Biallelic Alteration and Dysregulation of the Hippo Pathway in Mucinous Tubular and Spindle Cell Carcinoma of the Kidney

Renal Neoplasia: Rare Subtypes and Uncommon Clinical Presentations

Herein, the authors have discussed a series of uncommon familial kidney cancer syndromes (including hyperparathyroidism-jaw tumor syndrome and PTEN hamartoma tumor syndrome), sporadically occurring tumors (BRAF and MTOR pathway-mutated tumors, and juxtaglomerular cell tumors), and uncommon patterns of well-established subtypes of kidney cancer (mucinous tubular spindle cell carcinoma, fumarate hydratase-deficient, and TFE3-rearranged renal cell carcinoma). The rarity of these tumors often leads to diagnostic odysseys for pathologists and patients. Appropriate classification of these rare tumors has implications for screening at-risk family members in the case of hereditary tumor predisposition syndromes, accurate prognostication, and appropriate patient selection for clinical trials.

Interaction of noncoding RNAs with hippo signaling pathway in cancer cells and cancer stem cells

The Hippo signaling pathway has a regulatory function in the organogenesis process and cellular homeostasis, switching the cascade reactions of crucial kinases acts to turn off/on the Hippo pathway, altering the downstream gene expression and thereby regulating proliferation, apoptosis, or stemness. Disruption of this pathway can lead to the occurrence of various disorders and different types of cancer. Recent findings highlight the importance of ncRNAs, such as microRNA, circular RNA, and lncRNAs, in modulating the Hippo pathway. Defects in ncRNAs can disrupt Hippo pathway balance, increasing tumor cells, tumorigenesis, and chemotherapeutic resistance. This review summarizes ncRNAs' inhibitory or stimulatory role in - Hippo pathway regulation in cancer and stem cells. Identifying the relation between ncRNAs and the components of this pathway could pave the way for developing new biomarkers in the treatment and diagnosis of cancers.

HPV18 E7 inhibits LATS1 kinase and activates YAP1 by degrading PTPN14

High-risk human papillomavirus (HPV) oncoproteins inactivate cellular tumor suppressors to reprogram host cell signaling pathways. HPV E7 proteins bind and degrade the tumor suppressor PTPN14, thereby promoting the nuclear localization of the YAP1 oncoprotein and inhibiting keratinocyte differentiation. YAP1 is a transcriptional coactivator that drives epithelial cell stemness and self-renewal. YAP1 activity is inhibited by the highly conserved Hippo pathway, which is frequently inactivated in human cancers. MST1/2 and LATS1/2 kinases form the core of the Hippo kinase cascade. Active LATS1 kinase is phosphorylated on threonine 1079 and inhibits YAP1 by phosphorylating it on amino acids including serine 127. Here, we tested the effect of high-risk (carcinogenic) HPV18 E7 on Hippo pathway activity. We found that either PTPN14 knockout or PTPN14 degradation by HPV18 E7 decreased the phosphorylation of LATS1 T1079 and YAP1 S127 in human keratinocytes and inhibited keratinocyte differentiation. Conversely, PTPN14-dependent differentiation required LATS kinases and certain PPxY motifs in PTPN14. Neither MST1/2 kinases nor the putative PTPN14 phosphatase active sites were required for PTPN14 to promote differentiation. Together, these data support that PTPN14 inactivation or degradation of PTPN14 by HPV18 E7 reduce LATS1 activity, promoting active YAP1 and inhibiting keratinocyte differentiation.IMPORTANCEThe Hippo kinase cascade inhibits YAP1, an oncoprotein and driver of cell stemness and self-renewal. There is mounting evidence that the Hippo pathway is targeted by tumor viruses including human papillomavirus. The high-risk HPV E7 oncoprotein promotes YAP1 nuclear localization and the carcinogenic activity of high-risk HPV E7 requires YAP1 activity. Blocking HPV E7-dependent YAP1 activation could inhibit HPV-mediated carcinogenesis, but the mechanism by which HPV E7 activates YAP1 has not been elucidated. Here we report that by degrading the tumor suppressor PTPN14, HPV18 E7 inhibits LATS1 kinase, reducing inhibitory phosphorylation on YAP1. These data support that an HPV oncoprotein can inhibit Hippo signaling to activate YAP1 and strengthen the link between PTPN14 and Hippo signaling in human epithelial cells.

Research progress of the Hippo signaling pathway in renal cell carcinoma

Objective

This review aimed to summarize the role of the Hippo signaling pathway in renal cell carcinoma (RCC), a urologic malignancy with subtle initial symptoms and high mortality rates due to metastatic RCC. The Hippo signaling pathway, which regulates tissue and organ sizes, plays a crucial role in RCC progression and metastasis. Understanding the involvement of the Hippo signaling pathway in RCC provides valuable insights for the development of targeted therapies and improved patient outcomes.

Methods

In this review, we explored the impact of the Hippo signaling pathway on RCC. Through an analysis of existing literature, we examined its role in RCC progression and metastasis. Additionally, we discussed potential therapeutic strategies targeting the Hippo pathway for inhibiting RCC cell growth and invasion. We also highlighted the importance of investigating interactions between the Hippo pathway and other signaling pathways such as Wnt, transforming growth factor-beta, and PI3K/AKT, which may uncover additional therapeutic targets.

Results

The Hippo signaling pathway has shown promise as a target for inhibiting RCC cell growth and invasion. Studies have demonstrated its dysregulation in RCC, with altered expression of key components such as yes-associated protein/transcriptional coactivator with PDZ-binding motif (YAP/TAZ). Targeting the Hippo pathway has been associated with suppressed tumor growth and metastasis in preclinical models of RCC. Furthermore, investigating crosstalk between the Hippo pathway and other signaling pathways has revealed potential synergistic effects that could be exploited for therapeutic interventions.

Conclusion

Understanding the role of the Hippo signaling pathway in RCC is of paramount importance. Elucidating its functions and molecular interactions contributes to RCC diagnosis, treatment, and the discovery of novel mechanisms. This knowledge informs the development of innovative therapeutic strategies and opens new avenues for research in RCC. Further investigations are warranted to fully comprehend the complex interplay between the Hippo pathway and other signaling pathways, ultimately leading to improved outcomes for RCC patients.

