An acidic environment and hypoxia within the tumour are hallmarks of cancer that contribute to cell resistance to therapy. Deregulation of the PI3K/Akt pathway is common in colon cancer. Numerous Akt-targeted therapies are being developed, the activity of Akt-inhibitors is, however, strongly pH-dependent. Combination therapy thus represents an opportunity to increase their efficacy. In this study, the cytotoxicity of the Akt inhibitor perifosine and the Bcl-2/Bcl-xL inhibitor ABT-737 was tested in colon cancer HT-29 and HCT-116 cells cultured in monolayer or in the form of spheroids. The efficacy of single drugs and their combination was analysed in different tumour-specific environments including acidosis and hypoxia using a series of viability assays. Changes in protein content and distribution were determined by immunoblotting and a "peeling analysis" of immunohistochemical signals. While the cytotoxicity of single agents was influenced by the tumour-specific microenvironment, perifosine and ABT-737 in combination synergistically induced apoptosis in cells cultured in both 2D and 3D independently on pH and oxygen level. Thus, the combined therapy of perifosine and ABT-737 could be considered as a potential treatment strategy for colon cancer.

• Klíčová slova
• ABT-737, colon cancer, combined treatment, peeling analysis, perifosine, spheroids, synergism, tumour microenvironment,
• MeSH
• antitumorózní látky * farmakologie   MeSH
• apoptóza MeSH
• fosfatidylinositol-3-kinasy MeSH
• fosforylcholin * analogy a deriváty   farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• nádorové buněčné linie účinky léků   MeSH
• nádorové mikroprostředí MeSH
• nádory tračníku * farmakoterapie   MeSH
• protoonkogenní proteiny c-akt metabolismus   MeSH
• synergismus léků MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ABT-737 MeSH Prohlížeč
• antitumorózní látky * MeSH
• fosfatidylinositol-3-kinasy MeSH
• fosforylcholin * MeSH
• inhibitory proteinkinas MeSH
• perifosine MeSH Prohlížeč
• protoonkogenní proteiny c-akt MeSH

Colorectal cancer (CRC) is a disease with constantly increasing incidence and high mortality. The treatment efficacy could be curtailed by drug resistance resulting from poor drug penetration into tumor tissue and the tumor-specific microenvironment, such as hypoxia and acidosis. Furthermore, CRC tumors can be exposed to different pH depending on the position in the intestinal tract. CRC tumors often share upregulation of the Akt signaling pathway. In this study, we investigated the role of external pH in control of cytotoxicity of perifosine, the Akt signaling pathway inhibitor, to CRC cells using 2D and 3D tumor models. In 3D settings, we employed an innovative strategy for simultaneous detection of spatial drug distribution and biological markers of proliferation/apoptosis using a combination of mass spectrometry imaging and immunohistochemistry. In 3D conditions, low and heterogeneous penetration of perifosine into the inner parts of the spheroids was observed. The depth of penetration depended on the treatment duration but not on the external pH. However, pH alteration in the tumor microenvironment affected the distribution of proliferation- and apoptosis-specific markers in the perifosine-treated spheroid. Accurate co-registration of perifosine distribution and biological response in the same spheroid section revealed dynamic changes in apoptotic and proliferative markers occurring not only in the perifosine-exposed cells, but also in the perifosine-free regions. Cytotoxicity of perifosine to both 2D and 3D cultures decreased in an acidic environment below pH 6.7. External pH affects cytotoxicity of the other Akt inhibitor, MK-2206, in a similar way. Our innovative approach for accurate determination of drug efficiency in 3D tumor tissue revealed that cytotoxicity of Akt inhibitors to CRC cells is strongly dependent on pH of the tumor microenvironment. Therefore, the effect of pH should be considered during the design and pre-clinical/clinical testing of the Akt-targeted cancer therapy.

• Klíčová slova
• Akt kinase, alkalization, colorectal cancer, lactic acidosis, mass spectrometry imaging, perifosine, signal co-registration, tumor environment,
• Publikační typ
• časopisecké články MeSH

Wedelolactone is a multi-target natural plant coumestan exhibiting cytotoxicity towards cancer cells. Although several molecular targets of wedelolactone have been recognized, the molecular mechanism of its cytotoxicity has not yet been elucidated. In this study, we show that wedelolactone acts as an inhibitor of chymotrypsin-like, trypsin-like, and caspase-like activities of proteasome in breast cancer cells. The proteasome inhibitory effect of wedelolactone was documented by (i) reduced cleavage of fluorogenic proteasome substrates; (ii) accumulation of polyubiquitinated proteins and proteins with rapid turnover in tumor cells; and (iii) molecular docking of wedelolactone into the active sites of proteasome catalytic subunits. Inhibition of proteasome by wedelolactone was independent on its ability to induce reactive oxygen species production by redox cycling with copper ions, suggesting that wedelolactone acts as copper-independent proteasome inhibitor. We conclude that the cytotoxicity of wedelolactone to breast cancer cells is partially mediated by targeting proteasomal protein degradation pathway. Understanding the structural basis for inhibitory mode of wedelolactone might help to open up new avenues for design of novel compounds efficiently inhibiting cancer cells.

• Klíčová slova
• breast cancer, copper, proteasome, reactive oxygen species, wedelolactone,
• MeSH
• inhibitory proteasomu chemie   farmakologie   toxicita   MeSH
• kumariny chemie   farmakologie   toxicita   MeSH
• lidé MeSH
• měď metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádory prsu metabolismus   MeSH
• proteasomový endopeptidasový komplex chemie   metabolismus   MeSH
• proteolýza MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• simulace molekulového dockingu MeSH
• ubikvitinace MeSH
• vazba proteinů MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• inhibitory proteasomu MeSH
• kumariny MeSH
• měď MeSH
• proteasomový endopeptidasový komplex MeSH
• reaktivní formy kyslíku MeSH
• wedelolactone MeSH Prohlížeč