose-Response Relationship, Drug; Down-Regulation; E2F1 Transcription Factor; Farnesol; Humans; Male; Myotonin-Protein Kinase; Prostatic Neoplasms; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-akt; ras Proteins; Salicylates; Serine Proteinase Inhibitors; Signal Transduction

The anticancer anthracyclines, doxorubicin and daunorubicin, are highly cytotoxic to both cancer and normal cells. In this work, we have investigated the capacity of cellular myeloperoxidase to inactivate these agents. We show that incubation of human leukemia HL-60 cells with the anthracyclines in the presence of hydrogen peroxide and nitrite causes irreversible oxidation of the drugs, suggesting an extensive modification of their chromophores. Methimazole, 4-aminobenzoic acid hydrazide, or azide inhibits the reaction, suggesting that it is mediated by the cellular myeloperoxidase, an enzyme naturally present in large amounts in HL-60 cells. In contrast to the intact drugs, the oxidatively transformed anthracyclines were substantially less cytotoxic for HL-60 (assayed by apoptosis) and PC3 prostate cancer cells and H9c2 rat cardiac myoblasts in vitro (assayed by clonogenic survival), indicating that the oxidative metabolism of these agents leads to their inactivation. Using tandem mass spectrometry, we identified two specific metabolic products of the anthracycline degradation, 3-methoxyphthalic acid and 3-methoxysalicylic acid. These two metabolic products were obtained as authentic compounds and were nontoxic to HL-60 leukemic cells and cardiac myocytes. These findings may have important implications for the cellular pharmacology of anthracyclines and for clinical oncology.

Topics: Animals; Antibiotics, Antineoplastic; Biotransformation; Cell Line, Tumor; Daunorubicin; Doxorubicin; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; Male; Myocytes, Cardiac; Oxidation-Reduction; Peroxidase; Phthalic Acids; Prostatic Neoplasms; Rats; Salicylates

The majority of men with advanced prostate cancer (PCa) respond to androgen deprivation therapy (ADT) with objective evidence of tumor regression. However, these tumors will regrow in the presence of low-androgen levels after 12-18 months. Regrowth after ADT is associated with upregulation of growth factor (GF) mediated pathways. The compound farnesylthiosalicylate (FTS), a specific antagonist of the 21 kDa Ras protein, suppresses GF signaling and it might be a useful therapy against advanced PCa.. We measured androgen and GF dependent growth of androgen dependent LNCaP and androgen hypersensitive CWR-R1 PCa cells in response to specific inhibitors of GF pathways, including FTS. Inhibition of GF mediated signaling and cell-cycle pathways was confirmed by Western blotting of extracts from treated cells.. Both LNCaP and CWR-R1 cells were dependent on GF signaling pathways for cell growth. FTS, as well as suppressing cell growth, inhibited GF signaling pathway activity and reduced the levels of E2F1, p-Rb, and p-cdc2, all GF dependent mediators of cell-cycle progression.. These data suggest that FTS might be a useful agent against PCa that has relapsed after ADT.

Topics: Antineoplastic Agents; Cell Division; Cell Line, Tumor; Culture Media; Dihydrotestosterone; Farnesol; Humans; Male; Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Prostatic Neoplasms; Salicylates