Transient, multi-protein complexes are important facilitators of cellular functions. This includes the chaperome, an abundant protein family comprising chaperones, co-chaperones, adaptors, and folding enzymes—dynamic complexes of which regulate cellular homeostasis together with the protein degradation machinery1–6. Numerous studies have addressed the role of chaperome members in isolation, yet little is known about their relationships regarding how they interact and function together in malignancy7–17. As function is probably highly dependent on endogenous conditions found in native tumours, chaperomes have resisted investigation, mainly due to the limitations of methods needed to disrupt or engineer the cellular environment to facilitate analysis. Such limitations have led to a bottleneck in our understanding of chaperome-related disease biology and in the development of chaperome-targeted cancer treatment. Here we examined the chaperome complexes in a large set of tumour specimens. The methods used maintained the endogenous native state of tumours and we exploited this to investigate the molecular characteristics and composition of the chaperome in cancer, the molecular factors that drive chaperome networks to crosstalk in tumours, the distinguishing factors of the chaperome in tumours sensitive to pharmacologic inhibition, and the characteristics of tumours that may benefit from chaperome therapy. We find that under conditions of stress, such as malignant transformation fuelled by MYC, the chaperome becomes biochemically ‘rewired’ to form a network of stable, survival-facilitating, high-molecular-weight complexes. The chaperones heat shock protein 90 (HSP90) and heat shock cognate protein 70 (HSC70) are nucleating sites for these physically and functionally integrated complexes. The results indicate that these tightly integrated chaperome units, here termed the epichaperome, can function as a network to enhance cellular survival, irrespective of tissue of origin or genetic background. The epichaperome, present in over half of all cancers tested, has implications for diagnostics and also provides potential vulnerability as a target for drug intervention.

BACKGROUND Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) and its associated clinical syndrome COVID-19 are causing overwhelming morbidity and mortality around the globe, disproportionately affecting New York City. A comprehensive, integrative autopsy series that advances the mechanistic discussion surrounding this disease process is still lacking. METHODS Autopsies were performed at the Mount Sinai Hospital on 67 COVID-19 positive patients and data from the clinical records were obtained from the Mount Sinai Data Warehouse. The experimental design included a comprehensive microscopic examination carried out by a team of expert pathologists, along with transmission electron microscopy, immunohistochemistry, RNA in situ hybridization, as well as immunology and serology assays. RESULTS Laboratory results of our COVID-19 cohort show elevated inflammatory markers, abnormal coagulation values, and elevated cytokines IL-6, IL-8 and TNFα. Autopsies revealed large pulmonary emboli in four cases. We report microthrombi in multiple organ systems including the brain, as well as conspicuous hemophagocytosis and a secondary hemophagocytic lymphohistiocytosis-like syndrome in many of our patients. We provide electron microscopic, immunofluorescent and immunohistochemical evidence of the presence of the virus and the ACE2 receptor in our samples. CONCLUSIONS We report a comprehensive autopsy series of 67 COVID-19 positive patients revealing that this disease, so far conceptualized as a primarily respiratory viral illness, also causes endothelial dysfunction, a hypercoagulable state, and an imbalance of both the innate and adaptive immune responses. Novel findings reported here include an endothelial phenotype of ACE2 in selected organs, which correlates with clotting abnormalities and thrombotic microangiopathy, addressing the prominent coagulopathy and neuropsychiatric symptoms. Another original observation is that of macrophage activation syndrome, with hemophagocytosis and a hemophagocytic lymphohistiocytosis-like disorder, underlying the microangiopathy and excessive cytokine release. We discuss the involvement of critical regulatory pathways.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated clinical syndrome COVID-19 are causing overwhelming morbidity and mortality around the globe and disproportionately affected New York City between March and May 2020. Here, we report on the first 100 COVID-19-positive autopsies performed at the Mount Sinai Hospital in New York City. Autopsies revealed large pulmonary emboli in six cases. Diffuse alveolar damage was present in over 90% of cases. We also report microthrombi in multiple organ systems including the brain, as well as hemophagocytosis. We additionally provide electron microscopic evidence of the presence of the virus in our samples. Laboratory results of our COVID-19 cohort disclose elevated inflammatory markers, abnormal coagulation values, and elevated cytokines IL-6, IL-8, and TNFα. Our autopsy series of COVID-19-positive patients reveals that this disease, often conceptualized as a primarily respiratory viral illness, has widespread effects in the body including hypercoagulability, a hyperinflammatory state, and endothelial dysfunction. Targeting of these multisystemic pathways could lead to new treatment avenues as well as combination therapies against SARS-CoV-2 infection.

