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some steroid hormone-induced nuclear events can occur in minutes

the genomic effects of steroid hormones take longer, with changes in gene expression occurring on the timescale of hours

Classical steroid hormone signaling occurs when hormone binds nuclear receptors (NR) in the cytoplasm, setting off a chain of genomic events that results in, among other changes, dimerization and translocation to the nucleus where the ligand-bound receptor forms a complex with coregulators to modulate gene transcription through direct interactions with a hormone response element (HRE)

NRs have been found at the plasma membrane of cells, where they can propagate signal transduction often through kinase pathways

Membrane-localized ER, PR and AR have been reported to modulate the activity of MAPK/ERK, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), nitric oxide (NO), PKC, calcium flux and increase inositol triphosphate (IP3) levels to promote cell processes including autophagy, proliferation, apoptosis, survival, differentiation, and vasodilation

ERα36, a 36kDa truncated form of ERα that lacks the transcriptional activation domains of the full-length protein. Membrane-localized ERα36 can activate pathways including protein kinase C (PKC) and/or mitogen activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) to promote the progression of various cancers

G protein-coupled receptor 30 (GPR30), also referred to as G protein-coupled estrogen receptor (GPER), is a membrane-localized receptor that has been observed to respond to estrogen to activate rapid signaling

hormone-responsive G protein coupled receptor is Zip9, which androgens can activate

GPRC6A is another G protein-coupled membrane receptor that is responsive to androgen

androgen-mediated non-genomic signaling through this GPCR can modulate male fertility, hormone secretion and prostate cancer progression

non-NR proteins located at the cell surface can bind to steroid hormones and respond by eliciting rapid signaling events

Estrogens have been shown to induce rapid (i.e. seconds) calcium flux via membrane-localized ER (mER)

ER-calcium dynamics lead to activation of kinase pathways such as MAPK/ERK which can result in cellular effects like migration and proliferation

17β-estradiol (E2) has been reported to promote angiogenesis through the activation of GPER

Membrane NRs may also mediate rapid signaling through crosstalk with growth factor receptors (GFR)

A similar crosstalk occurs between the receptor tyrosine kinase insulin-related growth factor-1 receptor (IGF-IR) and ERα. Not only does IGF-IR activate ERα, but inhibition of IGF-IR downregulates estrogen-mediated ERα activity, suggesting that IGF-IR is essential for maximal ERα signaling

Further, ER activates IGF-IR pathways including MAPK

GPER is involved in the transactivation of the EGFR independent of classical ER

tight interconnection between genomic and non-genomic effects of NRs.

non-genomic pathways can also lead to genomic effects

androgen-bound AR associates with the kinase Src at the plasma membrane, activating Src which then leads to a signaling cascade through MAPK/ERK

However, Src can also increase the expression of AR target genes by the ligand-independent transactivation of AR

extranuclear steroid hormone actions can potentially reprogram nuclear NR events

estrogen modulated the expression of several genes including endothelial nitric oxide synthase (eNOS) via rapid signaling pathways

epigenetic changes can then mediate genomic events in uterine tissue and breast cancer cells

bone marrow suppression

cardiomyopathy

irreversible retinal toxicity

hypoglycaemia

daily doses up to 400 mg of HCQ or 250 mg CQ for several years are considered to carry an acceptable risk for CQ-induced retinopathies, with the exception of individuals of short stature

chronic CQ or HCQ therapy be monitored through regular ophthalmic examinations (3–6 month intervals), full blood counts and blood glucose level checks

long-term HCQ exposure, skeletal muscle function and tendon reflexes should be monitored for weakness

both CQ and HCQ, specific caution is advised in patients suffering from impaired hepatic function (especially when associated with cirrhosis), porphyria, renal disease, epilepsy, psoriasis, glucose-6-phosphate dehydrogenase deficiency and known hypersensitivity to 4-aminoquinoline compounds

CQ and HCQ can effectively increase the efficacy of various anti-cancer drugs

CQ can prevent the entrapment of protonated chemotherapeutic drugs by buffering the extracellular tumour environment and intracellular acidic spaces

This study recommends an adjuvant HCQ dose of 600 mg, twice daily.

HCQ addition was shown to produce metabolic stress in the tumours

HCQ (400 mg/day)

important effects of CQ and HCQ on the tumour microenvironment

The main and most studied anti-cancer effect of CQ and HCQ is the inhibition of autophagy

the expression levels of TLR9 are higher in hepatocellular carcinoma, oesophageal, lung, breast, gastric and prostate cancer cells as compared with adjacent noncancerous cells, and high expression is often linked with poor prognosis

TLR9-mediated activation of the NF-κB signalling pathway and the associated enhanced expression of matrix metalloproteinase-2 (MMP-2), MMP-7 and cyclo-oxygenase 2 mRNA

HCQ can activate caspase-3 and modulate the Bcl-2/Bax ratio inducing apoptosis in CLL, B-cell CLL and glioblastoma cells

In triple-negative breast cancer, CQ was shown to eliminate cancer stem cells through reduction of the expression of Janus-activated kinase 2 and DNA methyl transferase 1 [106] or through induction of mitochondrial dysfunction, subsequently causing oxidative DNA damage and impaired repair of double-stranded DNA breaks

CQ or HCQ would be considered for use in combination with immunomodulation anti-cancer therapies

Therapies used in combination with CQ or HCQ include chemotherapeutic drugs, tyrosine kinase inhibitors, various monoclonal antibodies, hormone therapies and radiotherapy

Most studies hypothesise that CQ and HCQ could increase the efficacy of other anti-cancer drugs by blocking pro-survival autophagy.

daily doses between 400 and 1200 mg for HCQ are safe and well tolerated, but two studies identified 600-mg HCQ daily as the MTD

HCQ is often administered twice daily to limit plasma fluctuations and toxicity