Acquired resistance to KRAS G12C small-molecule inhibitors via genetic/nongenetic mechanisms in lung cancer.

Inherent or acquired resistance to sotorasib poses a substantialt challenge for NSCLC treatment. Here, we demonstrate that acquired resistance to sotorasib in isogenic cells correlated with increased expression of integrin ß4 (ITGB4), a component of the focal adhesion complex. Silencing ITGB4 in tolerant cells improved sotorasib sensitivity, while overexpressing ITGB4 enhanced tolerance to sotorasib by supporting AKT-mTOR bypass signaling. Chronic treatment with sotorasib induced WNT expression and activated the WNT/ß-catenin signaling pathway. Thus, silencing both ITGB4 and ß-catenin significantly improved sotorasib sensitivity in tolerant, acquired, and inherently resistant cells. In addition, the proteasome inhibitor carfilzomib (CFZ) exhibited synergism with sotorasib by down-regulating ITGB4 and ß-catenin expression. Furthermore, adagrasib phenocopies the combination effect of sotorasib and CFZ by suppressing KRAS activity and inhibiting cell cycle progression in inherently resistant cells. Overall, our findings unveil previously unrecognized nongenetic mechanisms underlying resistance to sotorasib and propose a promising treatment strategy to overcome resistance.

The O-Linked N-Acetylglucosamine Containing Epitope H (O-GlcNAcH) is Upregulated in the Trophoblastic and Downregulated in the Fibroblastic Cells in Missed Miscarriage Human Chorionic Villi With Simple Hydropic Degeneration.

Epitope H contains an O-linked N-acetylglucosamine (O-GlcNAcH) residue in a specific conformation and/or environment recognized by the mouse monoclonal antibody H. O-GlcNAcH is present in several types of cells and in several polypeptides, including cytokeratin 8 and vimentin, on the latter in cells under stress. In the present work, we examined the expression of the O-GlcNAcH in 60 cases of endometrial curettings from missed miscarriage cases containing normal and simple hydropic degenerated chorionic villi in each case, using monoclonal antibody H and indirect immunoperoxidase and Western blot immunoblot. In all cases examined the expression of the O-GlcNAcH was cytoplasmic as follows: (1) syncytiotrophoblastic cells showed very low expression in chorionic villi (CV) with nonhydropic degeneration (NHD) and high expression in hydropic degenerated (HD) CV; (2) cytotrophoblastic cells showed low expression in CV with NHD and high expression in HD CV; (3) fibroblastic cells showed high expression in CV with NHD and very low expression in HD CV; (4) histiocytes showed very low expression in both types of CV; (5) endothelial cells showed high expression in both types of CV. An immunoblot of CV from one case of a legal abortion from a normal first-trimester pregnancy showed 5 polypeptides with 118.5, 106.3, 85, 53, and 36.7 kD bearing the epitope H and the 53 kD corresponded to cytokeratin 8. The expression of the O-GlcNAcH is upregulated in the trophoblastic cells and downregulated in the fibroblastic cells in the HD CV in comparison to the NHD CV.

Erratum: A Non-genetic Mechanism Involving the Integrin ß4/Paxillin Axis Contributes to Chemoresistance in Lung Cancer.

[This corrects the article DOI: 10.1016/j.isci.2020.101496.].

Alternative lengthening of telomeres, ATRX loss and H3-K27M mutations in histologically defined pilocytic astrocytoma with anaplasia.

