Journal: Oncogene

Article Title: Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

doi: 10.1038/s41388-022-02239-4

Figure Lengend Snippet: A Workflow showing the selection strategy for KHDRBS1 among DNA-damage response genes transcriptionally activated by Myc and significantly associated to breast cancer prognosis. Venn diagram showing the overlap between Myc-transcriptionally activated genes, DNA-damage response genes and genes associated to breast cancer. Specifically, genes were retrieved from: (i) microarray data of Myc-overexpressing mammospheres (M2) (GSE86407); (ii) published dataset (MD Anderson Human-DNA Repair Genes, https://www.mdanderson.org/documents/Labs/Wood-Laboratory/human-dna-repair-genes.html ), BioRad DNA-damage signaling pathway (SAB Target List H96) and recently published DNA-damage-associated genes (Supplementary Table ); and (iii) breast cancer versus normal breast tissues TCGA BRCA and GTeX gene expression data (Supplementary Table ). Genes were further selected for association to the worse relapse-free survival probability in breast cancer (Supplementary Table ) and novelty in the field, excluding known genes associated with BRCAness . B Box plot representing the distribution of log2 gene expression of KHDRBS1 retrieved from TCGA BRCA ( n = 1212) and GTeX ( n = 179) gene expression data (RNASeq2GeneNorm). p value was calculated with Wilcoxon rank sum test. C Kaplan–Meier plots of relapse-free survival (RFS) probability of BC patients stratified by high or low KHDRBS1 expression levels. D GSEA of DNA-repair gene signatures in IMEC-WT versus M2 ( n =3). E Scheme showing MYC and H3K4me3 PCR amplicons localization (red box) on IMEC-WT and M2 cells and layered H3K27ac signals on KHDRBS1 ( SAM68 ) promoter from ENCODE. Chromatin state was assessed by ChromHMM from ENCODE. MYC-MAX binding on multiple cell lines was assessed by ChIP-seq from ENCODE. F ChIP-qPCR estimating MYC binding at SAM68 promoter in IMEC-WT and M2 cells. Data are mean ± SEM ( n = 3). G qRT-PCR analysis of SAM68 gene expression in IMEC-WT and M2 cells. Data are mean ± SEM ( n = 3). H ChIP-qPCR of H3K4me3 deposition at KHDRBS1 ( SAM68 ) promoter in IMEC-WT and M2 cells. Data are mean ± SEM ( n = 3).

Article Snippet: For immunoprecipitation experiments, an equal amount of protein lysates was incubated overnight at 4 °C with 2 μg of anti-Sam68 antibody (H-4, mouse IgG 1 , Santa Cruz Biotechnology) mixed with protein G-Sepharose (Sigma-Aldrich).

Techniques: Selection, Microarray, Gene Expression, Expressing, Binding Assay, ChIP-sequencing, ChIP-qPCR, Quantitative RT-PCR