YAP promotes global mRNA translation to fuel oncogenic growth despite starvation

Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) play fundamental roles in stem/progenitor cell expansion during homeostasis, and their dysregulation often leads to tissue overgrowth. Here, we show that YAP activation is sufficient to overcome the restriction of global protein synthesis induced by serum starvation, enabling cells to sustain proliferation and survival despite an unfavorable environment. Mechanistically, YAP/TAZ selectively promoted the mTORC1-dependent translation of mRNAs containing 5' terminal oligopyrimidine (5'TOP) motifs, ultimately increasing the cellular polysome content. Interestingly, DNA damage-inducible transcript 4 (DDIT4), a negative regulator of mTORC1, was upregulated by serum starvation but repressed by YAP/TAZ. DDIT4 was sufficient to suppress the translation and transformative potential of uveal melanoma cells, which are often serum unresponsive due to G protein mutations. Our findings reveal a vital role for protein synthesis as a key modality of YAP/TAZ-induced oncogenic transformation and indicate the potential for targeting mTORC1 or translation to treat YAP/TAZ-driven malignancies.

Emerging Role of Hippo-YAP (Yes-Associated Protein)/TAZ (Transcriptional Coactivator with PDZ-Binding Motif) Pathway Dysregulation in Renal Cell Carcinoma Progression

Although Hippo-YAP/TAZ pathway involvement has been extensively studied in the development of certain cancers, the involvement of this cascade in kidney cancer progression is not well-established and, therefore, will be the focus of this review. Renal cell carcinoma (RCC), the most prevalent kidney tumor subtype, has a poor prognosis and a high mortality rate. Core Hippo signaling inactivation (e.g., LATS kinases) leads to the nuclear translocation of YAP/TAZ where they bind to co-transcriptional factors such as TEAD promoting transcription of genes which initiates various fibrotic and neoplastic diseases. Loss of expression of LATS1/2 kinase and activation of YAP/TAZ correlates with poor survival in RCC patients. Renal-specific ablation of LATS1 in mice leads to the spontaneous development of several subtypes of RCC in a YAP/TAZ-dependent manner. Genetic and pharmacological inactivation of YAP/TAZ reverses the oncogenic potential in LATS1-deficient mice, highlighting the therapeutic benefit of network targeting in RCC. Here, we explore the unique upstream controls and downstream consequences of the Hippo-YAP/TAZ pathway deregulation in renal cancer. This review critically evaluates the current literature on the role of the Hippo pathway in RCC progression and highlights the recent scientific evidence designating YAP/TAZ as novel therapeutic targets against kidney cancer.

Hippo signaling modulation and its biological implications in urological malignancies

Although cancer diagnosis and treatment have rapidly advanced in recent decades, urological malignancies, which have high morbidity and mortality rates, are among the most difficult diseases to treat. The Hippo signaling is an evolutionarily conserved pathway in organ size control and tissue homeostasis maintenance. Its downstream effectors, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), are key modulators of numerous physiological and pathological processes. Recent work clearly indicates that Hippo signaling is frequently altered in human urological malignancies. In this review, we discuss the disparate viewpoints on the upstream regulators of YAP/TAZ and their downstream targets and systematically summarize the biological implications. More importantly, we highlight the molecular mechanisms involved in Hippo-YAP signaling to improve our understanding of its role in every stage of prostate cancer, bladder cancer and kidney cancer progression. A better understanding of the biological outcomes of YAP/TAZ modulation will contribute to the establishment of future therapeutic approaches.

HPV18 E7 inhibits LATS1 kinase and activates YAP1 by degrading PTPN14

High-risk human papillomavirus (HPV) oncoproteins inactivate cellular tumor suppressors to reprogram host cell signaling pathways. HPV E7 proteins bind and degrade the tumor suppressor PTPN14, thereby promoting the nuclear localization of the YAP1 oncoprotein and inhibiting keratinocyte differentiation. YAP1 is a transcriptional coactivator that drives epithelial cell stemness and self-renewal. YAP1 activity is inhibited by the highly conserved Hippo pathway, which is frequently inactivated in human cancers. MST1/2 and LATS1/2 kinases form the core of the Hippo kinase cascade. Active LATS1 kinase is phosphorylated on threonine 1079 and inhibits YAP1 by phosphorylating it on amino acids including serine 127. Here, we tested the effect of high-risk (carcinogenic) HPV18 E7 on Hippo pathway activity. We found that either PTPN14 knockout or PTPN14 degradation by HPV18 E7 decreased phosphorylation of LATS1 T1079 and YAP1 S127 in human keratinocytes and inhibited keratinocyte differentiation. Conversely, PTPN14-dependent differentiation required LATS kinases and certain PPxY motifs in PTPN14. Neither MST1/2 kinases nor the putative PTPN14 phosphatase active site were required for PTPN14 to promote differentiation. Taken together, these data support that PTPN14 inactivation or degradation of PTPN14 by HPV18 E7 reduce LATS1 activity, promoting active YAP1 and inhibiting keratinocyte differentiation.

Single nucleotide polymorphism (SNP) chromosomal microarray as a diagnostic tool for mucinous tubular and spindle cell carcinoma: A validation study

Mucinous tubular and spindle cell carcinoma (MTSCC) shows significant overlap with papillary renal cell carcinoma (PRCC), and harbor recurrent copy-number alterations (CNA). We evaluated 16 RCC with features suggestive of MTSCC using chromosomal microarrays. The cohort was comprised of 8 females and males, each, with an age range of 33-79 years (median, 59), and a tumor size range of 3.4-15.5 cm (median, 5.0). Half the tumors were high-grade (8/16, 50%) with features such as necrosis, marked cytologic atypia, and sarcomatoid differentiation, and 5/16 (31%) were high stage (≥pT3a). Three (of 16, 19%) cases had a predominant (>95%) spindle cell component, whereas 5/16 (31%) were composed of a predominant (>95%) epithelial component. Most cases (12/16, 75%) exhibited a myxoid background and/or extravasated mucin, at least focally. Twelve (of 16, 75%) cases demonstrated CNA diagnostic of MTSCC (losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22). In addition, 2 high-grade tumors showed loss of CDKN2A/B, and gain of 1q, respectively, both of which are associated with aggressive behavior. Three (of 16, 19%) cases, demonstrated nonspecific CNA, and did not meet diagnostic criteria for established RCC subtypes. One (of 16, 6%) low-grade epithelial predominant tumor (biopsy) demonstrated characteristic gains of 7, 17, and loss of Y, diagnostic of PRCC. MTSCC can be a morphologically heterogenous tumor. Our study validates the detection of characteristic chromosomal CNA for diagnostic use that may be useful in challenging cases with unusual spindle cell or epithelial predominant features, as well as in high-grade tumors.

Label-free quantitative proteomics reveals the mechanisms of Aurora kinase B in renal cell carcinoma

Background

Renal cell carcinoma is the most common form of kidney cancer which is a global threat to human health, needing to explore effective therapeutic targets and treatment methods. Aurora kinase B acts as an important carcinogenic role in various kinds of tumors, while its mechanism in renal cell carcinoma is indistinct. Herein we explore the underlying mechanism of Aurora kinase B in renal cell carcinoma.