Anaplasia may be identified in a subset of tumors with a presumed pilocytic astrocytoma (PA) component or piloid features, which may be associated with aggressive behavior, but the biologic basis of this change remains unclear. Fifty-seven resections from 36 patients (23 M, 13 F, mean age 32 years, range 3-75) were included. A clinical diagnosis of NF1 was present in 8 (22%). Alternative lengthening of telomeres (ALT) was assessed by telomere-specific FISH and/or CISH. A combination of immunohistochemistry, DNA sequencing and FISH were used to study BRAF, ATRX, CDKN2A/p16, mutant IDH1 p.R132H and H3-K27M proteins. ALT was present in 25 (69%) cases and ATRX loss in 20 (57%), mostly in the expected association of ALT+/ATRX- (20/24, 83%) or ALT-/ATRX+ (11/11, 100%). BRAF duplication was present in 8 (of 26) (31%). H3-K27M was present in 5 of 32 (16%) cases, all with concurrent ATRX loss and ALT. ALT was also present in 9 (of 11) cases in the benign PA precursor, 7 of which also had ATRX loss in both the precursor and the anaplastic tumor. In a single pediatric case, ALT and ATRX loss developed in the anaplastic component only, and in another adult case, ALT was present in the PA-A component only, but ATRX was not tested. Features associated with worse prognosis included subtotal resection, adult vs. pediatric, presence of a PA precursor preceding a diagnosis of anaplasia, necrosis, presence of ALT and ATRX expression loss. ALT and ATRX loss, as well as alterations involving the MAPK pathway, are frequent in PA with anaplasia at the time of development of anaplasia or in their precursors. Additionally, a small subset of PA with anaplasia have H3-K27M mutations. These findings further support the concept that PA with anaplasia is a neoplasm with heterogeneous genetic features and alterations typical of both PA and diffuse gliomas.

Glioblastoma in natalizumab-treated multiple sclerosis patients.

We present two natalizumab-treated multiple sclerosis patients who developed glioblastoma multiforme (GBM) with variable outcomes. One patient had an isocitrate dehydrogenase (IDH)-wildtype GBM with aggressive behavior, who declined treatment and died 13 weeks after symptoms onset. The other patient underwent resection of an IDH-mutant secondary GBM that arose from a previously diagnosed grade II astrocytoma. He is still alive 5 years after the diagnosis of GBM. JC virus was not detected in either case. Whether natalizumab played a role in the development of GBM in those patients deserves further investigation.

Pigmented ganglioglioma in a patient with chronic epilepsy and cortical dysplasia.

We report a rare case of a 22-year-old woman with biopsy-proven pigmented ganglioglioma. The patient initially underwent a right temporal lobectomy for intractable seizures at the age of 9 and remained seizure free for several years but subsequently developed complex partial seizures. Due to enhancement of a left mesial occipital lesion on preoperative MRI of the brain, the patient underwent a left subdural electrode placement and simultaneous biopsy of the left mesial occipital lesion. Biopsy results revealed a rare pigmented ganglioglioma, World Health Organization Grade I. The seizure focus was identified in the left mesial occipital lobe and the patient underwent tumor resection. An extensive literature search revealed that our patient is the fourth case of pigmented ganglioglioma described in the literature and was positive for BRAF V600E mutation by molecular studies.

Hyperdense suprasellar mass: An unusual radiological presentation of intracranial dermoid cyst.

We report an exceedingly rare patient with a hyperdense suprasellar dermoid cyst and a pertinent review of the literature. Intracranial dermoid tumors are rare congenital lesions of the brain that account for less than 1% of all intracranial tumors. Even though they are rare, typical CT scan and MRI features and location allow radiological diagnosis in the majority of patients. Radiologically, dermoid cysts typically present as low density masses on CT scan and are generally hyperintense on T1-weighted MRI sequences with variable signal on T2-weighted sequences. The recognition of atypical features can avoid diagnostic pitfalls and is clinically relevant for overall surgical management.

A 40-year-old male with an intraventricular tumor. Combined tanycytic ependymoma and subependymoma.

Combined tumors showing histologic features of both ependymoma and subependymoma have been described. In this report we present a case of combined tanycytic ependymoma with foci of subependymoma (WHO grade II), occurring in a 40 year-old male, which arose in the wall of the lateral ventricle. The tanycytic ependymoma component showed elongated fibrillary cells with a fascicular pattern of growth, while the subependymoma component showed clustered cell bodies surrounded by a fibrillary stroma with a microcystic appearance.We consider the present case to be an unusual example of tanycytic ependymoma; which to the best of our knowledge has not been associated with a subependymoma.

Immunophenotype of myxopapillary ependymomas.