Journal: Oncogene

Article Title: Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

doi: 10.1038/s41388-022-02239-4

Figure Lengend Snippet: A Kaplan–Meier plots of distant relapse-free survival (DRFS) of BC patients stratified by high or low Sam68 protein expression levels. Patients were categorized according to all molecular subtypes ( n = 211) and Luminal-A ( n = 91), Luminal-B ( n = 61), HER2 + ( n = 27), TNBC ( n = 32), HER2 + + TNBC ( n = 59) BCs. B Box plot representing the distribution of log2 gene expression of KHDRBS1 retrieved from TCGA BRCA gene expression data (RNASeq2GeneNorm). p value was calculated with Wilcoxon rank sum test. The indicated statistics refer to each molecular subtype versus basal subtypes. * p value ≤ 0.05; ** p value ≤ 0.01; **** p value ≤ 0.0001. C ChIP-qPCR estimating MYC and MAX binding at SAM68 promoter in BCSphCs (#4 and #15). Data are mean ± SEM of two independent experiment for each BCSphCs. D Expression of Myc (green color) and Sam68 (red color) on paraffin-embedded sections on parental BC and corresponding PDX tissue. Nuclei were counterstained with Toto-3 (blue color). Scale bar represents 40 µm. E Relative mRNA expression levels of MYC and KHDRBS1 on BCSphCs (#4, #13, and #21) expressing a MycER fusion protein induced by 50 nM of OHT. Data are represented as fold mRNA level changes of OHT-treated cells over vehicle. Data are represented as mean ± SD of three independent experiments. * p value ≤ 0.05; ** p value ≤ 0.01. F Cell proliferation analysis of ER+ (MCF7), TNBC (BT549), TNBC BRCA mut (HCC1937) BC cell lines and BCSphCs (#1, #4, #13, and #21) transduced with doxycyclin-inducible non-targeting (nt) and short hairpin Sam68 (shSam68). Data are represented as fold variation of shSam68 over scr. ns not significant; ** p value ≤ 0.01. G Size of tumors generated by orthotopic injection of ER+ (MCF7), TNBC (BT549), TNBC BRCA mut (HCC1937) BC cell lines and BCSphCs (#4, #13) in immunocompromised mice (NOD/SCID) at the indicated time points. Data are expressed as mean ± SD ( n = 5 mice per group). ns not significant, *** p value ≤ 0.001.

Article Snippet: For immunoprecipitation experiments, an equal amount of protein lysates was incubated overnight at 4 °C with 2 μg of anti-Sam68 antibody (H-4, mouse IgG 1 , Santa Cruz Biotechnology) mixed with protein G-Sepharose (Sigma-Aldrich).

Techniques: Expressing, Gene Expression, ChIP-qPCR, Binding Assay, Transduction, Generated, Injection

Journal: Oncogene

Article Title: Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

doi: 10.1038/s41388-022-02239-4

Figure Lengend Snippet: A MYC binding on DNA-damage related genes transcription start sites (TSS) on IMEC-WT and M2 breast cells. B Representative immunofluorescence analysis of Rad51 foci formation in ER+ (MCF7), TNBC (BT549), TNBC BRCA mut (HCC1937) BC established cell lines and BCSphCs (#4) untreated (UT) and after 6 h of 8 Gy single dose γ-irradiation (IR). Nuclei were counterstained by Toto-3 (blue). Scale bar represents 10 µm. C Waterfall plot analysis of doxorubicin (DOX, 200 nM, left panel ), paclitaxel (PTX, 10 nM, middle panel ) and carboplatin (CARB, 100 µM, left panel ) response at 72 h in ER+ and TNBC BC established cell lines and BCSphCs. D Response rate distribution to chemotherapy for ER+ and TNBC BC established cell lines and BCSphCs treated as in ( C ). Middle line shows the median value of response per group, while single points represent the average value of BC cell response to DOX, PTX and CARB. Data are mean of three independent experiments. Statistical analysis was performed by using Kruskal–Wallis test. Ns not significant, * p value ≤ 0.05; ** p value ≤ 0.01. E Immunoblot analysis of PARP and Sam68 (input) and after immunoprecipitation (IP) with Sam68 antibody in BCSphCs (#15) treated for 4 h with vehicle, doxorubicin (DOX), paclitaxel (PTX) and carboplatin (CARB). Lamin-B was used as loading control. F Immunoblot analysis of nuclear PAR, PARP, and Sam68 in scramble (scr) and short hairpin Sam68 (shSam68) ER+ (MCF7), TNBC (BT549), and TNBC BRCA mut (HCC1937) BC cell lines and BCSphCs (#4) treated with vehicle, doxorubicin (DOX), paclitaxel (PTX) and carboplatin (CARB) for 4 h. H3 was used as loading control. G Cell proliferation analysis of ER+ (MCF7), TNBC (BT549), and TNBC BRCA mut (HCC1937) BC cell lines and BCSphCs (#1, #4, #13, #21) transduced with scramble and short hairpin Sam68 (shSam68) treated with vehicle, doxorubicin (DOX), paclitaxel (PTX) and carboplatin (CARB) for 72 h. Data are represented as fold variation of shSam68 over scramble. Data are mean ± SD of three independent experiments. ns not significant; * p value ≤ 0.05; ** p value ≤ 0.01. H , I Relative mRNA expression levels of RAD51 (H) and MYC (I) on scramble (scr) and short hairpin Sam68 (shSam68) ER+ (MCF7), TNBC (BT549), and TNBC BRCA mut (HCC1937) BC cell lines and BCSphCs (#12 and #13) treated with vehicle, doxorubicin (DOX), paclitaxel (PTX), and carboplatin (CARB) for 24 h. Data are represented as fold mRNA level changes of treated scr and shSam68 cells over vehicle. Data are represented as mean ± SD of three independent experiments. Ns not significant, * p value ≤ 0.05; ** p value ≤ 0.01; *** p value ≤ 0.001.