Methods and results

Label-free quantitative proteomics analysis was employed to analyze the differentially expressed proteins in 786-O cells which were treated with si-Aurora kinase B or si-ctrl. In the current study, 169 differentially expressed proteins were identified. The top 10 upregulated proteins were MX2, IFI44L, ISG20, DDX58, F3, IFI44, ECE1, PRIC285, NIT1, and IFIT2. The top 10 downregulated proteins were FKBP9, FSTL1, DDAH1, TGFB2, HMGN3, COIL, FAM65A, PTPN14, ARFGAP2, and EIF2C2. GO enrichment analysis showed that these differentially expressed proteins participated in biological processes, including defense response to virus, response to virus, and type I interferon signaling pathway. These differentially expressed proteins participated in cellular components, including focal adhesion, cell-substrate adherens junction, cell-substrate junction, and endoplasmic reticulum lumen. These differentially expressed proteins participated in molecule functions, including guanyl nucleotide binding, nucleotidase activity, double-stranded RNA binding, 2'-5'-oligoadenylate synthetase activity, and virus receptor activity. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the significantly changed proteins including OAS3, OAS2, JAK1, TAP1, and RAC1 were involved in Epstein-Barr virus infection.

Conclusions

Taken together, our results demonstrate the possible mechanisms that Aurora kinase B may participate in renal cell carcinoma. These findings may provide insights into tumorigenesis and a theoretical basis for developing potential therapies of renal cell carcinoma.

Papillary renal cell carcinoma with extensive spindle cell foci: mimicker of mucinous tubular and spindle cell carcinoma

Papillary renal cell carcinoma (PRCC) is the second most common renal cell carcinoma (RCC), accounting for 10-15% of cases. Mucinous tubular and spindle cell carcinoma (MTSCC), on the other hand, accounts for only 1% of renal tumors and has a more favorable prognosis compared to PRCC. We report a 75-year-old female with a left upper pole solid renal mass displaying features of both papillary renal cell carcinoma (PRCC) and mucinous tubular and spindle cell carcinoma (MTSC). In this case, a shaggy luminal surface, multiple papillations, and psammoma bodies, absence of E-cadherin expression, and strong CD10 expression favored PRCC. Both immunohistochemistry and genomic analysis are critical to diagnose and differentiate tumors that may have overlapping features accurately.

Gene of the month: VSTM2A

The V-set and transmembrane domain containing 2A (VSTM2A) gene is located on chromosome 7. In the physiological state, VSTM2A regulates preadipocyte cell differentiation. VSTM2A is highly expressed in normal human brain tissue and minimally expressed in other normal tissues. Mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney is a distinct renal tumour subtype with signature chromosomal copy number alterations and an indolent outcome in the majority of cases. VSTM2A overexpression is highly enriched in this renal cancer subtype and has been shown to have potential diagnostic value in distinguishing MTSCC from renal tumours with overlapping histological appearances.

Impaired Expression of the Salvador Homolog-1 Gene Is Associated with the Development and Progression of Colorectal Cancer

Salvador homolog-1 (SAV1) is a component of the Hippo pathway that regulates tissue growth and homeostasis by affecting diverse cell processes, including apoptosis, cell division, and differentiation. The aberrant expression of Hippo pathway components has been observed in various human cancers. This study aimed to examine the expression level of the SAV1 gene in colorectal cancer (CRC) and its prognostic value and associations with tumor progression. We obtained matched pairs of tumor tissue and non-cancerous mucosa of the large intestine from 94 CRC patients as well as 40 colon biopsies of healthy subjects collected during screening colonoscopy. The tissue samples and CRC cell lines were quantified for SAV1 mRNA levels using the quantitative polymerase chain reaction method, while SAV1 protein expression was estimated in the paired tissues of CRC patients using immunohistochemistry. The average level of SAV1 mRNA was decreased in 93.6% of the tumor tissues compared to the corresponding non-cancerous tissues and biopsies of healthy colon mucosa. A downregulated expression of SAV1 mRNA was also noted in the CRC cell lines. Although the average SAV1 immunoreactivity was increased in the CRC samples compared to the non-cancerous tissues, a decreased immunoreactivity of the SAV1 protein in the tumor specimens was associated with lymph node involvement and higher TNM disease stage and histological grade. The results of our study suggest that the impaired expression of SAV1 is involved in CRC progression.

Highly Recurrent IDH1 Mutations in Prostate Cancer With Psammomatous Calcification

Prostate cancer is a heterogeneous disease with several well-recognized morphologic subtypes and histologic variants-subsets of which are enriched for or associated with specific genomic alterations. Herein, we report a cohort of 4 unique prostate cancers characterized by intratumoral psammomatous calcification-which we have termed prostate cancer with psammomatous calcification (PCWPC). Clinicopathologic review demonstrates that PCWPCs are high-grade (grade group ≥3) tumors that involve the anterior prostate, and integrative targeted next-generation sequencing reveals recurrent hotspot IDH1 mutations. This morphology-molecular correlation is independently confirmed in The Cancer Genome Atlas prostatic adenocarcinoma cohort, with 3 of the 5 IDH1-mutant prostate cancers showing psammomatous calcification (rφ = 0.67; Fisher exact test, P < .0001). Overall, these findings suggest that PCWPC represents a novel subtype of prostate cancer enriched for an anterior location and the presence of hotspot IDH1 mutations. Recognition of these unique morphologic features could help identify IDH1-mutant prostate cancer cases retrospectively and prospectively-facilitating future large research studies and enabling clinical trial enrollment and precision medicine approaches for patients with advanced and/or aggressive disease.

Inflammatory Networks in Renal Cell Carcinoma

Cancer-associated inflammation has been established as a hallmark feature of almost all solid cancers. Tumor-extrinsic and intrinsic signaling pathways regulate the process of cancer-associated inflammation. Tumor-extrinsic inflammation is triggered by many factors, including infection, obesity, autoimmune disorders, and exposure to toxic and radioactive substances. Intrinsic inflammation can be induced by genomic mutation, genome instability and epigenetic remodeling in cancer cells that promote immunosuppressive traits, inducing the recruitment and activation of inflammatory immune cells. In RCC, many cancer cell-intrinsic alterations are assembled, upregulating inflammatory pathways, which enhance chemokine release and neoantigen expression. Furthermore, immune cells activate the endothelium and induce metabolic shifts, thereby amplifying both the paracrine and autocrine inflammatory loops to promote RCC tumor growth and progression. Together with tumor-extrinsic inflammatory factors, tumor-intrinsic signaling pathways trigger a Janus-faced tumor microenvironment, thereby simultaneously promoting or inhibiting tumor growth. For therapeutic success, it is important to understand the pathomechanisms of cancer-associated inflammation, which promote cancer progression. In this review, we describe the molecular mechanisms of cancer-associated inflammation that influence cancer and immune cell functions, thereby increasing tumor malignancy and anti-cancer resistance. We also discuss the potential of anti-inflammatory treatments, which may provide clinical benefits in RCCs and possible avenues for therapy and future research.