Myxopapillary ependymoma (MPE) is a slow-growing tumor occurring almost exclusively in the region of conus medullaris, cauda equina, and filum terminale. On microscopic examination, some of these tumors show solid sheets of cells with an epithelioid morphology mimicking a metastatic carcinoma. Several immunohistochemical studies addressed this issue with discordant results. We report the immunohistochemical findings of 9 additional cases of MPE. From 2004 to 2011, a total of 9 cases of MPE were recorded in our surgical pathology files. The histologic material and clinical data were reviewed for each case. There were 6 female and 3 male patients. The ages ranged from 15 to 58 years (mean, 31 y). Eight cases were intradural, lumbosacral (L1-S1), and 1 case was located in the sacrum. All tumors expressed CD99 and GFAP (100%). Eight tumors were positive for CD56 (89%). All tumors (100%) expressed focally CKAE1/AE3. One tumor (11%) was focally positive for CK8/18 and CK7. D2-40 was focally positive in 1 case (11%). PLAP and AFP were both negative in all cases. Synaptophysin was focally positive in 1 case. NSE was positive in all cases. All tumors were negative for CK5/6, CK20, E-cadherin, and TTF-1. Our study shows that the vast majority of MPE are positive for CD99, CD56, and GFAP. In selective cases, especially when the material obtained for pathologic evaluation is scanty and the tumor displays epithelioid appearance, the diagnosis may be challenging owing to cytokeratin positivity suggesting metastatic carcinoma. However, the clinical and radiologic features in addition to the positivity for GFAP should prompt pathologists to consider MPE in the differential diagnosis of such cases. Interestingly, we found that MPE are positive for NSE, which suggests a neuroglial differentiation.

Use of the reamer-irrigator-aspirator may reduce tumor dissemination during intramedullary fixation of malignancies.

Intramedullary nail fixation is the treatment of choice for impending and pathologic fractures secondary to metastatic cancer; however, this procedure has been shown to cause systemic embolization of intramedullary contents. This article reports the use of the reamer-irrigator-aspirator (RIA) (Synthes, Paoli, Pennsylvania) instead of a standard femoral reamer to decrease tumor intravasation during femoral intramedullary nail fixation for impending or pathologic fractures.Twenty-one consecutive patients indicated for fixation of malignant femoral lesions were treated with intramedullary nail placement. The RIA was used for canal preparation, and solid reamings were collected and submitted for analysis by a single pathologist. The volume of each specimen was recorded, and representative samples were examined histologically to determine their percent tumor content. These data were then used to estimate the volume of tumor retrieved by the RIA in each case. The mean volume of reamings collected by the RIA was 75.0 cc per case (range, 23.4-196.0 cc), and the mean tumor content was 24.8% (range, 1.0%-60.0%). The mean estimated volume of tumor retrieved in each case was 16.7 cc (range, 0.35-36.0 cc). In 2 cases, the tip of the RIA dissociated from the device intraoperatively but was retrieved without adverse consequence to the patient. Use of the RIA in cases of femoral intramedullary nail fixation for pathologic lesions or fractures effectively retrieves variable amounts of intramedullary contents, including tumor. By preventing the systemic dissemination of malignant cells, this technique may reduce the risk of distant metastases.

Hypoxia upregulates the expression of the O-linked N-acetylglucosamine containing epitope H in human ependymal cells.

Epitope H contains an O-linked N-acetylglucosamine (O-GlcNAc) residue in a specific conformation and/or environment recognized by mouse IgM monoclonal antibody H (mabH). Epitope H is present in several types of cells and in several polypeptides outside the CNS. Previous results have shown that in the adult human brains, epitope H is confined mostly to a minority of fibrous astrocytes, and it is greatly upregulated in the reactive astrocytes. Post-translational modification with O-GlcNAc occurs on many proteins involved in several cell processes, such as cell cycle progression, apoptosis, proteasome degradation pathways, and modulation of cellular function in response to nutrition and stress. Hypoxia is one of the major causes of cellular stress. Therefore, in this study, we used the mAbH and the indirect immunoperoxidase method to investigate the expression of epitope H in ependymal cells in brains of persons who died with signs of hypoxic encephalopathy. The results of the present study showed that practically all ependymal cells showed cytoplasmic staining for epitope H in supranuclear cytoplasm in the brain of two premature neonates and in ten infants who died with signs of hypoxic encephalopathy. However, the overwhelming majority of ependymal cells of the nine human embryos taken from legal abortions, ranging from 26 days until 13 weeks of gestational age, and of the ten infants' brains without any sign of hypoxic encephalopathy remained negative. Only occasionally did the ependymal cells show weak cytoplasmic staining in some foci. In addition, the reactive astrocytes in the hypoxic brains showed strong cytoplasmic staining, confirming previous results.