Introduction Heat shock protein 90 (HSP90) serves as a critical facilitator for oncogene addiction. There has been augmenting enthusiasm in pursuing HSP90 as an anticancer strategy. In fact, since the initial serendipitous discovery that geldanamycin (GM) inhibits HSP90, the field has rapidly moved from proof-of-concept clinical studies with GM derivatives to novel second-generation inhibitors. Areas covered The authors highlight the current status of the second-generation HSP90 inhibitors in clinical development. Herein, the authors note the lessons learned from the completed clinical trials of first- and second-generation inhibitors and describe various assays attempting to serve for a more rational implementation of these agents to cancer treatment. Finally, the authors discuss the future perspectives for this promising class of agents. Expert opinion The knowledge gained thus far provides perhaps only a glimpse at the potential of HSP90 for which there is still much work to be done. Lessons from the clinical trials suggest that HSP90 therapy would advance at a faster pace if patient selection and tumor pharmacokinetics of these drugs were better understood and applied to their clinical development. It is also evident that combining HSP90 inhibitors with other potent anticancer therapies holds great promise not only due to synergistic antitumor activity but also due to the potential of prolonging or preventing the development of drug resistance.

Non-mammary metastases to the breast and axilla are rare occurrences. However, they are important diagnostic considerations as their treatment and prognosis differ significantly from primary breast cancer. Between 1990 and 2010, we identified a total of 85 patients, 72 women and 13 men, with non-mammary malignancies involving the breast, axilla, or both. The tumor types consisted of carcinoma (58%), melanoma (22%) and sarcoma (20%). Ovary was the most common site of origin for carcinoma, and metastatic high-grade ovarian serous carcinoma was most frequently misdiagnosed as a primary breast carcinoma. Melanoma was the single most common non-carcinomatous tumor type to involve the breast and/or axilla, and uterine leiomyosarcoma was the most common type of sarcoma. Most patients (77%) had other metastases at the time of diagnosis of the tumor, but in 11% the breast or axillary lesion was the first presentation. Without a clinical history, non-mammary metastases were difficult to diagnose because the majority of cases presented with a solitary nodule and lacked pathognomonic pathologic features. There were, however, certain recurrent histological findings identified, such as the often relatively well-circumscribed growth pattern of the metastatic lesion surrounded by a fibrous pseudocapsule, and the absence of an in situ carcinoma. Overall, these patients had poor survival; 96% of patients with follow-up available are dead of disease, with a median survival of 15 months after the diagnosis of the breast or axillary lesion. This finding emphasizes the need to accurately identify these tumors as metastases in order to avoid unnecessary procedures and treatments in these patients. Keywords: axilla; breast; extramammary Metastases to the breast and axilla are rare and account for approximately 2% of all mammary malignancies. 1,2 The most common metastatic lesion to involve the breast is a metastasis from a contralateral mammary cancer. 1,2 If hematologic malignancies are also excluded, the number of non-mammary metastases drops to well below 1%. 1,3 Owing to the frequency of primary breast cancers and the rarity of non-mammary tumors involving the breast, a newly discovered lesion in the breast or axilla is usually presumed to be a primary or metastatic breast carcinoma. However, the recognition of non-mammary metastases to the breast and axilla is very important, as both the treatment and prognosis differ significantly. Materials and methodsAfter obtaining approval by our Institutional Review Board, we searched the pathology database of Memorial Sloan-Kettering Cancer Center between the years 1990-2010 for patients with non-mammary metastases to the breast and axilla. Hematologic malignancies were excluded, as they are systemic diseases. The medical records and pathology slides, when available, were reviewed and the clinicopathologic characteristics were recorded. Patient age, gender, primary tumor site, the presence of other metastases, laterality, number of lesions, interval from primary tumor diagnosis to breast/ a...

