Publications by authors named "Victor Mak"

The phosphoinositide-3 kinase (PI3K), a heterodimeric enzyme, plays a pivotal role in cellular metabolism and survival. Its deregulation is associated with major human diseases, particularly cancer. The p85 regulatory subunit of PI3K binds to the catalytic p110 subunit via its C-terminal domains, stabilising it in an inhibited state.

View Article and Find Full Text PDF

cGMP-dependent protein kinase I-α (PKG1α) is a target for pulmonary arterial hypertension due to its role in the regulation of smooth muscle function. While most work has focused on regulation of cGMP turnover, we recently described several small molecule tool compounds which were capable of activating PKG1α via a cGMP independent pathway. Selected molecules were crystallized in the presence of PKG1α and were found to bind to an allosteric site proximal to the low-affinity nucleotide binding domain.

View Article and Find Full Text PDF

The purpose of this study was to determine the impact of [F]FDG PET/CT on the initial staging, restaging, clinical management, and outcomes of patients with soft-tissue and bone sarcomas. This single-arm, prospective multicenter registry enrolled 304 patients with 320 [F]FDG PET/CT scans (November 2018 to October 2021). Eligibility included the initial staging of a grade 2 or higher or ungradable soft-tissue or bone sarcoma, with negative or equivocal findings for nodal or distant metastases on conventional imaging before curative-intent therapy, or restaging of patients with a history of treated sarcoma with a suspicion or confirmation of local recurrence or limited metastatic disease who were being considered for curative-intent or salvage therapy.

View Article and Find Full Text PDF

The formation of quaternary stereogenic centers convergent fragment coupling is a longstanding challenge in organic synthesis. Here, we report a strategy for the formation of quaternary stereogenic centers in polycyclic systems based upon the semi-pinacol reaction. In the key transformation, two fragments of a similar size and complexity are joined by a 1,2-addition of an alkenyl lithium to an epoxy ketone, and the resulting epoxy silyl ether undergoes a semi-pinacol rearrangement catalyzed by -(trimethylsilyl)bis(trifluoromethanesulfonyl)imide (TMSNTf) or trimethylsilyl trifluoromethanesulfonate (TMSOTf).

View Article and Find Full Text PDF

The insulin-like growth factor (IGF) axis plays important roles in cancer development and metastasis. The type 1 IGF receptor (IGF-1R) is a key member in the IGF axis and has long been recognized for its oncogenic role in multiple cancer lineages. Here we review the occurrence of IGF-1R aberrations and activation mechanisms in cancers, which justify the development of anti-IGF-1R therapies.

View Article and Find Full Text PDF

Recurrent deletion of 16q12.2 is observed in luminal breast cancer, yet the causal genomic alterations in this region are largely unknown. In this study, we identify that loss of AKTIP, which is located on 16q12.

View Article and Find Full Text PDF

Activation of PKG1α is a compelling strategy for the treatment of cardiovascular diseases. As the main effector of cyclic guanosine monophosphate (cGMP), activation of PKG1α induces smooth muscle relaxation in blood vessels, lowers pulmonary blood pressure, prevents platelet aggregation, and protects against cardiac stress. The development of activators has been mostly limited to cGMP mimetics and synthetic peptides.

View Article and Find Full Text PDF

Background The high positivity rate of prostate-specific membrane antigen (PSMA) PET in the setting of biochemical failure (BCF), even when conventional imaging is negative, is promising. Purpose To assess the disease detection rate of PSMA-based PET/CT with fluorine 18-DCFPyL as a radiotracer and the PET-directed management change in men with suspected limited recurrent prostate cancer. Materials and Methods This prospective multicenter registry (Ontario PSMA-PET Registry for Recurrent Prostate Cancer, or PREP) enrolled men with BCF after primary therapy (radical prostatectomy plus or minus salvage radiation therapy or primary radiation therapy) and zero to four disease sites at conventional imaging (CT and bone scintigraphy).

View Article and Find Full Text PDF

The C19 diterpenoid alkaloids (C19 DTAs) are a large family of natural products, many of which modulate the activity of ion channels and are therefore of interest for the study of neurological and cardiovascular diseases. The complex architectures of these molecules continue to challenge the state-of-the art in chemical synthesis, particularly with respect to efficient assembly of their polcyclic ring systems. Here, we report the total syntheses of (-)-talatisamine, (-)-liljestrandisine, and (-)-liljestrandinine, three aconitine-type C19 DTAs, using a fragment coupling strategy.

View Article and Find Full Text PDF

EGFR signaling promotes ovarian cancer tumorigenesis, and high EGFR expression correlates with poor prognosis. However, EGFR inhibitors alone have demonstrated limited clinical benefit for ovarian cancer patients, owing partly to tumor resistance and the lack of predictive biomarkers. Cotargeting EGFR and the PI3K pathway has been previously shown to yield synergistic antitumor effects in ovarian cancer.

