Adaptation to Chronic-Cycling Hypoxia Renders Cancer Cells Resistant to MTH1-Inhibitor Treatment Which Can Be Counteracted by Glutathione Depletion

Tumor hypoxia and hypoxic adaptation of cancer cells represent major barriers to successful cancer treatment. We revealed that improved antioxidant capacity contributes to increased radioresistance of cancer cells with tolerance to chronic-cycling severe hypoxia/reoxygenation stress. We hypothesized, that the improved tolerance to oxidative stress will increase the ability of cancer cells to cope with ROS-induced damage to free deoxy-nucleotides (dNTPs) required for DNA replication and may thus contribute to acquired resistance of cancer cells in advanced tumors to antineoplastic agents inhibiting the nucleotide-sanitizing enzyme MutT Homologue-1 (MTH1), ionizing radiation (IR) or both. Therefore, we aimed to explore potential differences in the sensitivity of cancer cells exposed to acute and chronic-cycling hypoxia/reoxygenation stress to the clinically relevant MTH1-inhibitor TH1579 (Karonudib) and to test whether a multi-targeting approach combining the glutathione withdrawer piperlongumine (PLN) and TH1579 may be suited to increase cancer cell sensitivity to TH1579 alone and in combination with IR. Combination of TH1579 treatment with radiotherapy (RT) led to radiosensitization but was not able to counteract increased radioresistance induced by adaptation to chronic-cycling hypoxia/reoxygenation stress. Disruption of redox homeostasis using PLN sensitized anoxia-tolerant cancer cells to MTH1 inhibition by TH1579 under both normoxic and acute hypoxic treatment conditions. Thus, we uncover a glutathione-driven compensatory resistance mechanism towards MTH1-inhibition in form of increased antioxidant capacity as a consequence of microenvironmental or therapeutic stress.

Diphenhydramine increases the therapeutic window for platinum drugs by simultaneously sensitizing tumor cells and protecting normal cells

Platinum-based compounds remain a well-established chemotherapy for cancer treatment despite their adverse effects which substantially restrict the therapeutic windows of the drugs. Both the cell type-specific toxicity and the clinical responsiveness of tumors have been associated with mechanisms that alter drug entry and export. We sought to identify pharmacological agents that promote cisplatin (CP) efficacy by augmenting the levels of drug-induced DNA lesions in malignant cells and simultaneously protecting normal tissues from accumulating such damage and from functional loss. Formation and persistence of platination products in the DNA of individual nuclei were measured in drug-exposed cell lines, in primary human tumor cells and in tissue sections using an immunocytochemical method. Using a mouse model of CP-induced toxicity, the antihistaminic drug diphenhydramine (DIPH) and two methylated derivatives decreased DNA platination in normal tissues and also ameliorated nephrotoxicity, ototoxicity, and neurotoxicity. In addition, DIPH sensitized multiple cancer cell types, particularly ovarian cancer cells, to CP by increasing intracellular uptake, DNA platination, and/or apoptosis in cell lines and in patient-derived primary tumor cells. Mechanistically, DIPH diminished transport capacity of CP efflux pumps MRP2, MRP3, and MRP5 particularly in its C2+C6 bimethylated form. Overall, we demonstrate that DIPH reduces side effects of platinum-based chemotherapy and simultaneously inhibits key mechanisms of platinum resistance. We propose that measuring DNA platination after ex vivo exposure may predict the responsiveness of individual tumors to DIPH-like modulators.

