Figure S2. PI5P4Kα expression enriched in basal compartment.

Figure S6. Prostate morphology resulting from genomic loss of Pip4k2b isoform.

Table S3. Crowley et al. markers for scRNA-Seq module scores

Figure S7. Immunohistochemical staining of CK5-PipPten model.

Figure S8. Differentially abundant pathways and metabolites from targeting PIP4K2A.

Abstract Although early prostate cancer depends on the androgen receptor signaling pathway, which is predominant in luminal cells, there is much to be understood about the contribution of epithelial basal cells in cancer progression. Herein, we observe cell type–specific differences in the importance of the metabolic enzyme phosphatidylinositol 5-phosphate 4-kinase alpha (PI5P4Kα; gene name PIP4K2A) in the prostate epithelium. We report the development of a basal cell–specific genetically engineered mouse model targeting Pip4k2a alone or in combination with the tumor suppressor phosphatase and tensin homolog (Pten). PI5P4Kα is enriched in basal cells, and no major histopathologic changes were detectable following gene deletion. Notably, the combined loss of Pip4k2a slowed the development of Pten mutant mouse prostatic intraepithelial neoplasia. Through the inclusion of a lineage tracing reporter, we utilize single-cell RNA sequencing to evaluate changes resulting from in vivo downregulation of Pip4k2a and characterize cell populations influenced in the established Probasin-Cre– and cytokeratin 5-Cre–driven genetically engineered mouse model. Transcriptomic pathway analysis points toward the disruption of lipid metabolism as a mechanism for reduced tumor progression. This was functionally supported by shifts of carnitine lipids in LNCaP prostate cancer cells treated with siPIP4K2A. Overall, these data nominate PI5P4Kα as a target for PTEN mutant prostate cancer. Implications: PI5P4Kα is enriched in prostate basal cells, and its targeted loss slows the progression of a model of advanced prostate cancer.

Abstract Proteomic networks are crucial for cellular homeostasis maintenance and, indeed, their aberrant regulation is implicated in cancer development and progression. Understanding alterations underlying these pathways, provides a way to design therapeutic interventions in human cancer. Improvements in mass spectrometry analysis have unlocked our potential to unveil cancer vulnerabilities. Here, we performed (phospho)proteomic analysis and ex-vivo drug testing on a cohort of refractory metastatic colorectal cancer (mCRC) tissues and matched patients-Derived Organoids (PDO) to identify new putative druggable biomarkers. The comparison between the proteome and phosphoproteome of 10 mCRCs tissues with their matched PDOs normalized to a pool of 6 colon mucosa tissues highlighted a strong overall correlation (R= 0.57 and R=0.6, respectively) suggesting a good level of similarity. Applying GSEA on our proteomic dataset, we identified up-regulation in MYC, cell cycle and MTORC1 signaling pathways in mCRC tissues and PDO, while kinase enrichment analysis highlighted an increase in Casein Kinase II (CKII) activity, an important cell cycle regulator. Our ex-vivo experiments showed that silmitasertib-mediated CKII inhibition reduced the cell viability in our PDO models, but with an overall modest effect. Analysis revealed that, even though not statistically significant, high Wnt signaling score correlated with an higher resistance to silmitasertib treatment (R=0.61; p=0.08). Previous works highlighted that MAPK activity is increased after silmitasertib treatment and responsible for resistance mechanisms to CKII inhibition. Strikingly, the combined trametinib-mediated MEK blockade and CKII blockade resulted in a synergistic interaction leading to enhanced antitumor activity, especially in PDO harboring high Wnt (R=0.74; p=0.022) and cell cycle (R=0.69; p=0.04) pathway activity. Moreover, the combined treatment strongly reduced S6 activity and RAPTOR expression, overcoming the significant effect exerted by the single agents. Surprisingly, none of them altered baseline MAPK activity, suggesting that silmitasertib and trametinib synergize their activity via inactivating the MTORC1-S6 axis in an ERK-independent manner. We are currently integrating genomic and transcriptomic data to better characterize the observed drug synergy. Taken together, our findings propose the silmitasertib and trametinib combination as a new therapeutic opportunity for refractory mCRC patients and strengthen the use of PDO as a suitable model for drug screening. Citation Format: Mattia Marinucci, Gina Faye Boot, Lara Zaidi, Cinzia Esposito, Mairene Coto Llerena, Savas Soysal, Otto Kolmar, Charlotte K Y Ng, Salvatore Piscuoglio. (Phospho)proteomic analysis reveals vulnerabilities in refractory metastatic colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3163.

