Targeting mitotic exit with hyperthermia or APC/C inhibition to increase paclitaxel efficacy

Abstract

Microtubule-poisoning drugs, such as Paclitaxel (or taxol, PtX), are powerful and commonly used anti-neoplastic agents for the treatment of several malignancies. PtX triggers cell death, mainly through a mitotic arrest following the activation of the spindle assembly checkpoint (SAC). Cells treated with PtX slowly slip from this mitotic block and die by mitotic catastrophe. However, cancer cells can acquire or are intrinsically resistant to this drug, posing one of the main obstacles for PtX clinical effectiveness. In order to override PtX resistance and increase its efficacy, we investigated both the enhancement of mitotic slippage and the block of mitotic exit.to test these opposing strategies, we used physiological hyperthermia (Ht) to force exit from PtX-induced mitotic block and the anaphase-promoting complex/cyclosome (APC/C) inhibitor, protAMe, to block mitotic exit. We observed that application of Ht on PtX-treated cells forced mitotic slippage, as shown by the rapid decline of cyclin B levels and by microscopy analysis. Similarly, Ht induced mitotic exit in cells blocked in mitosis by other antimitotic drugs, such as Nocodazole and the Aurora A inhibitor MLN8054, indicating a common effect of Ht on mitotic cells. On the other hand, protAMe prevented mitotic exit of PtX and MLN8054 arrested cells, prolonged mitosis, and induced apoptosis. In addition, we showed that protAMe prevented Ht-mediated mitotic exit, indicating that stress-induced APC/C activation is necessary for Ht-induced mitotic slippage.Finally, Ht significantly increased PtX cytotoxicity, regardless of cancer cells' sensitivity to PtX, and this activity was superior to the combination of PtX with pro-tAMe. Our data suggested that forced mitotic exit of cells arrested in mitosis by anti-mitotic drugs, such as PtX, can be a more successful anticancer strategy than blocking mitotic exit by inactivation of the APC/C.

Inhibition of kinesin family member 20B sensitizes hepatocellular carcinoma cell to microtubule‐targeting agents by blocking cytokinesis

“…At metaphase/anaphase transition, SAC activation is essential for the efficacy of taxol; however, some cancer cells can bypass its surveillance to escape from taxol inhibition . To address whether shKIF20B suppresses HCC cells in a SAC‐dependent way, a SAC inhibitor AZ3146 was applied .…”

“…5 For example, the regulation of SAC, which controls cell cycle progression during mitosis and synchronizes mitosis by attaching chromosomes to spindle microtubules, 6 is critical for taxol-mediated cell death. 7,8 However, reduced or malfunctioned SAC is commonly seen in cancer cells, 9 and such SAC defects usually correlate with MTA resistance. 10 Therefore, new approaches targeting alternative checkpoints besides SAC would help treat MTA-resistant HCC.…”

Moderate Hyperthermia Induces Apoptosis in Metaphase-Arrested Cells But Not in Interphase Hela Cells

“…For Balb-3T3 and L929 cells, it is not known why heat treatment causes a return to inter-phase, but it most likely also involves inactivation of Cdk1/cyclin B since that is a prerequisite for mitotic exit [31]- [33]. Interestingly, heat treatment of paclitaxel-arrested cells has been shown to induce apoptosis more efficiently when exit from mitosis is blocked by inhibiting the Anaphase-Promoting Complex (APC/C) [34].…”

Effects of hyperthermia as a mitigation strategy in DNA damage-based cancer therapies

“…For instance, several studies using anti-mitotic drugs such as paclitaxel, nocodazole and Aurora A in combination with hyperthermia have shown a significant increase in cytotoxicity together with mitotic catastrophe [54], an event that has also been observed when HeLa S3 cells were exposed at 41.5 o C prior to being subjected to irradiation [55]. In conclusion, ATM and ATR are the main molecules regulating the cell cycle checkpoints following hyperthermia-induced DNA damage (e.g.…”