Targeting KRAS for the potential treatment of pancreatic ductal adenocarcinoma: Recent advancements provide hope (Review)

KRAS-mediated upregulation of CIP2A promotes suppression of PP2A-B56α to initiate pancreatic cancer development

Oncogenic mutations in KRAS are present in ~95% of patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) and are considered the initiating event of pancreatic intraepithelial neoplasia (PanIN) precursor lesions. While it is well established that KRAS mutations drive the activation of oncogenic kinase cascades during pancreatic oncogenesis, the effects of oncogenic KRAS signaling on regulation of phosphatases during this process is not fully appreciated. Protein Phosphatase 2A (PP2A) has been implicated in suppressing KRAS-driven cellular transformation and low PP2A activity is observed in PDAC cells compared to non-transformed cells, suggesting that suppression of PP2A activity is an important step in the overall development of PDAC. In the current study, we demonstrate that KRASG12D induces the expression of an endogenous inhibitor of PP2A activity, Cancerous Inhibitor of PP2A (CIP2A), and phosphorylation of the PP2A substrate, c-MYC. Consistent with these findings, KRASG12D sequestered the specific PP2A subunit responsible for c-MYC degradation, B56α, away from the active PP2A holoenzyme in a CIP2A-dependent manner. During PDAC initiation in vivo, knockout of B56α promoted KRASG12D tumorigenesis by accelerating acinar-to-ductal metaplasia (ADM) and the formation of PanIN lesions. The process of ADM was attenuated ex vivo in response to pharmacological re-activation of PP2A utilizing direct small molecule activators of PP2A (SMAPs). Together, our results suggest that suppression of PP2A-B56α through KRAS signaling can promote the MYC-driven initiation of pancreatic tumorigenesis.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

Belamcanda chinensis extract inhibits non-small cell lung cancer proliferation and induces apoptosis via inhibiting the MAPK (Ras/Raf) and Akt pathways

Non-small cell lung cancer (NSCLC) is associated with high mortality and morbidity rates. Despite major progress of treatment of NSCLC over the past few decades, the prognosis of advanced NSCLC is poor, with 5-year survival rates ranging from 2 % to 13 %. Belamcanda chinensis is a traditional Chinese medicine used to promote blood circulation, reduce swelling, heal ulcers, disperse lumps and tumors, and resolve blood stasis. In the present study, the anti-proliferative and pro-apoptotic effects and potential mechanisms of action of Belamcanda chinensis extract (BCE) in SPC-A1 and NCI-H460 NSCLC cells were investigated using MTS, flow cytometry, and western blotting. Also, xenograft model in vivo was established to investigate the anti-NSCLC effects of BCE. The compounds in BCE were quantified using gas chromatography-mass spectrometry (GC-MS). Twenty compounds were found in BCE, and BCE induced cell cycle arrest significantly inhibited the proliferation of NSCLC. Furthermore, BCE was found to induce Cyto C release and the activation of Caspase-3, -8, -9, PARP, ultimately inducing apoptosis in NSCLC cells through both exogenous and endogenous apoptotic pathways (the mitochondrial pathway). BCE also blocked the MAPK (Ras/Raf) and Akt signaling pathways, significantly downregulating the expression of Ras, Raf, Erk1/2, p-Erk1/2, Akt, and p-Akt proteins. Furthermore, BCE significantly inhibited the growth of NSCLC cells SPC-A1 in nude mice and downregulated Ras, Raf, Akt, and p-Akt expression in vivo. The antitumor effects of BCE suggest its potential clinical application in patients with NSCLC, especially in those bearing Ras or Raf mutations.

KRAS-mediated upregulation of CIP2A promotes suppression of PP2A-B56α to initiate pancreatic cancer development

Oncogenic mutations in KRAS are present in approximately 95% of patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) and are considered the initiating event of pancreatic intraepithelial neoplasia (PanIN) precursor lesions. While it is well established that KRAS mutations drive the activation of oncogenic kinase cascades during pancreatic oncogenesis, the effects of oncogenic KRAS signaling on regulation of phosphatases during this process is not fully appreciated. Protein Phosphatase 2A (PP2A) has been implicated in suppressing KRAS-driven cellular transformation. However, low PP2A activity is observed in PDAC cells compared to non-transformed cells, suggesting that suppression of PP2A activity is an important step in the overall development of PDAC. In the current study, we demonstrate that KRASG12D induces the expression of both an endogenous inhibitor of PP2A activity, Cancerous Inhibitor of PP2A (CIP2A), and the PP2A substrate, c-MYC. Consistent with these findings, KRASG12D sequestered the specific PP2A subunit responsible for c-MYC degradation, B56α, away from the active PP2A holoenzyme in a CIP2A-dependent manner. During PDAC initiation in vivo, knockout of B56α promoted KRASG12D tumorigenesis by accelerating acinar-to-ductal metaplasia (ADM) and the formation of PanIN lesions. The process of ADM was attenuated ex vivo in response to pharmacological re-activation of PP2A utilizing direct small molecule activators of PP2A (SMAPs). Together, our results suggest that suppression of PP2A-B56α through KRAS signaling can promote the MYC-driven initiation of pancreatic tumorigenesis.

Inhibition of the RAF/MEK/ERK Signaling Cascade in Pancreatic Cancer: Recent Advances and Future Perspectives

Pancreatic cancer represents a formidable challenge in oncology, primarily due to its aggressive nature and limited therapeutic options. The prognosis of patients with pancreatic ductal adenocarcinoma (PDAC), the main form of pancreatic cancer, remains disappointingly poor with a 5-year overall survival of only 5%. Almost 95% of PDAC patients harbor Kirsten rat sarcoma virus (KRAS) oncogenic mutations. KRAS activates downstream intracellular pathways, most notably the rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling axis. Dysregulation of the RAF/MEK/ERK pathway is a crucial feature of pancreatic cancer and therefore its main components, RAF, MEK and ERK kinases, have been targeted pharmacologically, largely by small-molecule inhibitors. The recent advances in the development of inhibitors not only directly targeting the RAF/MEK/ERK pathway but also indirectly through inhibition of its regulators, such as Src homology-containing protein tyrosine phosphatase 2 (SHP2) and Son of sevenless homolog 1 (SOS1), provide new therapeutic opportunities. Moreover, the discovery of allele-specific small-molecule inhibitors against mutant KRAS variants has brought excitement for successful innovations in the battle against pancreatic cancer. Herein, we review the recent advances in targeted therapy and combinatorial strategies with focus on the current preclinical and clinical approaches, providing critical insight, underscoring the potential of these efforts and supporting their promise to improve the lives of patients with PDAC.

Targeted Combination Therapies: A New Frontier in the Treatment of TP53 and KRAS Mutation-Associated Cancers

This Patent Highlight discusses novel therapeutic strategies for treating cancers associated with TP53 or KRAS mutations, particularly colorectal, pancreatic, and non-small-cell lung cancers. It focuses on the use of combination therapies involving two distinct compounds and a KRAS inhibitor. Researchers are exploring the effectiveness of these combined therapies in patient treatment and investigating their potential applications in drug manufacturing. With cancer being a global health challenge, these innovative strategies could present a breakthrough in enhancing survival rates and improving the quality of life for patients.