MASTL regulates EGFR signaling to impact pancreatic cancer progression

IL-22 regulates MASTL expression in intestinal epithelial cells

Microtubule-associated serine-threonine kinase-like (MASTL) has recently been identified as an oncogenic kinase given its overexpression in numerous cancers. Our group has shown that MASTL expression is upregulated in mouse models of sporadic colorectal cancer and colitis-associated cancer (CAC). CAC is one of the most severe complications of chronic inflammatory bowel disease (IBD), but a limited understanding of the mechanisms governing the switch from normal healing to neoplasia in IBD underscores the need for increased research in this area. However, MASTL levels in patients with IBD and its molecular regulation in IBD and CAC have not been studied. This study reveals that MASTL is upregulated by the cytokine interleukin (IL)-22, which promotes proliferation and has important functions in colitis recovery; however, IL-22 can also promote tumorigenesis when chronically elevated. Upon reviewing the publicly available data, we found significantly elevated MASTL and IL-22 levels in the biopsies from patients with late-stage ulcerative colitis compared with controls, and that MASTL upregulation was associated with high IL-22 expression. Our subsequent in vitro studies found that IL-22 increases MASTL expression in intestinal epithelial cell lines, which facilitates IL-22-mediated cell proliferation and downstream survival signaling. Inhibition of AKT activation abrogated IL-22-induced MASTL upregulation. We further found an increased association of carbonic anhydrase IX (CAIX) with MASTL in IL-22-treated cells, which stabilized MASTL expression. Inhibition of CAIX prevented IL-22-induced MASTL expression and cell survival. Overall, we show that IL-22/AKT signaling increases MASTL expression to promote cell survival and proliferation. Furthermore, CAIX associates with and stabilizes MASTL in response to IL-22 stimulation.NEW & NOTEWORTHY MASTL is upregulated in colorectal cancer; however, its role in colitis and colitis-associated cancer is poorly understood. This study is the first to draw a link between MASTL and IL-22, a proinflammatory/intestinal epithelial recovery-promoting cytokine that is also implicated in colon tumorigenesis. We propose that IL-22 increases MASTL protein stability by promoting its association with CAIX potentially via AKT signaling to promote cell survival and proliferation.

Protein kinase inhibitors in the management of cancer: therapeutic opportunities from natural compounds

Kinase is an enzyme that helps in the phosphorylation of the targeted molecules and can affect their ability to react with other molecules. So, kinase influences metabolic reactions like cell signaling, secretory processes, transport of molecules, etc. The increased activity of certain kinases may cause various types of cancer, i.e. leukemia, glioblastoma, and neuroblastomas. So, the growth of particular cancer cells can be prevented by the inhibition of the kinase responsible for those cancers. Natural products are the key resources for the development of new drugs where approximately 60% of anti-tumor drugs are being developed with the same including specific kinase dwellers. This study comprised molecular interactions of various molecules (obtained from natural sources) as kinase inhibitors for the treatment of cancer. It is expected that by analyzing the skeleton behavior, the process of action, and the body-related activity of these organic products, new cancer-avoiding molecules can be developed.

Albendazole inhibits colon cancer progression and therapy resistance by targeting ubiquitin ligase RNF20

BACKGROUND

The repurposing of FDA-approved drugs for anti-cancer therapies is appealing due to their established safety profiles and pharmacokinetic properties and can be quickly moved into clinical trials. Cancer progression and resistance to conventional chemotherapy remain the key hurdles in improving the clinical management of colon cancer patients and associated mortality.

METHODS

High-throughput screening (HTS) was performed using an annotated library of 1,600 FDA-approved drugs to identify drugs with strong anti-CRC properties. The candidate drug exhibiting most promising inhibitory effects in in-vitro studies was tested for its efficacy using in-vivo models of CRC progression and chemoresistance and patient derived organoids (PTDOs).

RESULTS

Albendazole, an anti-helminth drug, demonstrated the strongest inhibitory effects on the tumorigenic potentials of CRC cells, xenograft tumor growth and organoids from mice. Also, albendazole sensitized the chemoresistant CRC cells to 5-fluorouracil (5-FU) and oxaliplatin suggesting potential to treat chemoresistant CRC. Mechanistically, Albendazole treatment modulated the expression of RNF20, to promote apoptosis in CRC cells by delaying the G2/M phase and suppressing anti-apoptotic-Bcl2 family transcription.

CONCLUSIONS

Albendazole, an FDA approved drug, carries strong therapeutic potential to treat colon cancers which are aggressive and potentially resistant to conventional chemotherapeutic agents. Our findings also lay the groundwork for further clinical testing.