Prognostic value of xanthine oxidoreductase expression in patients with non-small cell lung cancer.

BACKGROUND: Xanthine oxidoreductase (XOR) is a rate-limiting enzyme in the purine metabolism pathway. Lack of XOR expression is associated with unfavorable clinical outcomes. The objective of this study was to correlate XOR expression with prognosis in surgically resected non-small cell lung cancer (NSCLC). METHODS: Immunohistochemical staining was performed on deparaffinized specimens from 82 patients with stage I-IV NSCLC using a polyclonal anti-XOR rabbit antibody. Cytoplasmic XOR staining was scored on frequency and intensity scales from 0 to 4 with low expression defined as 0-1 and high expression defined as ≥2-4. XOR immunostaining was correlated with clinical characteristics and outcomes and analyzed using Kaplan-Meier and Cox proportional hazard methods. RESULTS: Positive XOR expression was observed in 53/82 cases (65%). Patients with high XOR frequency had a longer median survival of 3053 days (95% CI: 2190-3916) vs. 592 days (95% CI: 492-692 days) for patients with low XOR frequency, p=0.0089, HR 0.47. Neither XOR intensity nor the overall score of XOR frequency multiplied by XOR intensity demonstrated any significant association with survival. Surgical resection was performed on 61 patients of which 34 (56%) received adjuvant chemotherapy. Patients who received adjuvant chemotherapy with low XOR expression, 15/34 (44%) had a shortened median survival compared with patients who received adjuvant chemotherapy with high XOR expression (543 days vs. 2023 days, respectively, p=0.007 and HR=0.33). CONCLUSION: Low XOR expression was associated with shortened survival and also conferred a worse prognosis for patients with NSCLC who received adjuvant chemotherapy. Further studies of the XOR pathway are warranted to validate and mechanistically explain these outcomes.

Melanotic schwannoma: a case with strong CD34 expression, with histogenetic implications.

Melanotic schwannomas (MS) are rare tumors composed of cells with both schwannian and melanocytic features, which usually occur in the setting of Carney's Complex. We describe a case of a 36-year-old male who presented with a mass that was attached to the vertebral body as well as the nerve roots of L2 and L3. Immunohistochemical positivity for S-100, HMB-45, and Pan-melanoma markers, as well as characteristic morphologic and ultrastructural findings, suggested that the lesion was a MS. The interest in this case lies in the fact that this case of MS showed strong CD34 expression, a marker that is generally negative in melanocytic tumors. We discuss the biologic significance of the high CD34 expression by the tumor cells and attempt to shed light on the histogenesis of this rare entity.

Congenital fusion of the thalami (atresia of the third ventricle) associated with parietooccipital meningocele.

In this article we present a case of a male newborn with a CNS malformation that is characterized mainly by complete fusion of the thalami resulting in atresia of the 3rd ventricle accompanied by fusion of the anterior peduncles of the fornix, the presence of a single occult interventricular foramen lying at the midline, absence of the septum pellucidum, hypoplasia of the corpus callosum, disorganization of the head of the left caudate nucleus, and greatly dilated lateral ventricles (hydrocephalus). The patient underwent surgical correction of the meningocele on his 4th postnatal day. On his 13th postnatal day he had projectile vomiting due to a left parietooccipital hygroma that was drained via a shunt. On his 31st postnatal day he developed seizures and marked dilatation of the lateral ventricles, for which he underwent a ventriculoperitoneal shunt (Brown). On the 14th postoperative day the patient developed aspiration pneumonia and died.

Adrenocortical carcinoma presenting with a peritoneal effusion.

In this report, we describe the fine-needle aspiration findings of a case of adrenocortical carcinoma (ACC) that spread to the peritoneal cavity in an 80-year-old female. Cytologically, the peritoneal fluid exhibited clusters and single, small uniform cells with round nuclei and a fine chromatin pattern, which in conjunction with the immunohistochemical stains was diagnostic of ACC. Although ACC is the most common malignant neoplasm of the adrenal gland, its metastatic spread to the peritoneal cavity is exceptionally unusual.