A Pilot Study for Discovering Candidate Genes of Chromosome 18q21 in Methamphetamine Abusers: Case-control Association Study

A review of non-classical MAPK family member, MAPK4: A pivotal player in cancer development and therapeutic intervention

Mitogen-Activated Protein Kinases (MAPKs) are serine/threonine protein kinases that play a crucial role in transmitting extracellular signals to the intracellular environment, influencing a wide range of cellular processes including proliferation, differentiation, apoptosis, metabolic activities, immune function and stress response. MAPK4, a non-classical MAPK, is frequently overexpressed in various malignancies, including prostate, breast, cervix, thyroid, and gliomas. It orchestrates cell proliferation, migration, and apoptosis via the AKT/mTOR and/or PDK1 signaling pathways, thus facilitating tumor cell growth. Furthermore, MAPK4 expression is closely associated with the effectiveness of specific inhibitors like PI3K and PARP1, and also correlate with the survival rates of cancer patients. Increasing evidence highlights MAPK4's involvement in the tumor microenvironment, modulating immune response and inflammation-related diseases. This review comprehensively explores the structure, function, and oncogenic role of MAPK4, providing a deeper understanding of its activation and mechanisms of action in tumorigenesis, which might be helpful for the development of innovative therapeutic strategies for cancer management.

Familial Early-Onset Alzheimer's Caused by Novel Genetic Variant and APP Duplication: A Cross-Sectional Study

BACKGROUND

The clinical characteristics of symptomatic and asymptomatic carriers of early- onset autosomal dominant Alzheimer's (EOADAD) due to a yet-undescribed chromosomal rearrangement may add to the available body of knowledge about Alzheimer's disease and may enlighten novel and modifier genes. We report the clinical and genetic characteristics of asymptomatic and symptomatic individuals carrying a novel APP duplication rearrangement.

METHODS

Individuals belonging to a seven-generation pedigree with familial cognitive decline or intracerebral hemorrhages were recruited. Participants underwent medical, neurological, and neuropsychological evaluations. The genetic analysis included chromosomal microarray, Karyotype, fluorescence in situ hybridization, and whole genome sequencing.

RESULTS

Of 68 individuals, six females presented with dementia, and four males presented with intracerebral hemorrhage. Of these, nine were found to carry Chromosome 21 copy number gain (chr21:27,224,097-27,871,284, GRCh37/hg19) including the APP locus (APP-dup). In seven, Chromosome 5 copy number gain (Chr5: 24,786,234-29,446,070, GRCh37/hg19) (Chr5-CNG) cosegregated with the APP-dup. Both duplications co-localized to chromosome 18q21.1 and segregated in 25 pre-symptomatic carriers. Compared to non-carriers, asymptomatic carriers manifested cognitive decline in their mid-thirties. A third of the affected individuals carried a diagnosis of a dis-immune condition.

CONCLUSION

APP extra dosage, even in isolation and when located outside chromosome 21, is pathogenic. The clinical presentation of APP duplication varies and may be gender specific, i.e., ICH in males and cognitive-behavioral deterioration in females. The association with immune disorders is presently unclear but may prove relevant. The implication of Chr5-CNG co-segregation and the surrounding chromosome 18 genetic sequence needs further clarification.

MAPK4 silencing together with a PARP1 inhibitor as a combination therapy in triple‑negative breast cancer cells

Triple‑negative breast cancer (TNBC) is the most common type of cancer among females worldwide and is associated with poor prognosis. Poly ADP‑ribose polymerase‑1 (PARP1) inhibitors are effective against TNBC with mutations in the breast cancer type 1 susceptibility protein (BRCA1) and/or BRCA2 genes; however, the development of resistance to PARP1 inhibitors limits their use. Thus, identifying strategies to overcome this resistance is urgently required. The aim of the present study was to investigate the potential function and mechanism of small interfering (si)RNA‑MAPK4 (siMAPK4) in enhancing the efficacy of a PARP1 inhibitor and reducing the resistance. In the present study, data on the mRNA expression level of MAPK4 in normal breast tissues and TNBC tissues were obtained from The Cancer Genome Atlas database. The mRNA and protein expression levels of MAPK4 in normal breast cells and TNBC cells were analyzed using reverse transcription‑quantitative PCR and western blotting, respectively. The phosphorylated (p) histone H2AX (γH2AX) protein expression was assessed via immunofluorescence. Cell Counting Kit‑8, wound healing and TUNEL assays were used to determine the proliferative, migratory and apoptotic abilities of HCC1937 cells. MAPK4 was highly expressed in TNBC patient tissues and cell lines. Moreover, overexpression of MAPK4 could promote HCC1937 cell proliferation. Treatment of HCC1937 cells with the combination of siMAPK4 and a PARP1 inhibitor olaparib decreased their proliferation and migration and increased their apoptosis. The protein expression levels of the DNA repair‑related proteins p‑DNA‑dependent protein kinase catalytic subunit (DNA‑PK) and RAD51 recombinase (RAD51) were inhibited in the siMAPK4 and siMAPK4 + olaparib groups. However, the marker of a double‑stranded break γH2AX showed increased protein expression in the siMAPK4 + olaparib group. As MAPK4 could phosphorylate AKT at threonine 308 (AKTT308), the current study restored p‑AKT^T308 using a constitutively active AKT plasmid (AKT‑CA). p‑DNA‑PK and RAD51 showed high expression and γH2AX exhibited lower protein expression in the AKT‑CA group. The present findings suggested that siMAPK4 can enhance the sensitivity of TNBC cells to PARP1 inhibitors.

Heritability, SNP- and Gene-Based Analyses of Cannabis Use Initiation and Age at Onset

Prior searches for genetic variants (GVs) implicated in initiation of cannabis use have been limited to common single nucleotide polymorphisms (SNPs) typed in HapMap samples. Denser SNPs are now available with the completion of the 1000 Genomes and the Genome of the Netherlands projects. More densely distributed SNPs are expected to track the causal variants better. Therefore we extend the search for variants implicated in early stages of cannabis use to previously untagged common and low-frequency variants. We run heritability, SNP and gene-based analyses of initiation and age at onset. This is the first genome-wide study of age at onset to date. Using GCTA and a sample of distantly related individuals from the Netherlands Twin Register, we estimated that the currently measured (and tagged) SNPs collectively explain 25 % of the variance in initiation (SE = 0.088; P = 0.0016). Chromosomes 4 and 18, previously linked with cannabis use and other addiction phenotypes, account for the largest amount of variance in initiation (6.8 %, SE = 0.025, P = 0.002 and 3.6 %, SE = 0.01, P = 0.012, respectively). No individual SNP- or gene-based test reached genomewide significance in the initiation or age at onset analyses. Our study detected association signal in the currently measured SNPs. A comparison with prior SNP-heritability estimates suggests that at least part of the signal is likely coming from previously untyped common and low frequency variants. Our results do not rule out the contribution of rare variants of larger effect—a plausible source of the difference between the twin-based heritability estimate and that from GCTA. The causal variants are likely of very small effect (i.e., <1 % explained variance) and are uniformly distributed over the genome in proportion to chromosomes’ length. Similar to other complex traits and diseases, detecting such small effects is to be expected in sufficiently large samples.