LHPP suppresses proliferation, migration, and invasion in hepatocellular carcinoma and pancreatic cancer by inhibiting EGFR signaling pathway

Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) has been reported to be a new tumor suppressor with a significant inhibitory effect in various cancers. Although LHPP has been repeatedly shown to inhibit the progression of various tumors by inhibiting the phosphorylation of AKT, up to now, the studies on the function and mechanism of LHPP in tumors are insufficient. In this study, LHPP expression was found to be downregulated in both hepatocellular carcinoma (HCC) and pancreatic cancer (PC). Here, we found that LHPP could bind to epidermal growth factor receptor (EGFR) and inhibit its phosphorylation, which thereby inhibited the activation of EGFR downstream pathways ERK, AKT, and STAT3, and then weakening the ability to proliferate, invade, and migrate in HCC and PC. This paper showed a new physiological function of LHPP in inhibiting phosphorylation of EGFR and its potential anti-tumor mechanism and indicated that LHPP was a potential therapeutic target for HCC and PC.

Identification and characterization of a first-generation inhibitor of claudin-1 in colon cancer progression and metastasis

Colorectal cancer (CRC) is a leading cause of the cancer-related deaths worldwide. Thus, developing novel and targeted therapies for inhibiting CRC progression and metastasis is urgent. Several studies, including ours, have reported a causal role for an upregulated claudin-1 expression in promoting CRC metastasis through the activation of the Src and β-catenin-signaling. In murine models of colon tumorigenesis, claudin-1 overexpression promotes oncogenic properties such as transformation and invasiveness. Conversely, the downregulation of claudin-1 inhibits colon tumorigenesis. Despite being a desirable target for cancer treatment, there are currently no known claudin-1 inhibitors with antitumor efficacy. Using a rigorous analytical design and implementing in- vitro and in-vivo testing and a brief medicinal chemistry campaign, we identified a claudin-1-specific inhibitor and named it I-6. Despite its high potency, I-6 was rapidly cleared in human liver microsomes. We, therefore, synthesized I-6 analogs and discovered a novel small molecule, PDS-0330. We determined that PDS0330 inhibits claudin-1-dependent CRC progression without exhibiting toxicity in in-vitro and in-vivo models of CRC and that it binds directly and specifically to claudin-1 with micromolar affinity. Further analyses revealed that PDS-0330 exhibits antitumor and chemosensitizer activities with favorable pharmacokinetic properties by inhibiting the association with metastatic oncogene Src. Overall, our data propose that PDS-0330 interferes with claudin-1/Src association to inhibit CRC progression and metastasis. Our findings are of direct clinical relevance and may open new therapeutic opportunities in colon cancer treatment and/or management by targeting claudin-1.

Harnessing transcriptionally driven chromosomal instability adaptation to target therapy-refractory lethal prostate cancer

Metastatic prostate cancer (PCa) inevitably acquires resistance to standard therapy preceding lethality. Here, we unveil a chromosomal instability (CIN) tolerance mechanism as a therapeutic vulnerability of therapy-refractory lethal PCa. Through genomic and transcriptomic analysis of patient datasets, we find that castration and chemotherapy-resistant tumors display the highest CIN and mitotic kinase levels. Functional genomics screening coupled with quantitative phosphoproteomics identify MASTL kinase as a survival vulnerability specific of chemotherapy-resistant PCa cells. Mechanistically, MASTL upregulation is driven by transcriptional rewiring mechanisms involving the non-canonical transcription factors androgen receptor splice variant 7 and E2F7 in a circuitry that restrains deleterious CIN and prevents cell death selectively in metastatic therapy-resistant PCa cells. Notably, MASTL pharmacological inhibition re-sensitizes tumors to standard therapy and improves survival of pre-clinical models. These results uncover a targetable mechanism promoting high CIN adaptation and survival of lethal PCa.

Saikosaponin-A Exhibits Antipancreatic Cancer Activity by Targeting the EGFR/PI3K/Akt Pathway

BACKGROUND

A diagnosis of pancreatic cancer is pretty grim. Saikosaponin-A (SSA) is a Chinese herbal extract with anticancer activity. However, the therapeutic effect of SSA on pancreatic cancer remains elusive.

AIM

The study aims to evaluate the antitumor effects of SSA on pancreatic cancer cells in vitro and in vivo.

METHODS

After treatment with SSA, cell viability was measured using the CCK-8 assay, DAPI staining was performed to analyze the effect on nuclear morphology, propidium iodide (PI) staining was used to detect the cell cycle, and Annexin V/PI double staining was conducted to analyze apoptosis. Then, the expression of apoptosis-related proteins and EGFR/PI3K/Akt pathway-related proteins was determined using western blotting. The binding of SSA to EGFR was analyzed by performing molecular docking. The mouse pancreatic cancer model was established by subcutaneously injecting pancreatic cancer cells, and after 30 days of SSA gavage, the tumor volume was calculated. Tumor tissue sections were subjected to Ki67 immunohistochemical staining and HE staining.