The emerging role of NF2 alterations in new and established subtypes of renal cell carcinoma

Genomic alterations are increasingly important in the current paradigms for the classification, diagnosis, and treatment of renal cell carcinoma. Biallelic alterations involving NF2 have been identified across several currently recognized subtypes of renal cell carcinoma including clear cell renal cell carcinoma and papillary renal cell carcinoma among others and may be associated with a more aggressive disease course as well as advanced stage at presentation. In addition, emerging evidence suggests the existence of a clinicopathologically distinct subset of renal cell carcinoma cases driven by biallelic loss of NF2 expression. This subset of tumors is morphologically characterized by a constellation of morphologic features including hyalinizing fibrosis, eosinophilic cytology, psammomatous calcifications, and a nested growth pattern. These tumors include the recently described entities of biphasic hyalinizing psammomatous renal cell carcinoma as well as renal cell tumor with sex cord/gonadoblastoma-like features. Despite their oftentimes aggressive behavior, there is some evidence that these tumors may respond favorably to treatment regimens incorporating immune checkpoint inhibitors.

YAP/TAZ as master regulators in cancer: modulation, function and therapeutic approaches

Our understanding of the function of the transcriptional regulators YAP and TAZ (YAP/TAZ) in cancer is advancing. In this Review, we provide an update on recent progress in YAP/TAZ biology, their regulation by Hippo signaling and mechanotransduction and highlight open questions. YAP/TAZ signaling is an addiction shared by multiple tumor types and their microenvironments, providing many malignant attributes. As such, it represents an important vulnerability that may offer a broad window of therapeutic efficacy, and here we give an overview of the current treatment strategies and pioneering clinical trials.

The critical role of the Hippo signaling pathway in kidney diseases

The Hippo signaling pathway is involved in cell growth, proliferation, and apoptosis, and it plays a key role in regulating organ size, tissue regeneration, and tumor development. The Hippo signaling pathway also participates in the occurrence and development of various human diseases. Recently, many studies have shown that the Hippo pathway is closely related to renal diseases, including renal cancer, cystic kidney disease, diabetic nephropathy, and renal fibrosis, and it promotes the transformation of acute kidney disease to chronic kidney disease (CKD). The present paper summarizes and analyzes the research status of the Hippo signaling pathway in different kidney diseases, and it also summarizes the expression of Hippo signaling pathway components in pathological tissues of kidney diseases. In addition, the present paper discusses the positive therapeutic significance of traditional Chinese medicine (TCM) in regulating the Hippo signaling pathway for treating kidney diseases. This article introduces new targets and ideas for drug development, clinical diagnosis, and treatment of kidney diseases.

Proteomic profiling identifies novel diagnostic biomarkers and molecular subtypes for mucinous tubular and spindle cell carcinoma of the kidney

Mucinous tubular and spindle cell carcinoma (MTSCC) is a relatively rare renal epithelial neoplasm resembling type 1 papillary renal cell carcinoma (PRCC) morphologically and immunohistochemically. The accurate diagnosis of MTSCC remains a challenge. Here, by using proteomic profiling, we characterized MTSCC and PRCC to identify diagnostic biomarkers. We found that the MTSCC tumor proteome was significantly enriched in B‐cell‐mediated immunity when compared with the proteome of adjacent normal tissues of MTSCC or tumors of PRCC. Importantly, we identified MZB1, VCAN, and SOSTDC1 as diagnostic biomarkers to distinguish MTSCC from the solid variant of type 1 PRCC, with an AUC of 0.985 when combined. MZB1 was inversely correlated with tumor clinical stage and may play an anti‐tumor role by activating the complement system. Finally, unsupervised clustering revealed two molecular subtypes of MTSCC, displaying different morphology, expression signatures of oxidative phosphorylation, and aggravation. In summary, our analyses identified a three‐protein diagnostic panel and molecular subtypes for MTSCC. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

OUP accepted manuscript

Mucinous tubule and spindle cell carcinoma (MTSCC) of the kidney is a rare renal pleomorphic tumor considered as low-grade malignant, with occurring mainly in female. Few mucin-poor MTSCC cases have been reported so far. A typical MTSCC is composed of closely arranged tubules with pale mucus matrix and spindle cell components. Mucin-poor MTSCC is difficult to distinguish from other renal cell carcinomas due to small amount of mucus. We reported a case of mucin-poor MTSCC in a 37-year-old male with detailed imaging, histology, immunohistochemical and next-generation sequencing information, looking forward to providing an insight into mucin-poor MTSCC.

Renal cell tumor with sex-cord/gonadoblastoma-like features: analysis of 6 cases

Renal tumors are one of the most diverse groups of tumors in pathology. Many emerging and important entities have been described recently. Here, we describe a series of renal tumors occurring in adult patients, with distinct histologic features, and with a striking resemblance to gonadal sex cord-stromal tumors. Patients were three males and three females aged 39-82 years; tumor size ranged from 0.9 to 3.6 cm. Five tumors were organ-confined, while one case had a focal perinephric invasion. No aggressive behavior was noted. Microscopically, all the tumors were composed of loose or compact tubular structures with elongated or angulated shapes. The tumor cells were cylindrical or cuboidal, with pale eosinophilic cytoplasm, irregular nuclear membranes, and ISUP/WHO grade 2-3 nuclei. The stroma showed focal or prominent collagen deposition with prominent basement membrane-like material. In all cases, the tumor cells were positive for PAX8, CD10, and vimentin and retained positivity for FH and SDHB. Cathepsin K and AMACR were variably positive. Tumors were negative for HMB45, Melan A, TFE3, SF1, inhibin, calretinin, ER, PR, CD117, OCT3/4, SALL4, ALK, and WT1. Molecular studies showed no abnormalities in TFEB, TFE3, or FH genes. In 3/4 tested cases, mutation of the NF2 gene was present. In all the tested male cases, loss of the Y chromosome was found. In the relatively short follow-up, these tumors appear to have indolent behavior. This study expands the clinicopathologic diversity of renal cell tumors by describing a series of potentially novel tumors morphologically resembling gonadal sex-stromal tumors, with negativity for sex cord-stromal markers. Potential relationship to recently described biphasic hyalinizing psammomatous renal cell carcinoma is discussed.