Article Snippet: For immunoprecipitation experiments, an equal amount of protein lysates was incubated overnight at 4 °C with 2 μg of anti-Sam68 antibody (H-4, mouse IgG 1 , Santa Cruz Biotechnology) mixed with protein G-Sepharose (Sigma-Aldrich).

Techniques: Binding Assay, Immunofluorescence, Irradiation, Western Blot, Immunoprecipitation, Control, Transduction, Expressing

Journal: Oncogene

Article Title: Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

doi: 10.1038/s41388-022-02239-4

Figure Lengend Snippet: A Schematic model of DNA-repair signaling pathways mediating the resistance of BC stem-like cells to chemotherapy. B Workflow of purification of sphere cells from serially transplanted BC PDX and their use for in vitro and in vivo drug toxicity testing. C Size of tumors generated by orthotopic injection of scramble (scr) and short hairpin Sam68 (shSam68) BCSphCs treated with vehicle (veh) and BO2. Arrows indicate the start and the end of treatment. Data are expressed as mean of tumors generated by the injection of BCSphCs (#4, #13, and #21) ± SEM ( n = 5 mice per group). D Size of tumors generated by orthotopic injection of scramble (scr) and short hairpin Sam68 (shSam68) BCSphCs (#4, #13, #21) treated with vehicle, olaparib, BO2, cisplatin and olaparib plus BO2 and olaparib plus cisplatin and BO2. Arrows indicate the beginning and the end of treatment. Data are expressed as mean of tumors generated by the injection of BCSphCs (#4, #13, and #21) ± SEM ( n = 5 mice per group). **** p value ≤ 0.0001. E Immunoblot analysis of Rad51 in BCSphCs (#15) treated with dinaciclib for 24 h at the indicated concentration. Β-actin was used as loading control. F Cell viability percentage of scramble (scr) and short hairpin Sam68 (shSam68) BCSphCs (#4, #13, #15, and #21) treated with vehicle and dinaciclib (10 nM) for 6 days. Data are represented as mean ± SEM ( n = 2). * p value ≤ 0.05; *** p value ≤ 0.001. G Representative images ( left panel ) and quantification of area ( right panel ) of BC sphere cells (#21), transduced with scramble (scr) and short hairpin Sam68 (shSam68) lentiviral vectors, treated with vehicle and dinaciclib for 6 days. Data are represented as mean ± SEM ( n = 3). Ns not significant, ** p value ≤ 0.01; *** p value ≤ 0.001. Scale bar represents 100 µm. H Size of tumors generated by orthotopic injection of scramble (scr) and short hairpin Sam68 (shSam68) BCSphCs treated with vehicle (veh) and dinaciclib (din). Arrows indicate the start and the end of treatment. Data are expressed as mean of tumors generated by the injection of BCSphCs (#4, #7, #13) ± SEM ( n = 5 mice per group). **** p value ≤ 0.0001. I Cell viability percentage of BCSphCs (#4, #13, #14, #15, #21) treated with vehicle, olaparib and dinaciclib, alone or in combination, at the indicated concentrations for 6 days. Data are represented as mean ± SD ( n = 3). J Synergy plot representing the combination index (CI), computed in CompuSyn by using Chou-Talalay method, for each olaparib and dinaciclib dose pair, calculated from cell viability data of BCSphCs (#13). K Size of tumors generated by orthotopic injection of BCSphCs treated with vehicle, olaparib, dinaciclib and olaparib plus dinaciclib. Arrows indicate the start and the end of treatment. Data are expressed as mean of tumors generated with BCSphCs (#4, #7, #13) ± SEM ( n = 5 mice per group). *** p value ≤ 0.001.