To determine if imaging with a human epidermal growth factor receptor 2 (HER2)-targeting PET tracer can detect HER2-positive metastases in patients with HER2-negative primary breast cancer. Materials and Methods Patients with HER2-negative primary breast cancer and evidence of distant metastases were enrolled in an Institutional Review Board (IRB)-approved prospective clinical trial. Archived pathology from the patient’s primary breast cancer was retested to confirm HER2-negative disease. Patients with confirmed HER2-negative primary breast cancer underwent 89Zr-trastuzumab PET/CT to screen for 89Zr-trastuzumab metastases. Metastases avid for 89Zr-trastuzumab by PET/CT were biopsied and pathologically examined to define HER2 status. Patients with pathologically proven HER2-positive metastases subsequently received off-protocol HER2 targeted therapy to evaluate treatment response. Results Nine patients were enrolled, all of whom had pathologic retesting that confirmed HER2-negative primary breast cancer. Five demonstrated suspicious foci on 89Zr-trastuzumab PET/CT. Of these five with suspicious foci, two had biopsy proven HER2-positive metastases and went on to benefit from HER2 targeted therapy. Three of the five patients with suspicious foci had biopsy without evidence of HER2-positive disease, and were considered false positive false positive 89Zr-trastuzumab PET foci. Conclusion In this proof-of-concept study, we demonstrate that 89Zr-trastuzmab PET/CT detects unsuspected HER2-positive metastases in patients with HER2-negtive primary breast cancer. While these are only initial results in a small sample, it is a proof of concept that HER2-targeted imaging can identify additional candidates for HER2-targeted therapy. More specific HER2-targeting agents will be needed for clinical use.

Signal transducer and activator of transcription 3 (STAT3) plays a central role in the activation of multiple oncogenic pathways. Splicing variant STAT3β uses an alternative acceptor site within exon 23 that leads to a truncated isoform lacking the C-terminal transactivation domain. Depending on the context, STAT3β can act as a dominant-negative regulator of transcription and promote apoptosis. We show that modified antisense oligonucleotides targeted to a splicing enhancer that regulates STAT3 exon 23 alternative splicing specifically promote a shift of expression from STAT3α to STAT3β. Induction of endogenous STAT3β leads to apoptosis and cell-cycle arrest in cell lines with persistent STAT3 tyrosine phosphorylation compared with total STAT3 knockdown obtained by forced splicing-dependent nonsense-mediated decay (FSD-NMD). Comparison of the molecular effects of splicing redirection to STAT3 knockdown reveals a unique STAT3β signature, with a down-regulation of specific targets (including lens epithelium-derived growth factor, p300/CBP-associated factor, CyclinC, peroxisomal biogenesis factor 1, and STAT1β) distinct from canonical STAT3 targets typically associated with total STAT3 knockdown. Furthermore, similar in vivo redirection of STAT3 alternative splicing leads to tumor regression in a xenograft cancer model, demonstrating how pharmacological manipulation of a single key splicing event can manifest powerful antitumorigenic properties and validating endogenous splicing reprogramming as an effective cancer therapeutic approach.

Highlights d N-glycosylation transforms a chaperone, GRP94, from a folder into a scaffolding protein d These changes are pathologic in nature as they remodel proteome-wide connectivity d The N-glycosylated GRP94 variant is a small and distinct fraction of the GRP94 pool d Proteome dysfunctions mediated by the N-glycosylated GRP94 variant are actionable