Young female patients with multiple myeloma have low occurrence of osteolytic lesion

MAST4 promotes primary ciliary resorption through phosphorylation of Tctex-1

The primary cilium undergoes cell cycle-dependent assembly and disassembly. Dysregulated ciliary dynamics are associated with several pathological conditions called ciliopathies. Previous studies showed that the localization of phosphorylated Tctex-1 at Thr94 (T94) at the ciliary base critically regulates ciliary resorption by accelerating actin remodeling and ciliary pocket membrane endocytosis. Here, we show that microtubule-associated serine/threonine kinase family member 4 (MAST4) is localized at the primary cilium. Suppressing MAST4 blocks serum-induced ciliary resorption, and overexpressing MAST4 accelerates ciliary resorption. Tctex-1 binds to the kinase domain of MAST4, in which the R503 and D504 residues are key to MAST4-mediated ciliary resorption. The ciliary resorption and the ciliary base localization of phospho-(T94)Tctex-1 are blocked by the knockdown of MAST4 or the expression of the catalytic-inactive site-directed MAST4 mutants. Moreover, MAST4 is required for Cdc42 activation and Rab5-mediated periciliary membrane endocytosis during ciliary resorption. These results support that MAST4 is a novel kinase that regulates ciliary resorption by modulating the ciliary base localization of phospho-(T94)Tctex-1. MAST4 is a potential new target for treating ciliopathies causally by ciliary resorption defects.

Microtubule-Associated Serine/Threonine (MAST) Kinases in Development and Disease

Microtubule-Associated Serine/Threonine (MAST) kinases represent an evolutionary conserved branch of the AGC protein kinase superfamily in the kinome. Since the discovery of the founding member, MAST2, in 1993, three additional family members have been identified in mammals and found to be broadly expressed across various tissues, including the brain, heart, lung, liver, intestine and kidney. The study of MAST kinases is highly relevant for unraveling the molecular basis of a wide range of different human diseases, including breast and liver cancer, myeloma, inflammatory bowel disease, cystic fibrosis and various neuronal disorders. Despite several reports on potential substrates and binding partners of MAST kinases, the molecular mechanisms that would explain their involvement in human diseases remain rather obscure. This review will summarize data on the structure, biochemistry and cell and molecular biology of MAST kinases in the context of biomedical research as well as organismal model systems in order to provide a current profile of this field.

A 3D-printed orthopedic implant with dual-effect synergy based on MoS2 and hydroxyapatite nanoparticles for tumor therapy and bone regeneration

Treatments for malignant bone tumors are urgently needed to be developed due to the dilemma of precise resection of tumor tissue and subsequent bone defects. Although polyether-ether-ketone (PEEK) has widely attracted attention in the orthopedic field, its bioinertness and poor osteogenic properties significantly restrict its applications in bone tumor treatment. To tackle the daunting issue, we use a hydrothermal technique to fabricate novel PEEK scaffolds modified with molybdenum disulfide (MoS₂) nanosheets and hydroxyapatite (HA) nanoparticles. Our dual-effect synergistic PEEK scaffolds exhibit perfect photothermal therapeutic (PTT) property dependent on molybdous ion (Mo²⁺) concentration and laser power density, superior to conventional PEEK scaffolds. Under near-infrared (NIR) irradiation, the viability of MG63 osteosarcoma cells is significantly reduced by modified PEEK scaffolds, indicating a tumor-killing potential in vitro. Furthermore, the incorporation of HA nanoparticles on the surface of PEEK bolsters proliferation and adherence of MC3T3-E1 cells, boosting mineralization for further bone defect repair. The results of micro-computed tomography (micro-CT) and histological analysis of 4-week treated rat femora demonstrate the preeminent photothermal and osteogenesis capacity of 3D-printed modified scaffolds in vivo. In conclusion, the dual-effect synergistic orthopedic implant with photothermal anticancer property and osteogenic induction activity strikes a balance between tumor treatment and bone development promotion, offering a promising future therapeutic option.