Pathology and systemic therapy of non-clear cell renal cell carcinoma: an overview

Introduction: Non-clear cell renal cell carcinoma (nccRCC) represents a highly heterogenous group of kidney cancer entities. As most clinical trials predominantly include patients with clear cell RCC (ccRCC), nccRCC treatment guidelines are mainly extrapolated from recommendations in ccRCC. Here, we review and elucidate current data on the pathologic classification and treatment of nccRCC.Areas covered: This article gives an overview of the WHO classification of RCC, showing the histological diversity of nccRCC and focusing particularly on entities first characterized since 2016, their specific molecular behavior and their role as indicators for hereditary cancer syndromes. In this context, we discuss the available data on nccRCC treatment oprtions such as tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors, cytotoxic chemotherapy, and immune checkpoint inhibitors.Expert opinion: Although nccRCCs are relatively uncommon, entities of this type account for a subgroup of up to 20-25% of all RCCs. Advances in histopathology and molecular genetics, together with evidence gained from retrospective and prospective clinical data, have improved understanding of these tumors in recent years. Nevertheless, selective trials of current and novel therapies including new targeted agents in patients with nccRCC are urgently needed to further improve treatment guidelines.

Key Renal Neoplasms With a Female Predominance

Renal neoplasms largely favor male patients; however, there is a growing list of tumors that are more frequently diagnosed in females. These tumors include metanephric adenoma, mixed epithelial and stromal tumor, juxtaglomerular cell tumor, mucinous tubular and spindle cell carcinoma, Xp11.2 (TFE3) translocation-associated renal cell carcinoma, and tuberous sclerosis complex (somatic or germline) associated renal neoplasms. The latter category is a heterogenous group with entities still being delineated. Eosinophilic solid and cystic renal cell carcinoma is the best-described entity, whereas, eosinophilic vacuolated tumor is a proposed entity, and the remaining tumors are currently grouped together under the umbrella of tuberous sclerosis complex/mammalian target of rapamycin-related renal neoplasms. The entities described in this review are often diagnostic considerations when evaluating renal mass tissue on biopsy or resection. For example, Xp11.2 translocation renal cell carcinoma is in the differential when a tumor has clear cell cytology and papillary architecture and occurs in a young or middle-aged patient. In contrast, tuberous sclerosis complex-related neoplasms often enter the differential for tumors with eosinophilic cytology. This review provides an overview of the clinical, gross, microscopic, immunohistochemical, genetic, and molecular alterations in key renal neoplasms occurring more commonly in females; differential diagnoses are also discussed regardless of sex predilection.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

A WW Tandem-Mediated Dimerization Mode of SAV1 Essential for Hippo Signaling

The canonical mammalian Hippo pathway contains a core kinase signaling cascade requiring upstream MST to form a stable complex with SAV1 in order to phosphorylate the downstream LATS/MOB complex. Though SAV1 dimerization is essential for the trans-activation of MST, the molecular mechanism underlying SAV1 dimerization is unclear. Here, we discover that the SAV1 WW tandem containing a short Pro-rich extension immediately following the WW tandem (termed as "WW12ex") forms a highly stable homodimer. The crystal structure of SAV1 WW12ex reveals that the Pro-rich extension of one subunit binds to both WW domains from the other subunit. Thus, SAV1 WW12ex forms a domain-swapped dimer instead of a WW2 homodimerization-mediated dimer. The WW12ex-mediated dimerization of SAV1 is required for the MST/SAV1 complex assembly and MST kinase activation. Finally, we show that several cancer-related SAV1 variants disrupt SAV1 dimer formation, and thus, these mutations may impair the tumor-suppression activity of SAV1.

[Histological subtypes of renal cell carcinoma : Overview and new developments]

BACKGROUND

The classification of renal cell carcinoma (RCC) has changed remarkably in recent years.

OBJECTIVES

This is a short overview of the classification of RCC, focusing on new developments.

MATERIALS AND METHODS

A literature search was performed resulting in an overview of the classification of RCC. Emerging entities were discussed in detail.

RESULTS

Apart from the RCC subtypes in the WHO classification of 2016, several emerging entities came up over the last few years that are characterized by typical morphology, immunophenotype, and especially specific genetic alterations.

CONCLUSION

Precise classification of RCC is the key to better prognostic assessment with potential tumor-specific therapy and plays an important role in the recognition of possible association with hereditary tumor syndromes.

Towards a new WHO classification of renal cell tumor: what the clinician needs to know-a narrative review

In 1952, renal cell carcinomas had been divided into 2 categories—clear cell or granular cell—depending upon their cytoplasmic staining characteristics. In the following years, the inventory of renal epithelial tumors has expanded by the addition of tumors named by their architectural pattern (i.e., papillary RCC, tubulocystic RCC), anatomic location (i.e., collecting duct carcinoma, renal medullary carcinoma), associated diseases (i.e., acquired cystic disease-associated RCCs). With the extensive application of molecular diagnostic techniques, it becomes possible to detect genetic distinctions between various types of renal neoplasm and discover new entities, otherwise misdiagnosed or diagnosed as unclassified RCC. Some tumors such as ALK rearrangement-associated RCC, MiT family translocation renal carcinomas, SDH-deficient renal cancer or FH-deficient RCC, are defined by their molecular characteristics. The most recent World Health Organization (WHO) classification of renal neoplasms account for more than 50 entities and provisional entities. New entities might be included in the upcoming WHO classification. The aim of this review is to summarise and discuss the newly acquired data and evidence on the clinical, pathological, molecular features and on the prognosis of new RCC entities, which will hopefully increase the awareness and the acceptance of these entities among clinicians and improve prognostication for individual patients.

The tumor suppressor role of salvador family WW domain-containing protein 1 (SAV1): one of the key pieces of the tumor puzzle

PURPOSE

In the complex tumor scenario, understanding the function of proteins with protumor or antitumor roles is essential to support advances in the cancer clinical area. Among them, the salvador family WW domain-containing protein 1 (SAV1) is highlighted. This protein plays a fundamental role in the tumor suppressor face of the Hippo pathway, which are responsible for controlling cell proliferation, organ size, development and tissue homeostasis. However, the functional dysregulation of this pathway may contribute to tumorigenesis and tumor progression. As SAV1 is a tumor suppressor scaffold protein, we explored the functions performed by SAV1 with its partners, the regulation of its expression, and its antitumor role in various types of cancer.

METHODS

We selected and analyzed 80 original articles and reviews from Pubmed that focuses on the study of SAV1 in cancer.

RESULTS

SAV1 interacts with several proteins, has different functions and acts as tumor suppressor by other mechanisms besides Hippo pathway. SAV1 expression regulation seems to occur by microRNAs and rarely by mutation or promoter methylation. It is downregulated in different types of cancer, which leads to cancer promotion and progression and is associated with poor prognosis. In vivo models have shown that the loss of SAV1 contributes to tumorigenesis.

