Structures of SARS-CoV-2 N7-methyltransferase with DOT1L and PRMT7 inhibitors provide a platform for new antivirals

The RNA N7-methyltransferase (MTase) activity of SARS-CoV-2's nsp14 protein is essential for viral replication and is a target for the development of new antivirals. Nsp14 uses S-adenosyl methionine (SAM) as the methyl donor to cap the 5' end of the SARS-CoV-2 mRNA and generates S-adenosyl homocysteine (SAH) as the reaction byproduct. Due to the central role of histone MTases in cancer, many SAM/SAH analogs with properties of cell permeability have recently been developed for the inhibition of these MTases. We have succeeded in identifying two such compounds (SGC0946 and SGC8158) that display significant antiviral activity and bind to the SARS-CoV-2 nsp14 N7-MTase core. Unexpectedly, crystal structures of SGC0946 and SGC8158 with the SARS-CoV-2 nsp14 N7-MTase core identify them as bi-substrate inhibitors of the viral MTase, co-occupying both the SAM and RNA binding sites; positing novel features that can be derivatized for increased potency and selectivity for SARS-CoV-2 nsp14. Taken together, the high-resolution structures and the accompanying biophysical and viral replication data provide a new avenue for developing analogs of SGC0946 and SGC8158 as antivirals.

Tumour-free distance from serosa is a better prognostic indicator than depth of invasion and percentage myometrial invasion in endometrioid endometrial cancer

OBJECTIVE

To evaluate the prognostic performance of tumour-free distance (TFD) compared with depth of invasion (DOI) and percentage of myometrial invasion (MI).

DESIGN

Retrospective cohort study.

SETTING

Regional gynaecological oncology centre.

POPULATION

All women identified with stage I-III endometrioid endometrial carcinoma from January 2000 to December 2007, who had surgery at the Northern Gynaecological Oncology Centre (NGOC).

METHODS

Surgicopathological, follow-up and survival data were collected. Univariate and multivariate analyses were performed comparing TFD, DOI and MI with known prognostic factors. The prognostic accuracy of TFD was assessed by receiver operating characteristic (ROC) curve analyses, and an optimum cut-off was proposed.

MAIN OUTCOME MEASURES

Death from disease, recurrence and pelvic lymph node involvement.

RESULTS

A total of 288 women were identified. The median follow-up time was 67 months, with 40 recurrences and 32 disease-related deaths. When TFD, DOI and MI were separately examined in multivariate analyses with other covariates, TFD was an independent predictor of death from disease (HR 1.22; 95% CI 1.00-1.48; P = 0.05). In multivariate analyses including all three measures together (TFD, DOI and MI), TFD was an independent predictor of death from disease (HR 1.49; 95% CI 1.03-2.16; P = 0.04) and recurrence (HR 1.39; 95% CI 1.01-1.91; P = 0.05). TFD was also an independent predictor of lymph node involvement when examined separately (OR 0.74; 95% CI 0.56-0.96; P = 0.03), and together with DOI and MI (OR 0.67; 95% CI 0.49-0.92; P = 0.01), in women who had pelvic lymphadenectomy (n = 86). A TFD cut-off of 1.75 mm showed good prognostic performance.

CONCLUSIONS

The TFD measure may be a more accurate method of representing myometrial invasion in the staging for endometrial cancer.

Conservative surgical management of small-volume stage IB1 cervical cancer

OBJECTIVE

To determine outcomes of women with small-volume stage IB1 disease managed by conservative surgical treatment.

DESIGN

A retrospective review.

SETTING

The Northern Gynaecological Oncology Center, Queen Elizabeth Hospital, Gateshead, UK.

POPULATION

Women with stage IB1 cervical cancer who were managed by conservative surgery over a 6-year period between 1 January 2000 and 31 December 2005.

MAIN OUTCOME MEASURES

Pelvic lymph node metastases, recurrence rates and outcome survival.

RESULTS

A total of 17 women with conservatively managed stage IB1 cervical cancer were identified. Their ages were 25-67 years, median 37 years, 4 women were nulliparous. All women presented with an abnormal screening smear showing at least severe dyskaryosis. Estimated tumour volumes ranged from 16 to 640 mm3, median 72 mm3. Four women showed multifocal invasion. All four nulliparous women and one parous woman underwent fertility-sparing treatment, i.e. loop cone +/- laparoscopic pelvic node dissection. The other 12 women underwent laparoscopic assisted vaginal hysterectomy/total abdominal hysterectomy +/- pelvic lymph node dissection. There were no cases of residual disease in any of the definitive treatment specimens. There were no cases of metastatic spread to pelvic lymph nodes. To date, no women have developed recurrent disease, and all women are alive and well (median follow up, 29 months).

CONCLUSIONS

The conservative surgical management of small-volume stage IB1 cases in this series showed an excellent outcome with no cases showing pelvic lymph node involvement and no cases developing recurrent disease. A more formal assessment of tumour volume with a more active approach to determining the third dimension will allow more women the option of conservative treatment, thereby minimising the adverse effects of radical surgery.

Very brief transient ischemic attack

TIA is an important risk factor for ischemic stroke. Early diagnosis and management can result in a significant reduction in the risk of subsequent stroke. We report the case of a 54-year-old man who developed a 5-second episode of leg weakness and in whom a tight stenosis of the appropriate carotid artery was found. TIAs can sometimes be brief and have an atypical presentation, requiring a high level of suspicion for early diagnosis.

Evidence for the induction of casein kinase II in bovine lymphocytes transformed by the intracellular protozoan parasite Theileria parva

Theileria parva is an obligate, intracellular, parasitic protozoan that causes East Coast fever, an acute leukemia-like disease of cattle. T. parva and the related parasite, Theileria annulata, are unique among protozoa in that their intralymphocytic stages induce transformation of bovid lymphocytes. Comparison of in vitro protein kinase activities between uninfected IL-2-dependent T lymphoblasts and T. parva-infected lymphocytes revealed a 4.7- to 12-fold increase in total phosphorylation and the induction of a group of Theileria infection-specific phosphoproteins. The enzyme that phosphorylates these substrates is a serine/threonine kinase with substrate and effector specificities of casein kinase (CK) II. Northern blot analyses revealed a 3.9- to 6.0-fold increase in CKII alpha mRNA in the infected cells relative to the controls. Furthermore, a marked increase of CKII antigen was observed on Western blots of materials prepared from the infected cell lines. The antibovine CKII antibody used in these studies immunoprecipitated a protein kinase that phosphorylated casein in a reaction that was inhibited by low (nM) quantities of heparin. Our data show marked increases of bovine CKII at the transcriptional, translational and functional levels in T. parva-infected lymphocytes, relative to quiescent cells or IL-2-dependent parental lymphoblasts. Bovine CKII thus appears to be constitutively activated in these cells and we propose that this kinase may be an important element in the signal-transducing pathways activated by Theileria in bovid lymphocytes and perhaps in some leukemic cells.

Massive osteolysis of the skull. Case report

✓ The authors describe a case of massive osteolysis of the calvaria. There are no previous reports of this rare entity involving the skull.

Epidermoid cyst of the pineal region

An epidermoid cyst in the pineal region is reported to underscore the feasibility of successful surgical excision of such lesions and the need to review the management of posterior third ventricular lesions. An interesting, but unexplained, feature in this patient was renal glycosuria which cleared after excision of the tumour.