Estrogen-Responsive Gene MAST4 Regulates Myeloma Bone Disease

Our previous data showed that young female multiple myeloma (MM) patients had a low frequency of osteolytic lesions. Based on this clinical observation, we found that estrogen cell signaling played a regulatory role in MM bone disease (MMBD), and the estrogen-responsive gene microtubule-associated serine/threonine kinase family member 4 (MAST4) was a critical factor. The presence of estrogen in cell cultures promoted MAST4 expression in MM cells, while knocking down estrogen receptor 1 (ESR1) inhibited MAST4 expression. Chromatin immunoprecipitation assay suggested a binding site of ESR1 on the MAST4 promoter. Bisphosphonates, such as zoledronic acid (ZOL), which was widely used in MMBD control, could stimulate MAST4 expression in MM cells by promoting ESR1 expression. MAST4 interacted with phosphatase and tensin homolog (PTEN), therefore regulating the PI3K-Akt-mTOR pathway and the expression of downstream cytokines, such as CCL2/3/4. MAST4 knockdown (MAST4-KD) or ESR1 knockdown (ESR1-KD) MM cells had repressed PTEN activity, elevated PI3K-Akt-mTOR activity, and increased CCL2/3/4 expressions. Coculture of MAST4-KD or ESR1-KD MM cells with pre-osteoclasts (pre-OCs) stimulated OC formation in vitro, whereas neutralizing antibodies of CCL2/3/4 attenuated such stimulation. In mouse models, mice inoculated with MAST4-KD or ESR1-KD MM cells had severer MMBD than control knockdown (CTR-KD). The correlations between MAST4 and ESR1 expressions in MMBD, as well as related cell signaling pathways, were confirmed in analyses using gene expression profiles (GEPs) of patients' MM cells. The negative correlation of MAST4 expression and occurrence of MMBD was further validated by patients' immunohistochemical tissue array. Overall, our data suggested that estrogen cell signaling negatively regulated MMBD through MAST4. © 2022 American Society for Bone and Mineral Research (ASBMR).

Intratumor Heterogeneity of MIF Expression Correlates With Extramedullary Involvement of Multiple Myeloma

Macrophage migration inhibitory factor (MIF) has been shown to promote disease progression in many malignancies, including multiple myeloma (MM). We previously reported that MIF regulates MM bone marrow homing and knockdown of MIF favors the extramedullary myeloma formation in mice. Here, based on MIF immunostaining of myeloma cells in paired intramedullary and extramedullary biopsies from 17 patients, we found lower MIF intensity in extramedullary MM (EMM) versus intramedullary MM (IMM). Flow cytometry and histology analysis in xenograft models showed a portion of inoculated human MM cells lost their MIF expression (MIF^Low) in vivo. Of note, IMM had dominantly MIF^High cells, while EMM showed a significantly increased ratio of MIF^Low cells. Furthermore, we harvested the extramedullary human MM cells from a mouse and generated single-cell transcriptomic data. The developmental trajectories of MM cells from the MIF^High to MIF^Low state were indicated. The MIF^High cells featured higher proliferation. The MIF^Low ones were more quiescent and harbored abundant ribosomal protein genes. Our findings identified in vivo differential regulation of MIF expression in MM and suggested a potential pathogenic role of MIF in the extramedullary spread of disease.

Distribution of multiple myeloma in India: Heterogeneity in incidence across age, sex and geography

BACKGROUND

This study aimed to investigate the distribution of multiple myeloma (MM) in India and provide a comprehensive narrative about its incidence, including differential patterns across age, sex and geography.

METHODS

MM cases diagnosed during 2012-14 were obtained from 27 populations based cancer registries in India by consulting the latest National Cancer Registry Programme reports. Crude (CR) and age-specific (ASR) rates of MM incidence were determined. Age-adjusted rates (AARs) were estimated by standardizing the CR values using age-specific weights recommended for LMIC countries (including India) for men and women separately, along with the corresponding 95% confidence interval (95% CI) measures.

RESULTS

Altogether, 1916 MM cases (male/female: 1123/793) were documented (i.e. 1.19% of all cancers, 95% CI: 1.14-1.24%). Overall CR of MM in India was 1.27 (95% CI: 1.20-1.35)/ 100,000 in men and 0.95 (95% CI: 0.89-1.02)/ 100,000 in women, while the corresponding AARs were 1.13 (95% CI: 1.07-1.20) and 0.81 (95% CI: 0.75 - 0.88) per 100,000 respectively. The ASR values increased steadily with age. Most cases belonged to the 60-69 yrs bracket. However, regional and sex-specific differences in MM profile were observed. MM incidence was highest in the Southern and Northern zones, and least in the Northeast. The Northern and Central zones had higher proportion of MM in the 50-59 yrs age group, whereas Eastern zone had higher proportion of cases aged 70 yrs and above.

CONCLUSION

Incidence of MM in India is presented. Marked variations in MM incidence were noted with respect to age, sex and geography.