CONCLUSION

SAV1 plays a relevant role as tumor suppressor in several types of cancer, highlighting SAV1 and the Hippo pathway's importance to cancer. Thus, encouraging further studies to include the SAV1 as a molecular key piece in cancer biology and in clinical approaches to cancer.

Adverse histology, homozygous loss of CDKN2A/B, and complex genomic alterations in locally advanced/metastatic renal mucinous tubular and spindle cell carcinoma

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare subtype of renal cell carcinoma with characteristic histologic features and chromosomal alterations. Although typically indolent, a small subset of cases has been reported to exhibit aggressive clinical behavior. We retrospectively identified 33 patients with MTSCC, consisting of 10 cases of locally advanced/metastatic MTSCC (pT3 or N1 or M1) and 23 kidney-confined MTSCC (pT1/T2) without disease recurrence or progression. Utilizing a single-nucleotide polymorphism array and a targeted next-generation sequencing platform, we examined genome-wide molecular alterations in 24 cases, including 11 available samples from 8 patients with locally advanced/metastatic MTSCC. Ten patients with locally advanced/metastatic MTSCC were 8 females (80%) and 2 males (20%). At nephrectomy, 7 of these 10 cases (70%) were pT3 or pN1 while the remaining 3 (30%) were pT1/T2. Eight patients (80%) developed metastases and common sites included lymph node (4, 40%), bone (4, 40%), and retroperitoneum (3, 30%). Four patients died of disease (40%) during follow-up. Locally advanced/metastatic MTSCCs shared typical MTSCC genomic profiles with loss of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22, while some exhibited additional complex genomic alterations, most frequently a relative gain of 1q (7/8). Homozygous loss of CDKN2A/B was observed in 3 (38%) locally advanced/metastatic MTSCCs. Tumor necrosis, solid nested/sheet pattern, irregular trabecular/single-file infiltration in a desmoplastic stroma, lymphovascular space invasion, and increased mitotic activity were associated with locally advanced/metastatic MTSCCs (all p < 0.05). Our findings reveal that MTSCCs with aggressive clinical behavior have progressed through clonal evolution; CDKN2A/B deletion and additional complex genomic abnormalities may contribute to this process. Recognizing the morphologic presentation of high-grade MTSCC and evaluating adverse histologic features seen in these tumors can help establish a definitive diagnosis and stratify patients for treatment and prognostication.

Biphasic Hyalinizing Psammomatous Renal Cell Carcinoma (BHP RCC): A Distinctive Neoplasm Associated With Somatic NF2 Mutations

We report 8 cases of a distinctive, previously undescribed renal cell carcinoma associated with somatic mutations in the neurofibromin 2 (NF2) gene. All patients were adults, ranging from 51 to 78 years of age and of cases of known sex 6 of 7 were males. The carcinomas were predominantly unencapsulated, and all had a rounded, nodular interface with the native kidney. The neoplasms were all solid with papillary architecture evident in most cases (7/8), while 1 was only tubular. All cases were biphasic, characterized by larger and smaller carcinoma cells. The smaller cells clustered around basement membrane material similar to the characteristic pattern of the t(6;11) renal cell carcinoma associated with TFEB gene fusions. In 6 of 8 carcinomas, branching nodules of small cells clustered around basement membrane material within larger acini yielding a distinctive glomeruloid pattern. In 6 of 8 carcinomas, the small cells were focally spindle-shaped and unassociated with the basement membrane material. The stroma was sclerotic in all 8 carcinomas, and all 8 contained psammoma bodies that were abundant in 2. In some carcinomas, focal or predominant areas had a less distinctive appearance; 2 had areas that resembled clear cell renal cell carcinoma, 2 had high-grade eosinophilic areas, while 1 had branching tubular architecture that resembled mucinous tubular and spindle cell carcinoma. Two carcinomas demonstrated cellular necrosis. Although we have minimal clinical follow-up, 1 case presented with distant metastasis, progressed and resulted in patient death. While NF2 mutations may be found in other established renal cell carcinoma subtypes (often as secondary genetic alterations), they are potentially the genetic driver of this distinctive entity.

Report From the International Society of Urological Pathology (ISUP) Consultation Conference on Molecular Pathology of Urogenital Cancers: III: Molecular Pathology of Kidney Cancer

Renal cell carcinoma (RCC) subtypes are increasingly being discerned via their molecular underpinnings. Frequently this can be correlated to histologic and immunohistochemical surrogates, such that only simple targeted molecular assays, or none at all, are needed for diagnostic confirmation. In clear cell RCC, VHL mutation and 3p loss are well known; however, other genes with emerging important roles include SETD2, BAP1, and PBRM1, among others. Papillary RCC type 2 is now known to include likely several different molecular entities, such as fumarate hydratase (FH) deficient RCC. In MIT family translocation RCC, an increasing number of gene fusions are now described. Some TFE3 fusion partners, such as NONO, GRIPAP1, RBMX, and RBM10 may show a deceptive fluorescence in situ hybridization result due to the proximity of the genes on the same chromosome. FH and succinate dehydrogenase deficient RCC have implications for patient counseling due to heritable syndromes and the aggressiveness of FH-deficient RCC. Immunohistochemistry is increasingly available and helpful for recognizing both. Emerging tumor types with strong evidence for distinct diagnostic entities include eosinophilic solid and cystic RCC and TFEB/VEGFA/6p21 amplified RCC. Other emerging entities that are less clearly understood include TCEB1 mutated RCC, RCC with ALK rearrangement, renal neoplasms with mutations of TSC2 or MTOR, and RCC with fibromuscular stroma. In metastatic RCC, the role of molecular studies is not entirely defined at present, although there may be an increasing role for genomic analysis related to specific therapy pathways, such as for tyrosine kinase or MTOR inhibitors.

Contemporary Renal Tumor Categorization With Biomarker and Translational Updates: A Practical Review

CONTEXT.—

Renal tumor classification has evolved in recent decades, as evidenced by the comparable complexity of the 2016 revision to the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. A recent expansion of the knowledge base surrounding the cells of origin and evolutionary genomic characteristics of renal tumors has led to molecular characterization of novel entities and enriched understanding of established entities. This pace of research and its implementation into clinical practice has again begun to surpass that of our own classification schemata, with significant discoveries having been made since the introduction of the 2016 revision to the World Health Organization classification. In particular, biomarkers for renal tumor diagnosis and prognosis are in translation for future clinical application.

OBJECTIVES.—

To provide a brief framework for clinical characterization of renal tumors rooted in morphologic assessment, to briefly review the current and future status of renal tumor biomarkers with an emphasis on practical use of these ancillary tools for accurate diagnosis, and to discuss the impact of emerging technologies and clinical trials relevant to renal cell carcinoma classification and biomarker development.