The switch/sucrose non-fermentable (SWI/SNF) chromatin remodeling complex is frequently deregulated during progression to castration-resistant prostate cancer (CRPC). Proteolysis targeting chimera (PROTAC) therapies degrading SWI/SNF ATPases offer a novel approach to interfere with androgen receptor (AR) signaling in AR-dependent CRPC (CRPC-AR). To explore the utility of SWI/SNF therapy beyond AR-sensitive CRPC, we investigated SWI/SNF ATPase targeting agents in AR-negative CRPC. SWI/SNF targeting PROTAC treatment of cell lines and organoid models reduced the viability of not only CRPC-AR but also WNT-signaling dependent AR-negative CRPC (CRPC-WNT), which accounts for about 10% of all clinical CRPC cases. In CRPC-WNT models, we discovered that SWI/SNF ATPase SMARCA4 depletion interfered with WNT signaling via the master transcriptional regulator TCF7L2 (TCF4). Functionally, TCF7L2 maintains proliferation via the MAPK signaling axis in this subtype of CRPC by forming a complex with β-Catenin and AP-1 transcription factor c-JUN. These data suggest a mechanistic rationale for MAPK inhibition or interventions that disrupt the formation of the pro-proliferative TCF7L2-β-Catenin-JUN complex in the CRPC-WNT subclass of advanced prostate cancer. ### Competing Interest Statement .L.Y., X.Y., M.S., and Ju.T. are active employees of Genentech Inc. H.B. has served as consultant/advisory board member for Janssen, Astellas, Merck, Pfizer, Roche, Harpoon, Amgen, Bayer, Daiichi-Sankyo, Astra Zeneca, Harpoon and has received research funding (to institution) from Bristol Myers Squibb, Circle Pharma, Daiichi-Sankyo, Novartis. S.R.S. is an equity holder and member of the scientific advisory board of NeuScience, Inc., and a consultant at Third Bridge Group Limited. M.A.R has received research funding from Novartis, Roche, Ventana, Janssen, Astellas, and Eli Lilly and currently has a research collaboration agreement with Genentech Inc. M.A.R. is on the Scientific Advisory Board of Neogenomics Lab, is a Scientific Advisor and stockholder of Owkin, and co-founder of Verintas. M.A.R. is a co-inventor on prostate cancer patents in the diagnostic and treatment fields, including SWI/ SNF (Bern/Cornell). All other authors declare no competing interests.

Collisions of the transcription and replication machineries on the same DNA strand can pose a significant threat to genomic stability. These collisions occur in part due to the formation of RNA-DNA hybrids termed R-loops, in which a newly transcribed RNA molecule hybridizes with the DNA template strand. This study investigated the role of RAD52, a known DNA repair factor, in preventing collisions by directing R-loop formation and resolution. We show that RAD52 deficiency increases R-loop accumulation, exacerbating collisions and resulting in elevated DNA damage. Furthermore, RAD52's ability to interact with the transcription machinery, coupled with its capacity to facilitate R-loop dissolution, highlights its role in preventing collisions. Lastly, we provide evidence of an increased mutational burden from double-strand breaks at conserved R-loop sites in human tumor samples, which is increased in tumors with low RAD52 expression. In summary, this study underscores the importance of RAD52 in orchestrating the balance between replication and transcription processes to prevent collisions and maintain genome stability. Collisions of transcription and replication machineries on the same DNA strand threaten genomic stability. Here, the authors show that RAD52 prevents these collisions by regulating R-loop formation and resolution. RAD52 deficiency leads to increased R-loops, exacerbated collisions, DNA damage, and higher mutational burden in tumors.

