Circadian regulation of cell cycle and apoptosis proteins in mouse bone marrow and tumor

Abstract

Proapoptotic drugs such as docetaxel displayed least toxicity and highest antitumor efficacy following dosing during the circadian rest phase in mice, suggesting that cell cycle and apoptotic processes could be regulated by the circadian clock. In study 1, mouse bone marrow and/or tumor were obtained every 4 h for 24 h in C3H/HeN mice with or without MA13/C mammary adenocarcinoma in order to determine the circadian patterns in cell-cycle phase distribution and BCL-2 anti-apoptotic protein expression. In study 2, mouse bone marrow from B6D2F1 mice was sampled every 3 h for 24 h in order to confirm the BCL-2 rhythm and to study its relation with 24 h changes in the expression of proapoptotic BCL-2-associated X protein (BAX) protein and clock genes mPer2, mBmal1, mClock, and mTim mRNAs. The rhythms in G1-, S- or G2/M-phase cells were shifted in tumor compared with bone marrow. In the tumor, the mean proportion of G2/M-phase cells increased by 75% from late rest to late activity span (P from cosinor = 0.001). No 24 h rhythm was found for BCL-2 in tumors. In contrast to this, in the bone marrow, mean BCL-2 expression varied 2.8-fold in B6D2F1 mice (P=0.025) and 3- or 4.5-fold in tumor-bearing and nontumor-bearing C3H/HeN mice, with a peak during the early rest span (P=0.024 and P<0.001, respectively). BAX varied fivefold during the 24 h span with a major peak occurring near mid-activity (P=0.007). The mean mRNAs of mPer2, mClock, and mBmal1 varied twofold to threefold over the 24 h, with high values during the activity span (P<0.05). In the tumor, the circadian organization in cell-cycle phase distribution was shifted and BCL2 rhythm was ablated. Conversely, a molecular circadian clock likely regulated BCL-2 and BAX expression in the bone marrow, increasing cellular protection against apoptosis during the rest span.

Preclinical relevance of dosing time for the therapeutic index of gemcitabine–cisplatin

“…Indeed, the proportion of Sphase cells in the bone marrow of the mouse, we used here was highest in the second half of darkness, when locomotor activity was highest (Tampellini et al, 1998;Filipski et al, 2004). As this circadian stage, BAX expression was highest and BCL-2 expression was low (Granda et al, 2005). The rhythms in S-phase distribution and BCL-2/BAX expression are consistent with a better tolerability of gemcitabine during the light span.…”

“…The deregulation of G1 -S checkpoint control by the circadian clock can relate to altered clock gene expression patterns in the tumour, as it was found for GOS (Filipski et al, 2004. Conversely, the circadian control of G2 -M checkpoint appears to be maintained in most experimental malignances, a finding consistent with the circadian dependency of CDDP or oxaliplatin antitumour activity Granda et al, , 2005.…”

“…Similar circadian patterns have been shown for the chronopharmacology of anticancer drugs across different rodent species or strains . Mechanisms include rhythms in reduced glutathione content in liver and other organs and host tolerability for platinum complexes in rats and mice (Bélanger et al, 1988;Li et al, 1997) and rhythms in BCL-2 expression in bone marrow and host tolerability for docetaxel in B6D2F 1 and C3H/He mice (Tampellini et al, 1998;Granda et al, 2001Granda et al, , 2005. A similar circadian pattern in the anticancer efficacy of the same drug has also been shown in different experimental tumour models .…”

“…The rhythms in S-phase distribution and BCL-2/BAX expression are consistent with a better tolerability of gemcitabine during the light span. Conversely, circadian changes in S-phase and BCL-2 are usually markedly altered in experimental tumours Granda et al, 2005). The deregulation of G1 -S checkpoint control by the circadian clock can relate to altered clock gene expression patterns in the tumour, as it was found for GOS (Filipski et al, 2004.…”

Rescue chemotherapy using multidrug chronomodulated hepatic arterial infusion for patients with heavily pretreated metastatic colorectal cancer

“…30 Normal mammalian cells contain a molecular clock that regulates the cell cycle, apoptosis, gene expression, and DNA repair. [30][31][32][33][34] In contrast, cells in advanced tumors have lost these clock-dependent rhythms. 35,36 The objective of chronomodulated chemotherapy is to take advantage of the circadian differences between normal cells and tumor cells by delivering high drug doses at times when normal cells are relatively protected by low proliferative or metabolic activity, whereas tumor cells maintain high metabolic and proliferative activities.…”