Article Snippet: For immunoprecipitation experiments, an equal amount of protein lysates was incubated overnight at 4 °C with 2 μg of anti-Sam68 antibody (H-4, mouse IgG 1 , Santa Cruz Biotechnology) mixed with protein G-Sepharose (Sigma-Aldrich).

Techniques: Protein-Protein interactions, Purification, In Vitro, In Vivo, Generated, Injection, Western Blot, Concentration Assay, Control, Transduction

Journal: Oncogene

Article Title: Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

doi: 10.1038/s41388-022-02239-4

Figure Lengend Snippet: A Cell viability percentage of scramble (scr) and short hairpin Sam68 (shSam68) ER+ R (MCF7) BC cell line treated with vehicle and dinaciclib (10 nM) for 6 days. Data are represented as mean ± SEM ( n = 4). * p value ≤ 0.05; ** p value ≤ 0.01; *** p value ≤ 0.001. B Relative mRNA expression levels of RAD51 and MYC on scramble (scr) and short hairpin Sam68 (shSam68) ER+ R (MCF7) BC cells treated with vehicle and dinaciclib for 6 days. Data are represented as fold mRNA level changes of treated scr and shSam68 over vehicle ( n = 3). C Cell viability percentage in ER+ R (MCF7) BC cells treated with vehicle, olaparib and dinaciclib, alone or in combination, at the indicated concentrations for 6 days. Data are represented as mean ± SD ( n = 3). D Kaplan–Meier plots of relapse-free survival (RFS) probability of BC patients of all molecular subtypes stratified by high or low MYC , KHDRBS1 , and RAD51 expression levels. E Schematic model showing the persistence of a BC stem-like population, characterized by high expression levels of MYC, SAM68 , and RAD51 , following standard anticancer therapies.

Article Snippet: For immunoprecipitation experiments, an equal amount of protein lysates was incubated overnight at 4 °C with 2 μg of anti-Sam68 antibody (H-4, mouse IgG 1 , Santa Cruz Biotechnology) mixed with protein G-Sepharose (Sigma-Aldrich).

Techniques: Expressing

Journal: Virology journal

Article Title: Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections.

doi: 10.1186/s12985-015-0452-8

Figure Lengend Snippet: Fig. 1 Sam68 redistribution from the nucleus to the cytoplasm. Two different FMDV-susceptible cell lines (LFBK-αvβ6, left; and IBRS2, right) were mock-infected or infected with FMDV at a MOI of 10 and fixed at 5 hpi. Cells were examined by IFM probing with rabbit polyclonal anti-Sam68 followed by goat-anti-rabbit-AF488 (green) and mouse monoclonal anti-FMDV VP1 followed by goat-anti-mouse-AF568 (red). Nuclei were stained with DAPI (blue)

Article Snippet: Polyclonal rabbit anti-Sam68 directed against the Nterminus of Sam68 was purchased from Novus Biologicals (Littleton, CO).

Techniques: Infection, Staining

Journal: Virology journal

Article Title: Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections.

doi: 10.1186/s12985-015-0452-8

Figure Lengend Snippet: Fig. 2 FMDV-induced cytoplasmic Sam68 co-localizes with TIA-1. LFBK cells were mock-infected or infected with FMDV at a MOI of 10 and were fixed at 3 and 5 hpi. Cells were examined by IFM probing with rabbit polyclonal anti-Sam68 followed by goat-anti-rabbit-AF488 (green) and goat polyclonal anti-TIA-1 (a) or mouse monoclonal anti-G3BP (b) followed by donkey-anti-goat-AF568 (red, a) or goat-anti- mouse-AF568 (red; b). Nuclei were stained with DAPI (blue)

Article Snippet: Polyclonal rabbit anti-Sam68 directed against the Nterminus of Sam68 was purchased from Novus Biologicals (Littleton, CO).