Learning to detect lymphocytes in immunohistochemistry with deep learning

The immune system is of critical importance in the development of cancer. The evasion of destruction by the immune system is one of the emerging hallmarks of cancer. We have built a dataset of 171,166 manually annotated CD3⁺ and CD8⁺ cells, which we used to train deep learning algorithms for automatic detection of lymphocytes in histopathology images to better quantify immune response. Moreover, we investigate the effectiveness of four deep learning based methods when different subcompartments of the whole-slide image are considered: normal tissue areas, areas with immune cell clusters, and areas containing artifacts. We have compared the proposed methods in breast, colon and prostate cancer tissue slides collected from nine different medical centers. Finally, we report the results of an observer study on lymphocyte quantification, which involved four pathologists from different medical centers, and compare their performance with the automatic detection. The results give insights on the applicability of the proposed methods for clinical use. U-Net obtained the highest performance with an F1-score of 0.78 and the highest agreement with manual evaluation (κ=0.72), whereas the average pathologists agreement with reference standard was κ=0.64. The test set and the automatic evaluation procedure are publicly available at lyon19.grand-challenge.org.

Visualization and Quantitative Measurement of Drug-Induced Platinum Adducts in the Nuclear DNA of Individual Cells by an Immuno-Cytological Assay

Immunocytological staining with adduct-specific antibodies allows the visualization and measurement of structurally defined types of DNA damage in the nuclei of individual cells. Here we describe an immunocytological assay (ICA) procedure for the localization and quantification of such damage, in particular induced by platinum-based anticancer drugs, in cell lines , in primary cell suspensions and in frozen tissue sections.

Multifaceted Mechanisms of Cisplatin Resistance in Long-Term Treated Urothelial Carcinoma Cell Lines

Therapeutic efficacy of cisplatin-based treatment of late stage urothelial carcinoma (UC) is limited by chemoresistance. To elucidate underlying mechanisms and to develop new approaches for overcoming resistance, we generated long-term cisplatin treated (LTT) UC cell lines, characterised their cisplatin response, and determined the expression of molecules involved in cisplatin transport and detoxification, DNA repair, and apoptosis. Inhibitors of metallothioneins and Survivin were applied to investigate their ability to sensitise towards cisplatin. Cell growth, proliferation, and clonogenicity were examined after cisplatin treatment by MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, EdU (5-ethynyl-2’-deoxyuridine) incorporation assay, and Giemsa staining, respectively. Cell cycle distribution and apoptosis were quantified by flow cytometry. mRNA and protein expressions were measured by real-time quantitative (qRT)-PCR, western blot, or immunofluorescence staining. LTTs recovered rapidly from cisplatin stress compared to parental cells. In LTTs, to various extents, cisplatin exporters and metallothioneins were induced, cisplatin adduct levels and DNA damage were decreased, whereas expression of DNA repair factors and specific anti-apoptotic factors was elevated. Pharmacological inhibition of Survivin, but not of metallothioneins, sensitised LTTs to cisplatin, in an additive manner. LTTs minimise cisplatin-induced DNA damage and evade apoptosis by increased expression of anti-apoptotic factors. The observed diversity among the four LTTs highlights the complexity of cisplatin resistance mechanisms even within one tumour entity, explaining heterogeneity in patient responses to chemotherapy.

Expression of the Alzheimer's Disease Mutations AβPP695sw and PSEN1M146I in Double-Transgenic Göttingen Minipigs

Mutations in the amyloid-β protein precursor gene (AβPP), the presenilin 1 gene (PSEN1) or the presenilin 2 gene (PSEN2) that increase production of the AβPP-derived peptide Aβ42 cause early-onset Alzheimer's disease. Rodent models of the disease show that further increase in Aβ42 production and earlier brain pathology can be obtained by coexpressing AβPP and PSEN1 mutations. To generate such elevated Aβ42 level in a large animal model, we produced Göttingen minipigs carrying in their genome one copy of a human PSEN1 cDNA with the Met146Ile (PSEN1M146I) mutation and three copies of a human AβPP695 cDNA with the Lys670Asn/Met671Leu (AβPPsw) double-mutation. Both transgenes were expressed in fibroblasts and in the brain, and their respective proteins were processed normally. Immunohistochemical staining with Aβ42-specific antibodies detected intraneuronal accumulation of Aβ42 in brains from a 10- and an 18-month-old pig. Such accumulation may represent an early event in the pathogenesis of Alzheimer's disease.