RESULTS

SSA inhibited the proliferation of pancreatic cancer cells. As the concentration of SSA increased, the proportions of BxPC-3 and MIA PaCa-2 cells in the G0/G1 phase increased, the proportions of early and late apoptotic cells also increased, and the apoptosis rate gradually increased. Apoptosis inhibitor experiments indicated that SSA promoted the activation of caspase 3 to induce apoptosis in pancreatic cancer cells. In addition, SSA treatment significantly reduced the levels of phosphorylated EGFR, Akt, and PI3K in the two cell lines. Molecular docking results showed that SSA may have potential binding sites in EGFR. Results of the xenograft experiment confirmed the antitumor effects of SSA, as evidenced by the decreased tumor weight and downregulated expression of Ki67.

CONCLUSION

The results revealed that SSA exerted inhibitory effects on pancreatic cancer cells. These effects may be related to the inactivation of the EGFR/PI3K/Akt signalling pathway.

The MASTL-ENSA-PP2A/B55 axis modulates cisplatin resistance in oral squamous cell carcinoma

Platinum-based chemotherapy is the standard first-line treatment for oral squamous cell carcinoma (OSCC) that is inoperable, recurrent, or metastatic. Platinum sensitivity is a major determinant of patient survival in advanced OSCC. Here, we investigated the involvement of MASTL, a cell cycle kinase that mediates ENSA/ARPP19 phosphorylation and PP2A/B55 inhibition, in OSCC therapy. Interestingly, upregulation of MASTL and ENSA/ARPP19, and downregulation of PP2A/B55, were common in OSCC. MASTL expression was in association with poor patient survival. In established OSCC cell lines, upregulation of MASTL and ENSA, and downregulation of B55 genes, correlated with cisplatin resistance. We further confirmed that stable expression of MASTL in OSCC cells promoted cell survival and proliferation under cisplatin treatment, in an ENSA-dependent manner. Conversely, deletion of MASTL or ENSA, or overexpression of B55α, sensitized cisplatin response, consistent with increased DNA damage accumulation, signaling, and caspase activation. Moreover, GKI-1, the first-in-class small molecule inhibitor of MASTL kinase, phenocopied MASTL depletion in enhancing the outcome of cisplatin treatment in OSCC cells, at a dose substantially lower than that needed to disrupt mitotic entry. Finally, GKI-1 exhibited promising efficacy in a mouse tumor xenograft model, in conjunction with cisplatin therapy.

SILAC kinase screen identifies potential MASTL substrates

Microtubule-associated serine/threonine kinase-like (MASTL) has emerged as a critical regulator of mitosis and as a potential oncogene in a variety of cancer types. To date, Arpp-19/ENSA are the only known substrates of MASTL. However, with the roles of MASTL expanding and increased interest in development of MASTL inhibitors, it has become critical to determine if there are additional substrates and what the optimal consensus motif for MASTL is. Here we utilized a whole cell lysate in vitro kinase screen combined with stable isotope labelling of amino acids in cell culture (SILAC) to identify potential substrates and the residue preference of MASTL. Using the related AGC kinase family members AKT1/2, the kinase screen identified several known and new substrates highly enriched for the validated consensus motif of AKT. Applying this method to MASTL identified 59 phospho-sites on 67 proteins that increased in the presence of active MASTL. Subsequent in vitro kinase assays suggested that MASTL may phosphorylate hnRNPM, YB1 and TUBA1C under certain in vitro conditions. Taken together, these data suggest that MASTL may phosphorylate several additional substrates, providing insight into the ever-increasing biological functions and roles MASTL plays in driving cancer progression and therapy resistance.

Therapeutic natural compounds Enzastaurin and Palbociclib inhibit MASTL kinase activity preventing breast cancer cell proliferation

Microtubule-associated serine/threonine kinase-like (MASTL) regulates mitotic progression and is an attractive target for the development of new anticancer drugs. In this study, novel inhibitory molecules were screened against MASTL kinase, a protein involved in cell proliferation in breast cancer. Natural source-derived drugs Enzastaurin and Palbociclib were selected to identify their role as MASTL kinase inhibitors. Cytotoxic activity, kinase activity, and other cell-based assays of Enzastaurin and Palbociclib were evaluated on human breast cancer (MCF-7) cells. The potential natural compounds caused cytotoxicity in MCF-7 cells in a dose- and time-dependent manner. Further analysis by Annexin V and PI staining indicated that both drugs are potent inducers of apoptosis. Enzastaurin induced G2/M phase arrest, while Palbociclib caused G1 arrest. MASTL kinase activity was significantly abrogated with both the compounds showing EC₅₀ values of 17.13 µM and 10.51 µM, respectively. Taken together, these data strongly suggest that Enzastaurin and Palbociclib possess the ability to inhibit MASTL kinase activity and induce cell death in breast cancer cells, thus exhibiting significant therapeutic potential.