Techniques: Infection, Staining

Journal: Virology journal

Article Title: Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections.

doi: 10.1186/s12985-015-0452-8

Figure Lengend Snippet: Fig. 3 Sam68 interacts with FMDV IRES 4. a Cartoon diagram in the upper panel describes the modular structure of FMDV A24 IRES and the location of two unpaired UAAA and a CAAA sequence motifs in domain 4 and 3, respectively. Sam68 potential binding sites are shown as a grey incomplete oval. Lower panel in Fig. 3a shows anti-Sam68 Western blot (rabbit anti-Sam68) of pull-down experiments conducted between Sam68 and selected IRES domains. IRES domains used in the experiment are shown. b Determination Sam68 binding to FMDV IRES RNAs by EMSA. WT probe in the left panel consists of 5′ biotin labeled 65 nt long synthetic RNA representing residues 435–499 of FMDV A24-Cru IRES that spanned at least 20 bases upstream and downstream of the two UAAA sequence motifs present in IRES domain 4. The binding of Sam68 to RNA probe was carried out in the presence of 100-fold excess of tRNA. The concentrations of Sam68 used are indicated in each lane. In the mutant probe in the right panel, the two UAAA motifs aremutated to UACG. c Upper panel depicts cartoon representation of the wild-type and KH-domain deleted Sam68 constructs. Lower panel shows EMSA results with the addition of Sam68-WT (left) and Sam68-delta KH (right). Probe and conditions used were the same as in section (b). d Determination of binding interference by various 5′ NTR RNA segments on the complexes formed between WT probe representing partial FMDV IRES domain 4 and Sam68. The binding of Sam68 to WT probe was performed under similar conditions as mentioned in section (b) but using a 2 μM Sam68 and 30 nM of probe. WT probe-Sam68 binding was competed with 10-fold molar excess of either full-length IRES (lane 3) or miscellaneous RNAs, including the FMDV cre (lane 4), S-fragment (lane 5), and IRES domains 2, 3, 4 (lanes 6, 7, 8, respectively). Lane 1 contains the binding mixture of Sam68 and domain 4 RNA in the absence of competitor RNAs, whereas lane 9 contains a probe alone control. Lane 2 was left blank

Article Snippet: Polyclonal rabbit anti-Sam68 directed against the Nterminus of Sam68 was purchased from Novus Biologicals (Littleton, CO).

Techniques: Sequencing, Binding Assay, Western Blot, Labeling, Mutagenesis, Construct, Control

Journal: Virology journal

Article Title: Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections.

doi: 10.1186/s12985-015-0452-8

Figure Lengend Snippet: Fig. 4 Effect of Sam68-depletion on FMDV protein and RNA synthesis using cell-free extracts. a Depletion of Sam68 from BHK-21 CFE. BHK-21 CFE was prepared as described in Materials and Methods. The depletion of Sam68 was confirmed by Western blot probing of non-depleted (left lane) and depleted (right lane) extract with anti-Sam68. b Determination of the effect of Sam68-6H addition on the translation of FMDV A24-Cru. FMDV A24-Cru RNA was translated using non-depleted or depleted BHK-21 CFE that were supplemented with 0 or 1 μM Sam68-6H as marked. The reaction was carried out at 32 ° C for 2 h and the products were resolved by SDS-PAGE and Western blot probed for FMDV 3Dpol. c Determination of the effect of Sam68-6H addition on the synthesis of FMDV A24-Cru RNA. FMDV A24-Cru RNA was used for RNA synthesis using non-depleted or depleted BHK-21 CFE that were supplemented with 0–2.5 μM Sam68-6H as marked. The reaction was carried out at 37 ° C for 5 h and the products were SDS-PAGE resolved by dot blotting

Article Snippet: Polyclonal rabbit anti-Sam68 directed against the Nterminus of Sam68 was purchased from Novus Biologicals (Littleton, CO).