View Article and Find Full Text PDF

Ovarian cancer remains the leading cause of gynecologic cancer-related deaths among women worldwide. The dismal survival rate is partially due to recurrence after standardized debulking surgery and first-line chemotherapy. In recent years, targeted therapies, including antiangiogenic agents or poly (ADP-ribose) polymerase inhibitors, represent breakthroughs in the treatment of ovarian cancer.

View Article and Find Full Text PDF

PIK3R2 encodes the p85β regulatory subunit of phosphatidylinositol 3-kinase and is frequently amplified in cancers. The signaling mechanism and therapeutic implication of p85β are poorly understood. Here we report that p85β upregulates the protein level of the receptor tyrosine kinase AXL to induce oncogenic signaling in ovarian cancer.

View Article and Find Full Text PDF

Copy number loss of PIK3R1 (p85α) most commonly occurs in ovarian cancer among all cancer types. Here we report that ovarian cancer cells manifest a spectrum of tumorigenic phenotypes upon knockdown of PIK3R1. PIK3R1 loss activates AKT and p110-independent JAK2/STAT3 signaling through inducing changes in the phosphorylation of the docking protein Gab2, thereby relieving the negative inhibition on AKT and promoting the assembly of JAK2/STAT3 signalosome, respectively.

View Article and Find Full Text PDF

Purpose To determine the relationship of PET/CT staging to the management and outcomes of participants with apparent limited-stage (LS) Hodgkin lymphoma (HL) or aggressive non-HL (ANHL) treated with curative intent. Materials and Methods This prospective multicenter registry included 850 participants (467 men and 383 women; median age, 54.1 years) from nine centers who had LS HL or ANHL on the basis of clinical data and CT, or with equivocal CT for advanced stage, who were considered for curative-intent first-line therapy.

View Article and Find Full Text PDF

Background: To measure the clinical impact of pretreatment fludeoxyglucose positron emission tomography/computed tomography (PET/CT) on the staging and management of apparent limited stage indolent lymphoma being considered for curative radiation therapy.

Methods: We conducted a prospective multicenter registry study that included 197 patients accrued between May 1, 2012, and December 31, 2015. Pre-PET/CT stage, determined by clinical and CT data, was documented.

View Article and Find Full Text PDF

Significant progress has been made in the management of aggressive prostate cancer. The established old and new treatments have resulted in the significant delay in progression of disease, improvement of the quality of life, as well as the increase in the overall survival of men with advanced prostate cancer. However, these therapies carry with them possible adverse effects that primary care physicians are experienced in managing.

View Article and Find Full Text PDF

Human placental trophoblasts can be considered pseudomalignant, with tightly controlled proliferation, apoptosis, and invasiveness. Gestational trophoblastic disease (GTD) represents a family of heterogeneous trophoblastic lesions with aberrant apoptotic and proliferative activities and dysregulation of cell signaling pathways. We characterize the oncogenic effects of factor that binds to the inducer of short transcripts of HIV-1 [FBI-1, alias POZ and Krüppel erythroid myeloid ontogenic factor (POKEMON)/ZBTB7A] in GTD and its role in promoting cell aggressiveness in vitro and tumor growth in vivo.

View Article and Find Full Text PDF

The first total syntheses of (-)-trichorabdal A and (-)-longikaurin E are reported. A unified synthetic strategy is employed that relies on a Pd-mediated oxidative cyclization of a silyl ketene acetal to generate an all-carbon quaternary center and build the bicyclo[3.2.

View Article and Find Full Text PDF

Gestational choriocarcinoma is a malignant tumor derived from placental trophoblast and the most aggressive member of gestational trophoblastic disease (GTD). Apoptosis-stimulating protein of p53-2 (ASPP2) is a member of ASPP family that transactivates p53 and thereby functions as a tumor suppressor. In this study, the expression profile of ASPP2 in choriocarcinoma was examined in comparison with normal placentas and hydatidiform moles, the latter being a type of GTD that carries malignant potential.

View Article and Find Full Text PDF

Quantum mechanical calculations have been used to investigate type 2 intramolecular N-acylnitroso Diels-Alder reactions. Experimentally observed regioselectivities and diastereoselectivities of these reactions have been reproduced using B3LYP/6-31+G(d) DFT calculations. The factors that govern selectivity (i.

View Article and Find Full Text PDF

In recent years, much attention has been paid to the concept of cancer stem cells (CSC) and self-renewal related pathways in cancer biology. This review outlines the dysregulated stemness-related genes or transcription factors in gynecological cancers. Hedgehog (Hh) and Notch signaling are important pathways in tissue pattern programming and cell fate determination during embryonic development.

View Article and Find Full Text PDF