DATA SOURCES.—

We review recent literature relevant to renal tumor classification (including established and proposed entities), focusing on molecular characterization and biomarker assessment.

CONCLUSIONS.—

Accurate renal tumor diagnosis requires an up-to-date understanding of renal tumor classification, including an awareness of morphologic clues that should stimulate consideration of molecularly defined entities, as well as the ancillary biomarker testing required to confirm diagnoses.

YAP/TAZ Inhibition Induces Metabolic and Signaling Rewiring Resulting in Targetable Vulnerabilities in NF2-Deficient Tumor Cells

Merlin/NF2 is a bona fide tumor suppressor whose mutations underlie inherited tumor syndrome neurofibromatosis type 2 (NF2), as well as various sporadic cancers including kidney cancer. Multiple Merlin/NF2 effector pathways including the Hippo-YAP/TAZ pathway have been identified. However, the molecular mechanisms underpinning the growth and survival of NF2-mutant tumors remain poorly understood. Using an inducible orthotopic kidney tumor model, we demonstrate that YAP/TAZ silencing is sufficient to induce regression of pre-established NF2-deficient tumors. Mechanistically, YAP/TAZ depletion diminishes glycolysis-dependent growth and increases mitochondrial respiration and reactive oxygen species (ROS) buildup, resulting in oxidative-stress-induced cell death when challenged by nutrient stress. Furthermore, we identify lysosome-mediated cAMP-PKA/EPAC-dependent activation of RAF-MEK-ERK signaling as a resistance mechanism to YAP/TAZ inhibition. Finally, unbiased analysis of TCGA primary kidney tumor transcriptomes confirms a positive correlation of a YAP/TAZ signature with glycolysis and inverse correlations with oxidative phosphorylation and lysosomal gene expression, supporting the clinical relevance of our findings.

miR-624-5p promoted tumorigenesis and metastasis by suppressing hippo signaling through targeting PTPRB in osteosarcoma cells

Background

Accumulating evidence indicates that aberrant microRNA (miRNA) expression contributes to osteosarcoma progression. This study aimed to elucidate the association between miR-624-5p expression and osteosarcoma (OS) development and to investigate its underlying mechanism.

Methods

We analyzed GSE65071 from the GEO database and found miR-624-5p was the most upregulated miRNA. The expression of miR-624-5p and its specific target gene were determined in human OS specimens and cell lines by RT-PCR and western blot. The effects of miR-624-5p depletion or ectopic expression on OS proliferation, migration and invasion were evaluated in vitro using CCK-8 proliferation assay, colony formation assay, transwell assay, would-healing assay and 3D spheroid BME cell invasion assay respectively. We investigated in vivo effects of miR-624-5p using a mouse tumorigenicity model. Besides, luciferase reporter assays were employed to identify interactions between miR-624-5p and its specific target gene.

Results

miR-624-5p expression was upregulated in OS cells and tissues, and overexpressing miR-624-5p led to a higher malignant level of OS, including cell proliferation, migration and invasion in vitro and in vivo. Protein tyrosine phosphatase receptor type B (PTPRB) was negatively correlated with miR-624-5p expression in OS tissues. Using the luciferase reporter assay and Western blotting, PTPRB was confirmed as a downstream target of miR-624-5p. PTPRB restored the effects of miR-624-5p on OS migration and invasion. The Hippo signaling pathway was identified as being involved in the miR-624-5p/PTPRB axis.

Conclusions

In conclusion, our results suggest that miR-624-5p is a negative regulator of PTPRB and a risk factor for tumor metastasis in OS progression.

Integrated Proteogenomic Characterization of Clear Cell Renal Cell Carcinoma

To elucidate the deregulated functional modules that drive clear cell renal cell carcinoma (ccRCC), we performed comprehensive genomic, epigenomic, transcriptomic, proteomic, and phosphoproteomic characterization of treatment-naive ccRCC and paired normal adjacent tissue samples. Genomic analyses identified a distinct molecular subgroup associated with genomic instability. Integration of proteogenomic measurements uniquely identified protein dysregulation of cellular mechanisms impacted by genomic alterations, including oxidative phosphorylation-related metabolism, protein translation processes, and phospho-signaling modules. To assess the degree of immune infiltration in individual tumors, we identified microenvironment cell signatures that delineated four immune-based ccRCC subtypes characterized by distinct cellular pathways. This study reports a large-scale proteogenomic analysis of ccRCC to discern the functional impact of genomic alterations and provides evidence for rational treatment selection stemming from ccRCC pathobiology.

Five decades of urologic pathology: the accelerating expansion of knowledge in renal cell neoplasia

Those who are knowledgeable in cosmology inform us that the expansion of the universe is such that the velocity at which a distant galaxy is receding from the observer is continually increasing with time. We humbly paraphrase that as "The bigger the universe gets, the faster it gets bigger." This is an interesting analogy for the expansion of knowledge in the field of renal tumor pathology over the past 30 to 50 years. It is clear that a multitude of dedicated investigators have devoted incalculable amounts of time and effort to the pursuit of knowledge about renal epithelial neoplasms. As a consequence of the contributions of numerous investigators over many decades, the most recent World Health Organization classification of renal neoplasms includes about 50 well defined and distinctive renal tumors, as well as various miscellaneous and metastatic tumors. In addition, a number of emerging or provisional new entities are under active investigation and may be included in future classifications. In this review, we will focus on a number of these tumors, tracing as accurately as we can the origins of their discovery, relating relevant additions to the overall knowledge base surrounding them, and in some instances addressing changes in nomenclature.

The Hippo Signaling Pathway in Development and Disease

The Hippo signaling pathway regulates diverse physiological processes, and its dysfunction has been implicated in an increasing number of human diseases, including cancer. Here, we provide an updated review of the Hippo pathway; discuss its roles in development, homeostasis, regeneration, and diseases; and highlight outstanding questions for future investigation and opportunities for Hippo-targeted therapies.

Mucinous Tubular and Spindle-Cell Carcinoma of the Kidney: Clinical Features, Genomic Profiles, and Treatment Outcomes

BACKGROUND

Mucinous tubular and spindle-cell carcinoma (MTSCC) is a rare kidney cancer subtype with limited cases reported in the literature. We report on outcomes of 25 patients with this variant who were managed at our institution.

MATERIALS AND METHODS

The institution database was queried, and clinical data extracted for patients with MTSCC. Molecular features examined included next-generation sequencing with Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets and allele-specific copy number analysis using the Fraction and Allele-Specific Copy Number Estimates from Tumor Sequencing (FACETS) algorithm in a subset of patients.