Techniques: Western Blot, SDS Page

Journal: Virology journal

Article Title: Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections.

doi: 10.1186/s12985-015-0452-8

Figure Lengend Snippet: Fig. 6 Sam68 interacts with FMDV 3Cpro and 3Dpol. a Co-immunoprecipitation of FMDV 3Dpol and Sam68 during FMDV infection. BHK-21 cells either mock-infected or infected with FMDV at a MOI of 10 were lysed and the lysates were immunoprecipitated using either anti-FMDV 3Dpol or anti-Sam68 and the eluates examined by Western blot. One lane in each panel (as indicated below) was not subject to IP as a control. Equal amount of isotype control antibody served as an IP control. The eluates from the anti-3Dpol IP reaction were probed with anti-Sam68 (left panel). Conversely, the Sam68 IP eluates were probed with an anti-3Dpol (right panel). In the left panel, lane 1 corresponds to the isotype IP control, lane 2 is mock-infected cell lysate (1:10 dilution), lane 3 is a FMDV-infected cell lysate (1:10 dilution) that was not IP and lane 4 is the anti-3Dpol IP eluate from FMDV-infected cell lysates. Similarly, in the right panel, lane 1 corresponds to the isotype control, lane 2 is mock-infected cell lysate (1:10 dilution), lane 3 is a FMDV-infected cell lysate (1:10 dilution) that was not IP, and lane 4 is the anti-Sam68 IP eluate from FMDV-infected cell lysates. b The fragments (frag) listed in the table correspond to the amino acid (aa) sequence of FMDV 3Dpol, starting from the N-terminus: frag #1 aa 1–48, frag #2 aa 49–108, frag #3 aa 109–157, frag #4 aa 158–217, frag #5 aa 218–268, frag #6 aa 269–331, frag #7 aa 332–404, and frag #8 aa 405–470. A scrambled peptide was used as a negative control. c Computational prediction of the interaction between FMDV 3Dpol and Sam68. (i) Electrostatic surface representation of FMDV 3Dpol in the docking pose (PDB: 1U09); red color depicts the negatively charged surface, white shows the neutral surface, and blue color shows the positively charged surface. Color intensity is proportional to the surface charge. Areas under dashed lines indicate Sam68 binding interface of FMDV 3Dpol. (ii) Electrostatic surface representation of Sam68 in the docking pose. Surface charge and color annotation are same as section (i). Surface marked with dashed lines indicates FMDV 3Dpol binding interface of Sam68. (iii) Electrostatic representation of Sam68 docked to FMDV 3Dpol. [98] FMDV 3Dpol green docked on Sam68 blue in cartoon representation. The 3Dpol frag-4 residues 193–217 (orange), frag-5 residues 221, 222, 225, 226 (magenta) and frag-8 residues 453–470 (red) form the Sam68 binding interface of 3Dpol (d) LFBK cells were uninfected or infected with FMDV at a MOI of 10, and cells were harvested at 1, 3, and 5 hpi by treatment with versine. Left panel: cell lysates were IP with mouse monoclonal anti-FMDV 3Cpro, and examined by Western blot probing with rabbit polyclonal anti-Sam68 (N-terminus). Right panel: collected cells were lysed and separated into nuclear and cytoplasmic fractions, and the cytoplasmic fractions were examined by Western blot probing with rabbit polyclonal anti-Sam68 (N-terminus). Loading control is indicated confirming equivalent loading per lane

Article Snippet: Polyclonal rabbit anti-Sam68 directed against the Nterminus of Sam68 was purchased from Novus Biologicals (Littleton, CO).

Techniques: Immunoprecipitation, Infection, Western Blot, Control, Sequencing, Negative Control, Binding Assay