Sensitization to oxaliplatin in HCT116 and HT29 cell lines by metformin and ribavirin and differences in response to mitochondrial glutaminase inhibition

AIM OF STUDY

In the present study, we evaluated the effect of ribavirin and metformin on the sensitivity of oxaliplatin and 5-fluorouracil (5-FU) on colon cancer.

MATERIALS AND METHODS

Cell viability of two commercially available colon cancer cell lines (HT29 and HCT116) were analyzed by sulforhodamine B (SRB) assay.

RESULTS

A clinically achievable and nontoxic concentration of ribavirin and metformin showed a significant synergistic effect on oxaliplatin in HT29 and HCT116 cell lines. Ribavirin showed a synergistic effect on oxaliplatin in HT29 (R = 2.93, P < 0.001) and HCT116 (R = 1.71, P < 0.001), while only in HT29 metformin synergized with oxaliplatin by 2.66 (± 0.28, P < 0.01). In addition, both cell lines showed significant differences in response to Compound 968, inhibitor of mitochondrial glutaminase activity.

CONCLUSION

The data suggested that these cell lines not only turn to metabolic different sustainability process after oxaliplatin treatment but that they also have different basal metabolic requirements of glutamine in vitro which can be exploits in the future for colorectal cancer (CRC) treatment and further studies are required.

Adaptive metabolic rewiring to chronic SFK inhibition

Src family kinases (SFK) are key regulators of cellular proliferation, differentiation, survival, motility and angiogenesis. As such, SFK inhibitors are being tested in clinical trials to prevent metastasis as an alternative to current treatment regimens for a variety of cancers including breast cancer. To contribute to the development of molecular tools improving SFK-targeted therapies, we used the SFK inhibitor dasatinib and a well characterized triple negative breast cancer cell line (BT20). Comparison of the response of BT20 cells with acquired resistance to dasatinib and its’ parental counterpart suggest that chronic exposure to SFK inhibition results in increased dependency on TGFβ signaling for proliferation, both in the absence or the presence of dasatinib. In addition, we found that acquired (but not de novo) resistance to dasatinib was reduced by non-cytotoxic concentrations compounds hindering on PI3K, mTORC1 signaling, endoplasmic reticulum stress or autophagy.

Resistance to Dasatinib in primary chronic lymphocytic leukemia lymphocytes involves AMPK-mediated energetic re-programming

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in the western world. Although promising new therapies for this incurable disease are being tested in clinical trials, the therapeutic relevance of metabolic rewiring in chronic lymphocytic leukemia (CLL) is poorly understood. The aim of this study was to identify targetable metabolic differences in primary CLL lymphocytes by the use of Dasatinib. Dasatinib is a multi-tyrosine kinase inhibitor used to treat chronic myelogenous leukemia (CML) and is being tested in clinical trials for several cancers including CLL. This drug has been shown to be beneficial to CML patients suffering from diabetes by reducing their glucose plasma levels. In keeping with this previous observation, we report that Dasatinib induced glucose use while reducing lactate production, suggesting that this tyrosine kinase inhibitor decreases aerobic glycolysis and shifts glucose use in primary CLL lymphocytes. Our results suggest that primary CLL lymphocytes (independently of traditional prognostic factors) can be stratified in two subsets by their sensitivity to Dasatinib in vitro. Increased glucose use induced by Dasatinib or by inhibition of mitochondrial respiration was not sufficient to sustain survival and ATP levels in CLL samples sensitive to Dasatinib. The two subsets of primary CLL lymphocytes are characterized as well by a differential dependency on mitochondrial respiration and the use of anabolic or catabolic processes to cope with induced metabolic/energetic stress. Differential metabolic reprogramming between subsets is supported by the contrasting effect on the survival of Dasatinib treated CLL lymphocytes with pharmacological inhibition of two master metabolic regulators (mTorc1 and AMPK) as well as induced autophagy. Alternative metabolic organization between subsets is further supported by the differential basal expression (freshly purified lymphocytes) of active AMPK, regulators of glucose metabolism and modulators of AKT signaling. The contrasting metabolic features revealed by our strategy could be used to metabolically target CLL lymphocyte subsets creating new therapeutic windows for this disease for mTORC1 or AMPK inhibitors. Indeed, we report that Metformin, a drug used to treat diabetes was selectively cytotoxic to Dasatinib sensitive samples. Ultimately, we suggest that a similar strategy could be applied to other cancer types by using Dasatinib and/or relevant tyrosine kinase inhibitors.