Tribbles 2 mediates cisplatin sensitivity and DNA damage response in epithelial ovarian cancer

Aim was to identify methylated genes with functional involvement in cisplatin-resistance development of epithelial ovarian cancer (EOC). Genome-wide analyses of hypermethylated CpG-islands in resistant cell lines in combination with qRT-PCR analyses were used to identify epigenetically silenced genes. EOC-Type-II tumors were analyzed for gene methylation and expression and TCGA data were interrogated in-silico. Experiments revealed 37 commonly hypermethylated genes in resistant cells of which Tribbles 2 (TRIB2) showed the most pronounced downregulation on mRNA level and was characterized further. TRIB2 showed a reactivation after 5'-Aza-Cytidine treatment in resistant cells but a cisplatin-dependent, prominent upregulation on mRNA level in sensitive cells, only. Re-expression in resistant A2780 cells increased the sensitivity to cisplatin and other DNA-damaging agents, but not taxanes. Contrary, knockdown of TRIB2 increased resistance to cisplatin in sensitive cells. TRIB2 was involved in the induction of a cisplatin-dependent cell cycle arrest and apoptosis by influencing p21 and survivin expression. An increased Pt-DNA-adduct formation in TRIB2 re-expressing cells did not translate in higher levels of dsDNA damage (yH2AX-foci). Thus, TRIB2 is potentially involved in the signal transduction from nucleotide excision repair of intrastrand cross links. Importantly, patient stratification of two homogenous cohorts of EOC-Type-II patients from Jena (n = 38) and the TCGA (n = 149) by TRIB2 mRNA expression consistently revealed a significantly decreased PFS for patients with low TRIB2 levels (log-rank p < 0.05). Tumors from resistant patients expressed the lowest levels of TRIB2. Downregulation of TRIB2 contributes to platin-resistance and TRIB2 expression should be validated as prognostic and predictive marker for EOC.

Cisplatin-induced neuropathic pain is mediated by upregulation of N-type voltage-gated calcium channels in dorsal root ganglion neurons

Cisplatin is important in the treatment of various types of cancer. Although it is highly effective, it also has severe side effects, with neurotoxicity in dorsal root ganglion (DRG) neurons being one of the most common. The key mechanisms of neurotoxicity are still controversially discussed; however, disturbances of the calcium homeostasis in DRG neurons have been suggested to mediate cisplatin neurotoxicity. By using the whole-cell patch-clamp technique, immunostaining and behavioral experiments with Sprague-Dawley rats, we examined the influence of short- and long-term exposure to cisplatin on voltage-gated calcium channel (VGCC) currents (I_Ca(V)) in small DRG neurons. In vitro exposure to cisplatin reduced I_Ca(V) in a concentration-dependent manner (0.01-50μM; 13.8-77.3%; IC₅₀ 5.07μM). Subtype-specific measurements of VGCCs showed differential effects on I_Ca(V). While the I_Ca(V) of P/Q-, L- and T-type VGCCs were reduced, I_Ca(V) of N-type VGCCs were increased by 30.3% during depolarization to 0mV. Exposure of DRG neurons to cisplatin (0.5 or 5μM) for 24-48h in vitro significantly increased a CaMK II-mediated I_Ca(V) current density. Immunostaining and western blot analysis revealed an increase of N-type VGCC protein level in DRG neurons 24h after cisplatin exposure. Cisplatin-mediated activation of caspase-3 was prevented by inhibition of N-type VGCCs using Ɯ-conotoxin MVIIA. Behavioral experiments showed that Ɯ-conotoxin MVIIA treatment prevented neuropathic syndromes in vivo by inhibiting upregulation of the N-type protein level. Here we show evidence for the first time for a crucial role of N-type VGCC in the genesis of cisplatin-induced polyneuropathy.