RESULTS

All patients underwent primary tumor-directed therapy (nephrectomy = 23, cryoablation = 2). Metastases were diagnosed in 6 patients (24%), 3 (12%) of whom had de novo metastatic disease. Five of 6 patients with metastatic disease had high-grade histological features compared with 0 of 19 nonmetastatic patients (83% vs. 0%; P < .001, Fisher exact test). Three-year overall survival from diagnosis was 84.8% (95% confidence interval, 59.6-94.9) with a median follow-up time of 3.9 years (range, 1 month to 10.3 years). Three deaths occurred, all from metastatic disease. Four patients received systemic therapy with time to treatment failure ≤6 months across different agents with the exception of 1 patient with prolonged response with sunitinib treatment (30.6 months). The most frequent molecular alterations were neurofibromin 2 mutations (n = 2; 40%), germline alterations (n = 2; 40%) including checkpoint kinase 2 and BRCA2 DNA repair associated mutations, multiple chromosomal copy number losses, and mismatch repair deficiency in 1 patient.

CONCLUSION

MTSCC is characterized by localized tumors treated successfully with primary tumor-directed therapy. However, patients with high-grade histological features were more likely to develop metastatic disease with limited responses to standard therapies.

PTPN14 degradation by high-risk human papillomavirus E7 limits keratinocyte differentiation and contributes to HPV-mediated oncogenesis

High-risk human papillomavirus (HPV) E7 proteins enable oncogenic transformation of HPV-infected cells by inactivating host cellular proteins. High-risk but not low-risk HPV E7 target PTPN14 for proteolytic degradation, suggesting that PTPN14 degradation may be related to their oncogenic activity. HPV infects human keratinocytes but the role of PTPN14 in keratinocytes and the consequences of PTPN14 degradation are unknown. Using an HPV16 E7 variant that can inactivate retinoblastoma tumor suppressor (RB1) but cannot degrade PTPN14, we found that high-risk HPV E7-mediated PTPN14 degradation impairs keratinocyte differentiation. Deletion of PTPN14 from primary human keratinocytes decreased keratinocyte differentiation gene expression. Related to oncogenic transformation, both HPV16 E7-mediated PTPN14 degradation and PTPN14 deletion promoted keratinocyte survival following detachment from a substrate. PTPN14 degradation contributed to high-risk HPV E6/E7-mediated immortalization of primary keratinocytes and HPV⁺ but not HPV^- cancers exhibit a gene-expression signature consistent with PTPN14 inactivation. We find that PTPN14 degradation impairs keratinocyte differentiation and propose that this contributes to high-risk HPV E7-mediated oncogenic activity independent of RB1 inactivation.

Mucinous Tubular and Spindle Cell Carcinoma: A Review of Histopathology and Clinical and Prognostic Implications

Mucinous tubular and spindle cell carcinomas are rare kidney tumors with generally indolent behavior. As the name suggests, classic histomorphology reveals bland spindle cells, tubules, and mucinous stroma. Uncommon histologic features include mucin-poor stroma, high nuclear grade, cellular pleomorphism, and presence of necrosis. Rare cases can show aggressive growth and distant metastasis. Mucinous tubular and spindle cell carcinoma has characteristic chromosomal abnormalities and the molecular signature remains the same, irrespective of the varied histomorphology.

VSTM2A Overexpression Is a Sensitive and Specific Biomarker for Mucinous Tubular and Spindle Cell Carcinoma (MTSCC) of the Kidney

Our recent study revealed recurrent chromosomal losses and somatic mutations of genes in the Hippo pathway in mucinous tubular and spindle cell carcinoma (MTSCC). Here, we performed an integrative analysis of 907 renal cell carcinoma (RCC) samples (combined from The Cancer Genome Atlas and in-house studies) and the Knepper data set of microdissected rat nephrons. We identified VSTM2A and IRX5 as novel cancer-specific and lineage-specific biomarkers in MTSCC. We then assessed their expression by RNA in situ hybridization (ISH) in 113 tumors, including 33 MTSCC, 40 type 1 papillary RCC, 8 type 2 papillary RCC, 2 unclassified RCC, 15 clear cell RCC, and 15 chromophobe RCC. Sensitivity and specificity were calculated as the area under the receiver operating characteristics curve (AUC). All MTSCC tumors demonstrated moderate to high expression of VSTM2A (mean ISH score=255). VSTM2A gene expression assessed by RNA sequencing strongly correlated with VSTM2A ISH score (r(2)=0.81, P=0.00016). The majority of non-MTSCC tumors demonstrated negative or low expression of VSTM2A. IRX5, nominated as a lineage-specific biomarker, showed moderate to high expression in MTSCC tumors (mean ISH score=140). IRX5 gene expression assessed by RNA sequencing strongly correlated with IRX5 ISH score (r(2)=0.69, P=0.00291). VSTM2A (AUC: 99.2%) demonstrated better diagnostic efficacy than IRX5 (AUC: 87.5%), and may thus serve as a potential diagnostic marker to distinguish tumors with overlapping histology. Furthermore, our results suggest MTSCC displays an overlapping phenotypic expression pattern with the loop of Henle region of normal nephrons.

YAP/TAZ Signaling as a Molecular Link between Fibrosis and Cancer

Tissue fibrosis is a pathological condition that is associated with impaired epithelial repair and excessive deposition of extracellular matrix (ECM). Fibrotic lesions increase the risk of cancer in various tissues, but the mechanism linking fibrosis and cancer is unclear. Yes-associated protein (YAP) and the transcriptional coactivator with PDZ-binding motif (TAZ) are core components of the Hippo pathway, which have multiple biological functions in the development, homeostasis, and regeneration of tissues and organs. YAP/TAZ act as sensors of the structural and mechanical features of the cell microenvironment. Recent studies have shown aberrant YAP/TAZ activation in both fibrosis and cancer in animal models and human tissues. In fibroblasts, ECM stiffness mechanoactivates YAP/TAZ, which promote the production of profibrotic mediators and ECM proteins. This results in tissue stiffness, thus establishing a feed-forward loop of fibroblast activation and tissue fibrosis. In contrast, in epithelial cells, YAP/TAZ are activated by the disruption of cell polarity and increased ECM stiffness in fibrotic tissues, which promotes the proliferation and survival of epithelial cells. YAP/TAZ are also involved in the epithelial–mesenchymal transition (EMT), which contributes to tumor progression and cancer stemness. Importantly, the crosstalk with transforming growth factor (TGF)-β signaling and Wnt signaling is essential for the profibrotic and tumorigenic roles of YAP/TAZ. In this article, we review the latest advances in the pathobiological roles of YAP/TAZ signaling and their function as a molecular link between fibrosis and cancer.