The human genome comprises tens of thousands of long non-coding RNAs (lncRNAs), whose functionality is highly debated. In the field of hepatocellular carcinoma (HCC) research, as for other cancer types, lncRNAs are increasingly reported to act as oncogenes or tumor suppressors and are put forward as useful diagnostic or prognostic biomarkers. Here, we investigate the reliability of these claims by performing a meta-analysis of the associations between HCC and lncRNAs reported in the scientific literature, and by assessing lncRNA expression patterns in two HCC patient cohorts. While nowadays up to 6% of all HCC-related publications cite lncRNAs, we show that most reported associations between HCC and lncRNAs have not been reproduced. In general, lncRNAs are less often differentially expressed between HCC tissues and controls compared to protein-coding genes. However, HCC-associated lncRNAs are frequently up-regulated in tumor samples, consistent with the fact that they are often selected based on transcriptome-wide comparative analyses. We perform a detailed examination of the 25 lncRNAs that are most frequently cited in association with HCC. For 10 out of these 25 lncRNAs, including well known lncRNAs such as MALAT1, NEAT1, H19 and XIST, we identify important conflicts between the biological roles and expression patterns previously reported for them in HCC and the expression patterns that we observe here. Finally, we observe that HCC-associated publications that cite lncRNAs are retracted three times more often than publications that cite protein-coding genes. Our results thus highlight the poor reproducibility of lncRNA-related claims in association with HCC, which is problematic in a context where new biomarkers and molecular targets for therapy are greatly needed. ### Competing Interest Statement The authors have declared no competing interest.

INTRODUCTION:Pulmonary pleomorphic carcinoma (PPC) is an aggressive and highly heterogeneous NSCLC whose underlying biology is still poorly understood. METHODS:A total of 42 tumor areas from 20 patients with PPC were microdissected, including 39 primary tumors and three metastases, and the histologically distinct components were subjected to whole exome sequencing separately. We further performed in silico analysis of microdissected bulk RNA sequencing and methylation data of 28 samples from 14 patients with PPC. We validated our findings using immunohistochemistry. RESULTS:The epithelial and the sarcomatoid components of PPCs shared a large number of genomic alterations. Most mutations in cancer driver genes were clonal and truncal between the two components of PPCs suggesting a common ancestor. The high number of alterations in the RTK-RAS pathway suggests that it plays an important role in the evolution of PPC. The metastases morphologically and genetically resembled the epithelial or the sarcomatoid components of the tumor. The transcriptomic and epigenetic profiles of the sarcomatoid components of PPCs with matched squamous-like or adenocarcinoma-like components differed from each other, and they shared more similarities to their matched epithelial components. NCAM1/CD56 was preferentially expressed in the sarcomatoid component of squamous-like PPCs, whereas CDH1/E-Cadherin expression was down-regulated in the sarcomatoid component of most PPCs. CONCLUSION:Lung adenocarcinoma-like PPCs are mainly driven by RTK-RAS signaling, whereas epithelial-mesenchymal transition programs as highlighted by increased NCAM1 and decreased CDH1 expression govern the epithelial-sarcomatoid transition between the clonally related tumor components. Several alterations in PPCs pinpoint therapeutic opportunities.

Document containing methods on whole exome and targeted massively parallel sequencing analysis, 2-hydroxyglutarate (2HG) assay of cell lines, methylation profiling, and supplementary references.

Supplementary Methods and Figure Legends

A. Tumors were undetectable at 4 weeks by IVIS imaging when b-AP15 was administered from day 1 after injecting A673 cells expressing GFP-luciferase. NSG mice bearing A673 xenografts were treated with DMSO, bortezomib or b-AP15 after they reached 80-100mm3 and weekly tumor size measurements were taken. B. b-AP15 slowed the growth of the established A673 xenografts and C. prolonged survival of A673 tumor bearing mice compared to bortezomib. D. VLX-1570 and b-AP15 treatment did not cause significant weight loss in xenograft models. (two way Anova with Tukey's multiple comparison test).

File containing the legends for Supplementary Figures S1-S4 and Supplementary Tables S1-S6.

Supplementary Figure 2 from Loss of Osteoclasts Contributes to Development of Osteosarcoma Pulmonary Metastases

Ingenuity Pathway Analysis of positive hits identifies enrichment of genes involved in the ubiquitin-proteasome pathway.

PDF file containing the Supplementary Methods and Supplementary References.

Supplementary Table S4: Somatic single nucleotide variants (SNVs) and insertion/deletions (indels). Supplementary Table S5: Frequencies of mutations found in ER-positive/HER2-negative male breast cancer vs subsets of female breast cancer from the TCGA study. Supplementary Table S6: MutSigCV analysis of significantly mutated genes in MaBCs.